[Table of Contents]

Plasma and Fusion Research

Volume 8, 2403175 (2013)

Regular Articles

Influence of Safety Factor Profile on Bootstrap Current Fraction in Tokamak Fusion Reactors
Junji MANO, Kozo YAMAZAKI, Hideki ARIMOTO and Tatsuo SHOJI
Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
(Received 7 December 2012 / Accepted 11 September 2013 / Published 27 December 2013)

Abstract

To achieve a steady-state fusion power plant, non-inductive current-driven plasma operations should be maintained in tokamak fusion reactors. To establish an economical steady-state reactor, the bootstrap current must be enhanced to cover the majority of the plasma current and reduce the amount of externally driven current. The bootstrap current (BS) is affected by the safety factor (q) profile through transport; however, it is not known how changes in the safety factor profile affect the bootstrap current fraction. We conducted time-evolution analyses of the current-density profile for burning tokamak plasmas using a two-dimensional equilibrium, one-dimensional transport code (TOTAL code) with the current-diffusive ballooning mode (CDBM) model as the heat transport model. The effect of the safety factor profile on the BS current fraction IBS/Ip was evaluated for ITER-like plasmas. After various analyses for different q profiles, we conclude that the most effective way to increase the BS current fraction is to increase the minimum value for the safety factor. In this ITER simulation based on the CDBM model with 20-MW heating power, a maximum BS fraction of 0.6 was obtained using a central q-value of 10.0, a surface value of 6.0, and a minimum value of 3.0.

Keywords

total code, bootstrap current fraction, safety factor profile, current-diffusive ballooning mode

DOI: 10.1585/pfr.8.2403175

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This paper may be cited as follows:

Junji MANO, Kozo YAMAZAKI, Hideki ARIMOTO and Tatsuo SHOJI, Plasma Fusion Res. 8, 2403175 (2013).