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This paper reports the results of the high-power test of a remote steering launcher mockup at 140 GHz, which were performed at the ECRH installation for the future stellarator W7-X at IPP Greifswald. The mock-up test system consists of a 6.62 m long square corrugated waveguide with a steerable optic at the entrance and various diagnostics at the exit of the waveguide. A straight launcher and version with 2 integrated mitre-bends were investigated. The high-power tests of the straight setup have been performed with powers up to P 0 = 700 kW (typically 500 kW) and pulse lengths of up to 10 seconds. In the dog-leg verison, arcing limited the power and pulse length. For both polarizations (parallel and perpendicular to the steering plane), no arcing was observed within this range of power and pulse-length for the straight setup, in spite of the fact, that the experiments were performed under ambient atmospheric conditions. After the integration of 2 mitre bends in the setup, arcing limited the usable parameter range. The ohmic loss P Ω of the waveguide was measured via the temperature increase of the waveguide wall, and was used to calibrate the calculated angular dependence of the total ohmic losses of the waveguide. Short-pulse radiation pattern measurements with thermographic recording show high beam quality and confirm the steering range of −12• < φ < 12• . The version with two mitre bends produces similar results but with an increased level of sidelobes and arcing problems.

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Abstract:Electron Cyclotron Resonance Heating (ECRH) is the main heating system for W7-X. A 10 MW ECRH plant with cw-capability is under construction to support the W7-X operation, which aims at demonstrating the steady state capability of stellarators at reactor relevant plasma parameters. The ECRH system consists of 10 RF