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  • Resonant ultrasound spectroscopy: The essential toolbox
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-12-17
    Fedor F. Balakirev, Susan M. Ennaceur, Robert J. Migliori, Boris Maiorov, Albert Migliori

    Resonant Ultrasound Spectroscopy (RUS) is an ultrasound-based minimal-effort high-accuracy elastic modulus measurement technique. RUS as described here uses the mechanical resonances (normal modes of vibration or just modes) of rectangular parallelepiped or cylindrical specimens with a dimension of from a fraction of a millimeter to as large as will fit into the apparatus. Provided here is all that is needed so that the reader can construct and use a state-of-the-art RUS system. Included are links to open-source circuit diagrams, links to download Los Alamos National Laboratory open-source data acquisition software, links to request free analysis software, procedures for acquiring measurements, considerations on building transducers, 3-D printed stage designs, and a full mathematical explanation of how the analysis software extracts elastic moduli from resonances.

    更新日期:2019-12-31
  • Dual beam modulated magneto-optical measurement setup
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-12-04
    Shankar Acharya, Brian Collier, Wilhelmus Geerts

    A dual beam magneto-optical setup employing a dual axis photoelastic modulator (PEM) and an intensity-stabilized laser was designed and constructed. The beam transmitted through or reflected of the sample is split by a Wollaston prism into two orthogonal high-quality linearly polarized beams. Two photodetectors are used to measure the DC and 2ω components of each beam’s intensity. Theoretical calculations using Jones matrices show that the difference between the 2ω signals, i.e., ΔI2ω, is linearly proportional to the Kerr or Faraday rotation of the sample. Different from I2ω of a traditional single beam setup, the ΔI2ω does not contain an offset caused by the Fabry Perot interference in the PEM’s optical head, making the setup less sensitive for small sample movements and laser drifts including intensity, wavelength, and beam direction drifts all originating from mainly temperature fluctuations in the lab.

    更新日期:2019-12-31
  • Development of an interference-filter-type external-cavity diode laser for resonance ionization spectroscopy of strontium
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-12-09
    Yoshihiro Iwata, Donguk Cheon, Masabumi Miyabe, Shuichi Hasegawa

    A frequency tunable external-cavity diode laser (ECDL) using a narrow bandwidth (∼0.3 nm) interference filter has been developed for resonance ionization spectroscopy of strontium (Sr) with high isotopic selectivity. Improved wavelength and single mode stabilities of this interference-filter-type ECDL (IF-ECDL) over a commonly used (also home-made) Littrow-type ECDL were theoretically expected and experimentally confirmed by both a wavelength meter and a home-made Fabry-Perot interferometer. The measured spectral profile of the dominant isotope 88Sr using our IF-ECDL in the 689.4 nm intercombination transition shows that the Lorentzian component (∼1.3 MHz) of the spectrum width is consistent with the obtained fringe width of the interferometer. High 90Sr isotopic selectivity of ∼104 with respect to 88Sr is expected in this transition, which indicates that even if the manufacturing accuracy is not comparable to commercial Littrow-type ECDLs, our compact IF-ECDL having sufficient wavelength stability is a promising laser source for background-free analysis of radioactive 90Sr in marine samples.

    更新日期:2019-12-31
  • Multicolor femtosecond pump-probe system with single-electron sensitivity at low temperatures and high magnetic fields
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-12-19
    C. Traum, P. Henzler, S. Lohner, H. Becker, D. Nabben, P. Gumbsheimer, C. Hinz, J. F. Lippmann, S. Mahapatra, K. Brunner, D. V. Seletskiy, A. Leitenstorfer

    We present an ultrafast spectroscopy system designed for temporal and spectral resolution of transient transmission changes after excitation of single electrons in solid-state quantum structures. The system is designed for optimum long-term stability, offering the option of hands-off operation over several days. Pump and probe pulses are generated in a versatile Er:fiber laser system where visible photon energies may be tuned independently from 1.90 eV to 2.51 eV in three parallel branches. Bandwidth-limited pulse durations between 100 fs and 10 ps are available. The solid-state quantum systems under investigation are mounted in a closed-cycle superconducting magnet cryostat providing temperatures down to 1.6 K and magnetic fields of up to 9 T. The free-standing cryomagnet is coupled to the laser system by means of a high-bandwidth active beam steering unit to eliminate residual low-frequency mechanical vibrations of the pulse tube coolers. High-NA objective lenses inside the sample chamber are employed for focusing femtosecond laser pulses onto the sample and recollection of the transmission signal. The transmitted probe light is dispersed in a grating monochromator equipped with a liquid nitrogen-cooled CCD camera, enabling a frame rate of 559 Hz. In order to eliminate spurious background effects due to low-frequency changes in the thermal equilibrium of the sample, we operate with a lock-in scheme where, instead of the pump amplitude, the pump-probe timing is modulated. This feature is provided without any mechanical action by an electro-optic timing unit inside the femtosecond Er:fiber system. The performance of the instrument is tested with spectrally resolved pump-probe measurements on a single negatively charged CdSe/ZnSe quantum dot under a magnetic field of 9 T. Selective initialization and readout of charge and spin states is carried out via two different femtosecond laser pulses. High-quality results on subpicosecond intraband relaxation dynamics after single-electron excitation motivate a broad variety of future experiments in ultrafast quantum optics and few-fermion quantum dynamics.

    更新日期:2019-12-31
  • Polarization Stark spectroscopy for spatially resolved measurements of electric fields in the sheaths of ICRF antenna
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-12-03
    A. Kostic, K. Crombé, R. Dux, M. Griener, R. Ochoukov, I. Shesterikov, G. Suárez López, M. Usoltceva, R. Casagrande, E. H. Martin, J.-M. Noterdaeme

    A multichannel spectroscopic diagnostic based on the Stark effect on helium lines was developed and implemented in IShTAR (Ion Cyclotron Sheath Test ARrangement) to measure the spatial distribution of electric fields across the radio frequency sheaths of the ion cyclotron antenna. Direct measurements of the DC electric fields in the antenna sheaths are an important missing component in understanding the antenna-plasma edge interactions in magnetically confined fusion plasmas since they will be used to benchmark theoretical models against real antenna operation. Along with the high-resolution Czerny-Turner monochromator and a detector with an intensifier, the hardware relies on the 2 chained set of linear-to-linear fiber bundles that provide seven optical channels capable of resolving an 8.4 mm region in the vicinity of the antenna’s box. The diagnostic is supported with local helium gas puff, enabling it to operate in nonhelium plasmas. Spatially resolved electric field was measured for two discharge configurations, one with and one without the ICRF antenna. The results show a clear difference in the shape of the DC electric field’s spatial profile for the two cases studied, with the elevated values when the ICRF antenna was operating. This demonstrates the ability of the diagnostic to measure even small relative changes in the intensity of the electric field.

    更新日期:2019-12-31
  • Deducing rotational quantum-state distributions from overlapping molecular spectra
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-12-03
    Jan Voráč, Lukáš Kusýn, Petr Synek

    A novel method for fast and robust calculation of Boltzmann plots from molecular spectra is presented. Its use is demonstrated on the OH(A-X) spectrum near 310 nm. A limitation of the method is identified: for overlapping spectra of the OH(A-X) and N2(C-B, Δv = 1) band sequence, the calculation may often fail due to insufficient number of measured points. This is solved by introducing experimentally determined bounds for the N2(C) rotational distribution. Three cases are presented: (i) with undisturbed OH(A-X) emission, (ii) with strong emission of N2(C-B) in the said spectral range, and (iii) with weak but not negligible nitrogen emission. In case (ii), the data in the spectral range 306–320 nm are sufficient for the analysis. In case (iii), information from another spectral range with undisturbed N2(C-B) emission is necessary. These illustrate all relevant cases often encountered in laboratory plasmas. The calculated Boltzmann plots are not further analyzed in this article but can be used for development and validation of kinetic models with rotational resolution. The implementation of the reported method using the massiveOES software package written in the Python language is available in the supplementary material.

