Control of the radial electric field and of turbulent fluctuations in a tandem mirror plasma

Mase, A.; Itakura, A.; Inutake, M.; Ishii, K.; Jeong, Jung Hyun; Hattori, Kenichi; Miyoshi, S.

doi:10.1088/0029-5515/31/9/010

Cited by 80 publications

(46 citation statements)

References 25 publications

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“…The radial electric field E arising from the potential causes an E × B plasma rotation in the direction of the ion diamagnetic drift velocity, which may enhance instabilities, such as rotational flute and drift-wave modes, and degrade radial confinement. However, present studies show the suppression of low-frequency fluctuations of the density and the potential during axial confining potential formation during plug-ECH (P-ECH) [1][2][3][4][5][6]. Earlier works by Sanuki [7] and Chaudhry et al [8] discussed the effects of the ambipolar potential on the stability of drift waves.…”

Section: Introductionmentioning

confidence: 58%

“…1). The details on GAMMA 10 are provided elsewhere [1][2][3][4][5][6]. The x-axis and y-axis are perpendicular to the magnetic field in the vertical and horizontal directions, respectively.…”

Section: Tandem Mirror Gamma 10mentioning

confidence: 99%

“…In the tandem mirror GAMMA 10, an electrostatic potential for improving axial confinement is created by applying electron cyclotron resonance heating (ECH) in the end mirrors (plug/barrier cells) [1][2][3][4][5][6]. Two types of instability, a rotationally driven mode with the lowest azimuthal mode number and a drift-wave mode with high azimuthal mode numbers, are observed during the existence of confining potentials.…”

Section: Introductionmentioning

confidence: 99%

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Study of Fluctuation Suppression during Potential Formation in the Tandem Mirror GAMMA 10

Yoshikawa

Miyata

Mizuguchi

et al. 2010

Plasma and Fusion Research

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In the tandem mirror GAMMA 10, plasma confinement is achieved by not only a magnetic mirror configuration but also high potentials in both end regions. Before plug electron cyclotron resonance heating (P-ECH) was applied, drift-type fluctuations were observed in potential and density measurements. Potential and density fluctuation suppression during potential formation by the application of P-ECH was clearly observed using a gold neutral beam probe (GNBP) system. We study the relationship between the suppression levels of potential fluctuations and the effects of the produced potentials by varying the applied ECH power. Moreover, the particleflux-related values obtained by the phase difference between the potential and density fluctuations are measured using the GNBP. We can clearly show that radial anomalous transport induces radial particle transport, which decreases the plasma stored energy.

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Section: Introductionmentioning

confidence: 58%

Section: Tandem Mirror Gamma 10mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Study of Fluctuation Suppression during Potential Formation in the Tandem Mirror GAMMA 10

Yoshikawa

Miyata

Mizuguchi

et al. 2010

Plasma and Fusion Research

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“…ECH by using gyrotron is an essential method for potential confinement and for obtaining high electron temperature in tandem mirror devices [12,13]. A gyrotron is also a powerful tool for ECH and ECCD.…”

Section: Introductionmentioning

confidence: 99%

Overview of recent progress and future in GAMMA 10/PDX project

Nakashima

Imai

Sakamoto

et al. 2016

AIP Conference Proceedings

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Abstract. This paper presents an overview of the recent progress of GAMMA 10/PDX project. In the GAMMA 10/PDX project, development of fusion reactor relevant research related to magnetic mirror devices has been conducted. One of the main objectives is divertor simulation studies under the similar condition of actual fusion devices, which contributes to comprehensive development strategy towards the divertor plasma physics and plasma wall interaction (PWI) studies. The recent progress of this research is that an additional plasma heating (ICRF and ECH) significantly increased the ion flux up to 3.3×10 23 /m 2 s at the end-mirror exit, which proved an effectiveness of additional plasma heating for generating high ion flux from the mirror end. Superimposing a short pulse of ECH produces the maximum heat flux of 21 MW/m 2 by improving the west plug ECH antenna system, which exceeds the heat-load of ITER divertor plates. In detached plasma formation experiments using the divertor simulation experimental module (D-module), comparison of various radiator gases (Xe, Ar, Ne, N 2 ) injected into D-module showed that Xe was the most effective gas on electron cooling and reduction of heat and ion fluxes. In the development of high-power gyrotrons, a number of electron cyclotron heating experiments using high-power gyrotrons have been performed under strong collaboration and we made a remarkable contribution to LHD and QUEST. The first 28 GHz MW tube has attained 1.38 MW and new MW-level dual frequency gyrotron test is also in progress and 1.22 MW at 28GHz is achieved. Multi-channel/multi-pass Thomson scattering system has been developed and simultaneous measurement of radially 6 points with 10 Hz can be available. The multi-pass function of this system also improved the measurement accuracy and time resolution. Microwave interferometer system has been developed in the GAMMA 10/PDX end-cell, which contributes to detailed diagnostics for divertor simulation plasmas in D-module.

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“…Open-ended systems of the mirror or the tandem mirror type, as has been demonstrated experimentally [23,24], have the ability, through their access to the emerging field lines at the ends, to control the potential of the plasma relative to the chamber walls, including control over the radial distribution of that potential. This control can be used to enhance confinement either through limiting or through inducing plasma rotation, and for the stabilization of certain classes of plasma instabilities.…”

mentioning

confidence: 99%