FIRST
TESTS OF THE NEW
MULTI-FREQUENCY ECRH SYSTEM AT
ASDEX UPGRADE F. Leuterer, D. Wagner, A. Manini, F. Monaco, M. Münich, F. Ryter, H. Schütz, H. Zohm, T. Franke Max-Plank-Institut für Plasmaphysik, EURATOM-IPP,
Boltzmannstr.2, D-85748 Garching, Germany
M. Thumm1, R. Heidinger2, G. Gantenbein1 Forschungszentrum
Karlsruhe, EURATOM-FZK 1Institut für
Hochleistungsimpuls- und Mikrowellentechnik, 2Institut für
Materialforschung, PO Box 3640, D-76021 Karlsruhe, Germany W. Kasparek Institut für Plasmaforschung, Universität
Stuttgart, Pfaffenwaldring 31,
D-70569 Stuttgart, Germany A.G. Litvak3, L.G. Popov4, V.O. Nichiporenko4, V.E. Myasnikov4, G.G. Denisov3, E.M. Tai4, E.A. Solyanova4, S.A. Malygin4 3
Institute of Applied Physics, RAS, 46 Ulyanov St., Nizhny Novgorod, 603950, Russia 4
GYCOM Ltd, 46 Ulyanov St., Nizhny Novgorod, 603155, Russia The power deposition in ECRH (Electron
Cyclotron Resonance Heating) of fusion plasmas is
primarily determined by the magnetic field. For a single frequency ECRH system
this has the consequence that for central heating the magnetic field is no
longer a free parameter. However, for
tokamak plasmas with different plasma currents or different equilibria, the
magnetic field should be a free parameter in order to operate at a reasonable
edge safety factor q(a). Furthermore, in a plasma with given parameters, some
experimental features, like suppression of neoclassical tearing modes (NTM),
require to drive current on the high field side without changing the magnetic
field1. These requests can be satisfied if the gyrotron frequency
is variable. A new broadband ECRH system is currently under construction at
the ASDEX Upgrade tokamak at IPP Garching.. This system will employ
multi-frequency gyrotrons which are step-tunable in the frequency range 105‑140
GHz. In its final stage the system will consist of 4 gyrotrons with a
total power of 4 MW and a pulse length of 10 s. It employs a fast steerable
launcher in the plasma vessel for feedback controlled power deposition that
allows for poloidal steering of 10 deg. within 100 ms. Transmission line
elements, such as corrugated waveguides, polarizer mirrors and vacuum
windows, are designed to cope for this frequency band2. The first
two-frequency gyrotron, operating at 105 GHz and 140 GHz, is currently
being put into operation at ASDEX Upgrade. 1. F. Leuterer et al., “ECRH Experiments in ASDEX
Upgrade”, Fusion Engineering and Design, 53 (2001) 277-287. 2. F. Leuterer et al., Status of
the New ECRH System for ASDEX Upgrade, Fusion Engineering and Design, 74 (2005), 199-203. Note:
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