[Table of Contents]

Plasma and Fusion Research

Volume 9, 3403091 (2014)

Regular Articles

Effect of Density Control and Impurity Transport on Internal Transport Barrier Formation in Tokamak Plasma
Tomoyuki YAMAKAMI, Takaaki FUJITA, Hideki ARIMOTO and Kozo YAMAZAKI1)
Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
1)
Nagoya University Professor Emeritus
(Received 10 December 2013 / Accepted 25 February 2014 / Published 4 July 2014)

Abstract

In future fusion reactors, density control, such as fueling by pellet injection, is an effective method to control the formation of the internal transport barrier (ITB) in reversed magnetic shear plasma, which can improve plasma performance. On the other hand, an operation with ITB can cause accumulation of impurities inside the core ITB region. We studied the relation between pellet injection and ITB formation and the effect of impurity transport on the core of ITB for tokamak plasmas by using the toroidal transport analysis linkage. For ITB formation, we showed that the pellet has to be injected beyond the position where the safety factor q takes the minimum value. We confirmed that the accumulation of impurities causes the attenuation of ITB owing to radiation loss inside the ITB region. Moreover, in terms of the divertor heat flux reduction by impurity gas, the line radiation loss is high for high-Z noble gas impurities, such as Kr, whereas factor Q decreases slightly.

Keywords

internal transport barrier, impurity transport, pellet injection, tokamak reactor, high-Z impurity

DOI: 10.1585/pfr.9.3403091

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This paper may be cited as follows:

Tomoyuki YAMAKAMI, Takaaki FUJITA, Hideki ARIMOTO and Kozo YAMAZAKI, Plasma Fusion Res. 9, 3403091 (2014).