Performance Tests of the 600-kW cw, 80-MHz, Radio-Frequency Systems for the FMIT Accelerator

The high-power rf system for the Fusion Materials Irradiation Test (FMIT) accelerator consists of 14 sets of equipment,** each of which can deliver up to 600 kW (cw) at 80 MHz into a load having a VSWR of 1.4 or less (any phase). The equipment was designed and constructed to FMIT specifications by Continental Electronics Mfg. Co. (CEMC) of Dallas, Texas. Four sets have been shipped to Los Alamos for use with the accelerator [two with the radio-frequency quadrupole (RFQ) and two with the drift-tube linac (DTL)]. The first set was fully tested at CEMC; results are summarized in Table I. Further tests conducted at Los Alamos, both into a resistive (electrolytic) load and into a resonant cavity (Q ~ 21 000), have confirmed that this system meets, and in most cases far exceeds, the specified performance limits. The first of the 13 production sets (No. 5) also was tested at CEMC before shipping any of the rf equipment to the Hanford Engineering and Development Laboratory at Richland, Washington. Because of the differences in behavior observed when No. 1 was operated at Los Alamos with a different tube installed in the final power amplifier (FPA) cavity, CEMC agreed to test No. 5 with two tubes having widely differing characteristics (notably primary screen emission). As expected, behavior differed markedly, and some design modification was necessary to meet all specifications with either tube. Results of final performance tests on No. 5 are summarized in Table I also.