Anomalous ion heating in REPUTE-1 ultra-low q and reversed field pinch plasmas

Fujita, T.; Saito, K.; Matsui, Jun; Kamada, Y.; Morimoto, Hiroshi; Yoshida, Zensho; Inoue, N.

doi:10.1088/0029-5515/31/1/001

Cited by 28 publications

(21 citation statements)

References 23 publications

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“…The same phenomenon is observed in experimental plasmas 5,28 in which a MHD relaxation controlled by collisionless or collisional magnetic reconnection takes place. This phenomenon is considered to be associated with the generation of collisionless ion viscosity, which leads directly to the ion heating.…”

Section: Introductionsupporting

confidence: 77%

“…Since the existence of the longitudinal magnetic field makes a plasma less compressible, this result indicates that the plasma compressibility is a key factor in determining the behavior of driven reconnection. The anomalous ion heating is often observed in experimental plasmas 5,28 in which a MHD relaxation controlled by magnetic reconnection takes place. This paper may give an explanation of this phenomenon.…”

mentioning

confidence: 99%

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Particle simulation study of collisionless driven reconnection in a sheared magnetic field

Horiuchi¹,

Sato²

1997

Physics of Plasmas

170

128

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Nonlinear development of collisionless driven reconnection and the consequent energy conversion process between the field and particles in a sheared magnetic field are investigated by means of a two-and-one-half-dimensional particle simulation. Magnetic reconnection takes place in two steps irrespective of a longitudinal magnetic field, but the growth rate of the reconnection field varies in proportion to the E؋B drift velocity at an input boundary. It is clearly observed that the triggering mechanism of collisionless driven reconnection for the fast growing phase changes from an electron meandering dominance in a weak longitudinal field to an electron inertia dominance in a strong field. The electron acceleration and heating take place in the reconnection area under the influence of reconnection electric field, while the electron energy is converted to the ion energy through the action of an electrostatic ͑ambipolar͒ field excited by magnetic compression in the downstream. It is also found that, in the presence of a longitudinal magnetic field, the electron acceleration by the reconnection field takes place effectively and the generated force-free current is maintained for a long period while forming an asymmetric spatial profile of current layer. © 1997 American Institute of Physics. ͓S1070-664X͑97͒00302-9͔

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Section: Introductionsupporting

confidence: 77%

mentioning

confidence: 99%

Particle simulation study of collisionless driven reconnection in a sheared magnetic field

Horiuchi¹,

Sato²

1997

Physics of Plasmas

170

128

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“…Further, inequality ͑55͒ shows that this mechanism of the ion heating probably makes the ion temperature higher than the electron's. That the temperature of the heavier ions is higher than that of the lighter ones, as observed in the experiment, 13 is a more straightforward corollary of the set of Eqs. ͑16͒ and ͑17͒: ͗͑ϩ͒"U:"U͘ represents the ion heating power per unit mass of plasma; hence the heavier ions are more strongly heated.…”

Section: ␤ϳ ͑52͒mentioning

confidence: 52%

“…It is also observed that there exists anomalous plasma resistance and the temperature of heavier ions is higher than that of the lighter ones. [8][9][10][11][12][13][14][15] Since the only external heating is ohmic, the classical ion energy input is from collisional equipartition with the electrons. This process always causes T i ϽT e , owing to the second law of thermodynamics.…”

Section: Jϭ"؋bϭb ͑1͒mentioning

confidence: 99%

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Model for relaxation in reversed-field pinch plasmas

Wang

Qiu

1996

Physics of Plasmas

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In this article, a model for anomalous ion heating, a dynamo current-sustained edge toroidal field, and a sawtooth oscillation during the relaxation in the reversed-field pinch ͑RFP͒ plasma is presented. The dynamo ͑␣͒, the turbulent resistivity ͑␤͒ and viscosity ͑͒, dependent on the magnetohydrodynamics ͑MHD͒ fluctuations, are incorporated into the model. Turbulent viscous dissipation of the fluctuation energy is proposed as the mechanism of the anomalous ion heating. This is a straightforward corollary of the turbulent viscosity heating of ions in that the temperature of the heavier ions is higher than that of the lighter ions and that the ion temperature increases with the MHD fluctuation level. Correspondingly, the turbulent resistivity heats electrons anomalously. It is shown that the dynamo current, generated by the back-transfer of fluctuating magnetic field helicity to mean magnetic field, sustains the RFP magnetic configuration. In the edge the total current density is approximately equal to the dynamo current density, while at the core the dynamo current opposes the applied electric-field-driven current, flattening the current profile. Provided the ␣ dynamo has a periodic behavior in time, the physical quantities of the RFP plasma have a sawtooth time dependence. The local poloidal current density in the edge increases during the sawtooth crash and peaks at the end of the crash, as do the ion and electron temperatures. In contrast, the toroidal current density at the core decreases during the crash and arrives at its minimum at the end of the crash. Qualitatively, the conclusions drawn from the present model are in good agreement with many of the experimental results ͓Scime et al., Phys. Rev. Lett. 68, 2165 Ji et al., ibid. 73, 668 ͑1994͔͒ and the numerical simulations.

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