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Effect of the rising edge of ultrashort laser pulse on the target normal sheath acceleration of ions Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-02-27 J Psikal
Laser-driven ion acceleration is theoretically/numerically mostly studied with the assumption of an idealised main ultrashort pulse of the Gaussian temporal shape, where nanosecond/multi-picosecond pedestals and short prepulses preceding the main pulse can be incorporated in the form of modifications in the initial density profile of irradiated ionised targets. This paper shows that the relatively
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QScatter: numerical framework for fast prediction of particle distributions in electron-laser scattering Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-02-23 Óscar Amaro, Marija Vranic
The new generation of multi-PetaWatt laser facilities will allow tests of strong field quantum electrodynamics (QED), as well as provide an opportunity for novel photon and lepton sources. The first experiments are planned to study the (nearly) head-on scattering of intense, focused laser pulses with either relativistic electron beams or high-energy photon sources. In this work, we present a numerical
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A mixed Fourier-variational approach to solve differential or integro-differential wave equations for magnetised plasmas Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-02-15 Dirk Van Eester, E A Lerche
The All ORders Spectral Algorithm (AORSA) wave equation solver by Jaeger (Jaeger et al 2001 Phys. Plasmas 8 1573) solves the integro-differential wave equation relevant for the radio frequency (RF) domain and for fusion-relevant conditions in tokamaks or stellarators, retaining all finite Larmor radius corrections by substituting the continuous Fourier integrals by a sum over a discrete set of modes
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Investigations into penetration depth profiles of hydrogenic species in beryllium plasma-facing components via molecular dynamics simulations Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-02-15 A Liptak, K D Lawson, M I Hasan
During the operation of nuclear fusion reactors, plasma-facing components lining the reactor vessel are continually bombarded by plasma species. The penetration and subsequent trapping of these bombarding plasma ions has implications for component damage as well as in-vessel inventory. Accurately predicting the expected ion penetration depth profiles at a range of plasma ion and surface temperatures
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A new FILDSIM model for improved velocity-space sensitivity modelling and reconstructions Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-02-15 Bo S Schmidt, Jesús Poley-Sanjuán, José Rueda-Rueda, Joaquín Galdon-Quíroga, Marcelo Baquero-Ruiz, Henrik Järleblad, Bernard C G Reman, Mads Rud, Andrea Valentini, Manuel García-Muñoz, Mirko Salewski
We present a new version of the FILDSIM code (Galdon-Quíroga et al 2018 Plasma Phys. Control. Fusion 60 105005), which significantly refines the modelling of the fast-ion loss detector (FILD) signal. We demonstrate that the FILD weight functions computed using this new version of FILDSIM are more accurate relative to synthetic benchmarks than those computed using the previous version. Thus, the new
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Effect of hyper-resistivity on ballooning modes with resonant magnetic perturbations Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-02-15 S Y Chen, M L Mou, T Q Liu, Y M Zhang, L K Dong, H Fan, X Lu, C J Tang
The impact of hyper-resistivity on non-ideal ballooning modes (BMs) is studied in the presence of resonant magnetic perturbation (RMP) through considering the hyper-resistivity, resistivity and diamagnetic effect in the BM model with an equilibrium distorted by RMP, which is stable for ideal BMs. Similar to the resistivity, the hyper-resistivity is also destabilizing for the BMs, but RMPs make the
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Stability and debris-mitigation of a solid tape target delivery system for intense laser-matter interactions towards high-repetition-rate Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-02-15 Michael Ehret, Diego de Luis, Jon Imanol Apiñaniz, Jose Luis Henares, Roberto Lera, José Antonio Pérez-Hernández, Pilar Puyuelo-Valdes, Luca Volpe, Giancarlo Gatti
The VEGA-3 laser system at the Centro de Láseres Pulsados delivers laser pulses up to 1 PW at 1 Hz repetition rate, focused to intensities up to 2.5×1020 W cm−2. A versatile and compact solid target suitable for up to 0.05 Hz is presented which can operate in the challenging petawatt laser environment close to the laser-plasma interaction. Strips are spooled in a tape target system to deliver a solid
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Reduction of fast ion drag in the presence of ‘hollow’ non-Maxwellian electron distributions Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-02-13 A P L Robinson
It is argued that the electronic stopping power in a plasma should be expected to exhibit significant differences in the presence of effects that shift the electron distribution function away from a Maxwellian. This is potentially important for nuclear reactions produced by laser-driven ion beams, where non-Maxwellian effects may have to be considered. We have calculated the electronic stopping power
