Study on Photonic Crystal Cavity for Harmonic Multiplying Gyroklystron using Axis-encircling Electron Beam

Photonic band structure is employed in the second stage using the concept of photonic bandgap (PBG) to overcome mode competition and the limited beam propagation in harmonic multiplication devices. When the line defect is made inside of PBG structure it works as cavity excited by single mode. If suitable PBG condition for the cyclotron maser instability with higher beam harmonics is found, gyroklystron can be operated in single high order mode without mode competition. The numerical simulation using MAGIC code is carried out in two-stage harmonic multiplying gyroklystron