Dual-frequency 19 / 38 GHz MW Gyrotron Design for Spherical Tokamak

In spherical tokamaks, the magnetic field is strongly non-uniform inside the plasma, so the electron-cyclotron resonance heating (ECRH) condition is fulfilled only in small volume for fixed microwave frequency. Therefore, for spherical tokamak facilities the plasma heating and confinement regime depends on the position of ECRH area. For this purpose, the gyrotron capable for CW operation with output power of 1 MW at two different frequencies of 19 GHz and 38 GHz is designed.