Cusp electron gun with modulation electrode for a THz gyro-amplifier

A terahertz gyrotron traveling wave amplifier (gyro-TWA) centered at 370GHz is under development for the electron paramagnetic resonance (EPR) imaging application. This paper reports the investigation of a triode-type cusp electron gun for the terahertz gyro-TWA. The simulation results showed that at the beam alpha (the ratio of transverse to axial velocity) center of 1.07, an optimal alpha spread of ~10% was achieved, when it was operated at a beam voltage of 50 kV and a beam current of 0.35 A.