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Trapped-electron runaway effect

Part of: Energetic Electrons

Published online by Cambridge University Press:  28 April 2015

E. Nilsson ,
J. Decker ,
N. J. Fisch  and
Y. Peysson
E. Nilsson*
Affiliation:
CEA, IRFM, F-13108 Saint-Paul-lez-Durance, France
J. Decker
Affiliation:
Ecole Polytechnique Fédérale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas (CRPP), CH-1015 Lausanne, Switzerland
N. J. Fisch
Affiliation:
Princeton Plasma Physics Laboratory, Princeton University, Princeton, NJ 08543, USA
Y. Peysson
Affiliation:
CEA, IRFM, F-13108 Saint-Paul-lez-Durance, France
*
†Email address for correspondence: emelie.nilsson@cea.fr
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Abstract

In a tokamak, trapped electrons subject to a strong electric field cannot run away immediately, because their parallel velocity does not increase over a bounce period. However, they do pinch toward the tokamak center. As they pinch toward the center, the trapping cone becomes more narrow, so eventually they can be detrapped and run away. When they run away, trapped electrons will have a very different signature from circulating electrons subject to the Dreicer mechanism. The characteristics of what are called trapped-electron runaways are identified and quantified, including their distinguishable perpendicular velocity spectrum and radial extent.

Type
Research Article
Information
Journal of Plasma Physics , Volume 81 , Issue 4 , August 2015 , 475810403
Copyright
Copyright © Cambridge University Press 2015 

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