In order to understand breakdown characteristic of the photonic band-gap(PBG) structures working at high power and high repetition rate

the PBG accelerator structure is simulated and analyzed at X band(11.424 GHz) in this paper.The results show that the E/H value of the PBG accelerating structure with ronnd metallic inner rods is at 240

and its T value is at 300 K.By replacing the ronnd inner rods with oval-shaped metal rods

the peak E/H value increases by 140 and the T value decreases by 150 K.The electromagnetic field of a new quasi-PBG accelerating structure is simulated

too

with the Q value of over 10000 and E/H = 570.Because of the inner Al2O3 ceramic rods

it is a structure of high gradient acceleration.