ITER ECH switch design and analysis

Dennis L. Youchison, Alex M. Melin, Arnold Lumsdaine, Charles R. Schaich, Gregory R. Hanson

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

The electron cyclotron heating system (ECH) on ITER uses 24 evacuated microwave transmission lines carrying up to 1.4 MW of power each at 170 GHz to provide resonance heating of electrons in the ITER plasma and to enable plasma current drive. A critically important component in this system is the microwave switch that allows the microwaves to be directed from the gyrotrons to either dummy loads or between launchers in the upper and equatorial ports of the ITER tokamak while maintaining the vacuum integrity of the transmission lines. A moveable, water-cooled CuCrZr mirror is used to redirect the microwave transmission between two orthogonal waveguides. In this article we describe the optimized design of the mirror cooling passages produced by computational fluid dynamics analysis using ANSYS CFXwith k-s and k-m shear stress transport turbulence models, and verify that the design parameters for mass flow rate, inlet temperature and pressure are adequate for good thermomechanical performance. Non-uniform heating of the mirror face from the incident microwaves induces deflections that should be less than 25 microns to meet the integrated transmission line efficiency specification. In the current 1.4 MW switch design, 0.03 kg/s of 36°C water at 10 bar inlet pressure can remove the 2660 W of ohmic heating in the mirror produced by the elliptical polarization power and maintain the surface temperature below 150°C. The water delta-T is 21°C with a 0.5 bar pressure drop in the mirror. The maximum predicted displacement in the center of the mirror face is less than 25 fim.

Original languageEnglish
Pages (from-to)324-330
Number of pages7
JournalFusion Science and Technology
Volume72
Issue number3
DOIs
StatePublished - Oct 2017

Funding

The authors gratefully acknowledge the efforts of Ira Griffith at the U.S. ITER Project Office for design and CAD support. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Fusion Energy Sciences, under contract number DE-AC05-00OR22725. This manuscript has been authored by UT-Battelle, LLC, under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-publi caccess-plan).

FundersFunder number
U.S. Department of Energy
Office of Science
Fusion Energy SciencesDE-AC05-00OR22725

    Keywords

    • Electron cyclotron heating
    • Microwaves
    • Mirror
    • Switch
    • Waveguide

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