Plasma resistivity in the presence of a reversed-field pinch dynamo

Schoenberg, Kurt F.; Moses, R.W.; Hagenson, R.L.

doi:10.1063/1.864821

Cited by 86 publications

(41 citation statements)

References 7 publications

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“…Ignition by ohmic heating is consistent with classical plasma resistivity and is a strong possiblility in the RFP because of the high current density. Classical plasma resistivity is observed in the experiment, 45 where the higher voltages required to drive current in RFPs relative to tokamaks being a result of geometric factors (i.e., higher pitch) rather than "anomalous " resistivity.…”

Section: Heatingmentioning

confidence: 91%

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Magnetic Fusion Energy Plasma Interactive and High Heat Flux Components: Volume 5, Technical assessment of critical issues in the steady state operation of fusion confinement devices

1988

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Section: Heatingmentioning

confidence: 91%

“…45 This demonstration is significant because it indicates how the plasma currents, and hence the confining fields, in an RFP may be sustained. All that is required is a means for replacing the helicity that is lost on the tlov resistive time scale (e.g., OFCD), and relaxation processes do the rest.…”

Section: C-26mentioning

confidence: 99%

Magnetic Fusion Energy Plasma Interactive and High Heat Flux Components: Volume 5, Technical assessment of critical issues in the steady state operation of fusion confinement devices

1988

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“…(13). We found that it was necessary to operate the tokamak at relatively high edge q in order to provide a stable tokamak discharge that would not be terminated by spheromak injection.…”

Section: Zov-mentioning

confidence: 99%

Efficiency and scaling of current drive and refuelling by spheromak injection into a tokamak

Brown

Bellan

1992

Nucl. Fusion

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ABSTRACT. The first measurements of current drive (refluxing) and refuelling by spheromak injection into a tokamak are discussed in detail. The current drive mechanism is attributed to the process of helicity injection, and refuelling is attributed to the rapid incorporation of the dense spheromak plasma into the tokamak. After an abrupt increase (up to go%), the tokamak current decays by a factor of three because of plasma cooling caused by the merging of the relatively cold spheromak with the tokamak. The tokamak density profile peaks sharply because of the injected spheromak plasma (ne increases by a factor of six) and then becomes hollow, suggestive of an interchange instability. Also discussed is the energy efficiency of spheromak injection current drive and the scaling of this process to larger machines. Refuelling by spheromak injection appears to be a viable scheme for larger machines. However, refluxing by spheromak injection is limited by geometrical and electrical efficiencies (both about 10%) as well as a high repetition rate requirement.

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“…͑19͒ and ͑22͒, it can be found that the term U؋B gives no contribution to the generation and dissipation of the mean magnetic field helicity. 81 In Eqs. ͑22͒ and ͑23͒, the ϩ sign expresses the helicity gain and the Ϫ sign the helicity loss.…”

Section: Fϭ␣bϫ␤"؋b ͑11͒mentioning

confidence: 99%

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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Plasma resistivity in the presence of a reversed-field pinch dynamo

Cited by 86 publications

References 7 publications

Magnetic Fusion Energy Plasma Interactive and High Heat Flux Components: Volume 5, Technical assessment of critical issues in the steady state operation of fusion confinement devices

Magnetic Fusion Energy Plasma Interactive and High Heat Flux Components: Volume 5, Technical assessment of critical issues in the steady state operation of fusion confinement devices

Efficiency and scaling of current drive and refuelling by spheromak injection into a tokamak

Model for relaxation in reversed-field pinch plasmas

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