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Effect of toroidal Alfvén eigenmodes on fast particle confinement in the spherical tokamak Globus-M

Part of: Focus on Fusion PLA Tribute to V D Shafranov: 1929-2014

Published online by Cambridge University Press:  08 October 2015

Yu. V. Petrov ,
N. N. Bakharev ,
V. K. Gusev ,
V. B. Minaev ,
V. A. Kornev ,
G. S. Kurskiev ,
M. I. Patrov ,
N. V. Sakharov ,
S. Yu. Tolstyakov  and
P. B. Shchegolev
Yu. V. Petrov*
Affiliation:
Ioffe Institute, St Petersburg, 194021, Russia
N. N. Bakharev
Affiliation:
Ioffe Institute, St Petersburg, 194021, Russia
V. K. Gusev
Affiliation:
Ioffe Institute, St Petersburg, 194021, Russia
V. B. Minaev
Affiliation:
Ioffe Institute, St Petersburg, 194021, Russia
V. A. Kornev
Affiliation:
Ioffe Institute, St Petersburg, 194021, Russia
G. S. Kurskiev
Affiliation:
Ioffe Institute, St Petersburg, 194021, Russia
M. I. Patrov
Affiliation:
Ioffe Institute, St Petersburg, 194021, Russia
N. V. Sakharov
Affiliation:
Ioffe Institute, St Petersburg, 194021, Russia
S. Yu. Tolstyakov
Affiliation:
Ioffe Institute, St Petersburg, 194021, Russia
P. B. Shchegolev
Affiliation:
Ioffe Institute, St Petersburg, 194021, Russia
*
†Email address for correspondence: [email protected]
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Abstract

In experiments with neutral beam injection at the early stage of a Globus-M discharge, instabilities were observed that were excited by fast ions in the frequency range of 50–200 kHz, which were identified as toroidal Alfvén eigenmodes (TAE) (Petrov et al., Plasma Phys. Rep., vol. 37, 2011, pp. 1001–1005). In contradiction with the NSTX and MAST tokamaks, a regime of TAE generation was realized with strongly developed single modes. Magnetic measurements with fast Mirnov probes have shown that most of the modes have toroidal number $n=1$. The influence of the modes on the fast particle confinement was recorded by means of a tangentially directed neutral particle analyser (NPA) and neutron detector. Hydrogen and deuterium were used as target plasma and injected beam for study of the isotopic effect. At deuterium injection into the deuterium plasma, TAE led to the neutron rate dropping by 25 %, whereas NPA fluxes of high energy dropped by 75 %. At hydrogen injection, the drop in the measured NPA fluxes did not exceed 25 %.

Type
Research Article
Information
Journal of Plasma Physics , Volume 81 , Issue 6 , December 2015 , 515810601
Copyright
© Cambridge University Press 2015 

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