This paper describes a novel scheme for correcting the second order (chromatic sextupole) magnet lattice and its deployment on a fourth generation Multi-Bend Achromat electron storage ring. The method is analogous to the well-established LOCO scheme, but uses an off-energy orbit response matrix to characterise the second order optics of a lattice. The matrix is constructed from the difference between

The typical treatment of time-dependent potentials, such as those used for radio frequency cavities, is to average a potential’s time component through the interval that a reference particle spends in the cavity. Such an approach, using the so-called transit-time factor, uses time as the independent variable in the Hamiltonian. In this paper, we instead propose a fully covariant Hamiltonian to treat

Optics measurements at the LHC are mainly based on turn-by-turn signal from hundreds of beam position monitors (BPMs). Faulty BPMs produce erroneous signal causing unreliable computation of optics functions. Therefore, detection of faulty BPMs prior to optics computation is crucial for adequate optics analysis. Most of the faults can be removed by applying traditional cleaning techniques. However,

At the X-ray free-electron laser SwissFEL, at the Paul Scherrer Institute, Switzerland, beam loss monitors are used to determine loss positions along the linear accelerator and protect critical elements such as the undulator magnets from excess radiation. These monitors are integrated into the machine protection system (MPS) allowing beam losses to be limited by dynamically reducing the repetition

We model the effect of ground movement, based on empirical experience, on the transport properties of long neutron guides by ray-tracing simulations. For a simple model, our results reproduce the large losses found by an earlier study, while for a more realistic engineering model of guide mounting, we find the losses to be significantly smaller. A detailed study of the guide for the cold neutron spectrometer

Generation of extremely bright, coherent synchrotron radiation in a short wavelength range is of remarkable interest in the synchrotron light source community. In this paper, a novel technique is adopted to produce coherent radiation, which uses an angular dispersion mechanism to enhance the microbunching of electrons by introducing a slight energy modulation in the long straight section of the storage

X-ray free electron laser oscillators (XFELOs) are future light sources that produce fully coherent hard X-ray pulses. Based on the low-gain principle, XFELO traps X-ray pulses in an optical cavity composed of multiple Bragg-reflecting mirrors that have high reflectivity in a bandwidth about ten meV. The crystal mirrors exposed to intense X-ray beams in the optical cavity are subject to thermal deformations

CsxKySb photocathodes grown on GaAs and molybdenum substrates were evaluated using a -300 kV dc high voltage photogun and diagnostic beamline. Photocathodes grown on GaAs substrates with varying antimony layer thickness (estimated range from 1 um) yielded similar thermal emittance per rms laser spot size values (~ 0.4 mm mrad/mm) but very different operating lifetime. Similar thermal emittance was

Beam intensity, proton fraction and beam emittance represent the most important characteristics of a beam extracted by a proton source. Beam parameters are strongly related to the parameters of the plasma from whom the beam is extracted. The recent improvement of plasma diagnostics devoted to compact ion sources, and in particular the development of the optical emission spectroscopy, allows an ever

As the highest power proton linear accelerator (linac) in continuous wave (CW) mode, China initiative Accelerator Driven sub-critical System (CiADS) linac will deliver 2.5 MW proton beam to the target inside the reactor. Vacuum transition from 5×104 Pa to 1×10−6 Pa is required at the Accelerator to Target (A2T) section. A vacuum differential system (VDS) located at the High Energy Beam Transport (HEBT)

Space charge is typically one of the performance limitations for the operation of high intensity and high brightness beams in circular accelerators. In the Proton Synchrotron (PS) at CERN, losses are observed for vertical tunes above Qy=6.25, especially for beams with large space charge tune shift. The work presented here shows that this behaviour is associated to structure resonances excited by space

Operation of particle accelerators and correction of unavoidable magnet or alignment errors critically depend on the assessment of both global and local observables such as tune or resonance driving terms. With most of the observables being a sum of different error sources, careful disentangling is necessary in order to establish an optimal correction and allow for smooth operation. In the LHC, linear

A 200 MeV, 10 mA, Medium Energy High Intensity Proton Accelerator (MEHIPA) is proposed to form the second stage of the Indian ADS programme. The linac consists of a normal conducting 3 MeV Radio Frequency Quadrupole (RFQ) and a 200 MeV superconducting section consisting of three different families of Single Spoke Resonators (SSR-A, SSR-B, and SSR-C). Here we discuss a detailed physics design of MEHIPA

In a storage ring, turn-to-turn fluctuations in the intensity of spontaneous synchrotron radiation occur due to two mechanisms. The first mechanism is the quantum uncertainty in the number of emitted photons. The second mechanism is the turn-to-turn variations in the relative positions of classical point-like electrons in the bunch. We present a unified description of both effects in the framework

The energy spread of the electron beam is a critical parameter in X-ray free-electron lasers (XFELs) and needs to be optimized for best performance. The uncorrelated energy spread of the electrons can be a few keV or less in XFEL injectors, thus very challenging to measure. The standard method to characterize the electron beam energy spread, consisting in streaking the beam with a transverse deflector

