First JT-60 high power 110 to 130 MHz test results with an X2242 tetrode

Tests of the X2242 were run in the JAERI (Japan Atomic Energy Research Institute) Tokamak-60 (JT-60) ICRF (ion cyclotron range of frequencies) system. The tests evaluated this newly developed tetrode´s performance under conditions relevant to the planned CIT (Compact Ignition Tokamak) and JT-60U (JT-60 Upgrade) ICRF systems. The behavior of a large high-power tube at frequencies above 100 MHz was also studied. Complete instrumentation was provided, including an acoustic monitor that senses boiling at the tube anode to permit prompt diagnosis. High-power test results were 1.6 MW for 0.5 s at 131 MHz, 1.0 MW for 10 s at 131 MHz, and 1.5 MW for 6 s at 110 MHz. Performance was studied under load VSWR of 1.5 and 2 over a 0 to 360° phase range. With a VSWR of 1.5, plate dissipation was 1.4 times higher than that of matched load