Optimization of a Cusp Gun With a Grid for a Terahertz Gyrotron Traveling-Wave Amplifier

A magnetic cusp gun with a control grid was optimized through parametric simulations for a gyrotron traveling-wave amplifier with an output power of 10 kW and a central operating frequency of 220 GHz. The ON and OFF of the electron beam are controlled by applying appropriate biases to the grid. An axis-encircling electron beam of current 1.5 A, a pitch factor of 1.23, and a relative pitch-factor spread of ~3.5% were predicted when the gun was operated at 70 kV.