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Soft H-L back transitions by applying resonant magnetic perturbations in the low q 95 EAST plasmas Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-02-13 L M Shao, R Chen, Y W Sun, M F Wu, W Gao, K D Li, X Li, M N Jia, Q Ma, L Y Meng, H H Wang, M R Wang, G S Xu, Q Zang, L Zhang, C Zhou, the EAST Team3
Controlled ‘soft’ H-L transitions with a simultaneous ramp-down of plasma density and stored energy, generated by applying resonant magnetic perturbations (n = 2 RMPs), relevant to the control of ITER terminations, are achieved in the EAST tokamak. These H-mode plasmas are run at median electron densities and a low safety factor q 95 ( q95=3.5 –4.0) under neutral beam injection (NBI) dominant heating
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Metal evaporation dynamics in electron cyclotron resonance ion sources: plasma role in the atom diffusion, ionisation, and transport Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-02-13 A Pidatella, D Mascali, A Galatà, B Mishra, E Naselli, L Celona, R Lang, F Maimone, G S Mauro, D Santonocito, G Torrisi
We present a numerical study of metals dynamics evaporated through resistively heated ovens in electron cyclotron resonance (ECR) plasma traps, used as metal ion beam injectors for accelerators and multi-disciplinary research in plasma physics. We use complementary numerical methods to perform calculations in the framework of the PANDORA trap. The diffusion and deposition of metal vapours at the plasma
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Anomalous hot electron generation via stimulated Raman scattering in plasma with up-ramp density profiles Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-02-08 X Y Jiang, S M Weng, H H Ma, C F Wu, Z Liu, M Chen, B Eliasson, Z M Sheng
We investigate the evolution and propagation of the electron plasma waves (EPWs) excited by stimulated Raman scattering (SRS) in the inhomogeneous plasma theoretically and numerically with particle-in-cell (PIC) simulations. A theoretical model of EPWs in inhomogeneous plasmas is presented, which shows that the evolution of the EPW wavenumber is mainly related to the plasma density profile rather than
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Parametric analysis of electron beam quality in laser wakefield acceleration based on the truncated ionization injection mechanism Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-02-07 Srimanta Maity, Alamgir Mondal, Eugene Vishnyakov, Alexander Molodozhentsev
Laser wakefield acceleration (LWFA) in a gas cell target separating injection and acceleration section has been investigated to produce high-quality electron beams. A detailed study has been performed on controlling the quality of accelerated electron beams using a combination of truncated ionization and density downramp injection mechanisms. For this purpose, extensive two-dimensional particle-in-cell
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The fastVFP code for solution of the Vlasov–Fokker–Planck equation Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-02-07 A R Bell, M Sherlock
We describe the fastVFP code for solution of the Vlasov–Fokker–Planck equation for non-local electron transport and the generation of magnetic field, especially for application to laser-produced plasmas. We describe the essential features of the code that make it fast and robust and suitable for inclusion as a transport package in a fluid simulation. We present a few sample results that demonstrate
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Investigation of core transport changes in DIII-D discharges with off-axis T e profile peaks Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-02-07 R Xie, M E Austin, K Gentle, C C Petty
DIII-D discharges that transition to H-mode solely with off-axis electron cyclotron heating (ECH) often exhibit strong off-axis peaking of electron temperature profiles at the heating location. Electron heat transport properties near these off-axis temperature peaks have been studied using modulated ECH. The Fourier analyzed electron temperature data have been used to infer electron thermal diffusivity
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Investigation of γ-photon sources using near-critical density targets towards the optimization of the linear Breit–Wheeler process Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-02-06 Iuliana-Mariana Vladisavlevici, Xavier Ribeyre, Daniel Vizman, Emmanuel d’Humières
In this paper we analyze the production of high energy synchrotron gamma photons in laser-plasma interaction for a laser intensity in 1022– 5⋅1023Wcm−2 and a near-critical density target using two dimensional particle-in-cell simulations. In the optimum configuration to maximize the conversion efficiency of the laser energy to γ-photons, we studied the production of electron–positron pairs by the linear
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Adaptive low-temperature plasmas Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-02-06 Michael Keidar
This paper highlights the uniqueness of low-temperature plasma (LTP), that is its ability to change the chemical composition in situ. An adaptive LTP platform is a plasma device that can adjust the plasma composition to obtain optimal desirable outcomes through its interaction with a target. This approach relies on the ability of measuring the real time response of target to plasma action. In biological
