A 1-Megawatt CW RF Power Source for 80 MHz

The Fusion Materials Irradiation Test (FMIT) accelerator requires 13 RF amplifiers at 80 MHz, with a CW output of 600 kW each. The EIMAC 8973 (formerly the X-2170) was chosen as the amplifier tube for this application. Never before had the 8973 been operated at this power level and frequency; therefore a test program was initiated to determine its capabilities. The tube was operated Class B in the grounded-grid, grounded-screen configuration. Maximum CW output power was in excess of 1 MW, with a plate efficiency greater than 60% and a 14-dB gain. Details of the test setup and the results will be presented.