Density and Temperature Fluctuations in on Alcator C-Mod Plasmas with Peaked Density Profiles

POSTER

Abstract

Core density and temperature fluctuations in plasmas with peaked density profiles are observed with a heterodyne electron-cyclotron-emission (ECE) system in the Alcator C-Mod tokamak. ECE systems typically measure electron temperature only; this ECE system is also able to detect density fluctuations in certain cases due to its oblique viewing angle and refractive effects as the densities near cut-off. The diagnostic is unique in that the signal fluctuations are an amplified version of the density fluctuations. The peaked density profiles are a result of internal transport barriers (ITB's) generated by two different methods: off-axis ion cyclotron resonance heating (ICRH) and lithium pellet injection. The principle results described here are the first measurements of localized core fluctuations in the Alcator C-Mod ITB and of fluctuations associated with the quench of the density rise due to the ITB.

*Work supported by DoE DE-FG02-96ER54373

Authors

  • P.E. Phillips

    • Fusion Research Center, Univ. of Texas, Austin TX 78735

  • W.L. Rowan

    • Fusion Research Center, University of Texas at Austin

  • M.B. Sampsell

  • R.B. Bravenec

    • Fusion Research Center, The University of Texas at Austin
    • Fusion Research Center, Univ. of Texas, Austin TX 78712

  • A.G. Lynn

    • Univ. of New Mexico, NM 87131
    • University of New Mexico

  • Nils Basse

    • MIT PSFC
    • Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, MA

  • B. Bose

  • E.M. Edlund

  • C. Fiore

  • A. Hubbard

  • L. Lin

  • M. Porkolab

    • Plasma Science Fusion Center, Massachusetts Insitute of Technology
    • Plasma Science Fusion Center, Massachsetts Institute of Technology

  • E.S. Marmar

    • MIT PSFC

  • S.J. Wukitch

    • PSFC, MIT Cambridge MA 02139