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PROTO-SPHERA: a magnetic confinement experiment which emulates the jet + torus astrophysical plasmas Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-02-06 Franco Alladio, Paolo Micozzi, Luca Boncagni, Annamaria Pau, Shayesteh Naghinajad, Samanta Macera, Yacopo Damizia, Paolo Buratti, Francesco Filippi, Giuseppe Galatola Teka, Francesco Giammanco, Edmondo Giovannozzi, Matteo Iafrati, Alessandro Lampasi, Paolo Marsili
The PROTO-SPHERA experiment, built at the CR-ENEA laboratory in Frascati, was in part inspired by the jet + torus astrophysical plasmas, a rather common morphology in Astrophysics. This paper illustrates how the said plasma morphology can be reproduced in a laboratory with the setup of the PROTO-SPHERA experiment. The experiment as such displayed the appearance and sustainment of a plasma torus around
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Model magnetospheric accretion and bipolar jets with intense lasers Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-02-01 Chunqing Xing, Jiayong Zhong, Pengfei Tang, Xu Zhao, Zhe Zhang, Wei Sun, Dawei Yuan, Huigang Wei, Bo Han, Zhu Lei, Huiya Liu, Jun Xiong, Yihang Zhang, Lei Cheng, Yufeng Dong, Jianzhao Wang, Zhimeng Zhang, Jian Teng, Weiming An, Yongli Ping, Bin Qiao, Weimin Zhou, Jianqiang Zhu, Gang Zhao, Jie Zhang
Astronomical observations show that classical T Tauri stars (TTSs) always possess active accretion activity and jet launching. However, limited by high dust opacity and observation resolution, direct investigations of the details are arduous. The physics of the accretion activity and the jet formation is still an open question. In this paper, we carry out the experiment with intense lasers irradiating
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Commissioning of the imaging neutral particle analyser for the ASDEX Upgrade tokamak Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-02-01 J Rueda-Rueda, M Garcia-Munoz, E Viezzer, P A Schneider, J Garcia-Dominguez, P Oyola, J Galdon-Quiroga, J Hidalgo-Salaverri, X Du, M A Van Zeeland, M Videla-Trevin, A Jansen van Vuuren, ASDEX Upgrade Team6
An imaging neutral particle analyser (INPA) diagnostic has been installed and commissioned at the ASDEX Upgrade (AUG) tokamak. The AUG INPA diagnostic provides energy and radially resolved measurements of the fast-ion (FI) distribution, complementing the existing set of diagnostic which measure the confined FI population. To this end, it analyses charge exchange (CX) neutrals produced in reactions
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Effect of nonlinearity, magnetic islands on turbulence and observation of electron energization, temperature anisotropy at Earth’s magnetopause (magnetosphere) Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-01-25 Manoj K Upadhyay, R Uma, R P Sharma
Space missions’ observations have shown that waves such as lower hybrid waves (LHWs), whistler waves, and kinetic Alfven waves play a vital role in magnetic reconnection, turbulence, and particle acceleration. This paper studies the effect of nonlinearity and the magnetic islands on lower hybrid turbulence and current sheets in Earth’s magnetopause region. The evolution of electromagnetic LHW has been
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Numerical eigenanalysis of continuum geodesic acoustic mode by ideal magnetohydrodynamic model Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-01-24 W Guo, J Ma
In this study, we have developed a new eigenvalue code to solve the three-variables ideal magnetohydrodynamic (MHD) equation in flux coordinate system with the help of a symbolic vector analysis module and an automatic numerical discretization module, which were developed with the use of symbolic computation technique and were greatly facilitated the development of toroidal full MHD eigenvalue code
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Influence of electron cyclotron current drive on the transition between normal sawteeth and the stationary state Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-01-24 W J Chen, W Zhang, Z W Ma, H X Zhang, X Wang
The transition between normal sawteeth and a sawtooth-free stationary state after electron cyclotron current drive (ECCD) deposition has been numerically investigated by the CLT code. The periods of normal sawteeth decrease if co-ECCD deposits inside the initial q=1 surface and increase when co-ECCD deposits outside the q=1 surface. When co-ECCD deposits in the vicinity of the q=1 surface, the normal
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Benign termination of runaway electron beams on ASDEX Upgrade and TCV Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-01-23 U Sheikh, J Decker, M Hoppe, M Pedrini, B Sieglin, L Simons, J Cazabonne, J Caloud, J Cerovsky, S Coda, C Colandrea, A Dal Molin, B Duval, O Ficker, M Griener, G Papp, G Pautasso, C Paz-Soldan, C Reux, E Tomesova, T Wijkamp, the ASDEX Upgrade Team, the TCV Team10, the MST1 Team11
This paper discusses the development of a benign termination scenario for runaway electron (RE) beams on ASDEX Upgrade and TCV. A systematic study revealed that a low electron density (n e) companion plasma was required to achieve a large MHD instability, which expelled the confined REs over a large wetted area and allowed for the conversion of magnetic energy to radiation. Control of the companion
