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

Authors
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

Abstract
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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