    更新日期:2019-12-31
  • Highly versatile laboratory X-ray scattering instrument enabling (nano-)material structure analysis on multiple length scales by covering a scattering vector range of almost five decades
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-12-04
    Joerg Bolze, Milen Gateshki

    A compact laboratory X-ray scattering platform that uniquely enables for high-performance ultra-small-angle X-ray scattering (USAXS), small- and wide-angle X-ray scattering (SAXS/WAXS), and total scattering (atomic pair distribution function analysis; PDF) experiments was developed. It covers Bragg spacings from sub-Angstroms to 1.7 μm, thus allowing the analysis of dimensions and complex structures in (nano-)materials on multiple length scales. The accessible scattering vector q-range spans over almost five decades (qmin = 0.0036 nm−1, qmax = 215 nm−1), without any gaps. Whereas SAXS is suitable to characterize materials on a length scale of 1–100 nm, with USAXS, this range can be significantly extended to the micrometer range. On the other end, from WAXS and particularly from PDF measurements, information about the local atomic order and disorder can be obtained. The high performance, exceptional versatility, and ease-of-use of the instrument are enabled by a high-resolution 2-circle goniometer with kinematic mounts, a modular concept based on prealigned, quickly interchangeable X-ray components, and advanced detector technology. For USAXS measurements, a modified Bonse-Hart experimental setup with single crystal collimator and analyzer optics is used. SAXS/WAXS measurements are enabled by focusing optics, an evacuated beam path, and a 2D detector. For total scattering experiments, a high-energy X-ray source is used in combination with a hybrid pixel array detector that is based on a CdTe sensor for the highest counting efficiency. To ensure high resolution and sensitivity in these various applications, special care is taken to suppress any type of background scattering signal. The high resolution that can be achieved with the USAXS collimation system is demonstrated on a set of monodisperse, colloidal silica dispersions and derived colloidal crystals, with particle diameters in the range of hundreds of nanometers up to 1.6 µm. USAXS and SAXS results are shown to be consistent with those obtained by static light scattering (SLS) and dynamic light scattering. It is demonstrated that the obtainable USAXS data bridge the gap in q between SAXS and SLS. The capabilities of the instrument to acquire high-quality total scattering data for PDF analysis are demonstrated on amorphous SiO2 nanoparticles as well as on NaYF4 upconversion nanocrystals. To the best of our knowledge, it is for the first time that we present a single laboratory instrument that enables measurements of high-quality X-ray scattering data within such a wide q-range, by combining four complementary elastic X-ray scattering techniques. The modular design concept of the instrument allows for incremental improvements as well as to add more applications in the future.

    更新日期:2019-12-31
  • Radio frequency filter for an enhanced resolution of inelastic electron tunneling spectroscopy in a combined scanning tunneling- and atomic force microscope
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-12-04
    Angelo Peronio, Norio Okabayashi, Florian Griesbeck, Franz Giessibl

    The combination of inelastic electron tunneling spectroscopy (IETS), also used for IET spectrum based on scanning tunneling microscopy with atomic force microscopy (AFM) enables us to measure the vibrational energies of a single molecule along with the force exerted by the tip of a microscope, which deepens our understanding on the interaction between the tip and the molecule on a surface. The resolution of IETS is a crucial factor in determining the vibrational energies of a molecule. However, radio frequency (RF) noise from the environment significantly deteriorates the resolution. We introduce an RF noise filtering technique, which enables high resolution IETS while maintaining uncompromised AFM performance, demonstrated by vibrational measurements of a CO molecule on a copper surface.

    更新日期:2019-12-31
  • A multi-spot laser induced breakdown spectroscopy system based on diffraction beam splitter
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-12-06
    Yu Zhu, Ping-Wei Zhou, Seng-Cheng Zhong, Qi-Xian Peng, Li-Guo Zhu

    A quick simultaneous multispot laser induced breakdown spectroscopy (LIBS) system has been proposed. The basic idea is to combine the Diffraction Beam Splitter (DBS) with the linear-to-linear fiber bundle. The DBS divided the incident laser beam into five sub-beams, and then, a lens focused the incident sub-beam to produce a plasma array, where the distance between the neighbor subplasma was constant and the plasma emission was imaged on the fiber bundle. Each ablated spot on the sample generated the corresponding spectroscopy signals, which were collected by the defined fibers of the fiber bundle, propagated to the spectrograph slit, and then analyzed by the intensified charge-coupled device (ICCD) detector, where the two-dimensional capability of the charge-coupled device detectors was explored for the spectroscopy and position analyses. The five spectroscopy ribbon presented on the ICCD corresponded to the plasma radiation of the five ablated spots. The feasibility of a simultaneous multipoint spectroscopy detection at a single pulse ablation was confirmed by subjecting to the spectroscopy analyses of a copper plane, layered material, and magnesium-molybdenum mixture. The multispot LIBS system can be used in the ejecta research of detonation physics, fluid physics, and so on.

    更新日期:2019-12-31
  • Time-resolved thermally induced aberrations in a flash-lamp pumped Nd:Glass disk amplifier using a 2 × 2 position sensitive detector array
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-12-06
    M. Ahmad, M. Galletti, P. Oliveira, E. Dilworth, D. J. Robinson, M. Galimberti, A. J. Crawford, I. Musgrave, M. J. D. Esser

    A novel technique of measuring the prompt, thermally induced wave-front aberrations in a large aperture flash-lamp pumped Nd3+ glass disk amplifier is presented. Implementing a 2 × 2 lens array and a 2 × 2 position sensitive detector array as a diagnostic system, the wave-front profile was successfully reconstructed for the first five Zernike terms for a temporal window of 8.5 ms.

    更新日期:2019-12-31
  • A transition-edge sensor-based x-ray spectrometer for the study of highly charged ions at the National Institute of Standards and Technology electron beam ion trap
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-12-16
    P. Szypryt, G. C. O’Neil, E. Takacs, J. N. Tan, S. W. Buechele, A. S. Naing, D. A. Bennett, W. B. Doriese, M. Durkin, J. W. Fowler, J. D. Gard, G. C. Hilton, K. M. Morgan, C. D. Reintsema, D. R. Schmidt, D. S. Swetz, J. N. Ullom, Yu. Ralchenko

    We report on the design, commissioning, and initial measurements of a Transition-Edge Sensor (TES) x-ray spectrometer for the Electron Beam Ion Trap (EBIT) at the National Institute of Standards and Technology (NIST). Over the past few decades, the NIST EBIT has produced numerous studies of highly charged ions in diverse fields such as atomic physics, plasma spectroscopy, and laboratory astrophysics. The newly commissioned NIST EBIT TES Spectrometer (NETS) improves the measurement capabilities of the EBIT through a combination of high x-ray collection efficiency and resolving power. NETS utilizes 192 individual TES x-ray microcalorimeters (166/192 yield) to improve upon the collection area by a factor of ∼30 over the 4-pixel neutron transmutation doped germanium-based microcalorimeter spectrometer previously used at the NIST EBIT. The NETS microcalorimeters are optimized for the x-ray energies from roughly 500 eV to 8000 eV and achieve an energy resolution of 3.7 eV–5.0 eV over this range, a more modest (<2×) improvement over the previous microcalorimeters. Beyond this energy range, NETS can operate with various trade-offs, the most significant of which are reduced efficiency at lower energies and being limited to a subset of the pixels at higher energies. As an initial demonstration of the capabilities of NETS, we measured transitions in He-like and H-like O, Ne, and Ar as well as Ni-like W. We detail the energy calibration and data analysis techniques used to transform detector counts into x-ray spectra, a process that will be the basis for analyzing future data.

    更新日期:2019-12-31
  • Optical spectroscopy as a diagnostic tool for metal ion beam production with an ECRIS
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-12-18
    F. Maimone, J. Mäder, R. Lang, P. T. Patchakui, K. Tinschert, R. Hollinger

    At GSI, the CAPRICE ECRIS is used to provide heavy ion beams to the UNILAC (Universal Linear Accelerator) accelerator. In order to satisfy the demand of metal ion beams, a resistively heated oven is routinely used. This evaporation technique allows the ion beam production from natural and enriched solid elements or compounds with high efficiency and low material consumption. Often it is required to provide high charge state ion beams from rare or extremely rare isotopes as 48Ca, e.g., for the investigation of super heavy elements. In order to maintain the ion beam stable for the entire scheduled beam time, the plasma inside the ion source must remain as stable as possible. The tuning of ion source parameters and oven power affecting the oven temperature and, in turn, the evaporation rate is necessary. A strong relationship between the microwave power and the oven heating was observed, thus affecting the power control, the plasma stability, and the material consumption. Hence, it was investigated how an optical spectrometer can be used as a predictive diagnostic tool to detect ion source instabilities. Furthermore, the effect of parasitic oven heating by coupling of microwaves was investigated. Optical emission spectroscopy was performed by analyzing the light from the plasma and from the oven through the extraction aperture. The measurements enabled us to distinguish between resistive heating and microwave heating. The results of this investigation are presented.

    更新日期:2019-12-31
  • Gigahertz-repetition-rate, narrowband-deep-ultraviolet light source for minimization of acquisition time in high-resolution angle-resolved photoemission spectroscopy
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-12-18
    K. Yoshioka, J. Omachi, M. Sakano, T. Shimojima, K. Ishizaka, M. Kuwata-Gonokami

    Ultrahigh-repetition-rate (1.1 GHz), deep-ultraviolet coherent light at 208.8 nm is generated by applying an external Fabry–Pérot cavity for repetition-rate multiplication to the fourth harmonics of a 10-ps, mode-locked Ti:sapphire laser. Its small pulse energy minimizes the unwanted space charge effect, while its high repetition rate drastically reduces the acquisition time in high-energy resolution angle-resolved photoemission spectroscopy using hemispherical electron analyzers. The absence of the space charge effect in the photoemission spectrum near the Fermi edge of polycrystalline Au at 8 K demonstrates this idea.

