Design and Simulation of a Cusp Gun for Gyro-Amplifier Application in High Frequency RF Accelerators

D.H. Rowlands, W. He, C.G. Whyte, A.R. Young, A.W. Cross, A.D.R. Phelps, E.G. Rafferty, C.W. Robertson, K. Ronald and J. Thomson

Gyro-amplifiers have potential as the high frequency RF drivers for particle accelerators. They require relativistic electron beams with low velocity spread and with a high fraction of the electron energy associated with the cyclotron motion. For harmonic operation and mode control an axis-encircling beam is desirable. The passage of an electron beam through a non-adiabatic magnetic field reversal (cusp) converts part of the electron beam’s axial velocity into axis-encircling transverse velocity. A cusp-based electron beam forming system, yielding a 10MW, 150kV, 70A axis-encircling beam will be presented. This cusp gun is being designed as the electron beam source for a microwave gyro-amplifier that is relevant for high frequency accelerator applications. The latest results from numerical simulations and experiments are presented and compared.

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