The design and simulation of a thermionic cusp-based axis-encircling electron beam for use in harmonic gyro-devices

A thermionic cusp gun is proposed for use in a 3 MW second harmonic X-band gyro-TWA with a helically corrugated waveguide interaction region. The passage of an electron beam through a non-adiabatic magnetic field reversal converts part of the electron beam's axial velocity into axis-encircling transverse velocity. The paper presents the design and simulation of this cusp based electron beam forming system, yielding a 10 MW, 83 A axis encircling beam with an axial velocity spread /spl Delta/v/sub z/<16% suitable for use in harmonic gyro-devices.