    更新日期:2019-12-31
  • Correction of the VIR-visible data set from the Dawn mission
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-12-19
    B. Rousseau, A. Raponi, M. Ciarniello, E. Ammannito, F. G. Carrozzo, M. C. De Sanctis, S. Fonte, A. Frigeri, F. Tosi

    Data acquired at Ceres by the visible channel of the Visible and InfraRed mapping spectrometer (VIR) on board the NASA Dawn spacecraft are affected by the temperatures of both the visible (VIS) and the infrared (IR) sensors, which are, respectively, a charged coupled device and a HgCdTe array. The variations of the visible channel temperatures measured during the sessions of acquisitions are correlated with the variations in the spectral slope and shape for all the mission phases. The IR channel temperature is more stable during the acquisitions; nonetheless, it is characterized by a bimodal distribution whether the cryocooler (and, therefore, the IR channel) is used or not during the visible channel operations. When the infrared channel temperature is high (175 K, i.e., not in use and with the cryocooler off), an additional negative slope and a distortion are observed in the spectra of the visible channel. We developed an empirical correction based on a reference spectrum for the whole dataset; it is designed to correct the two issues related to the sensor temperatures that we have identified. The reference spectrum is calculated to be representative of the global Ceres’ surface. It is also made of the data acquired when the visible and infrared channel temperatures are equal to the ones measured during an observation of the Arcturus star by VIR, which is consistent with several ground-based observations. The developed correction allows reliable analysis and mapping to be performed by minimizing the artifacts induced by fluctuations of the VIS temperature. Thanks to this correction, a direct comparison between different mission phases during which the VIR experienced different visible and infrared channel temperatures is now possible.

    更新日期:2019-12-31
  • Apparatus for electrically detected electron nuclear double resonance in solid state electronic devices
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-12-23
    Brian R. Manning, Ryan J. Waskiewicz, Duane J. McCrory, Patrick M. Lenahan

    We have developed a sensitive electron nuclear double resonance spectrometer in which the detection takes place through electrically detected magnetic resonance. We demonstrate that the spectrometer can provide reasonably high signal to noise spectra of 14N interactions with deep level centers in a fully processed bipolar junction transistor at room temperature.

    更新日期:2019-12-31
  • Production of highly charged ions of rare species by laser-induced desorption inside an electron beam ion trap
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-12-06
    Ch. Schweiger, C. M. König, J. R. Crespo López-Urrutia, M. Door, H. Dorrer, Ch. E. Düllmann, S. Eliseev, P. Filianin, W. Huang, K. Kromer, P. Micke, M. Müller, D. Renisch, A. Rischka, R. X. Schüssler, K. Blaum

    This paper reports on the development and testing of a novel, highly efficient technique for the injection of very rare species into electron beam ion traps (EBITs) for the production of highly charged ions (HCI). It relies on in-trap laser-induced desorption of atoms from a sample brought very close to the electron beam resulting in a very high capture efficiency in the EBIT. We have demonstrated a steady production of HCI of the stable isotope 165Ho from samples of only 1012 atoms (∼300 pg) in charge states up to 45+. HCI of these species can be subsequently extracted for use in other experiments or stored in the trapping volume of the EBIT for spectroscopic measurements. The high efficiency of this technique extends the range of rare isotope HCIs available for high-precision atomic mass and spectroscopic measurements. A first application of this technique is the production of HCI of the synthetic radioisotope 163Ho for a high-precision measurement of the QEC-value of the electron capture in 163Ho within the “Electron Capture in Holmium” experiment [L. Gastaldo et al., J. Low Temp. Phys. 176, 876–884 (2014); L. Gastaldo et al., Eur. Phys. J.: Spec. Top. 226, 1623–1694 (2017)] (ECHo collaboration) ultimately leading to a measurement of the electron neutrino mass with an uncertainty on the sub electronvolt level.

    更新日期:2019-12-31
  • Development of a new high temperature oven for the production of intense metal ion beams with ECR ion sources
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-12-03
    W. Huang, D. Z. Xie, L. T. Sun

    High Temperature Ovens (HTOs) have widely been used to evaporate refractory materials in electron cyclotron resonance ion sources to produce hundreds of microamperes of multiply and highly charged metal ion beams. To meet the demands of milliamperes of multiply charged uranium and other heavy metal ion beams for future accelerators, a new and low-cost HTO is under development at Lawrence Berkeley National Laboratory for better long-term stability at high evaporation rates. ANSYS simulations have been carried out to optimize the new HTO with low heating current to reduce the electromagnetic forces as an HTO is immersed in the strong ECRIS magnetic fields. A larger loading volume is employed to deal with higher material consumption. Off-line tests have shown that the unloaded new HTO operates stably up to 1800–1900 °C with low temperature gradients and good repeatability. This paper presents and discusses the conceptual design features of the new HTO and off-line tests.

    更新日期:2019-12-31
  • Tomography reconstruction of beams extracted from an ion source
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-12-03
    S. Saminathan, F. Ames, R. Baartman, M. Marchetto, O. Lailey, A. Mahon

    Commissioning of the CANREB (CANadian Rare isotope facility with Electron Beam ion source) system and its associated beamlines has recently begun at TRIUMF. At the head of this beamline is an ion source used to produce stable alkaline ions with energy up to 60 keV for the CANREB system. Throughout commissioning, it is essential to have a means of verifying beam quality and ensuring that the required beam parameters along the beamline are met. This is accomplished using tomography reconstruction, which consists of taking one-dimensional scans at different projections and reconstructing an image of the beam in two dimensions using the maximum entropy algorithm. Tomography enables the visualization of the shape of the beam as well as the investigation into the possible presence of aberrations. Initially, tomography reconstruction is performed by using simulated beam profiles at the measurement locations and is then performed by using measured beam profiles. Additionally, these measurements are benchmarked by fitting the initial beam parameters in our beam optics model, and the results are presented.

    更新日期:2019-12-31
  • The biased disc of an electron cyclotron resonance ion source as a probe of instability-induced electron and ion losses
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-12-04
    O. Tarvainen, R. Kronholm, T. Kalvas, H. Koivisto, I. Izotov, V. Skalyga, V. Toivanen, L. Maunoury

    Electron Cyclotron Resonance Ion Source (ECRIS) plasmas are prone to kinetic instabilities resulting in loss of electron and ion confinement. It is demonstrated that the biased disk of an ECRIS can be used as a probe to quantify such instability-induced electron and ion losses occurring in less than 10 µs. The qualitative interpretation of the data is supported by the measurement of the energy spread of the extracted ion beams implying a transient plasma potential >1.5 kV during the instability. A parametric study of the electron losses combined with electron tracking simulations allows for estimating the fraction of electrons expelled in each instability event to be on the order of 10% of the total electron population.

    更新日期:2019-12-31
  • Fabrication of porous emitters for ionic liquid ion source by wire electrical discharge machining combined with electrochemical etching
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-12-06
    Xinyu Liu, Weiguo He, Xiaoming Kang, Mingming Xu

    Ionic liquid ion source (ILIS) is a promising ion source, which can be applied to space propulsion, microfabrication, and surface modification. Fabrication of high-quality ILIS emitters is one of the key technologies for the application of ILIS. A new method is proposed for the fabrication of porous emitters with a designed shape. This method uses wire electrical discharge machining (WEDM) combined with electrochemical etching, and the porous emitter is fabricated by two steps. First, the porous metal is machined by WEDM to get the external geometry of the emitter. Then, electrochemical etching is employed to remove the recast layer. A series of experiments has been conducted to find the appropriate machining parameters. Experiments reveal that sharp porous emitter tips for the ILIS can be fabricated by WEDM combined with electrochemical etching at 5 V etching voltage. Moreover, the apex curvature radius of the emitter is controllable by adjusting the etching time. It is found that the apex curvature radius varies from 4.5 μm to 18.4 μm when increasing etching time from 40 s to 120 s at 5 V etching voltage. Those emitters have been applied to ILIS tests, and their I-V characteristics are investigated. Furthermore, this method has been used to machine dense fields of emitters. A 1 cm2 emitter array chip integrated with 676 emitters has been successfully machined, and the I-V characteristic curve of the emitter array chip is also achieved.

    更新日期:2019-12-31
  • Possibility of generating H+, or H2+, or H3+dominated ion beams with a 2.45 GHz permanent magnet ECR ion source
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-12-10
    Shixiang Peng, Wenbin Wu, Haitao Ren, Jingfeng Zhang, Yuan Xu, Ailin Zhang, Tao Zhang, Tenghao Ma, Yaoxiang Jiang, Jiang Sun, Jiamei Wen, Zhiyu Guo, Jiaer Chen

    At Peking University (PKU), experimental research as well as theoretical study on how to produce high intense H+, H2+, or H3+ dominated ion beams with a compact permanent magnet 2.45 GHz electron cyclotron resonance (PMECR) ion source have been continuously carried out in the past few decades. Based on the comprehension of hydrogen plasma processes inside a 2.45 GHz PMECR discharge chamber, a three-phase diagram of ion fraction dominant regions that illustrates the relationship between the H+, H2+, and H3+ ion species and working parameters was presented. Meanwhile, a numerical model based on the particle population balance equations was developed for quantitative comprehension of electron cyclotron heated hydrogen plasma. Calculated results of H+, H2+, and H3+ fractions against gas pressure, microwave density, and wall material obtained with this numerical model agree well with the measured ones. Recently, a miniaturized ECR ion source has been developed, and a 52 mA hydrogen beam was extracted. Under the guidance of the model, H+, H2+, and H3+ beams with a fraction of 88%, 80%, and 82%, respectively, were obtained with this miniaturized ECR ion source under suitable working parameters. A PMECR ion source for a proton therapy facility has been built at PKU recently. A 34 mA beam H+ fraction of 91% was obtained at the first attempt.

