Microbunching may occur at short wavelengths where the longitudinal space-charge wakes dominate or at longer wavelengths dominated by edge radiation. Formulas are also obtained for the jitter in themore » bunch arrival time downstream of the compressors that results from the bunch-to-bunch variation of current, energy, and chirp. For this case, we calculate the minimum initial bunch length that can be compressed without producing an upright tail in phase space and associated current spike. For macroscopic wavelengths, impedance formulas and tracking simulations show that the wakefields can be dominated by the resistive impedance of coherent edge radiation. The longitudinal wakes affect the macroscopic energy and current profiles of the compressed bunch and cause microbunching at short wavelengths. In a two-stage compression and acceleration system, where each stage compresses a chirped bunch in a magnetic chicane, wakefields affect high-current bunches. Modeling Two-Stage Bunch Compression With Wakefields: Macroscopic Properties And Microbunching Instabilityīosch, R.A.
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Benson, Stephen Nguyen, Dinh Cong Tennant, Christopher Wilson, GuyĪ method of bunch length compression method for a free electron laser (FEL) that avoids parasitic compressions by 1) applying acceleration on the falling portion of the RF waveform, 2) compressing using a positive momentum compaction (R.sub.56>0), and 3) compensating for aberration by using nonlinear magnets in the compressor beam line.
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Details of the study and results leading to an optimum condition for our system will be presented.īunch length compression method for free electron lasers to avoid parasitic compressionsĭouglas, David R. The particle distribution at the RF-gun exit will be tracked numerically through the alpha- magnet and beam transport. Via beam dynamics calculations and experiments, we investigate the bunch compression efficiency for various RF-gun fields. To obtain effective bunch compression, it is crucial to provide a proper longitudinal phase-space distribution at the gun exit matched to the subsequent beam transport system. Ultra-short electron bunches can be produced with a bunch compression system consisting of a thermionic cathode RF-gun, an alpha- magnet as a magnetic bunch compressor, and a linear accelerator as a post acceleration section. Saisut, J.Ī femtosecond electron source has been developed at the Plasma and Beam Physics Research Facility (PBP), Chiang Mai University (CMU), Thailand. Bunch compression efficiency of the femtosecond electron source at Chiang Mai University