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Quasioptical modeling of the electron cyclotron emission diagnostic Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-01-19 K Yanagihara, S Kubo
We report the first applications of the quasioptical (QO) code PARADE (PAraxial RAy DEscription) for modeling the electron cyclotron emission (ECE) diagnostic. Geometrical optics (GO) has been exploited to predict the ECE intensity received by an antenna, but is not sufficient since GO drops the information lying on the transverse cross section of the antenna sensitivity. Hence, we studied a QO model
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Modeling of high-field-side high-density regime in the Globus-M2 tokamak Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-01-19 K Dolgova, E Vekshina, V Rozhansky
Formation of a high-field-side high-density (HFSHD) regime and the role of the high-field-side (HFS) poloidal electric field in the scrape-off layer of the spherical tokamak Globus-M2 are analyzed using SOLPS-ITER edge plasma simulations. The dependence of the HFS poloidal electric field sign and, consequently, radial drift fluxes on the discharge density is discussed. It is demonstrated that the HFS
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Feasibility study of an XPCI diagnostic to observe the evolution of micro-voids in an ICF target Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-01-18 F Barbato, L Savino, A Schiavi, S Atzeni
Bulk perturbations (voids or crystalline structure) inside the ablator of a capsule used for inertial confinement fusion are seeds for instabilities that can hinder the ignition. The study of these defects and their evolution during the implosion is one of the steps needed to achieve fusion. The current methods used by the field are to infer these effects indirectly with measurements of implosion velocity
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The magnetic gradient scale length explains why certain plasmas require close external magnetic coils Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-01-18 John Kappel, Matt Landreman, Dhairya Malhotra
The separation between the last closed flux surface of a plasma and the external coils that magnetically confine it is a limiting factor in the construction of fusion-capable plasma devices. This plasma-coil separation must be large enough so that components such as a breeding blanket and neutron shielding can fit between the plasma and the coils. Plasma-coil separation affects reactor size, engineering
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Kinetic modeling of the plasma–wall interaction in the DTT divertor region Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-01-17 F Cichocki, P Innocente, V Sciortino, P Minelli, F Taccogna
A precise estimate of the local energy fluxes and erosion profiles at the divertor monoblocks of a fusion reactor requires a kinetic modeling of the plasma–wall interaction. Here, a two-dimensional Particle-in-Cell code is used to quantify the particle and energy fluxes and ion impact distribution functions across the divertor monoblocks of the ‘Divertor Tokamak Test’ reactor, focusing on poloidal
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Progress in the development of the ITER baseline scenario in TCV Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-01-17 B Labit, O Sauter, T Pütterich, F Bagnato, Y Camenen, S Coda, C Contré, R Coosemans, F Eriksson, O Février, E Fransson, A N Karpushov, O Krutkin, S Marchioni, A Merle, A Pau, L Piron, M Vallar, S Van Mulders, I Voitsekhovitch, the TCV team8, the MST1 team9, the EUROfusion tokamak exploitation team10
Under the auspices of EUROfusion, the ITER baseline (IBL) scenario has been jointly investigated on AUG and TCV in the past years and this paper reports on the developments on TCV. Three ITER shapes, namely the JET, AUG and ITER IBL have been reproduced in TCV, illustrating that the higher the triangularity the larger the ELM perturbation and the more difficult it is to reach stationary states with
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Data-driven plasma science based plasma etching process design in OLED mass production referring to PI-VM Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-01-16 Seolhye Park, Jaegu Seong, Yoona Park, Yeongil Noh, Haneul Lee, Namjae Bae, Ki-Baek Roh, Rabul Seo, Bongsub Song, Gon-Ho Kim
The production efficiencies of organic light emitting diode (OLED) displays and semiconductor manufacturing have been dramatically improving with the help of plasma physics and engineering technology by utilizing a process monitoring methodology based on physical domain knowledge. This domain knowledge consists of plasma-heating and sheath physics, plasma chemistry, and plasma-material surface reaction
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The first observation of GAM induced by negative biasing in J-TEXT tokamak Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-01-12 Qinghu Yang, Zhipeng Chen, Jinlong Guo, Xin Xu, Zhongyong Chen, Zhoujun Yang, the J-TEXT team1
Recently, the geodesic acoustic modes (GAMs) induced by negative electrode biasing (EB) are first observed in J-TEXT tokamak, and the electrostatic and magnetic fluctuation characteristics of GAMs and ambient turbulence (AT) are measured by combined Langmuir-magnetic probe. Experimental results reveal that with the ramped up negative biasing, the mean flow shear gradually strengthens, and exciting