    更新日期:2019-12-31
  • Ion charge state and energy distributions of laser produced plasma from pure metals and their alloy
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-12-12
    J. J. Zhang, H. Y. Zhao, G. C. Wang, L. T. Sun, X. Z. Zhang, G. P. Li, H. W. Zhao

    A high intensity highly charged laser ion source has been studied at the Institute of Modern Physics for the last few years. In order to investigate the processes of plasma heating and expansion of laser produced plasma, the charge state and energy distributions of the ions from pure copper, silver, and copper-silver alloy, in which the atom number ratio between copper and silver is 2:3, were measured with a 90° cylindrical electrostatic ion analyzer. It was shown that the yields of highly charged copper ions from the pure copper target are higher compared with those of the alloy target. In contrast, higher yields of highly charged silver ions were obtained from the copper-silver alloy target. Moreover, the ion energy distributions were derived from the time-of-flight spectra for the ions with different ion charge states and compared between the pure metal and alloy targets.

    更新日期:2019-12-31
  • Compact water-cooled surface wave plasma source for remote plasma cleaning
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-12-12
    Hyun Jong You, Oleksii Girka

    This paper describes the design and operation of a compact surface wave plasma source for remote plasma processing [i.e., plasma enhanced chemical vapor deposition chamber cleaning, dry etching (SiO2, Si3N4, and silicon), photoresist stripping (SU-8), and decapsulation of microchips]. In order to get higher radical generation and increased industrial throughput, the source is designed to generate plasma at a high flowrate. The source is designed to be compact so that it can be more beneficial in the case of positioning multiple sources on a large processing chamber for faster radical cleaning with better uniformity. The source can operate from low to high flowrates (i.e., 100 SCCM H2 or 10 slm NF3) and provide high decomposition rates for NF3. The etching rate for SiO2 (higher than 450 nm/min) is achieved with 2.5 kW microwave power and 3–5 slm. The key advantages of the source are compactness, higher microwave coupling due to indirect water-cooling, and thereby high operating flow and decomposition rates.

    更新日期:2019-12-31
  • Status of the gasdynamic ion source for multipurpose operation (GISMO) development at IAP RAS
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-12-13
    V. A. Skalyga, A. F. Bokhanov, S. V. Golubev, I. V. Izotov, M. Yu. Kazakov, E. M. Kiseleva, R. L. Lapin, S. V. Razin, R. A. Shaposhnikov, S. S. Vybin

    A new experimental facility named GISMO (Gasdynamic Ion Source for Multipurpose Operation) was constructed at the IAP RAS to continue investigations in the field of gasdynamic ion sources. The source utilizes 28 GHz/10 kW gyrotron radiation for heating magnetically confined plasma. Magnetic field configuration provided by a fully permanent magnet system is much like a simple mirror trap. The GISMO source is aimed at the production of bright ion beams with hundreds of milliamperes current. The facility has been tested for continuous-wave (CW) operation with 2 kW of heating power to check durability of a microwave injection system and the plasma chamber. A 2-electrode extraction system with an integrated Einzel lens was designed for a formation of CW high current beam with up to 100 kV accelerating voltage. The first results on ion beam production at GISMO are presented together with the general progress status of the facility.

    更新日期:2019-12-31
  • Status of high intensity proton injector for Facility for Antiproton and Ion Research
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-12-18
    Rustam Berezov, Olivier Delferriere, Jerome Fils, Yannick Gauthier, Ralph Hollinger, Klaus Knie, Carl Kleffner, Olivier Tuske

    The high intensity proton injector for the international accelerator Facility for Antiproton and Ion Research located at GSI-Darmstadt in Germany consists of a pulsed 2.45 GHz microwave ion source, a Low Energy Beam Transport (LEBT), and an electrostatic chopper matching the proton beam to the radio frequency quadrupole. The ion source is based on electron cyclotron resonance plasma production and it has to provide a proton beam at 95 keV energy and up to 100 mA current. The LEBT system with two short solenoids each including two magnetic steerers will transport the proton beam into the compact proton linac, accelerating it to the energy of 68 MeV and serving as the injector of the upgraded heavy ion synchrotron (SIS18). This paper describes the commissioning of the proton injector including beam characterization measurements that have been done at CEA/Saclay in France and is currently at the final commissioning stage.

    更新日期:2019-12-31
  • Characteristics of miniature pulsed penning ion source: Experiment and PIC simulation
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-12-20
    N. V. Mamedov, A. S. Rohmanenkov, V. I. Zverev, S. P. Maslennikov, A. A. Solodovnikov, A. A. Uzvolok, D. I. Yurkov

    In the present work, the results of the experimental and particle in cell (PIC) simulation studies of the discharge combustion modes in a miniature Penning ion source (PIS) under the pulse-periodic power supply conditions are presented. Dynamics of discharge ignition and discharge operation mode at a pulsed anode voltage supply are investigated for different values of anode voltage and gas pressure in various magnetic field configurations. Typical examples of current pulse waveforms are shown. Also, numerical simulations of the PIS were performed using 3D PIC combined with Monte Carlo collisions in the code VSim. Temporal dependencies of electron, ion, and potential distributions in the Penning cell are simulated. Differences between the numerical and experimental results are discussed.

    更新日期:2019-12-31
  • Proton generation from hydrocarbon polymer targets for laser ion source
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-12-23
    Kazumasa Takahashi, Yuki Matsumoto, Masayuki Kuzumoto, Toru Sasaki, Takashi Kikuchi

    A laser ion source can provide intense pulsed ion beams from a solid target. On the other hand, generation of a proton beam with a laser ion source requires using compound targets containing hydrogen. In this research, we demonstrated proton generation from three kinds of hydrocarbon polymer targets: polyethylene (C2H4)n, polypropylene (C3H6)n, and polystyrene (C8H8)n. The laser used was a Nd:YAG laser (532 nm/17 ns), and the energy was 0.2 J. The ion current and the fraction of ion species were measured using a Faraday cup and an electrostatic ion analyzer. The results indicated that the peak currents and fraction to total particle number of proton were similar for the different hydrocarbon polymer targets and also showed that increasing the laser intensity effectively increases the number of proton particles because the larger the laser intensity, the larger the total charge.

    更新日期:2019-12-31
  • Review of high intensity ion source development and operation
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-12-24
    Richard Pardo

    The Electron Cyclotron Resonance Ion Source (ECRIS) has transformed the nuclear physics research field over the last 47 years. Today, the performance of ion sources is the first parameter that defines the design performance of existing facilities as well as the design approach and performance of new facilities. In this paper, I will review the current “state of the art” performance capabilities for ECRISs as well as other ion sources and how those current capabilities form the primary design criteria for new nuclear physics facilities and set the limiting performance for existing facilities. I will close with a short-term look into the future for these ion sources and other competing types.

    更新日期:2019-12-31
  • The vacuum arc ion source for indium and tin ions implantation into phase change memory thin films
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-12-26
    Dmitry Seleznev, Alexander Kozlov, Timur Kulevoy, Alexey Sitnikov, Petr Lazarenko, Yuri Vorobyov, Mikhail Smayev, Alexey Yakubov, Alexey Sherchenkov, Sergey Kozyukhin

    One of the most prospective electrical and optical nonvolatile memory types is the phase change memory based on chalcogenide materials, particularly Ge2Sb2Te5. Introduction of dopants is an effective method for the purposeful change of Ge2Sb2Te5 thin film properties. In this work, we used the ion implantation method for the introduction of In and Sn into Ge2Sb2Te5 thin films by a Multipurpose Test Bench (MTB) at the National Research Center “Kurchatov Institute”-Institute for Theoretical and Experimental Physics. For Sn and In ion implantation into Ge2Sb2Te5, the following MTB elements were used: a vacuum arc ion source, an electrostatic focusing system, and a system for current and beam profile measurements. The MTB parameters for Sn and In ion implantation and its effect on the material properties are presented. Implanted Ge2Sb2Te5 thin films were irradiated by femtosecond laser pulses. It was shown that the ion implantation resulted in a decrease in the threshold laser fluence necessary for crystallization compared to the undoped Ge2Sb2Te5.

