Studies of RF Breakdown of Metals in Dense Gases

A study of RF breakdown of metals in gases has begun as part of a program to develop RF cavities filled with dense hydrogen gas to be used for muon ionization cooling. A pressurized 805 MHz test cell is being used at Fermilab to compare the conditioning and breakdown behavior of copper, molybdenum, chromium, and beryllium electrodes as functions of hydrogen and helium gas densities. These results will be compared to the predicted or known RF breakdown behavior of these metals in vacuum.