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Generation of meter-scale hydrogen plasmas and efficient, pump-depletion-limited wakefield excitation using 10 GeV electron bunches Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-01-12 C Zhang, D Storey, P San Miguel Claveria, Z Nie, K A Marsh, M Hogan, W B Mori, E Adli, W An, R Ariniello, G J Cao, C Clarke, S Corde, T Dalichaouch, C E Doss, C Emma, H Ekerfelt, E Gerstmayr, S Gessner, C Hansel, A Knetsch, V Lee, F Li, M Litos, B O’Shea, G White, G Yocky, V Zakharova, C Joshi
High repetition rates and efficient energy transfer to the accelerating beam are important for a future linear collider based on the beam-driven plasma wakefield acceleration scheme (PWFA-LC). This paper reports the first results from the Plasma Wakefield Acceleration Collaboration (E300) that are beginning to address both of these issues using the recently commissioned FACET-II facility at SLAC national
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Improvement of core heat transport in NBI plasmas of heliotron J using high-intensity gas puffing Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-01-11 C Wang, S Kobayashi, K Nagasaki, D Qiu, M Luo, P Zhang, K Y Watanabe, R Seki, A Miyashita, Y Kondo, S Inagaki, F Kin, T Minami, S Kado, S Ohshima, S Konoshima, T Mizuuchi, H Okada
Controlling the heat transport profile is important for high performance in magnetically confined fusion plasmas. In this study, improved electron heat transport was achieved in neutral beam injection plasmas by applying high-intensity gas puffing (HIGP) on a stellarator/heliotron device called Heliotron J. Compared with conventional gas puffing (GP) fueling discharge, a higher and more peaked electron
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Assessing global beryllium erosion via tomographic reconstruction of 3D beryllium emission profiles in ITER Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-01-11 Vladislav S Neverov, Richard A Pitts, Radmir I Khusnutdinov, Andrey G Alekseev, Evgeny N Andreenko, Matthew Carr, Martin Kocan, Maarten De Bock, Alexey V Gorshkov, Andrey M Kozlov, A B Kukushkin, Jack Lovell, Alex Meakins, Anton A Morozov, Evgeny Veshchev
A new method for estimating the global erosion of beryllium (Be) in ITER is proposed. The method uses ray tracing-aided tomography to reconstruct the three-dimensional (3D) profile of beryllium visible-light emissivity in boundary plasma from images captured with filtered cameras of VIS/IR wide angle viewing system, H-alpha (and Visible) Spectroscopy diagnostics and signals collected with divertor
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The radial localization of the transition from low to high confinement mode in the ASDEX Upgrade tokamak Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2024-01-11 M Cavedon, T Happel, P Hennequin, R Dux, K Höfler, U Plank, T Pütterich, U Stroth, E Viezzer, E Wolfrum, the ASDEX Upgrade Team2
A novel experimental method is applied to localize the initial suppression of turbulence, in the form of density fluctuations, at the transition from the low (L-) to the high (H-) confinement mode in toroidal magnetic fusion plasmas. The high radial and temporal resolution, combined with the unprecedented statistical significance, provided the awaited information on a possible dominant E×B shear layer
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Validating the simulation of beam-ion charge exchange in MAST Upgrade Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2023-12-28 P Ollus, S Allan, J R Harrison, A R Jackson, T Kurki-Suonio, K G McClements, C A Michael, D Moulton, B S Patel, M Robson, A Snicker, J Varje, C Vincent, the MAST-U Team6
Simulation of the impact of charge-exchange (CX) reactions on beam ions in the Mega Amp Spherical Tokamak (MAST) Upgrade was compared to measurements carried out with a fission chamber (neutron fluxes) and a fast ion deuterium-alpha (FIDA) diagnostic. A simple model was developed to reconstruct the outer-midplane neutral density based on measurements of deuterium-alpha emission from edge neutrals,
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Initial Fulcher band observations from high resolution spectroscopy in the MAST-U divertor Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2023-12-28 N Osborne, K Verhaegh, M D Bowden, T Wijkamp, N Lonigro, P Ryan, E Pawelec, B Lipschultz, V Soukhanovskii, T van den Biggelaar, the MAST-U Team2
High resolution D2∗ Fulcher band spectroscopy was used in the MAST-U divertors during Super-X and (shorter-legged) elongated divertor density ramps with D2 fuelling from the mid-plane high-field side. In the Super-X case, the upper divertor showed ground state rotational temperatures of the D2 molecules increasing from ~6000 K, starting at the detachment onset, to ~9000 K during deepening detachment
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Scenario optimization for the tokamak ramp-down phase in RAPTOR: Part B. safe termination of DEMO plasmas Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2023-12-27 S Van Mulders, O Sauter, C Contré, E Fable, F Felici, P Manas, M Mattei, F Palermo, M Siccinio, A A Teplukhina