    更新日期:2019-12-31
  • Development of continuous wave high voltage negative ion beam injector for tandem accelerator
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-12-30
    A. Sanin, Yu. Belchenko, A. Ivanov, A. Gmyrya

    A vacuum-insulated tandem accelerator, delivering the continuous wave 8 mA, 2 MeV proton beam, is operated regularly at the Budker Institute of Nuclear Physics, where a 10 mA, 25 keV negative ion injector is used. Recently, a new injector with an upgraded negative ion source and beam preacceleration has been developed to increase the tandem accelerated current. The transport line of the new injector is composed of a bending magnet with 90° ion beam turn, an acceleration tube for negative ion acceleration to the energy up to 150 keV, and a 0.6 m long transport section. The H− ion beam production, its acceleration, and transport were studied at a test stand, which is equipped with electrical and optical diagnostics. The data on 14 mA, 133 keV continuous wave negative ion beam production and transport are presented. The undesirable coacceleration of secondary electrons, produced in the acceleration tube, was recorded as well. The coaccelerated electrons’ current contributed up to 2% of the total accelerated beam at the operational vacuum in the low energy beam transport. The coaccelerated electrons were removed from the beam with a magnetic filter. The numerical modeling of the beam transport was carried out. A reasonable agreement between the modeled and experimental data was obtained.

    更新日期:2019-12-31
  • V-band nanosecond-scale pulse reflectometer diagnostic in the TCV tokamak
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-12-03
    P. Molina Cabrera, S. Coda, L. Porte, A. Smolders, TCV Team

    This article describes the realization of a novel approach to short pulse (∼1 ns) reflectometry (SPR) recently implemented in the tokamak configuration variable tokamak. Taking advantage of a fast arbitrary waveform generator and vector-network-analyzer extension modules, the design offers flexibility regarding pulse output frequency, duration, and repetition rate. Such flexibility allows the instrument to overcome traditional SPR spatial sampling limitations while reducing hardware complexity. In order to measure the group-delay of nanosecond-scale pulses, both traditional analog and novel digital sampling techniques have been explored. A group-delay range resolution of 17 ps (2.6 mm) in average over the V-band has been achieved with both timing techniques against a waveguide mirror featuring 10 dB power fluctuations. Direct pulse sampling during L-mode plasmas shows that reflected pulse widths increase only by 4% in average. However, pulse width dispersion does occur in L-mode plasmas and leads to an increase in the group-delay uncertainty up to 40 ps (6 mm). Raw histograms of group-delay data show interesting qualitative changes from the L mode to the H-mode. Frequency spectra of group-delay data allow the identification of macroscopic density fluctuations as well as edge quasicoherent modes during edge-localized mode-free H-modes. Finally, fast changes to the density profile have been measured with microsecond time resolution and subcentimeter spatial resolution in both O and X-mode polarizations.

    更新日期:2019-12-31
  • A comprehensive study of the uncertainties in bolometric tomography on JET using the maximum likelihood method
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-12-06
    E. Peluso, T. Craciunescu, A. Murari, P. Carvalho, M. Gelfusa, JET Contributors

    Essential physical quantities of magnetically confined plasmas are derived on a routine basis from bolometric reconstructions. In the last few years at the Joint European Torus (JET), the Maximum Likelihood method has demonstrated the capability of providing reliable reconstructions for this class of ill-posed problems. The article is focused on quantifying the effects of important sources of errors, usually underestimated, that can influence both the reconstructions and the derived quantities. A complete set of phantoms has been used to test the robustness of the technique. The main sources of uncertainties investigated in this contribution are random noise, presence of outliers in the measurements, uncertainty of the position of the magnetic topology, and missing measurements from damaged or unreliable bolometers. The study provides a comprehensive quantification of the uncertainties to associate with most typical emissivities encountered in practice and constitutes a good basis for a more accurate evaluation of the power balances on the JET.

    更新日期:2019-12-31
  • MPRAD: A Monte Carlo and ray-tracing code for the proton radiography in high-energy-density plasma experiments
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-12-10
    Yingchao Lu, Hui Li, Kirk A. Flippo, Kwyntero Kelso, Andy Liao, Shengtai Li, Edison Liang

    Proton radiography is used in various high-energy-density (HED) plasma experiments. In this paper, we describe a Monte Carlo and ray-tracing simulation tool called multimegaelectronvolt proton radiography (MPRAD) that can be used for modeling the deflection of proton beams in arbitrary three dimensional electromagnetic fields as well as the diffusion of the proton beams by Coulomb scattering and stopping power. The Coulomb scattering and stopping power models in cold matter and fully ionized plasma are combined using interpolation. We discuss the application of MPRAD in a few setups relevant to HED plasma experiments where the plasma density can play a role in diffusing the proton beams and affecting the prediction and interpretation of the proton images. It is shown how the diffusion due to plasma density can affect the resolution and dynamical range of the proton radiography.

    更新日期:2019-12-31
  • Improved calibration of the OMEGA gas Cherenkov detector
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-12-10
    A. B. Zylstra, H. W. Herrmann, Y. H. Kim, A. McEvoy, K. Meaney, V. Yu. Glebov, C. Forrest, M. Rubery

    Inertial fusion implosions are diagnosed using γ rays to characterize the implosion physics or measure basic nuclear properties, including cross sections. For the latter, previously reported measurements at laser facilities using gas Cherenkov detectors are limited by a large systematic uncertainty in the detector response. We present a novel in situ calibration technique using neutron inelastic scattering, which we apply to the new GCD-3 detector. The calibration accuracy is improved by ∼3× over the previous method.

    更新日期:2019-12-31
  • A model for real time,in situestimation of cesium coverage on metal substrate using infrared imaging under vacuum
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-12-11
    Pranjal Singh, Mainak Bandyopadhyay

    The present work is to develop an infra-red (IR) camera based in situ diagnostic tool for the determination of cesium (Cs) coverage suitable for ion source applications. Cs seeding is done to reduce the surface work function that enhances the surface assisted negative hydrogen ion production. The temporal Cs deposition on a metal surface (for, e.g., tungsten or molybdenum) follows Langmuir adsorption isotherm (LAI) kind of behavior. The surface temperature varies while the Cs deposition is reflected in the IR camera temperature measurements for a constant surface emissivity value. In this paper, a model on the relationship between Cs coverage in correlation with surface emissivity and temperature variation based on the theory of LAI is presented. A surface ionization probe (SIP) in the form of a cathode-anode assembly together with an IR camera viewing arrangement is designed to measure the Cs flux and the surface temperature simultaneously to test our model. In the present experiment, the Cs flux measurement using SIP is validated with a standard quartz crystal microbalance (QCM). The proposed model would be useful to correlate Cs coverage on plasma grid-like surface conditions under negative ion source relevant vacuum conditions.

    更新日期:2019-12-31
  • Investigation of the eddy current effect on the high frequency response of the Mirnov probe on J-TEXT
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-12-16
    Chengshuo Shen, Zhenming Cai, Tian Ren, Xitong Zhang, Qiming Hu, Nengchao Wang, Zhuo Huang, Song Zhou, Jianchao Li, Mao Li, Da Li, Dongliang Han, Yonghua Ding

    This paper investigates the high frequency response of the Mirnov probe based on a test platform, which is capable of generating a uniform AC magnetic field within the frequency range of 1–300 kHz. The eddy current effect is quantitatively reflected by the phase shift ϕc and normalized amplitude δ of the measured magnetic field between cases with and without a conducting plate located near the Mirnov probe. This method compensates the resonant effect in the Mirnov probe circuit and hence reflects purely the eddy current effect. The eddy current effect increases with the decrease in the distance between the probe and the conducting plate. With the increase in frequency, the magnitude of δ decreases to a saturated value at 10 kHz but increases significantly above 100 kHz for 304-stainless steel, while the eddy current effect with graphite appears at around 10 kHz and the magnitude of δ decreases to the minimum at 125 kHz, followed by a significant increase above 125 kHz. With the increase in f, the magnitude of ϕc increased until 2.5 kHz and 40 kHz for steel and graphite, respectively, then decreased with a further increase in f. The phasor expression is introduced to describe the AC magnetic field and allows an easy expression of the eddy current field. The phase of the eddy current field decreases toward −180° with f. The amplitude of the eddy current field increases with f and reaches its maximum when the skin depth reduces to a critical value. The eddy current field decreases with a further increase in the frequency.

    更新日期:2019-12-31
  • Performance of new crystal cathode pressure gauges for long-pulse operation in the Wendelstein 7-X stellarator
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-12-17
    Uwe Wenzel, Georg Schlisio, Matthias Mulsow, Thomas Sunn Pedersen, Martin Singer, Mirko Marquardt, Dirk Pilopp, Nils Rüter

    To improve the reliability of the ASDEX pressure gauges in the plasma vessel of the Wendelstein 7-X stellarator, nine of them were equipped with a LaB6 crystal electron emitter for the first time. These crystal cathode pressure gauges were operated during the last campaign in 2018 (operation phase 1.2b) with only 2 A heating current for over 40 h in a magnetic field of about 2.1 T without failure. Owing to this excellent performance, we have decided to equip all pressure gauges with crystal cathodes for the next campaign of Wendelstein 7-X (operation phase 2). We report on a pretest in a superconducting magnet, show a measurement of the neutral pressure in Wendelstein 7-X, and demonstrate the long-term stability of the crystal cathode pressure gauges.

