Design and R&D of an ECRH system on JET

The design of the ECRH system for JET
A.G.A. Verhoeven1, W.A. Bongers1, B.S.Q. Elzendoorn1, M. Graswinckel1,
P. Hellingman1, W. Kooijman1, O.G. Kruijt1, J. Maagdenberg1, D. Ronden1,
K. Likin4, A. Bruschi5, S. Cirant5, S. Novak5, B. Piosczyk6,
M. Thumm6, H. Bindslev7, A. Kaye8, C. Fleming8, H. Zohm9
1FOM-Instituut voor Plasmafysica 'Rijnhuizen', Association EURATOM-FOM; verhoeve@rijnh.nl; P.O. Box 1207, 3430 BE Nieuwegein, the Netherlands;
4Euratom/CIEMAT, Madrid; 5Euratom/CNR-Milano;
8Euratom-JET/UKAEA Culham; 9Euratom/IPP-Garching;
An ECRH (electron-cyclotron resonance heating) system is being designed for JET in the frame-work of the JET-Enhanced Performance project (JET-EP). This project is implemented under the European Fusion Development Agreement (EFDA).
The ECRH system consists of 6 gyrotrons, 1 MW each, in order to deliver 5 MW into the plasma. The system will especially be equipped to enable the control of neo-classical tearing modes (NTM). A frequency of 113.3 GHz is selected to enable a wide range of operating toroidal magnetic fields from 3 to 4 T. Furthermore, operations at second harmonic at lower fields are foreseen and a possible future upgrade to 170 GHz (the frequency presently foreseen for ITER) can be accomplished, using the same systems including the double-disk diamond windows at the torus side. ... mehrThe main elements of the ECRH system are:
· gyrotrons with a depressed collector, each 1 MW, 10 s, with a diamond window and Gaussian output mode
· evacuated corrugated HE11 waveguides will transport the mm-wave power to the double-disk diamond windows on the tokamak side
· a plug-in launcher, steerable in both toroidal and poloidal angle, able to handle eight mm-wave beams. Four steerable launching mirrors will be installed, handling each two mm-wave beams. Water cooling of all the mirrors, including the movable mirror, is foreseen in order to increase the ITER relevance. An existing test facility was being modified to include life-cycle tests. A separate contribution on this is foreseen by B.S.Q. Elzendoorn
· a power-supply and modulation system, including series IGBT switches, to enable independent control of each gyrotron. An all-solid-state body power supply will stabilise the gyrotron output power and enable fast modulations up to 10 kHz. A separate contribution on this is foreseen by A.B. Sterk
Unfortunately, because of lack of funding, the project was cancelled early 2002. The design work was well on the way at that moment and it was foreseen to finalise the design work at the end of 2002.