Coherent Synchrotron Radiation Simulation for CBETA (original) (raw)
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The compact STorage ring for Accelerator Research and Technology (cSTART) project aims to store electron bunches of LWFA-like beams in a very large momentum acceptance storage ring. The project will be realized at the Karlsruhe Institute of Technology (KIT, Germany). Initially, the Ferninfrarot Linac- Und Test-Experiment (FLUTE), a source of ultra-short bunches, will serve as an injector for cSTART to benchmark and emulate laser-wakefield accelerator-like beams. In a second stage a laser-plasma accelerator will be used as an injector, which is being developed as part of the ATHENA project in collaboration with DESY and Helmholtz Institute Jena (HIJ). With an energy of 50 MeV and damping times of several seconds, the electron beam does not reach equilibrium emittance. Furthermore, the critical frequency of synchrotron radiation is 50 THz and in the same order as the bunch spectrum, which implies that the entire bunch radiates coherently. We perform longitudinal particle tracking simu...
Physical Review Special Topics - Accelerators and Beams, 2015
In an experiment conducted on the Jefferson Laboratory IR free-electron laser driver, the effects of coherent synchrotron radiation (CSR) on beam quality were studied. The primary goal of this work was to explore CSR output and effect on the beam with variation of the bunch compression in the IR recirculator. Here we examine the impact of CSR on the average energy loss as a function of bunch compression as well as the impact of CSR on the energy spectrum of the bunch. Simulation of beam dynamics in the machine, including the one-dimensional CSR model, shows very good agreement with the measured effect of CSR on the average energy loss as a function of compression. Finally, a well-defined structure is observed in the energy spectrum with a feature in the spectrum that varies as a function of the compression. This effect is examined in simulations, as well, and a simple explanation for the variation is proposed.
Start to End Simulation of the CBETA Energy Recovery Linac
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CBETA is an energy recovery linac accelerating from 6 MeV to 150 MeV in four linac passes, using a single return line accepting all energies from 42 MeV to 150 MeV. We simulate a 6-dimensional particle distribution from the injector through the end of the dump line. Space charge forces are taken into account at the low energy stages. We compare results using field maps to those using simpler magnet models. We introduce random and systematic magnet errors to the lattice, apply orbit correction algorithm, and study the impact on the beam distribution.
Compensating effect of the coherent synchrotron radiation in bunch compressors
Typical bunch compression for a high-gain free-electron laser (FEL) requires a large compression ratio. Frequently, this compression is distributed in multiple stages along the beam transport line. However, for a high-gain FEL driven by an energy recovery linac (ERL), compression must be accomplished in a single strong compressor located at the beam line's end; otherwise the electron beam would be affected severely by coherent synchrotron radiation (CSR) in the ERL's arcs. In such a scheme, the CSR originating from the strong compressors could greatly degrade the quality of the electron beam. In this paper, we present our design for a bunch compressor that will limit the effect of CSR on the e-beam's quality. We discuss our findings from a study of such a compressor, and detail its potential for an FEL driven by a multipass ERL developed for the electron-Relativistic Heavy Ion Collider.
Emittance growth and energy loss due to coherent synchrotron radiation in a bunch compressor
Physical Review Special Topics-accelerators and Beams, 2000
Bunches of high charge (10 nC) are compressed in length in the CTF II bunch compressor from 1.2 mm rms to less than 0.4 mm. The short bunches start to radiate coherently, thus affecting the horizontal and longitudinal phase spaces of the beam. This paper reports the results of measurements and simulations concerning the increase of the beam emittance and the impact on the energy distribution. Beam emittances were measured for different bunch compression factors and bunch charges. For each compressor setting, the energy spectrum of the beam was recorded in order to measure the energy loss due to coherent synchrotron radiation. For bunch charges of 10 nC a maximum increase of the horizontal emittance of 50% was observed at full compression, while the mean beam energy decreased by 5% from 39 MeV to 37 MeV. Both effects were correlated with an increase of the energy spread from 2.3% to 8.5% rms. The experimental results are compared with simulations.
Intensity limitations due to space charge for bunch compression in synchrotrons
Physical Review Accelerators and Beams, 2018
Bunch compression achieved via a fast bunch rotation in longitudinal phase space is a well-accepted scheme to generate short, intense ion bunches for various applications. During bunch compression, coherent beam instabilities and incoherent single particle resonances can occur because of increasing space charge, resulting in an important limitation for the bunch intensity. We present an analysis of the relevant space charge driven beam instability and resonance phenomena during bunch compression. A coupled longitudinal-transverse envelope approach is compared with particle-in-cell (PIC) simulations. Two distinct cases of crossing are discussed and applied to the GSI SIS-18 heavy-ion synchrotron. It is shown that during bunch compression, the 90°condition of phase advance is associated with a fourth order single particle resonance and the 120°condition with the recently discovered dispersion-induced instability. The agreement between the envelope and PIC results indicates that the stop band is defined by the 120°d ispersion instability, which should be avoided during bunch compression.
CoSyR: a novel beam dynamics code for the modeling of synchrotron radiation effects
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The self-consistent nonlinear dynamics of a relativistic charged particle beam interacting with its complete self-fields is a fundamental problem underpinning many of the accelerator design issues in high brightness beam applications, as well as the development of advanced accelerators. Particularly, synchrotron radiation induced effects in a magnetic dispersive beamline element can lead to collective beam instabilities and emittance growth. A novel beam dynamic code is developed based on a Lagrangian method for the calculation of the particles’ radiation near-fields using wavefront/wavelet meshes via the Green’s function of the Maxwell equations. These fields are then interpolated onto a moving mesh for dynamic update of the beam. This method allows radiation co-propagation and selfconsistent interaction with the beam in the simulation at greatly reduced numerical errors. Multiple levels of parallelisms are inherent in this method and implemented in our code CoSyR to enable at-scal...
Simulations of Jitter Coupling due to Wakefields in the FACET Linac
2009
Facilities for Accelerator Science and Experimental Test Beams (FACET) is a proposed facility at SLAC that would use the initial twothirds of the linac to transport e+ and e-beams to an experimental region. A principal use of this facility is to identify the optimum method for accelerating positrons in a beam driven plasma wakefield accelerator. To study this, a positron bunch, followed an RF-cycle later by an electron bunch, will be accelerated to an asymmetric chicane designed to move the positrons behind the electrons, and then on to the plasma wakefield test stand. A major focus of study was the coupling of jitter of the positron bunch to the electron bunch via linac wakes.
COHERENT SYNCHROTRON RADIATION INDUCED EMITTANCE GROWTH IN A CHICANE BUNCHER
1998
Short high-current microbunches are of considerable importance for future linear colliders and electron beam sources of coherent radiation such as x-ray free-electron lasers. There is recent interest in beam degradation associated with the transport of short high-current electron beams in magnetic bends and bunchers. We compare the observed emittance growth in an existing magnetic buncher system at Boeing with that calculated when coherent synchrotron radiation (CSR) effects are included, and conclude that the CSR effects are significant. 1891 0-7803-4376-X/98/$10.00