An optimized plasma current ramp-down strategy is critical for safe and fast termination of plasma discharges in a tokamak demonstration fusion reactor (DEMO), both in planned and emergency scenarios, avoiding plasma disruptions and excessive heat loads to the first wall. Plasma stability limits and machine-specific technical requirements constrain the stable envelope through which the plasma must
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Disruption avoidance and investigation of the H-Mode density limit in ASDEX Upgrade Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2023-12-27 B Sieglin, M Maraschek, A Gude, F Klossek, F Felici, M Bernert, O Kudlacek, A Pau, W Treutterer, the ASDEX Upgrade Team3, the EUROfusion WPTE Team4
In recent years a strong effort has been made to investigate disruption avoidance schemes in order to aid the development of integrated operational scenarios for ITER. Within the EUROfusion programme the disruptive H-mode density limit (HDL) has been studied on the WPTE (Work Package Tokamak Exploitation) devices ASDEX Upgrade, TCV and JET. Advanced real-time control coupled with improved real-time
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Scenario optimization for the tokamak ramp-down phase in RAPTOR: Part A. Analysis and model validation on ASDEX Upgrade Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2023-12-27 S Van Mulders, O Sauter, C Contré, F Felici, R Fischer, T Pütterich, B Sieglin, A A Teplukhina, the ASDEX Upgrade Team5
We discuss how the combination of experimental observations and rapid modeling has enabled to improve understanding of the tokamak ramp-down phase in ASDEX Upgrade. A series of dedicated experiments has been performed, to disentangle the effect of individual actuators like plasma current, auxiliary heating and plasma shaping. Optimized discharge termination strategies with increased margin with respect
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Energy gain of wetted-foam implosions with auxiliary heating for inertial fusion studies Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2023-12-27 R W Paddock, T S Li, E Kim, J J Lee, H Martin, R T Ruskov, S Hughes, S J Rose, C D Murphy, R H H Scott, R Bingham, W Garbett, V V Elisseev, B M Haines, A B Zylstra, E M Campbell, C A Thomas, T Goffrey, T D Arber, R Aboushelbaya, M W Von der Leyen, R H W Wang, A A James, I Ouatu, R Timmis, S Howard, E Atonga, P A Norreys
Low convergence ratio implosions (where wetted-foam layers are used to limit capsule convergence, achieving improved robustness to instability growth) and auxiliary heating (where electron beams are used to provide collisionless heating of a hotspot) are two promising techniques that are being explored for inertial fusion energy applications. In this paper, a new analytic study is presented to understand
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Safety factor influence on the edge E × B velocity establishment in tokamak plasmas Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2023-12-22 R Varennes, L Vermare, X Garbet, P Hennequin, G Dif-Pradalier, Y Sarazin, V Grandgirard, O Panico, P Donnel, K Obrejan
This study is motivated by experiments on Tore Supra and WEST tokamaks where a deepening of the E × B velocity—governed by the radial electric field Er —near the edge is observed when the safety factor decreases in L-mode plasmas. Flux-driven global simulations of ion temperature gradient turbulence recover qualitatively the trend observed in the experiments, i.e. the E × B velocity increases when
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High temporal resolution of pedestal dynamics via machine learning on density diagnostics Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2023-12-21 Diogo R Ferreira, Andreas Gillgren, Andrei Ludvig-Osipov, Pär Strand, JET Contributors3
At the Joint European Torus, the reference diagnostic to measure electron density is Thomson scattering. However, this diagnostic has a low sampling rate, which makes it impractical to study the temporal dynamics of fast processes, such as edge localized modes. In this work, we use machine learning to predict the density profile based on data from another diagnostic, namely reflectometry. By learning
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Machine learning techniques for sequential learning engineering design optimisation Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2023-12-21 L R Humphrey, A J Dubas, L C Fletcher, A Davis
When designing a fusion power plant, many first-of-a-kind components are required. This presents a large potential design space across as many dimensions as the component’s parameters. In addition, multiphysics, multiscale, high-fidelity simulations are required to reliably capture a component’s performance under given boundary conditions. Even with high performance computing (HPC) resources, it is
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Identification of MHD modes on EAST using a deep learning framework Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2023-12-20 Lingyi Kong, Bihao Guo, Biao Shen, Tonghui Shi, Dalong Chen, Yao Huang, Qirui Zhang, Bingjia Xiao
The improvement of plasma parameters is severely limited by magnetohydrodynamic (MHD) instabilities. The identification of MHD modes is crucial for the study and control of MHD instabilities. In this study, an MHD mode identifier is developed based on a temporal convolutional network and long short-term memory (LSTM) network. The identifier is trained and tested on a small dataset containing 33 shots
