Development of Resonant Diplexers for high-power ECRH – Status, Applications, Plans
1 Institut f. Grenzflächenverfahrenstechnik und Plasmatechnologie, D-70569 Stuttgart, Germany
2 Max-Planck-Institut für Plasmaphysik, EURATOM Ass., 85748 Garching and 17491 Greifswald, Germany
3 Department of OptoMechatronics, TNO Tech. Sciences, NL-2600 AD, Delft, The Netherlands
4 Dutch Institute For Fundamental Energy Research, NL-3439 Nieuwegein, The Netherlands
5 Inst. of Applied Physics, Russian Academy of Science, 603950 Nizhny Novgorod, Russia
6 Istituto di Fisica del Plasma, EURATOM-ENEA-CNR Ass., I-20125 Milano, Italy
7 Japan Atomic Energy Agency (JAEA), 801-1, Mukoyama, Naka, Ibaraki 311-0193, Japan
a Corresponding author: email@example.com
Published online: 12 March 2015
The development of diplexers for ECRH has been pursued at a number of institutes because of their attractive variety of applications: Power combination, non-mechanical, electrically controlled switching (of combined beams) between launchers with tens of kHz, and discrimination of low-power ECE signals from high-power ECRH is feasible. In a first part, this paper reports on plasma experiments with a ring resonator (Mk IIa) at ASDEX Upgrade. Commissioning experiments on fast switching between two launchers for synchronous stabilization of neoclassical tearing modes, as well as in-line ECE measurements have been performed, and experimental issues and first results are discussed. A clear influence of the switching phase on the amplitude of the 3/2 NTM mode was measured, complete stabilization could, however, not be demonstrated yet mainly due to imperfect resonator control. Concepts for improved tracking of the diplexers to the gyrotron frequency are presented. In a second part, the design of diplexers with ring resonators matched to HE11 fields is briefly discussed; these devices can be connected to corrugated waveguides without any mode converters. A compact version (MQ IV) is under investigation, which is compatible with the ITER ECRH system (170 GHz, 63.5 mm waveguide, vacuum tight casing), with the final goal of high-power tests at the 170 GHz gyrotron facility at JAEA in Naka, Japan. First low-power test results are presented.
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