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takahashi_madison.pdf2014-08-18 01:58:18Toshiki Takahashi

Simulation study on FRC translation

Author: Toshiki Takahashi
Requested Type: Consider for Invited
Submitted: 2014-05-30 04:02:14

Co-authors: S. Koike, K. Matsuzaki, T. Asai

Contact Info:
Gunma University
1-5-1 Tenjin-Cho
Kiryu, Gunma   376-851
Japan

Abstract Text:
Field-Reversed Configurations (FRCs) are highly elongated high-beta plasma [1]. Since they are topologically in a simply-connected shape, therefore they can be translated along the guide field [2]. In FRC experiment history, translation technique has been well developed, because the FRC plasma has to be translated from the formation region surrounded by such as the quartz tube to the confinement region in a metal chamber.
Here, global motion of two axially-colliding field-reversed configurations is simulated by 2-D MHD model. We modeled to separate the external and plasma magnetic field. Translation velocity is controlled by time-varying external magnetic field, and the maximum translation velocity in our case is found to 1.3 times larger than Alfven velocity.
We have also carried out the MHD simulation to find the mechanism of flux lifetime extension by means of axial neutral gas flow injection; it is thought as a process equivalent to FRC translation into a region where neutral gas is filled. We have derived the MHD equations with the source terms due to ionization of neutral particles. Extension of the flux lifetime has been found and its increment rate increases with the injection energy. We have investigated the flux variance calculated from the Faraday’s law, and found that the inductive electric field due to the Lorentz force is a dominant reason for lifetime extension.

[1] M. Tuszewski, Nucl. Fusion 28, 2033 (1988).
[2] D. J. Rej et al., Phys. Fluids 29, 852 (1986).

Characterization: 1.1

Comments:

Workshop on Exploratory Topics in Plasma and Fusion Research (EPR) and US-Japan Compact Torus (CT) Workshop
August 5-8, 2014
Madison, Wisconsin

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