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On scalable liquid-metal MHD solvers for fusion breeder blanket multiphysics applications Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2023-12-20 R W Eardley-Brunt, A J Dubas, A Davis
While substantial research effort has been made recently in the development of computational liquid-metal magnetohydrodynamics (MHD) solvers, this has typically been confined to closed-source and commercial codes. This work aimed to investigate some open-source alternatives. Two OpenFOAM-based MHD solvers, mhdFoam and epotFoam, were found to show strong scaling profiles typical of fluid dynamics codes
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Moment tracking and their coordinate transformations for macroparticles with an application to plasmas around black holes Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2023-12-19 Alexander Warwick, Jonathan Gratus
Particle-in-cell (PIC) codes usually represent large groups of particles as a single macroparticle. These codes are computationally efficient but lose information about the internal structure of the macroparticle. To improve the accuracy of these codes, this work presents a method in which, as well as tracking the macroparticle, the moments of the macroparticle are also tracked. Although the equations
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Experimental evidence of very short power decay lengths in H-mode discharges in the COMPASS tokamak Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2023-12-11 J Hecko, M Komm, M Sos, J Adamek, P Bilkova, K Bogar, P Bohm, F Jaulmes, I Mysiura, M Tomes, P Vondracek, M Hron, R Panek, COMPASS Team14
Analysis of heat fluxes in scrape-off layer (SOL) plasma is important for the prediction of divertor tile heat loads in future reactor-sized tokamak machines. Typically, the radial heat flux profile can be accurately characterized by the decay length parameter λ q . The predictions are then based on the dependence of λ q on plasma and machine parameters. In recent years, several empirical scaling models
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Experimental investigation on magnetic field strength providing thrust saturation in a magnetic nozzle radiofrequency plasma thruster Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2023-12-11 Kazunori Takahashi, Soya Sumikawa
Magnetic field strength applied to a magnetic nozzle radiofrequency (rf) plasma thruster having a 10.5 cm diameter source tube is increased up to about 3 kG by pulsing the solenoid current. A target plate is installed at 30 cm downstream of the source and an impulse bit exerted to the target is measured to assess the thrust, where the thrust balance measurement was impossible due to the interaction
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Structure of the electron temperature profile around the separatrix Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2023-12-08 S Díaz Esteban, M Griener, E Wolfrum, R Fischer, D Wendler, D Stieglitz, C U Schuster, D Silvagni, W Zholobenko, K Lackner, U Stroth, the ASDEX Upgrade Team1
The temperature decay length ( λTe ) in the near scrape-off layer (SOL) reflects the ratio between the transport parallel to the magnetic field lines via Spitzer–Härm electron conduction and the perpendicular mechanisms involving neoclassical and anomalous transport. The implementation of the thermal helium beam diagnostic on ASDEX Upgrade has enabled an excellent spatiotemporal study of the structure
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Hybrid optimization of laser-driven fusion targets and laser profiles Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2023-12-08 Z Li, Z Q Zhao, X H Yang, G B Zhang, Y Y Ma, H Xu, F Y Wu, F Q Shao, J Zhang
Quasi-isentropic compression is an effective method to achieve high-density and high-temperature implosion in laser-driven inertial confinement fusion (ICF). However, it requires precise matching between the laser profile and the target structure. Designing the optimal laser profile and the corresponding target for ICF is a challenge due to the large number of parameters involved. In this paper, we
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Spatiotemporal analysis of the runaway distribution function based on green function and regularization method Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2023-12-06 Sheng Dong, RuiJie Zhou, YongKuan Zhang, ChaoWei Mai, GuoQiang Zhong, ShiYao Lin, LiQun Hu
Runaway electrons (REs) in experimental advanced superconducting tokamak (EAST) typically have an energy level of tens of MeV. Synchrotron radiation images of REs contain a wealth of information, making it crucial to handle this data properly to uncover hidden features. We observed distinct synchrotron radiation images emitted by the REs at different time points throughout the discharges and the focus
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Enhancement of fusion reactivity under non-Maxwellian distributions: effects of drift-ring-beam, slowing-down, and kappa super-thermal distributions Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2023-12-06 Haozhe Kong, Huasheng Xie, Bing Liu, Muzhi Tan, Di Luo, Zhi Li, Jizhong Sun
