Report of recent experiments with the European 1 MW, 170 GHz CW and SP prototype gyrotrons for ITER

Abstract

The European 1 MW, 170 GHz industrial CW prototype gyrotron has been designed within EGYC (European GYrotron Consortium) in collaboration with the industrial partner Thales Electron Devices (TED) and under the coordination of Fusion for Energy (F4E). This is a conventional (hollow) cavity gyrotron that is based on the 1 MW, 170 GHz short-pulse (SP) modular gyrotron, which has been designed and manufactured by KIT in collaboration with TED. The SP prototype has been tested in multiple experimental campaigns since 2015 and the nominal cavity mode TE32,9 is exited at 170.1 GHz, producing RF power above 1 MW with 35 % interaction efficiency. The first phase of the experiments with the CW industrial gyrotron was successfully completed at KIT in 2016, verifying most of the ITER specifications. Short pulses (<10ms) deliver RF power higher than 0.9 MW with a total efficiency of 26 % (in non-depressed collector operation). The Gaussian mode content of the RF beam is 97 %. Pulses with duration of 180 s (limited by the high-voltage power supply at KIT) produce power more than 0.8 MW with maximum efficiency 38 % (in depressed collector operation). In this work the achievements with the SP and the CW prototype gyrotrons are summarized.

Experimental Testing of the European TH1509U 170-GHz 1-MW CW Industrial Gyrotron—Long Pulse Operation

“…With these experiments, most of the ITER specifications were achieved, including the high voltage (HV) properties of the gyrotron, the frequency of the nominal cavity mode, the stability of the tube vacuum, as well as the TEM00 mode purity and the alignment of the RF beam at the output optics unit. The maximum RF power achieved in 180 s pulses, which is the pulse length limitation of the KIT test stand, was 0.8 MW at various operation points with a maximum efficiency of 38 % in depressed collector operation [5]- [7]. Similar performance was achieved later at the FALCON test stand at EPFL.…”

Metrology techniques for the verification of the alignment of the EU gyrotron prototype for ITER

“…The second metrology campaign was planned while the gyrotron prototype was in operation for finding the operational maps and RF stability regions which allowed to locate the gyrotron in the center of the region where the RF performance is optimal. This RF operation is usually done with repetitive horizontal displacements of the gyrotron by means of the so-called XY-table [9]. The operation is done with the SC magnet ON (i.e., in the presence of high magnetic fields) and the optimal metrology technique under this conditions was the photogrammetry (magnetic proof targets).…”

Progress on performance tests of ITER gyrotrons and design of dual-frequency gyrotrons for ITER staged operation plan

“…The EU will supply six gyrotrons and India will supply two gyrotrons for use after FP phase; development tests are underway. The EU gyrotrons feature a cavity resonator for TE 32,9 mode oscillation resonator and a diode MIG [8]. The EU is also developing a 2 MW coaxial gyrotron with a triode MIG [9].…”