High-Power Performance of a Resonant Diplexer for Advanced ECRH

Abstract

In Electron cyclotron resonance heating systems, high-power multiplexers can be employed as power combiners, adjustable power dividers, fast switches to toggle the power between two launchers, as well as frequency sensitive directional couplers to combine heating and diagnostic applications on one launcher. In the paper, various diplexer designs for quasi-optical and corrugated waveguide transmission systems are discussed. Numerical calculations, low-power tests and especially high-power experiments performed at the ECRH system of W7-X are shown, which demonstrate the capability of these devices. Near term plans for applications on ASDEX Upgrade and FTU are presented. Based on the present results, options for implementation of power combiners and fast switches in the ECRH system of ITER is discussed.

Commissioning of inline ECE system within waveguide based ECRH transmission systems on ASDEX upgrade

“…A special feature of the AUG ECCD system is the fast directional switch (FADIS) Mk II, a circular corrugated waveguide compatible version of FADIS designed by the IPF Stuttgart [4]. The main purpose of FADIS is to improve the efficiency of ECCD stabilization of NTMs by enabling the switching of the gyrotron power between two launchers positioned at the same toroidal location but at different vertical positions, such that each launcher is targeting a different phase of the NTM island.…”

“…A CW capable inline electron cyclotron emission (ECE) separation system for feedback control, featuring oversized corrugated waveguides, is commissioned on ASDEX upgrade (AUG). The system is based on a combination of a polarization independent, non-resonant, Mach-Zehnder diplexer equipped with dielectric plate beam splitters [2,3] employed as corrugated oversized waveguide filter, and a resonant Fast Directional Switch, FADIS [4,5,6,7] as ECE/ECCD separation system. This paper presents an overview of the system, the low power characterisation tests and first high power commissioning on AUG.…”

Controlled Mirror Motion System for Resonant Diplexers in ECRH Applications

“…high-power tests with the W7-X ECRH (IPPGreifswald) and at AUG (IPP-Garching) and low-power tests at IPF, University of Stuttgart. A selection of these experiments has been reported in a previous publication [6], in which the emphasis was put on the impact a controlled FADIS may have in ECRH applications. Here, we report on two fundamental high-power experiments with the controlled mirror system: (1) power equalisation and (2) control to resonance.…”

Utilization of collinear ECE detection/ECRH heating for active stabilization of plasma instabilities

“…In [8] promising results are shown in high power experiments with a feedback/feedforward controlled FADIS equipped with output power sensors and a frequency sensor. FADIS was tuned on the slope to demonstrate fast and slow switching and tuned on the resonance dip for power combination and the line-of-sight application.…”