Suprathermal electron dynamics and MHD instabilities in a tokamak. (October 2015)

• Record Type: Journal Article
• Authors: Kamleitner, J; Coda, S; Decker, J; Graves, J P; the TCV team
• Is Part Of: Plasma physics and controlled fusion. Volume 57:Number 10(2015:Oct.)
• Page Start: B277
• Page End: 391
• Publication Date: 2015-10
• Subjects: Plasma (Ionized gases) -- Periodicals; Controlled fusion -- Periodicals; 530.44
• DOI: 10.1088/0741-3335/57/10/104009
• Languages: English
• ISSNs: 0741-3335

Abstract

<abstract> <title>Abstract</title> <p>The dynamics of suprathermal electrons in the presence of magnetohydrodynamics (MHD) activity and the excitation of MHD modes by suprathermal electrons are studied experimentally to improve the understanding of the interaction of fast particles with MHD instabilities in a tokamak. The study focuses on three different aspects of the internal kink mode with poloidal/toroidal mode number <inline-formula><tex-math><?CDATA $m/n=1/1$ ?></tex-math><?MML <mml:math><mml:mstyle displaystyle='false'><mml:mi>m</mml:mi><mml:mrow><mml:mo>/</mml:mo></mml:mrow><mml:mi>n</mml:mi><mml:mo>=</mml:mo><mml:mn>1</mml:mn><mml:mrow><mml:mo>/</mml:mo></mml:mrow><mml:mn>1</mml:mn></mml:mstyle></mml:math> ?><inline-graphic xlink:href="ark:/27927/pgj2j51dtr7" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /></inline-formula>: the sawtooth instability, electron fishbones and coupled bursts alternating with sawtooth crashes (CAS), all located where the safety factor <inline-formula><tex-math><?CDATA $(q)$ ?></tex-math><?MML <mml:math><mml:mstyle displaystyle='false'><mml:mo stretchy="false">(</mml:mo><mml:mi>q</mml:mi><mml:mo stretchy="false">)</mml:mo></mml:mstyle></mml:math> ?><inline-graphic xlink:href="ark:/27927/pgj2j51dtjx" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /></inline-formula> profile approaches or takes the value <inline-formula><tex-math><?CDATA $q=1$ ?></tex-math><?MML <mml:math><mml:mstyle displaystyle='false'><mml:mi>q</mml:mi><mml:mo>=</mml:mo><mml:mn>1</mml:mn></mml:mstyle></mml:math> ?><inline-graphic xlink:href="ark:/27927/pgj2j51dtm1" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /></inline-formula>. New quantitative results on suprathermal electron transport and an investigation of electron acceleration during sawtooth crashes are followed by the characterization of initial electron fishbone observations on the Tokamak à configuration variable (TCV). Finally, <inline-formula><tex-math><?CDATA $m/n=1/1$ ?></tex-math><?MML <mml:math><mml:mstyle displaystyle='false'><mml:mi>m</mml:mi><mml:mrow><mml:mo>/</mml:mo></mml:mrow><mml:mi>n</mml:mi><mml:mo>=</mml:mo><mml:mn>1</mml:mn><mml:mrow><mml:mo>/</mml:mo></mml:mrow><mml:mn>1</mml:mn></mml:mstyle></mml:math> ?><inline-graphic xlink:href="ark:/27927/pgj2j51dtdq" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /></inline-formula> bursts associated with the sawtooth cycle, coupled to a persisting <inline-formula><tex-math><?CDATA $m/n=2/1$ ?></tex-math><?MML <mml:math><mml:mstyle displaystyle='false'><mml:mi>m</mml:mi><mml:mrow><mml:mo>/</mml:mo></mml:mrow><mml:mi>n</mml:mi><mml:mo>=</mml:mo><mml:mn>2</mml:mn><mml:mrow><mml:mo>/</mml:mo></mml:mrow><mml:mn>1</mml:mn></mml:mstyle></mml:math> ?><inline-graphic xlink:href="ark:/27927/pgj2j51dtgt" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /></inline-formula> mode and alternating with sawtooth crashes, are discussed, in particular in view of the fast electron dynamics and their role in confinement degradation and mode excitation.</p> </abstract>