Observation of Electron Bernstein Wave Heating in the MST Reversed Field Pinch

POSTER

Abstract

We report the first observation of electron Bernstein wave heating in the MST RFP. Similar to a high density stellarator, the RFP is inaccessible to electromagnetic ECRH. The plasma current and \textbar B\textbar operating range of MST allows a 5.5 GHz RF source (100kW, 4ms pulse) to heat on the fundamental and up to 4th harmonic EC resonances. With an x-ray diagnostic most sensitive to edge electrons located $+$12 degrees toroidally from the antenna, the measured emission is a strong function of predicted heating inside versus outside the Bt$=$0 reversal layer of the RFP. Measured during a scan of plasma current, distinct edges in a plot of emissivity versus predicted deposition layer align with the deposition layers crossing of this reversal layer and confirm EBW heating on the fundamental through 4th EC harmonic. Additional confirmation of the absorption location has been demonstrated by using auxiliary poloidal current drive to reduce electron diffusion rates and sweep the location of the Bt$=$0 surface across a static RF absorption location in RFP discharges. In these discharges EBW enhancement of the 15-40keV x-ray energies has been observed. Work supported by USDOE.

Authors

  • Andrew Seltzman

    University of Wisconsin

  • Jay Anderson

    University of Wisconsin-Madison, University of Wisconsin, University of Wisconsin - Madison

  • Ami DuBois

    University of Wisconsin

  • Abdulgader Almagri

    University of Wisconsin-Madison, University of Wisconsin, University of Wisconsin - Madison

  • Paul Nonn

    University of Wisconsin, Madison, University of Wisconsin

  • Karsten McCollam

    University of Wisconsin-Madison, University of Wisconsin, University of Wisconsin - Madison

  • Brett Chapman

    University of Wisconsin-Madison, University of Wisconsin - Madison, University of Wisconsin, UW-Madison

  • J.A. Goetz

    University of Wisconsin-Madison, Madison, WI, USA, University of Wisconsin, University of Wisconsin - Madison

  • Cary Forest

    University of Wisconsin-Madison, University of Wisconsin - Madison, University of Wisconsin, Univ of Wisconsin, Madison