| Issue |
EPJ Web Conf.
Volume 313, 2024
22nd Joint Workshop on Electron Cyclotron Emission and Electron Cyclotron Resonance Heating (EC22)
|
|
|---|---|---|
| Article Number | 04001 | |
| Number of page(s) | 7 | |
| Section | Technology | |
| DOI | https://doi.org/10.1051/epjconf/202431304001 | |
| Published online | 15 November 2024 | |
https://doi.org/10.1051/epjconf/202431304001
In-situ Low Power Tests of the ASDEX Upgrade ECRH Transmission Lines
1 Max Planck Institute for Plasma Physics, Tokamak Scenario Development, 85748 Garching, Germany
2 Karlsruhe Institute of Technology, Institute for Pulsed Power and Microwave Technology, 76344 Eggenstein-Leopoldshafen, Germany
* Corresponding author: dietmar.wagner@ipp.mpg.de
Published online: 15 November 2024
An Electron Cyclotron Resonance Heating (ECRH) system employing 8 gyrotrons is in routine operation at the ASDEX Upgrade tokamak at IPP Garching. The gyrotrons are of two-frequency type operating at 105 and 140 GHz with a maximum output power of up to 1 MW and 10 s pulse length. The gyrotron output beams are coupled to 8 waveguide transmission lines via quasi-optical Matching Optics Units (MOUs). The oversized corrugated HE11 waveguides with a diameter of 87 mm are operated at atmospheric pressure with overall lengths between 65 and 103 meters. The number of quasi-optical miter bends per line is between 6 and 8. High mode purity in the transmission lines is critical with respect to both, losses and atmospheric breakdowns in the waveguides. Beam measurements at low power have been performed along the transmission lines and are compared to high power measurements. Near-field calculations and measurements of mm-wave beams radiated from open-ended HE11 waveguides show, that varying intensity patterns determine the distribution of Ohmic loading in compact mm-wave beam launching antennas, where the first mirror is located in the reactive near-field or close to the Fresnel maximum.
© The Authors, published by EDP Sciences, 2024
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