We report on the stable and continuous operation of a kilohertz laser-plasma accelerator. Electron bunches with 2.6,pC charge and 2.5,MeV peak energy were generated via injection and trapping in a downward plasma density ramp. This density transition was produced in a specially designed asymmetrically shocked gas jet. The reproducibility of the electron source was also assessed over a period of a week

In this paper, we derive the longitudinal and transverse resistive wall impedance for a beam traveling in a round pipe with $v

Laser and beam driven wakefields promise orders of magnitude increases in electric field gradients for particle accelerators for future applications. Key areas to explore include the emittance properties of the generated beams and overcoming the dephasing limit in the plasma. In this paper, the first in-depth study of the self-injection mechanism into wakefield structures from non-homogeneous cluster

The beam impedance of a ceramic break with titanium nitride (TiN) coating consists of three electric components in parallel : resistive wall term caused by TiN, radiation term, and capacitive term made by the ceramic itself. The entire wall current continues to run in the thin TiN even when the skin depth is much larger than the chamber thickness, except for the extremely thin TiN satisfying the condition

A Linear Transformer Driver (LTD) generator capable of delivering up to 0.9 MA current pulses with 160 ns rise time has been assembled and commissioned at UC San Diego. The machine is an upgrade of the LTD-III pulser from Sandia National Laboratories, consisting of 40 capacitors and 20 spark gap switches, arranged in a 20-brick configuration. The driver was modified with the addition of a new trigger

The determination of dynamic aperture in storage rings and colliders is a numerically intensive procedure. When realistic space-charge forces come into consideration, the numerical load becomes even heavier. Furthermore, dynamic aperture estimation using chaos indicators like frequency map analysis~(FMA) raises reliability issues when the dynamical system has a time-dependent perturbation like the

Hydrodynamic optically-field-ionized (HOFI) plasma channels up to long are investigated. Optical guiding is demonstrated of laser pulses with a peak input intensity of $\SI{6E17}{W.cm^{-2}}$ through long plasma channels with on-axis densities measured interferometrically to be as low as $n_{e0} = \SI[separate-uncertainty=true]{1.0(3)e17}{cm^{-3}}$. Guiding is also observed at lower axial densities

A novel approach for positron injection and acceleration in laser driven plasma wakefield is proposed. One ring-shaped beam and one co-axially propagating Gaussian beam drive wakefields in a preformed plasma volume filled with both electrons and positrons. The laser’s ponderomotive force as well as the charge separation force in the front bucket of the first bubble are utilized to provide the transverse

We present a linearized method to study transverse instabilities due to electron clouds. It is based on an accurate and compact characterization of the cloud dipolar and quadrupolar forces, that can be easily obtained from quick single-pass numerical simulations. The long-term stability properties of the bunch are then predicted by solving the linearized Vlasov equation, taking into account the dipolar

Multiobjective genetic algorithms (MOGAs) have proven to be powerful in solving multiobjective problems in the accelerator field. Nevertheless, for explorative problems that have many variables and local optima, the performance of MOGA is not always satisfactory, especially when a small population size is used due to practical limitations, e.g., limited computing resources. To deal with this challenge

Electron cloud is a critical phenomenon in particle accelerators operating with high intensity and positively charged beams, as it is responsible for beam instabilities, vacuum degradation, and heat load on cryogenic sections. Electron clouds provoke a conditioning of the beam pipe that is reflected on the reduction of its Secondary Electron Yield (SEY). However, such a benefit is partially lost when

This paper presents a method that uses a gap scan of the phase shifter to optimize the intensity of a free-electron laser (FEL) by matching its phase with that of the electron beam. Phase shifters are essential instruments especially for a long undulator line, which is segmented by drift sections. The phase-matched (in-phase), and the 180 off-set (out-of-phase) conditions are investigated using linear

Two-dimensional electromagnetic (EM) particle-in-cell (PIC) simulations of a radial magnetically-insulated-transmission-line are presented and compared to the model of E. M. Waisman, M. P. Desjarlais, and M. E. Cuneo [Phys. Rev. Accel. Beams 22, 030402 (2019)] in the "high-enhancement’’ (WDC-HE) limit. The simulations use quasi-equilibrium current and voltage values based on the Sandia National Laboratories

A novel high-gradient accelerating structure with low phase velocity, v/c=0.38, has been designed, manufactured and high-power tested. The structure was designed and built using the methodology and technology developed for CLIC 100 MV/m high-gradient accelerating structures, which have speed of light phase velocity, but adapts them to a structure for non-relativistic particles. The parameters of the

An energy of $\unit[362]{MJ}$ is stored in each of the two LHC proton beams for nominal beam parameters. This will be further increased to about $\unit[700]{MJ}$ in the future High Luminosity LHC (HL-LHC) and uncontrolled beam losses represent a significant hazard for the integrity and safe operation of the machine. In this paper, a number of failure mechanisms that can lead to a fast increase of beam

The Advanced Photon Source plans to upgrade to a multi-bend achromat (MBA) lattice that will dramatically decrease the electron beam emittance, thereby enhancing the X-ray brightness by two to three orders of magnitude. Electron beam focusing in the MBA requires small-aperture vacuum components that must also have a small impedance so as to minimize rf-heating and collective instabilities. As part