Breakdown Characterization in 805 MHz Pillbox-like Cavity in Strong Magnetic Fields

RF Breakdown in strong magnetic fields has a negative impact on a cavity performance. The MuCool Test Area at Fermilab has unique capabilities that that allow us to study the eects of static magnetic field on RF cavity operation. We have tested an 805 MHz pillbox-like cavity in external magnetic fields up to 5 T. Results confirm our basic model of breakdown in strong magnetic fields. We have measured maximum achievable surface gradient dependence on external static magnetic field. Damage inspection of cavity walls revealed a unique observed breakdown pattern. We present the analysis of breakdown damage distribution and propose the hypothesis to explain certain features of this distribution.