Plasma and Fusion Research

Volume 12, 1202007 (2017)

Rapid Communications


Localized Density Fluctuation in the Downstream of Detached Plasma
Kohei TAKEYAMA, Noriyasu OHNO, Masayuki YOSHIKAWA1), Hirohiko TANAKA and Shin KAJITA2)
Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
1)
Plasma Research Center, University of Tsukuba, 1-1-1 Tennodai-cho, Tsukuba 305-8572, Japan
2)
Institute of Materials and Systems for Sustainability, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
(Received 17 December 2016 / Accepted 27 January 2017 / Published 21 February 2017)

Abstract

The density fluctuation was measured with a 70-GHz microwave interferometry system in the linear divertor plasma simulator NAGDIS-II while changing from the attached to the detached states. In the detached plasma, a large amplitude fluctuation of ≤ 10 kHz appeared in the peripheral region. The fluctuation has a maximum value at the neutral gas pressure of 30 - 34 mTorr. Further, the measurement of the light emission associated with the plasma recombination indicates that the large amplitude fluctuation is located at just downstream of the recombination front, in which the recombination process is the most enhanced.


Keywords

density fluctuation, recombination front, detached plasma, microwave interferometer, NAGDIS-II

DOI: 10.1585/pfr.12.1202007


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