Plasma and Fusion Research

Volume 12, 1402006 (2017)

Regular Articles

Implementation of Neoclassical Effects in Momentum Transport Analysis at LHD

Jasper BECKERS, Katsumi IDA^1,2), Mikirou YOSHINUMA¹⁾, Masahiko EMOTO¹⁾, Ryosuke SEKI¹⁾, Masayuki YOKOYAMA^1,2) and Roger JASPERS

: Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
1): National Institute for Fusion Science, 322-6 Oroshi Toki 509-5292, Japan
2): SOKENDAI, 322-6 Oroshi, Toki 509-5292, Japan

(Received 5 November 2016 / Accepted 21 January 2017 / Published 21 February 2017)

Abstract

Plasma rotation plays an important role in the suppression of turbulence, leading to an increase in energy and particle confinement. Significant rotation also leads to a stabilisation of the resistive wall mode. The external momentum input from Neutral Beam Injection (NBI) in current generation fusion plasmas may not be available for future self-heated fusion reactors. Therefore it is important to analyse the phenomenon of spontaneous rotation. At NIFS plasma rotation and momentum transport of the Large Helical Device (LHD) plasma is analysed using a code suite called TASK3D-a. In this work neoclassical effects, which can be especially significant in non-axisymmetric plasmas, were implemented in TASK3D-a. Initial analysis of neoclassical radial momentum flux profiles shows that in NBI-driven momentum input neoclassical effects, especially neoclassical damping, become dominant in the non-center plasma region. It was also found that during and after pellet-injection the neoclassical damping force becomes strong. With the implementation of neoclassical effects new features can be examined in the momentum flux-gradient relations; in the damping-dominated situation following pellet injection a large excursion in momentum flux is found. This work can aid in the search for neoclassical transport-optimised configurations for enhanced (spontaneous) plasma rotation.

Keywords

momentum transport, neoclassical viscosity, neoclassical driving torque, bulk-ion/impurity velocity difference, momentum flux-gradient relation

DOI: 10.1585/pfr.12.1402006

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References

[1] R. Groebner et al., Phys. Rev. Lett. 64, 3015 (1990).
[2] K. Ida et al., Phys. Rev. Lett. 65, 1364 (1990).
[3] A. Garofalo et al., Phys. Rev. Lett. 89, 235001 (2002).
[4] K. Ida et al., Phys. Rev. Lett. 74, 1990 (1995).
[5] M. Yokoyama et al., “Extended Capability of the Integrated Transport Analysis Suite, TASK3D-a, for LHD Experiment, and its Impacts on Facilitating Stellarator-Heliotron Research”, 26th IAEA-FEC, Kyoto (Oct. 2016).
[6] K. Ida and J. Rice, Nucl. Fusion 54, 045001 (2014).
[7] Ö. Gürcan et al., Phys. Rev. Lett. 100, 135001 (2008).
[8] K. Ida et al., J. Phys. Soc. Jpn. 67, 4089 (1998).
[9] J. Rice et al., Nucl. Fusion 37, 421 (1997).
[10] K. Ida et al., Nucl. Fusion 50, 064007 (2010).
[11] A. Fukuyama, TASK code, http://bpsi.nucleng.kyoto-u.ac.jp/task/
[12] H. Lee, K. Ida et al., Plasma Phys. Control. Fusion 55, 014011 (2013).
[13] K. Ida et al., Phys. Plasmas 4, 310 (1997).
[14] N. Nakajima and M. Okamoto, J. Phys. Soc. Jpn. 61, 833 (1992).
[15] K. Watanabe et al., Nucl. Fusion 35, 335 (1995).
[16] N. Nakajima and M. Okamoto, J. Phys. Soc. Jpn. 60, 4146 (1991).
[17] C.D. Beidler and W. D'haeseleer, Plasma Phys. Control. Fusion 37, 463 (1995).
[18] K. Ida et al., Phys. Rev. Lett. 86, 5297 (2001).
[19] S. Murakami et al., Fusion Technol. 27, 256 (1995).
[20] S. Satake et al., Nucl. Fusion 45, 1362 (2005).