The <i>n</i>=1 rotational instability in field-reversed configurations

The ideal magnetohydrodynamic stability is investigated of localized interchange modes in a large-aspect ratio tokamak plasma. The resulting stability criterion includes the effects of toroidal rotation and rotation shear and contains various well-known limiting cases. The analysis allows for a general adiabatic index, resulting in a stabilizing contribution from the convective effect. A further stabilizing effect from rotation exists when the angular frequency squared decreases radially more rapidly than the density. Flow shear, however, also decreases the stabilizing effect of magnetic shear through the KelvinHelmholtz mechanism. Numerical simulations reveal the merits and limitations of the performed local analysis.

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“…In contrast to the magnetorotational instability, this instability is often observed in experiments, see, e.g. [3,4,6,7].…”

Section: The Kinetic Energy Term S Kmentioning

confidence: 99%

“…The rotational or centrifugal Rayleigh-Taylor instability e.g. almost always appears in field-reversed configurations [3] and has recently been observed in a magnetic dipole experiment [4]. This instability, together with the Kelvin-Helmholtz instability [5] has been extensively studied in the 1970s and 1980s in Q-machines, see, e.g.…”

Section: Introductionmentioning

confidence: 99%

Stability of localized modes in rotating tokamak plasmas

Haverkort

Blank

2011

Plasma Phys. Control. Fusion

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“…Experimental and theoretical studies of FRC stability have mainly focused on elongated (E > 1) and oblate (0 < E < 1) FRC plasmas, formed by the FRTP (Slough & Hoffman, (1993), Fujimoto et al, 2002;Tuszewski, et al, 1990;Tuszewski et al, 1991;Kumashiro et al,1993;Asai et al, 2006) and CHSW methods (Yamada et al, 1990;Ono et al, 1993;Gerhardt et al 2008), respectively. Details of the two methods are introduced in the next section.…”

Section: Formation Methods For Frc Plasmamentioning

confidence: 99%

“…), and on spheromak-merging facilities such as the TS-3 (Ono et al, 1993) and MRX (Gerhardt et al, 2006). In addition, the stability of prolate and oblate FRCs has been analyzed by means of visible and x-ray photography with an end-on camera (Slough & Hoffman, 1993;Tuszewski et al, 1991), computer tomography reconstruction of the visible emission profile (Asai et al, 2006), as well as mode analysis of the external B  -magnetic probe array (Mirnov coil array) (Slough & Hoffman, 1993;Tuszewski et al, 1990Tuszewski et al, , 1991Kumashiro et al, 1993;Ikeyama et al, 2008) and the internal magnetic probe array (Ono et al, 1993;Gerhardt et al, 2006).…”

mentioning

confidence: 99%

“…The m/n=1/1 tilt mode instability is thought to be most dangerous. The stability of prolate and oblate FRC plasma has been investigated experimentally on several FRTP www.intechopen.com devices (FRX-C/LSM (Tuszewski et al, 1990(Tuszewski et al, , 1991, LSX, (Slough & Hoffman, 1993), NUCTE-III (Kumashiro et al, 1993;Asai et al, 2006;Ikeyama et al, 2008), etc. ), and on spheromak-merging facilities such as the TS-3 (Ono et al, 1993) and MRX (Gerhardt et al, 2006).…”

mentioning

confidence: 99%

See 1 more Smart Citation

MHD Activity in an Extremely High-Beta Compact Toroid

Asai¹,

Takahashi²

2012

Topics in Magnetohydrodynamics

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Multichannel optical diagnostic system for field-reversed configuration plasmas

Takahashi

Gota

Fujino

et al. 2004

Review of Scientific Instruments

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A constructed diagnostic system consisting of a 60-channel set of optical detectors with flexible viewing configurations is realized to investigate three-dimensional magnetohydrodynamic (MHD) motions and the internal structure of a field-reversed configuration (FRC) plasma. The system can detect radiation from the plasma in the wavelength range of 420–820 nm. Optical filters are used to select the wavelength ranges required in the experiment. The sensitivities of all the optical detectors are calibrated using radiation from the FRC plasma at a quiescent phase. Radiation profiles measured by orthogonal viewing configuration of the detectors are shown at three toroidal cross sections. From these profiles, the time evolution of the three-dimensional MHD motion of the plasma is depicted. The radiation profile measured by a one-dimensional viewing configuration yields not only an electron density profile inside the separatrix but also the width of an edge-layer plasma. A bright halo around the edge-layer plasma is observed using a Balmer-α line filter. The orthogonal viewing configuration can also be used to analyze the internal structure of the FRC. The deviated position of the major axis is estimated from the comparison between the measured radiation profiles and the nonconcentric density profile based on the rigid rotor profile model.

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The n=1 rotational instability in field-reversed configurations

Abstract: Data from an array of external probes provide the first clear evidence for the n=1 rotational instability in field-reversed configurations. The time evolution and the axial structure of this instability are clarified.

Cited by 13 publications

References 6 publications

Stability of localized modes in rotating tokamak plasmas

Stability of localized modes in rotating tokamak plasmas

MHD Activity in an Extremely High-Beta Compact Toroid

Multichannel optical diagnostic system for field-reversed configuration plasmas

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