Numerical analysis on the high frequency characteristics of MILO

Through numerical calculation, the high frequency characteristics of magnetically insulated line oscillator (MILO) coaxial slow wave structure (SWS), the frequencies of the eigen modes and their distributions of coaxial SWS are presented. The sizes of MILO are: the inner radius of the primary SWS and the RF choke 4.6 cm and 4.2 cm, the cathode radius 3 cm. When the frequency in MILO is from 3.6 to 4.4 GHz, the RF chock cavity stops leakage of microwaves toward the pulse power, unexpectedly increases the output power. The cutoff frequency of the primary SWS is from 4.5 to 4.9 GHz. A wave whose frequency is near cutoff is evanescent in the primary SWS. In addition, we calculate the eigen frequencies of MILO with open boundary. The frequencies of 3π/8, π/2, 5π/8, 3π/4 mode achieved in the computer simulation are 3.18, 3.76, 3.93, 4.11 GHz and the corresponding frequencies in "cold" measurement are 3.80, 3.94, 4.08, 4.18 GHz. The experimental results are in accordance with the results of the numerical solution.