Non-Maxwellian distributions of particles are commonly observed in fusion studies, especially for magnetic confinement fusion plasmas. The particle distribution has a direct effect on fusion reactivity, which is the focus of this study. We investigate the effects of three types of non-Maxwellian distributions, namely drift-ring-beam, slowing-down, and kappa super-thermal distributions, on the fusion
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Interpretation of ion cyclotron emission from sub-Alfvénic beam-injected ions heated plasmas soon after L-H mode transition in EAST Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2023-12-01 Lunan Liu, Xinjun Zhang, R Ochoukov, Wei Zhang, K G McClements, R O Dendy, M Salewski, Yubao Zhu, Chengming Qin, D Moseev, V Bobkov, B Chapman-Oplopoiou, A Zalzali
Ion cyclotron emission (ICE) at deuterium ion cyclotron harmonics, driven by sub-Alfvénic beam-injected deuterium ions, has been observed by the high-frequency B-dot probe in the EAST tokamak. The origin of ICE shifts from the plasma core to the plasma edge soon after an L-H mode transition, where the beam-injected deuterium ions have a relatively peak bump-on tail structure in the energy direction
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Coherence of turbulent structures with varying drive in stellarator edge plasmas Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2023-12-01 P Huslage, G Birkenmeier, B Shanahan, C Killer
This work investigates the parallel coherence of plasma filaments through numerical simulations using the hot-ion two-fluid hermes-2 model within the BOUT++ framework. Realistic field lines in the scrape-off layer (SOL) of magnetic fusion devices, especially in stellarator configurations possess a highly varying curvature along the magnetic field line. A varying curvature creates a parallel E×B velocity
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Analysis of the neutral fluxes in the divertor region of Wendelstein 7-X under attached and detached conditions using EMC3-EIRENE Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2023-11-27 Dieter Boeyaert, Yuhe Feng, Heinke Frerichs, Thierry Kremeyer, Dirk Naujoks, Felix Reimold, Oliver Schmitz, Victoria Winters, Sergey Bozhenkov, Joris Fellinger, Marcin Jakubowski, Ralf König, Maciej Krychowiak, Valeria Perseo, Georg Schlisio, Uwe Wenzel, the W7-X Team3
This paper analyzes the neutral fluxes in the divertor region of the W7-X standard configuration for different input powers, both under attached and detached conditions. The performed analysis is conducted through EMC3-EIRENE simulations. They show the importance of the horizontal divertor to generate neutrals, and resolve the neutral plugging in the divertor region. Simulations of detached cases show
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Vertical stray field measurements using an electron beam in the MEPhIST-0 tokamak Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2023-11-24 E A Vinitskiy, N E Efimov, A S Prishvitsyn, I A Sorokin, S A Krat
In the MEPhIST-0 tokamak, toroidal magnetic coil system is implemented as a single continuous toroidal solenoid. This design ensures synchronized operation of each segment of the solenoid and requires only one power supply line to operate. However, this configuration has the downside of introducing stray vertical and radial magnetic field components, which result from the inclination of the solenoid
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Interplay of plasma resistivity and rotation on β limits in free boundary diverted tokamaks Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2023-11-21 D Brunetti, J P Graves, C J Ham, S Saarelma
A plasma resistivity-β driving mechanism aimed at explaining the appearance of long wavelength global instabilities in free boundary high-β tokamak plasmas with a divertor is presented. These perturbations resemble very closely the resistive wall mode phenomenon. Performing a proper toroidal analysis, we show that the magnetohydrodynamic stability is worsened by the interplay of plasma β and resistivity
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Analytic Hall magnetohydrodynamics toroidal equilibria via the energy-Casimir variational principle Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2023-11-17 A Giannis, D A Kaltsas, G N Throumoulopoulos
Equilibrium equations for magnetically confined, axisymmetric plasmas are derived by means of the energy-Casimir variational principle in the context of Hall magnetohydrodynamics (MHD). This approach stems from the noncanonical Hamiltonian structure of Hall MHD, the simplest, quasineutral two-fluid model that incorporates contributions due to ion Hall drifts. The axisymmetric Casimir invariants are
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Geometry effects on energy selective focusing of laser-driven protons with open and closed hemisphere-cone targets Plasma Phys. Control. Fusion (IF 2.2) Pub Date : 2023-11-17 M King, A Higginson, C McGuffey, R Wilson, G Schaumann, T Hodge, J B Ohland, S Gales, M P Hill, S F Pitt, C Spindloe, C N Danson, M S Wei, F N Beg, M Roth, D Neely, R J Gray, P McKenna
Relativistically intense laser light interacting with solid density targets can accelerate protons to multi-MeV energies via the target normal sheath acceleration process. The use of hollow hemisphere targets with a hollow conical region to focus protons of selected energies, for applications such as isochoric heating of matter and for the fast ignition approach to inertial confinement fusion, is explored