Romanelli, M. (Michele), Szepesi, Gabor, Peeters, A. G., Apicella, M. L., Marinucci, M., Mazzotta, C., Mazzitelli, G. and Frigione, D.. (2011) Linear microstability analysis of a low-Z impurity doped tokamak plasma. Nuclear Fusion, Vol.51 (No.10). Article: 103008. ISSN 0029-5515

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Abstract

Improved electron and deuterium energy and particle confinement in the presence of low-Z impurities have been observed in many tokamaks under various experimental conditions. Peaked electron density profiles have been obtained in the Frascati Tokamak Upgrade (FTU) ohmic plasmas where a high concentration of lithium has been detected following the installation of a Liquid Lithium Limiter (LLL). This paper presents the results of a gyrokinetic study on the effects of lithium and other low-Z impurities on the linear stability of deuterium and electron temperature driven modes and their associated fluxes for plasma parameters such as those found in the core of LLL-FTU plasmas. Simulations show that a lithium concentration in excess of n(Li)/n(e) = 15%, as estimated in the initial phase of a reference FTU discharge, is found to have a strong stabilizing effect on the TEM and high-frequency ETG modes. A significant stabilization of the electron driven modes can still be observed when the lithium concentration is reduced to 3%. In the presence of a significant impurity concentration (n(Li)/n(e) = 3-15%) the long wavelength ITG modes drive an inward electron and deuterium flux and outward lithium flux. This process may lead eventually to an increased electron and deuterium density peaking and a reduced Z(eff) (lithium density below nLi/ne = 1%).

Item Type:	Journal Article
Subjects:	Q Science > QC Physics
Divisions:	Faculty of Science > Physics
Library of Congress Subject Headings (LCSH):	Tokamaks, Plasma confinement, Plasma turbulence, Lithium
Journal or Publication Title:	Nuclear Fusion
Publisher:	Institute of Physics Publishing Ltd.
ISSN:	0029-5515
Date:	October 2011
Volume:	Vol.51
Number:	No.10
Page Range:	Article: 103008
Identification Number:	10.1088/0029-5515/51/10/103008
Status:	Peer Reviewed
Publication Status:	Published
Access rights to Published version:	Restricted or Subscription Access
Funder:	Research Councils UK (RCUK), European Commission (EC), Engineering and Physical Sciences Research Council (EPSRC), Culham Centre for Fusion Energy (CCFE)
Grant number:	EP/1501045 (RCUK), EP/H002081/1 (EPSRC)
URI:	http://wrap.warwick.ac.uk/id/eprint/40332

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