    更新日期:2019-12-31
  • Development of 1.2-GHz ECR ion source and Wien filter for inexpensive ion beam processing system
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-12-18
    Toyohisa Asaji, Hiroya Uyama, Takuro Umetsugu, Tsubasa Nakamura, Takeshi Hitobo, Yushi Kato

    A desktop-sized ion beam processing system with an inexpensive electron cyclotron resonance (ECR) ion source has been developed for industrial applications at the National Institute of Technology, Toyama College. A commercially available 1.2- to 1.3-GHz transceiver is adopted as a microwave source to generate the ECR plasma. The minimum-B magnetic field is formed by arranging small rectangular permanent magnets. A Wien filter with orthogonal electric and magnetic fields is employed as a beam separator. At the end of the beam line, a processing chamber with a substrate stage for ion beam applications, such as ion implantation and microfabrication, is installed. Here, we report the results of the first experiment. Ar ion beams with a current of approximately 62 µA were obtained at an extraction voltage of 4 kV. In addition, we demonstrate that Ar and Xe ions can be separated by the Wien filter.

    更新日期:2019-12-31
  • Preliminary result of cavity ring-down spectroscopy system for radio frequency negative ion source test facility
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-12-19
    Lizhen Liang, Chundong Hu, Jingyang Yan, Yuanzhe Zhao, Yahong Xie

    Negative ion source is a core part of the neutral beam injection system for magnetic confinement fusion devices. The density of produced hydrogen negative ions is a critical parameter of the negative ion source. Cavity ring-down spectroscopy (CRDS) is an ultrasensitive absorption diagnostic technique for density measurement. Based on the photodetachment process, CRDS can measure the integrated line-of-sight hydrogen negative ion density in a high power ion source. The CRDS diagnostic system has been applied to Hefei utility negative ion test equipment with the radio frequency (RF) source, which is now one of the references for the China Fusion Engineering Test Reactor neutral beam injection system. Typical ring-down signals are obtained to calculate the density of hydrogen negative ions. The time evolution of hydrogen negative ion density is successfully measured. Preliminary experiments show the accurate relationship between RF power and measured hydrogen negative ion density.

    更新日期:2019-12-31
  • Development of gamma ray spectrometer with high energy and time resolutions on EAST tokamak
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-12-18
    R. J. Zhou, G. Q. Zhong, L. Q. Hu, M. Tardocchi, D. Rigamonti, L. Giacomelli, M. Nocente, G. Gorini, T. S. Fan, Y. M. Zhang, Z. M. Hu, M. Xiao, K. Li, Y. K. Zhang, B. Hong, Y. Zhang, S. Y. Lin, J. Z. Zhang

    A new gamma ray spectrometer with high energy and time resolutions has been developed and installed on the EAST tokamak to study fast ion and runaway electron behaviors. The spectrometer is based on a LaBr3(Ce) scintillator detector and a fully digital data acquisition system that is based on a digitizer with digital pulse processing algorithms. The energy resolution of the spectrometer is about 3.9% at 662 keV, and the spectrometer can operate stably at a counting rate as high as 1 MHz, monitored by using a light emitting diode monitoring system. The measured gamma ray spectrum is simulated based on Geant4 and unfolded with the high-resolution boosted Gold deconvolution algorithm, aiming at reconstructing the energy distribution functions of fast ions and runaway electrons.

    更新日期:2019-12-31
  • Wide-aperture dense plasma fluxes production based on ECR discharge in a single solenoid magnetic field
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-12-20
    V. A. Skalyga, S. V. Golubev, I. V. Izotov, R. A. Shaposhnikov, S. V. Razin, A. V. Sidorov, A. F. Bokhanov, M. Yu. Kazakov, R. L. Lapin, S. S. Vybin

    Results of experimental investigation of the ECR discharge in a single coil magnetic field as an alternative to rf and helicon discharges for wide-aperture dense plasma fluxes production are presented. A possibility of obtaining wide-aperture high density hydrogen plasma fluxes with homogeneous transverse distribution was demonstrated in such a system. The prospects of using this system for obtaining high current ion beams are discussed.

    更新日期:2019-12-31
  • Preliminary design of diagnostic system for negative neutral beam injector at ASIPP
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-12-20
    Yongjian Xu, Chundong Hu, Lizhen Liang, Yahong Xie, Caichao Jiang, Jianglong Wei, Ling Tao, Yuanlai Xie

    According to the latest physics design of the China Fusion Engineering Test Reactor (CFETR), two neutral beam injectors (NBIs), which deliver a total of 40 MW in not less than 3600 s with 1 MeV D0, are demanded to support current drive and plasma rotation. To minimize the risks and time to provide the CFETR with reliable NBIs, a negative NBI test facility will be developed at the Institute of Plasma Physics, Chinese Academy of Science. Its mission is to understand the characteristics of the RF driven ion source and negative ion generation and extraction and to improve RF efficiency and beam quality. In order to achieve this goal, a set of diagnostic tools will be used in this test facility. For source diagnostics, optical emission spectroscopy, cavity ring-down spectroscopy, laser absorption spectroscopy, and electrostatic probes are planned to be used. Beam emission spectroscopy, W-wire calorimeters, 1D carbon fiber composite diagnostic calorimeters, beam dump with thermocouples, and water-flow calorimetry are used to assess the beam properties. The design of the diagnostic system is presented.

    更新日期:2019-12-31
  • A parametric method for correcting polluted plasma current signal and its application on Keda Torus eXperiment
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-12-26
    Tijian Deng, Tao Lan, Jie Wu, Mingsheng Tan, Hangqi Xu, Junfeng Zhu, Chen Chen, Yolbarsop Adil, Sen Zhang, Jiaren Wu, Yiming Zu, Wenzhe Mao, Hong Li, Jinlin Xie, Ahdi Liu, Zixi Liu, Zhengwei Wu, Hai Wang, Xiaohui Wen, Haiyang Zhou, Zian Wei, Chijin Xiao, Weixing Ding, Ge Zhuang, Wandong Liu

    We have developed a parametric method for eliminating the background component of the plasma current, which is measured by a Rogowski coil and polluted by the toroidal magnetic field in the vacuum vessel of the Keda Torus eXperiment (KTX) reversed field pinch (RFP) device. The method considers the toroidal magnetic field windings, the KTX vacuum chamber, and the Rogowski coil as a linear time-invariant system; in this case, a constant frequency response function characterizes the system. Using this response function, the current component caused by pollution from the toroidal magnetic field can be predicted exactly for an arbitrary input current to the toroidal magnetic field windings. Compared with the traditional proportional compensation method, the proposed method has great flexibility and universality and it is potentially applicable to cases in which the toroidal field current signal changes over time with plasma feedback signals. Furthermore, the method can be applied to other similarly affected signals, such as magnetic field signals. As an example, we have corrected the poloidal and toroidal magnetic field signals better to reveal the true physical processes for the RFP state.

    更新日期:2019-12-31
  • MANTIS: A real-time quantitative multispectral imaging system for fusion plasmas
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-12-31
    A. Perek, W. A. J. Vijvers, Y. Andrebe, I. G. J. Classen, B. P. Duval, C. Galperti, J. R. Harrison, B. L. Linehan, T. Ravensbergen, K. Verhaegh, M. R. de Baar, TCV, EUROfusion MST1 Teams

    This work presents a novel, real-time capable, 10-channel Multispectral Advanced Narrowband Tokamak Imaging System installed on the TCV tokamak, MANTIS. Software and hardware requirements are presented together with the complete system architecture. The image quality of the system is assessed with emphasis on effects resulting from the narrowband interference filters. Some filters are found to create internal reflection images that are correlated with the filters’ reflection coefficient. This was measured for selected filters where significant absorption (up to 65% within ∼70 nm of the filter center) was measured. The majority of this was attributed to the filter’s design, and several filters’ performance is compared. Tailored real-time algorithms exploiting the system’s capabilities are presented together with benchmarks comparing polling and event based synchronization. The real-time performance is demonstrated with a density ramp discharge performed on TCV. The behavior of spectral lines’ emission from different plasma species and their interpretation are qualitatively described.

    更新日期:2019-12-31
  • Off-axis parabolic mirror relay microscope for experiments with ultra-cold matter
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-12-17
    Michal Hejduk, Brianna R. Heazlewood

    A new optical system is introduced for the imaging of Coulomb crystals held in a cryogenic ion trap where there are space limitations preventing the placement of an objective close to the fluorescing ions. The optical system features an off-axis parabolic (OAP) mirror relay microscope that will serve to acquire images of a lattice of fluorescing ions confined within an ultra-high-vacuum vessel operating at temperatures below 10 K. We report that the OAP mirror relay setup can resolve features smaller than the separation between neighboring ions in Coulomb crystals. The setup presented here consists of two 90-degree OAP mirrors arranged into a relay from which standard microscope optics deliver the image to a camera. This design allows the first element in the imaging setup—an OAP mirror—to be located as close as possible to the ion trap, achieving high resolution without the need for a direct line-of-sight to the trap center or for a view port to be located in close proximity to the ion trap. Such an arrangement would not be possible with a standard microscope objective, which is the approach commonly adopted by the field. OAP mirrors represent a novel solution for delivering polychromatic images with micrometer-scale resolution over extended distances.

