The design of the JET-ECRH system

and design considerations for ITER

A.G.A. Verhoeven1, W.A. Bongers1, B.S.Q. Elzendoorn1,

M. Graswinckel1, P. Hellingman1, W. Kooijman1, O.G. Kruijt1,

G.A.H. Maagdenberg1, D.M.S. Ronden1, J. Stakenborg1, A.B. Sterk1,

J. Tichler1, F.C. Schüller1, S. Alberti2, M. Henderson2, J.A. Hoekzema3,

J.W. Oosterbeek3, A. Fernandez4, K. Likin4, A. Bruschi5, S. Cirant5,

S. Nowak5, B. Piosczyk6, M. Thumm6, A. Kaye7, C. Fleming7, H. Zohm8,

C. Damiani9, A. Guigon9, J. Paméla9

1FOM-Instituut voor Plasmafysica 'Rijnhuizen', Association EURATOM-FOM; verhoeve@rijnh.nl; P.O. Box 1207, 3430 BE Nieuwegein, the Netherlands;

2Euratom/CRPP-Lausanne; 3Euratom/FZJ-Jülich; 4Euratom/CIEMAT, Madrid; 5Euratom/CNR-Milano; 6Euratom/FZK-Karlsruhe; 7Euratom-JET/UKAEA Culham; 8Euratom/IPP-Garching; 9EFDA-JET, Culham, UK

An ECRH (electron cyclotron resonance heating) system has been designed for JET in the framework of the JET Enhanced-Performance project (JET-EP) under the European Fusion Development Agreement (EFDA). Due to financial constraints it has recently been decided not to implement this project. Nevertheless, the design work conducted from April 2000 to January 2002 shows a number of features which can be relevant in preparation of future ECRH systems such as the ITER one.

The ECRH system was foreseen to comprise 6 gyrotrons, 1 MW each, in order to deliver 5 MW into the plasma. The main aim was to enable the control of neo-classical tearing modes (NTM). The paper will concentrate on:

· the power-supply and modulation system, including series IGBT switches, to enable independent control of each gyrotron and an all-solid-state body power supply to stabilise the gyrotron output power and to enable fast modulations up to 10 kHz.

· A plug-in launcher, that is steerable in both toroidal and poloidal angle, and able to handle 8 separate mm-wave beams. Four steerable launching mirrors were foreseen to handle two mm-wave beams each. Water cooling of all the mirrors was a particularly ITER relevant feature.

Now the JET-EP is stopped, we transfer our attention to the ITER ECRH system and its test facilities to be installed in CRPP, Lausanne. We concentrate on the high-voltage power supplies and gyrotron-modulation parameters and on the upper-port launcher design work and prototype test programs.