Effect on plasma rotation of lower hybrid (LH) waves in Alcator C-Mod

J. P. Lee, M. Barnes, R. R. Parker, J. E. Rice, F. I. Parra, P. T. Bonoli, M. L. Reinke

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

The injection of LH waves for current drive into a tokamak changes the ion toroidal rotation. In Alcator C-Mod, the direction of the steady state rotation change due to LH waves depends on the plasma current and the density. The change in rotation can be estimated by balancing the external torque of lower hybrid waves with the turbulent radial transport of the momentum. For high plasma current, the turbulent pinch and diffusion of the injected counter-current momentum are sufficient to explain the rotation change. However, for low plasma current, the change in the the intrinsic momentum transport (residual stress) for a non-rotating state is required to explain the co-current rotation change. Accordingly, we investigate the intrinsic momentum transport for the non-rotating state when diamagnetic flow and ExB flow cancel each other. The change in the intrinsic momentum transport due to lower hybrid waves is significant when the plasma current is low, which may explain the rotation reversal for low plasma current. The effect of changed q (safety factor) profile by lower hybrid on the intrinsic momentum transport is estimated by gyrokinetics.

Original languageEnglish (US)
Title of host publicationRadiofrequency Power in Plasmas - Proceedings of the 20th Topical Conference
PublisherAmerican Institute of Physics Inc.
Pages398-401
Number of pages4
ISBN (Print)9780735412101
DOIs
StatePublished - 2014
Externally publishedYes
Event20th Topical Conference on Radiofrequency Power in Plasmas - Sorrento, Italy
Duration: Jun 25 2013Jun 28 2013

Publication series

NameAIP Conference Proceedings
Volume1580

Conference

Conference20th Topical Conference on Radiofrequency Power in Plasmas
Country/TerritoryItaly
CitySorrento
Period6/25/136/28/13

ASJC Scopus subject areas

  • General Physics and Astronomy

Keywords

  • Ion rotation
  • Lower hybrid
  • Tokamaks

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