加速器物理
FEM simulations are a standard step in the design of accelerator magnets. It is custom for accelerator applications to characterize the field quality in terms of field expansion coefficients. With a commonly accepted approach, expansion…
The snapshot model of crystal atoms was implemented in the Monte Carlo code ChaS (Channeling Simulator) and is being successfully used for simulation of ultrarelativistic particle channeling. The model was criticized by Sushko et al. (J.…
Simulations of electron and positron channelling in a crystalline undulator with a small amplitude and a short period (A Kostyuk, Phys. Rev. Lett. 110 (2013) 115503) were repeated by V G Bezchastnov, A V Korol and A V Solov'yov (J. Phys. B:…
The analytical expression of the magnetic field distribution within the aperture of a circular vacuum chamber due to the induced eddy is derived. Two cases are discussed, one is the absence of iron, the other is that the vacuum chamber is…
The fast beam-ion instability (FII) is caused by the interaction of an electron bunch train with the residual gas ions. The ion oscillations in the potential well of the electron beam have an inherent frequency spread due to the nonlinear…
A high peak current, flat longitudinal phase space electron beam is desirable for efficient x-ray free electron laser (FEL) radiation in next generation light sources. To attain such a beam requires the extensive design of the linear…
A fast-switching, high-repetition-rate magnet and power supply have been developed for and operated at TRIUMF, to deliver a proton beam to the new ultracold neutron (UCN) facility. The facility possesses unique operational requirements: a…
Radio Frequency Quadrupole (RFQ) accelerators often need to face the challenges of space charge effects from high beam currents. This study investigated how to reach RFQ beam dynamics designs with not only high beam transmission and short…
Muon colliders and neutrino factories are attractive options for future facilities aimed at achieving the highest lepton-antilepton collision energies and precision measurements of parameters of the Higgs boson and the neutrino mixing…
At the end of the Large Hadron Collider's Run 2, CERN's Proton Injector Linac 2, commissioned in 1978, delivered its final beam in December 2018. For Run 3, from March 2021, a new H$^{-}$ will take over the role: Linac4. The machine has…
Sirius is a Synchrotron Light Source Facility based on a 4th generation low emittance storage ring. The facility is presently in the final assembly phase in Campinas, Brazil, and comprises a 3 GeV electron storage ring, a full energy…
Superconducting cavities (SRF) are widely used in new generation particle accelerators, increasing the requirements and specifications for new designs. The LLRF control system, including the detuning control due to mechanical perturbations,…
A longitudinal coupled bunch mode diagnostic was built to identify and characterize coupled bunch modes in the Max IV 3 GeV ring. A longitudinal coupled bunch Mode 0 dipole instability was identified and a longitudinal Mode 0 dipole damper…
Radiation of charged particles passing through a set of equidistant ridges on the surface of a single crystal is calculated. The ridges are rectangular in shape, each of thickness of half of the particle trajectory period at planar…
We have commissioned the digital Low Level RF (LLRF) system for storage ring RF at Advanced Light Source at Lawrence Berkeley National Lab (LBNL). The system is composed of 42 synchronous sampling channels for feedback control, diagnostics,…
The J-PARC Main Ring (MR) has achieved the delivery of the 30 GeV proton beam with the beam power of 500 kW to the neutrino experiment in May 2018. The longitudinal coupled-bunch instabilities have been observed in the MR for the beam power…
The ISIS synchrotron at the Rutherford Appleton Laboratory in the UK now routinely uses a dual harmonic RF system to accelerate beam currents in excess of 230uA to run two target stations simultaneously. The acceleration in the ISIS…
The coax based MO distribution system in the ALS is going to be replaced by a modernized, lower phase noise and more interference tolerant version, ready to support ALS-U operation. System aspects are shown and several commercial analog and…
The radiation pressure inside an RF cavity resonator, resulting from the Lorentz force, couples the fundamental electromagnetic mode to the mechanical modes and may lead to static and dynamic ponderomotive instability. The analysis for…
We report on the progress in modelling performance of the H- ion source at LANSCE. The key aspect we address is the lifetime of the tungsten filament. The lifetime depends on multiple parameters of the ion source and can dramatically vary…