Thin RF Windows for High-Pressure Gas-Filled Cavities

RF cavities for muon ionization cooling channels can be separated by RF windows to improve the internal voltage profile in each cavity and to make the cavities independent of each other. The window material must be sufficiently transparent to muons so as not to affect the beam cooling. The windows should thus be thin and made of a low-Z material. A thin, flat, beryllium window was studied in order to improve the performance of pressurized RF cavities. Electromagnetic analysis was performed to solve for the fields, frequency, quality factor, and RF power loss density. Natural convection analysis of the gas within the cavity was performed to solve for the gas temperature and the gas film coefficient. Thermal analysis of the window was performed to determine its temperature profile. For the case of pressurized RF cavities, in contrast to those that operate in vacuum, thinner and simpler window designs can be used. This is due to the external gas cooling of the window.