Analysis of MHD Behaviour by Using Optical Detectors in the GAMMA 10 Tandem Mirror

Saosaki, S.; Ichimura, M.; Tanaka, Satoru; Nakamura, M.; Ohta, Y.; Kadoya, K.; Kawabata, T.; Oikavva, M.; Kano, H.; Kobayashi, S.; Yoshikawa, Masayuki; Hōjō, H.; Nakashima, Y.; Inutake, M.; Yatsu, K.

doi:10.13182/fst01-a11963456

Cited by 3 publications

(5 citation statements)

References 6 publications

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“…It has been reported that the electrostatic fluctuations were suppressed by MLO experimentally in GAMMA10 [10], which is consistent with the stability criterion (14) or (19).…”

supporting

confidence: 83%

“…The plasma escaping from the central cell touches the MLO, because the plasma radius is 0.18 m at the central cell. Thus, the MLO is heated by high-energy ions and electrons, so that it can emit a secondary electron current easily and can contribute the line-tying effects on the interchange instability [10].…”

Section: Introductionmentioning

confidence: 99%

“…The effects of the conducting ends on an interchange instability are considered based on the particle simulation results. The sheath potential in front of the limiter is neglected in the reduced MHD simulation on the assumption that the MLOs are hot enough to emit a secondary electron current in GAMMA10 [10].…”

Section: Introductionmentioning

confidence: 99%

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An interchange instability in an open system and the line-tying effect on it

Katanuma¹,

Okuyama²,

Kato³

2013

Nucl. Fusion

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An interchange instability is the most dangerous instability to an open system such as GAMMA10 (Inutake et al 1985 Phys. Rev. Lett. 55 939). A line tying is a powerful tool for stabilizing an interchange instability because the magnetic field lines terminate at the conducting ends in an open system. This paper studies the mechanism of the appearance of line tying in an interchange instability by a particle simulation (taking into account the electron inertia along a magnetic field line precisely) and the line-tying effect on the interchange instability in GAMMA10 by a reduced MHD simulation. We have newly found the nonlinear (quasi-linear) stability criterion to an interchange instability with conducting ends. The limiters of Movable Limiter Outside the anchor mirror cell (MLO) installed in GAMMA10 are found to have a stabilization effect on the interchange instability, which is consistent with the experimental results.

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“…It has been reported that the electrostatic fluctuations were suppressed by MLO experimentally in GAMMA10 [10], which is consistent with the stability criterion (14) or (19).…”

supporting

confidence: 83%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

An interchange instability in an open system and the line-tying effect on it

Katanuma¹,

Okuyama²,

Kato³

2013

Nucl. Fusion

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show abstract

“…From the above-described experimental evidence, the observed rigid rotational phenomena for both bulk electrons and ions are consistently interpreted in terms of a flute interchange mode driven by the pressure difference [17,18,20] between the central cell and the anchor region caused by the anchor cold gas puffing. This is also consistent with the results from previously reported electrostatic probe measurements in the peripheral plasma regions of the central cell and the anchor [17,18,20]; i.e. fluctuations having an azimuthal mode number of m = −1 (i.e.…”

Section: Experimental Results and Physics Interpretationsmentioning

confidence: 73%

“…In this paper, the detailed data on the internal core plasma structural behaviour during the MHD destabilization are presented by the use of the developed x-ray diagnostics in comparison to the previous reports with probe measurements and H α diagnostics dominated over the peripheral plasma region [17,18], as well as the mode identification with microwave scattering and reflectometor diagnostics [16,19], since the requirement of the direct observations of interior plasma structural behaviour including the plasma temperature profiles during the MHD instability have still remained as an unsolved issue in order to construct the overall view of the MHD phenomena.…”

Section: Introductionmentioning

confidence: 99%

Observations of temporal and spatial behaviour of plasmas in relation to the interchange stability boundary scaling in GAMMA 10

Minami

Cho

Kohagura

et al. 2002

Plasma Phys. Control. Fusion

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Observations of internal core plasma structural behaviour during the magnetohydrodynamic (MHD) destabilization of the central cell plasmas are carried out by the use of our developed semiconductor x-ray detector arrays installed in both central cell and anchor regions of the GAMMA 10 tandem mirror. In the present paper, it is found from the developed x-ray diagnostics that the bulk plasmas rotate without a change in its shape and structure with an E × B velocity during the destabilization. The onset of the off-axis rotation is identified to be closely related to a scaling of the MHD stability boundary (i.e. the anchor beta requirements for stabilizing central cell hot ion plasmas). These data confirm pressure driven interchange instability in tandem mirror plasmas, and reveal the rigid rotational bulk plasma structure as the first demonstrated interior plasma property during the destabilization.

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Measurement of low frequency plasma fluctuations with a visible light detector in GAMMA 10

Higaki

Ichimura

Horinouchi

et al. 2004

Review of Scientific Instruments

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Low frequency fluctuations of a plasma in the central cell of the GAMMA10 tandem mirror have been observed with electrostatic probes (ESPs) installed at the peripheral region of the plasma. Typical plasma parameters for a hot ion mode operation are ne∼2×1012 cm−3, Ti∼4 keV, Te∼100 eV, B=4 kG, and rp=18 cm. Although the ESP is an effective tool to measure local plasma parameters and fluctuations, it can be damaged with the higher electron temperature. Here, a new visible light detector was introduced, which could measure the plasma fluctuations without contacting the plasma. The obtained results were compared with those of ESPs. It is found that the visible light detector is applicable when the electron temperature becomes much higher in the future experiment.

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Analysis of MHD Behaviour by Using Optical Detectors in the GAMMA 10 Tandem Mirror

Cited by 3 publications

References 6 publications

An interchange instability in an open system and the line-tying effect on it

An interchange instability in an open system and the line-tying effect on it

Observations of temporal and spatial behaviour of plasmas in relation to the interchange stability boundary scaling in GAMMA 10

Measurement of low frequency plasma fluctuations with a visible light detector in GAMMA 10

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