Design of Magnetron Injection Gun and Solenoid for G-Band Gyro-TWT Based on Collaborative Optimization Method

In this article, a collaborative design method for gyrotron magnetron injection gun (MIG) and solenoid is proposed for the first time. On this basis, the shape of the electrodes and solenoid sizes is optimized by the means of global optimization techniques. Simplified theory and numerical methods of MIG have been developed, and the results agree well with the PIC simulation. By using the new method, the calculation time is reduced and the numerical stability has been greatly improved compared with that directly solving the Lorentz equation. As an example, a helical electron beam with a velocity pitch ratio of 1.20 and a transverse velocity spread of 1.65% is obtained for G-band gyro-TWT.