Recent results of the 2 MW-0.17 THz European pre-prototype coaxial-cavity gyrotron for ITER

M. Thumm, T. Rzesnicki, B. Piosczyk, J. Flamm, G. Gantenbein, A. Illy, J. Jin, S. Kern, A. Samartsev, A. Schlaich
A 2 MW, CW, 0.17 THz coaxial-cavity gyrotron for electron cyclotron heating and current drive in the International Thermonuclear Experimental Reactor (ITER) is under development within the European Gyrotron Consortium (EGYC * ), a cooperation of several European research institutions. To support the development of the industrial prototype of a CW gyrotron, a short-pulse tube (pre-prototype) is operated at KIT Karlsruhe (former FZK, Karlsruhe) for experimental verification of the design of
more » ... the design of critical components, like the electron gun, beam tunnel, cavity and quasi-optical (q.o.) mm-wave output coupler. Recently a significant progress has been achieved. In particular, output power of up to 2.2 MW at 30 % output efficiency (non-depressed collector operation) has been obtained in single-mode operation at 0.17 THz with a fundamental Gaussian mode content of almost 96 %. After replacement of the narrow-band fused-silica output window by a broadband silicon-nitride Brewster window (frequency tunable gyrotron) first experiments gave an output power of 1.8 MW with an efficiency of 26% in the TE 28,16 mode at 0.1413 THz. In addition, in the next azimuthal neighbor mode TE 29,16 at 0.1433 THz, an output power of 1.25 MW has been generated with an efficiency of 23%. Measurements of the intensity profiles of the mm-wave output beams show very good mode purity also for these other frequencies and modes.
doi:10.5445/ir/1000022737 fatcat:byglzswudvbgzkqum23bbeoizm