    更新日期:2019-12-31
  • Submicrometric absolute positioning of flat reflective surfaces using Michelson interferometry
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-12-17
    C. Bienvenue, S. Vallières, S. Payeur, P. Antici

    We present a Target Positioning Interferometer (TPI), a system that uses variations of the wavefront curvature to position solid reflective surfaces with submicrometric precision. The TPI is a Michelson interferometer into which a lens is inserted in the target arm and the mirror of the reference arm is slightly tilted. The TPI configuration presented in this work allows us to position the surface of a reflective target on a beam focus within an uncertainty of 350 nm (2σ) in a subsecond timeframe, using a lens with a numerical aperture of NA = 0.20. We support our experimental findings with numerical simulations of the interference pattern using the ABCD matrices’ method, allowing us to define scaling laws for using the TPI with different optics and environments, as well as suggestions to improve the TPI accuracy and adapt the system to different applications. This system is very well suited for accurate and repeatable target positioning used in laser-driven ion acceleration, where a precise alignment is key to optimize the proton acceleration mechanism.

    更新日期:2019-12-31
  • An apparatus based on an atomic force microscope for implementing tip-controlled local breakdown
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-12-20
    T. St-Denis, K. Yazda, X. Capaldi, J. Bustamante, M. Safari, Y. Miyahara, Y. Zhang, P. Grutter, W. Reisner

    Solid-state nanopores are powerful tools for sensing of single biomolecules in solution. Fabrication of solid-state nanopores is still challenging, however; in particular, new methods are needed to facilitate the integration of pores with larger nanofluidic and electronic device architectures. We have developed the tip-controlled local breakdown (TCLB) approach, in which an atomic force microscope (AFM) tip is brought into contact with a silicon nitride membrane that is placed onto an electrolyte reservoir. The application of a voltage bias at the AFM tip induces a dielectric breakdown that leads to the formation of a nanopore at the tip position. In this work, we report on the details of the apparatus used to fabricate nanopores using the TCLB method, and we demonstrate the formation of nanopores with smaller, more controlled diameters using a current limiting circuit that zeroes the voltage upon pore formation. Additionally, we demonstrate the capability of TCLB to fabricate pores aligned to embedded topographical features on the membranes.

    更新日期:2019-12-31
  • Development of high-speed ion conductance microscopy
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-12-23
    Shinji Watanabe, Satoko Kitazawa, Linhao Sun, Noriyuki Kodera, Toshio Ando

    Scanning ion conductance microscopy (SICM) can image the surface topography of specimens in ionic solutions without mechanical probe–sample contact. This unique capability is advantageous for imaging fragile biological samples but its highest possible imaging rate is far lower than the level desired in biological studies. Here, we present the development of high-speed SICM. The fast imaging capability is attained by a fast Z-scanner with active vibration control and pipette probes with enhanced ion conductance. By the former, the delay of probe Z-positioning is minimized to sub-10 µs, while its maximum stroke is secured at 6 μm. The enhanced ion conductance lowers a noise floor in ion current detection, increasing the detection bandwidth up to 100 kHz. Thus, temporal resolution 100-fold higher than that of conventional systems is achieved, together with spatial resolution around 20 nm.

    更新日期:2019-12-31
  • A radio-frequency spin-polarized scanning tunneling microscope
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-12-30
    J. Friedlein, J. Harm, P. Lindner, L. Bargsten, M. Bazarnik, S. Krause, R. Wiesendanger

    A scanning tunneling microscope for spin-resolved studies of dynamic systems is presented. The cryogenic setup allows the scanning tunneling microscope to achieve a cutoff frequency beyond 26 GHz at the tunnel junction and to be operable at temperatures of 1.1 K–100 K in a magnetic field of up to 3 T. For this purpose, the microscope and its wiring as well as the associated cryostat system were specially designed and manufactured. For sample preparation, an ultrahigh vacuum system was developed, which is equipped with modular preparation platforms. Measurements showing the characteristics of the scanning tunneling microscope in the time and frequency domain are presented. As a proof of concept, experimental data of the Pd/Fe/Ir(111) sample system at 95 K in a magnetic field of 3 T are presented.

    更新日期:2019-12-31
  • Table-top nuclear magnetic resonance system for high-pressure studies within situlaser heating
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-12-03
    Thomas Meier, Anand Prashant Dwivedi, Saiana Khandarkhaeva, Timofey Fedotenko, Natalia Dubrovinskaia, Leonid Dubrovinsky

    High pressure Nuclear Magnetic Resonance (NMR) is known to reveal the behavior of matter under extreme conditions. However, until now, significant maintenance demands, space requirements, and high costs of superconducting magnets render its application unfeasible for regular modern high pressure laboratories. Here, we present a table-top NMR system based on permanent Halbach magnet arrays with a diameter of 25 cm and height of 4 cm. At the highest field of 1013 mT, 1H-NMR spectra of ice VII have been recorded at 25 GPa and ambient temperature. The table-top NMR system can be used together with double sided laser heating setups. Feasibility of high-pressure high-temperature NMR was demonstrated by collecting 1H-NMR spectra of H2O at 25 GPa and 1063(50) K. The change in the signal intensity in a laser-heated NMR diamond anvil cell has been found to yield a convenient way for temperature measurements.

    更新日期:2019-12-31
  • A simple method forin situmeasurement of vacuum window birefringence
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-11-11
    W. H. Yuan, H. L. Liu, W. Z. Wei, Z. Y. Ma, P. Hao, Z. Deng, K. Deng, J. Zhang, Z. H. Lu

    We present a simple method to measure the degrees of circular polarization (DoCP) of laser light inside a vacuum chamber and the birefringence of a vacuum window by detecting the fluorescence emitted by Doppler cooled ions in an ion trap. Imperfect laser polarization will cause ions to be pumped to the dark state which will decrease the fluorescence rates of the ions. With a simulation based on the rate equations of the relevant energy levels of 25Mg+ ions, we find that the fluorescence rate is sensitive to the DoCP of the laser. Based on the simulation result, we present a new method to optimize the DoCP of the laser inside the vacuum chamber by adjusting fast axis azimuthal angles of a half-wave plate and a quarter-wave plate outside the vacuum chamber. The laser light is optimized to be circularly polarized with an uncertainty of the DoCP of 7.8 × 10−5. With the obtained polarization information on both sides of the vacuum window and treating the vacuum window as an unknown wave plate, the phase delay and the fast axis azimuthal angle of the vacuum window can be determined in the form of Mueller matrix. The phase delay is determined to be 197.60(39)°, and the fast axis azimuthal angle is determined to be 104.00(5)°.

    更新日期:2019-11-28
  • Soft X-ray spectroscopy with transition-edge sensors at Stanford Synchrotron Radiation Lightsource beamline 10-1
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-11-05
    Sang-Jun Lee, Charles J. Titus, Roberto Alonso Mori, Michael L. Baker, Douglas A. Bennett, Hsiao-Mei Cho, William B. Doriese, Joseph W. Fowler, Kelly J. Gaffney, Alessandro Gallo, Johnathon D. Gard, Gene C. Hilton, Hoyoung Jang, Young Il Joe, Christopher J. Kenney, Jason Knight, Thomas Kroll, Jun-Sik Lee, Dale Li, Donghui Lu, Ronald Marks, Michael P. Minitti, Kelsey M. Morgan, Hirohito Ogasawara, Galen C. O’Neil, Carl D. Reintsema, Daniel R. Schmidt, Dimosthenis Sokaras, Joel N. Ullom, Tsu-Chien Weng, Christopher Williams, Betty A. Young, Daniel S. Swetz, Kent D. Irwin, Dennis Nordlund

    We present results obtained with a new soft X-ray spectrometer based on transition-edge sensors (TESs) composed of Mo/Cu bilayers coupled to bismuth absorbers. This spectrometer simultaneously provides excellent energy resolution, high detection efficiency, and broadband spectral coverage. The new spectrometer is optimized for incident X-ray energies below 2 keV. Each pixel serves as both a highly sensitive calorimeter and an X-ray absorber with near unity quantum efficiency. We have commissioned this 240-pixel TES spectrometer at the Stanford Synchrotron Radiation Lightsource beamline 10-1 (BL 10-1) and used it to probe the local electronic structure of sample materials with unprecedented sensitivity in the soft X-ray regime. As mounted, the TES spectrometer has a maximum detection solid angle of 2 × 10−3 sr. The energy resolution of all pixels combined is 1.5 eV full width at half maximum at 500 eV. We describe the performance of the TES spectrometer in terms of its energy resolution and count-rate capability and demonstrate its utility as a high throughput detector for synchrotron-based X-ray spectroscopy. Results from initial X-ray emission spectroscopy and resonant inelastic X-ray scattering experiments obtained with the spectrometer are presented.

