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Using an alpha magnet to compress the electron bunches from a photocathode RF gun

Research paper by A. Rajabi, A.R. Niknam B. Shokri

Indexed on: 25 Oct '19Published on: 20 Oct '19Published in: Journal of instrumentation : an IOP and SISSA journal



Abstract

We report here the design, simulation, and characterization of a compact electron injector for the formation of high-current, femtosecond electron bunches from a photocathode RF gun without mandatory use of ultra-short laser pulses and a high power RF supply. The proposed injector consists of a 1.6-cell S-band photocathode RF gun to produce the electron beam and a small bunch compressor to increase the peak current. The RF gun is designed to operate at a 65 MV/m accelerating field gradient, and the bunch compressor is a small α-magnet with a maximum magnetic field gradient of 340 G/cm. The output beam from the gun has 100 pC charge per-bunch that is equivalent to a beam current of ~15 A, and output beam from the injector has an RMS bunch length of ~ 439 fs, a peak current of 0~ 12 A and an RMS normalized horizontal emittance of 1.21 mm-mrad.