HIGH-GRADIENT PHOTONIC BAND-GAP (PBG) STRUCTURE BREAKDOWN TESTING AT Ku-BAND ∗

Photonic Band-gap (PBG) structures continue to be a promising area of research into future accelerator structures. Previous experiments at X-Band have demonstrated that PBG structures can operate at high gradient and low breakdown probability, provided that pulsed heating is controlled. Two single-cell standing-wave structures have been constructed at MIT to investigate breakdown performance of PBG structures. A metallic structure with small round rods will be used to intentionally test performance with very high surface temperature rise, while an over-moded structure with dielectric rods will investigate alternative solutions to the issue of surface temperature rise. Both structures are expected to reach gradients of at least 100 MV/m and will utilize novel diagnostics, including fast camera imaging and optical spectroscopy of breakdowns.