Three dimensional analysis and simulation of wide-aperture input cavities for klystron amplifier

The wide-aperture input cavities with three coupling structures are addressed, and the field distributions of the cold cavities and beam modulation after the electron beams propagate through the input cavity gaps are analyzed. The results show that the fields with single scallop coupling hole and annular coupling hole in operation mode are more uniform than that with double-scallop coupling hole. For large scale drift tubes, the loaded quality factors of the input cavity with annular coupling hole are lower than those with single scallop coupling hole, and the cavity with annular coupling hole matches well with input waveguides. With the same input microwave power, the beam modulation and the power absorption from driving microwaves in the annular coupling hole input cavity are better than