Results and lessons learned from conditioning 1 MW CW 350 MHz coaxial vacuum windows

The reliability of the radio frequency (RF) windows on the Low Energy Demonstration Accelerator (LEDA) is critical to the success of the Accelerator Production of Tritium Program (APT). On the APT accelerator there will be over 1,000 windows, each passing on the order of 250 kW of CW RF power. This power level is well above power levels historically used in RF windows. Based on the high-power RF test results of the RF window prototypes from vendors, the coaxial windows made by EEV Ltd. of Chelmsford, England, were selected for LEDA. This paper describes the high-power RF testing of the 16 EEV coaxial windows. The RF window diagnostic equipment, data acquisition system and test stand are described. The results of the high power RF testing of the windows are presented. The successes and failures in the conditioning, manufacturing and testing techniques of the windows are presented. The conditioning timeline, power profile and the conditioning waveform are also discussed