    更新日期:2019-11-28
  • Quantitative infrared spectroscopy of environmentally sensitive and rough materials
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-11-14
    Beibei Xu, Zhiwei Peng, Zupeng Wu, Xu A. Zhang, YuHuang Wang

    Fourier transform infrared (FTIR) spectroscopy is a widely used characterization technique for studying chemical compositions and light-matter interactions in the infrared range. However, it remains challenging to use conventional FTIR equipment to characterize materials that are environmentally sensitive and/or have rough surfaces due to their dynamic response to external stimuli (e.g., humidity) and light scattering from the sample surface. Here, we describe an approach enabling quantitative infrared spectroscopy measurements of these challenging samples, including transmittance, reflectance, and emissivity. We designed and 3D-printed a miniaturized environmental chamber that can be directly inserted into the sample holder of a conventional integrating sphere to perform total transmission and reflection measurements in controlled environments. Moreover, a calibration method was developed to exclude light scattering from rough surfaces of the sample and the distortion created by infrared windows. To illustrate the potential application of this method, we have performed quantitative infrared measurements, both specular and diffusive, on a sapphire standard reference with a specular surface, as well as a textile sample that has a rough surface and is dynamically responsive to changes in humidity. The calibrated results measured with the equipped chamber match those measured without the IR windows, demonstrating the viability of our environmental chamber and the proposed calibration method. This quantitative infrared spectroscopy measurement technique may help advance fields such as metasurfaces and adaptive textiles, where samples are often rough, dynamically responsive, and/or environmentally sensitive.

    更新日期:2019-11-28
  • Space- and time-resolved UV-to-NIR surface spectroscopy and 2D nanoscopy at 1 MHz repetition rate
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-11-20
    Bernhard Huber, Sebastian Pres, Emanuel Wittmann, Lysanne Dietrich, Julian Lüttig, Daniel Fersch, Enno Krauss, Daniel Friedrich, Johannes Kern, Victor Lisinetskii, Matthias Hensen, Bert Hecht, Rudolf Bratschitsch, Eberhard Riedle, Tobias Brixner

    We describe a setup for time-resolved photoemission electron microscopy with aberration correction enabling 3 nm spatial resolution and sub-20 fs temporal resolution. The latter is realized by our development of a widely tunable (215–970 nm) noncollinear optical parametric amplifier (NOPA) at 1 MHz repetition rate. We discuss several exemplary applications. Efficient photoemission from plasmonic Au nanoresonators is investigated with phase-coherent pulse pairs from an actively stabilized interferometer. More complex excitation fields are created with a liquid-crystal-based pulse shaper enabling amplitude and phase shaping of NOPA pulses with spectral components from 600 to 800 nm. With this system we demonstrate spectroscopy within a single plasmonic nanoslit resonator by spectral amplitude shaping and investigate the local field dynamics with coherent two-dimensional (2D) spectroscopy at the nanometer length scale (“2D nanoscopy”). We show that the local response varies across a distance as small as 33 nm in our sample. Further, we report two-color pump–probe experiments using two independent NOPA beamlines. We extract local variations of the excited-state dynamics of a monolayered 2D material (WSe2) that we correlate with low-energy electron microscopy (LEEM) and reflectivity measurements. Finally, we demonstrate the in situ sample preparation capabilities for organic thin films and their characterization via spatially resolved electron diffraction and dark-field LEEM.

    更新日期:2019-11-28
  • Observing sub-Poissonian statistics of twisted single photons using oscilloscope
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-11-21
    Nijil Lal, Biveen Shajilal, Ali Anwar, Chithrabhanu Perumangatt, R. P. Singh

    Heralded single photon sources (HSPSs) from spontaneous parametric down-conversion are widely used as single photon sources. We study the photon number statistics of an HSPS carrying orbital angular momentum in our laboratory and observe the sub-Poissonian statistics using only photodetectors and an oscilloscope.

    更新日期:2019-11-28
  • Single-pass non-destructive electronic detection of charged particles
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-11-01
    Markus Kiffer, Stefan Ringleb, Nils Stallkamp, Béla Arndt, Ilya Blinov, Sugam Kumar, Stefan Stahl, Thomas Stöhlker, Manuel Vogel

    We have devised an experimental method and apparatus for the simultaneous nondestructive determination of the absolute ion number, ion kinetic energy, and length of bunches of charged particles. We have built and operated a corresponding electronic detector that is based on induced charges and their subsequent low-noise amplification at cryogenic temperatures. We have performed measurements with bunches of low-energy highly charged ions from an electron-beam ion source that show the capability of the methods and their implementation. We discuss requirements for, and applications of, such detectors with a particular view on the obtainable information and their sensitivity.

    更新日期:2019-11-28
  • Laser ablation plasma with solenoid field confinement
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-11-01
    G. C. Wang, H. Y. Zhao, Q. Y. Jin, J. J. Zhang, L. T. Sun, H. W. Zhao

    A Laser Ion Source (LIS) can produce high charge state and high intensity ion beams (∼emA), especially, refractory metallic ion beams, which makes it a promising candidate as an ion source for heavy ion cancer therapy facilities and future accelerator complexes, where pulsed high intensity and high charged heavy ion beams are required. However, it is difficult for the LIS to obtain a long pulse width while ensuring high current intensity, thus limiting the application of the LIS. To solve the conflict, magnetic fields are proposed to confine the expansion of the laser produced plasma. With a solenoid along the normal direction to the target surface, the lateral adiabatic expansion of the laser ablation plasma is suppressed which extends the pulse width of the ion beam effectively. The characteristics of laser ablation plasma with solenoid field confinement will be presented and discussed in this paper.

    更新日期:2019-11-28
  • Low current heaterless hollow cathode neutralizer for plasma propulsion—Development overview
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-11-01
    Dan Lev, Gal Alon, Leonid Appel

    Hollow cathodes serve as electron sources for the operation of electric thrusters aboard spacecraft. Conventionally, hollow cathodes utilize a heating element to raise the temperature of the electron emitting material embedded in the cathode. To simplify cathode design and operation, in recent years, heaterless cathode technology has been under development in various facilities around the world. This paper overviews the development of a low current heaterless hollow cathode, designed and produced by Rafael, and denoted the ARC-1A. The ARC-1A generates a discharge current of 0.3–1.2 A and is ignited using breakdown voltages below 400 V. Each of the development phases is elaborated upon. These phases included activities such as a technology study, the development of manufacturing processes, the study of failure modes, and performance characterization and culminated with two primary tests—a 5000 h endurance test and a 3500 cold ignition cycles test. In its current state of development, the ARC-1A proves suitable for a wide range of low power electric thrusters and was successfully coupled with two different Hall effect thrusters in a wide range of low discharge current levels (0.5–1.1 A).

    更新日期:2019-11-28
  • Formation of large negative deuterium ion beams at ELISE
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-11-04
    D. Wünderlich, R. Riedl, I. Mario, A. Mimo, U. Fantz, B. Heinemann, W. Kraus

    Negative ion sources for neutral beam injection (NBI) in fusion experiments are based on the surface production of H− or D− on cesiated low work function surfaces. In the recent years, it was demonstrated at the large RF driven ion source of the ELISE (Extraction from a Large Ion Source Experiment) test facility that the requirements for the ITER NBI systems can be fulfilled by hydrogen. This is a big step toward the first operational period of ITER, planned for up to 2035. However, for the following operational period, neutral beam systems working in deuterium are needed. Operation of negative hydrogen ion sources in deuterium is significantly more demanding than in hydrogen: the amount of coextracted electrons is much higher and their increase during pulses is much more pronounced, limiting the achievable performance. This paper presents the results of investigations aimed to improve the insight into the physics related to this isotope effect. Due to the higher atomic mass of deuterium, cesium is removed much more effectively from reservoirs at the walls, resulting in a depletion of these reservoirs and a strongly increased cesium density in the plasma. Additionally, a correlation between the fluxes of charged particles toward the inner ion source surfaces and the coextracted electrons is identified.

    更新日期:2019-11-28
  • Preliminary results of BETSI test bench upgrade at CEA-Saclay
    Rev. Sci. Instrum. (IF 1.587) Pub Date : 2019-11-06
    O. Tuske, O. Delferrière, Y. Gauthier, F. Harrault, Y. Sauce

    The Banc d’Etude et de Tests des Sources d’Ions (BETSI) test bench was built in 2009 for the Spiral2 project. Year after year, upgrades were done on the low energy beam line in order to have a complete injector equipped with 2 solenoids and vacuum chambers with multiple viewports for various kinds of beam-diagnostics. BETSI was designed for a 50 kV high voltage, and all the sources that were installed on the platform were also designed for that voltage. As the advanced light ion source extraction system ions source family is getting larger, the design is made for higher extraction voltages. As the common extraction voltage is 100 kV, the BETSI platform was upgraded to this voltage value. The control-command was upgraded, and at this voltage, a great care on the electromagnetic protections was taken in order to protect the equipment when spark occurs. This paper describes the choice of the upgrade, its installation, and some performances already obtained with a permanent magnet ion source equipped with a large accelerating tube.

    更新日期:2019-11-28
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