A re-analysis of exponential rigid-rotor astron equilibria

Lovelace, R. V. E.; Larrabee, D. A.; Fleischmann, H. H.

doi:10.1063/1.862314

Cited by 17 publications

(7 citation statements)

References 3 publications

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“…"Prompt loss," i.e., immediate loss of unconfined ions, forces the distribution function to zero at the confinement boundary; this was the approach taken in solutions developed in Ref. 11. However, the endloss time for unconfined ions in FRCs is not negligible.…”

Section: Kinetic Ion Modelmentioning

confidence: 96%

“…A major defect of RR equilibria is the absence of a confinement boundary. The existence of such a boundary was first recognized for Astron systems 11 and later in the context of FRCs per se. 18 The latter derived a kinetic "confinement boundary" illustrated in Fig.…”

Section: Kinetic Ion Modelmentioning

confidence: 98%

“…Early Astron-relevant equilibrium computations accounted for end-loss by assuming prompt end-loss in the unconfined regions of phase space, i.e., f ¼ 0 there. 11 Analytic solutions to the Vlasov-Maxwell system have been developed in an attempt to relax the uniform temperature and rigid rotation assumptions: these began with a flexible form of the distribution and then forced it to satisfy the Vlasov equation. 12 These early studies entirely neglected the effect of the electrostatic potential.…”

Section: Kinetic Ion Modelmentioning

confidence: 99%

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Hybrid equilibria of field-reversed configurations

Steinhauer

2011

Physics of Plasmas

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This paper presents the first detailed model of hybrid equilibria relevant to field-reversed configuration experiments, leading to a system of equations that are solved for a range of fully two-dimensional equilibria. Several features of these highly kinetic objects are explored. The range of equilibria is primarily dependent on a single free parameter related to the flow shear. The level of flow shear has a profound effect on the structure, especially near the separatrix. This likely has a strong influence on both stability and transport properties. Higher flow shear is favorable in every respect. The key factor behind the influence of flow shear is the relatively rapid end loss of unconfined ions. Differences between hybrid and static-fluid equilibrium models are highlighted, including the integrity of surface functions, the effect of flow shear, and the scrape-off layer thickness.

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Section: Kinetic Ion Modelmentioning

confidence: 96%

Section: Kinetic Ion Modelmentioning

confidence: 98%

Section: Kinetic Ion Modelmentioning

confidence: 99%

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Hybrid equilibria of field-reversed configurations

Steinhauer

2011

Physics of Plasmas

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“…The condition H < Cl 0 \Po | was derived in Ref. [84], without any discussion regarding the possible existence of a third invariant.…”

Section: Equilibria With No Plasma Pressurementioning

confidence: 99%

“…As we have discussed, the relevance of the limit for absolute confinement, H = -£l o ?d depends on the existence of stochastic orbits. Only when such orbits exist is it appropriate to include a cut-off in the equilibrium distribution function [84] for…”

Section: /Cjp>mentioning

confidence: 99%

Field-reversed configurations with a component of energetic particles

Finn¹,

Sudan²

1982

Nucl. Fusion

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This review is concerned with the physics of field-reversed configurations created by energetic particles of large orbits, of which the earliest example is the Astron. The Astron concept has evolved into the Ion Ring Compressor in which a low-energy ring of ions is magnetically compressed to high energy for heating the confined plasma to thermonuclear ignition. A third version is the hybrid in which field reversal is created both by plasma currents as in a θ-pinch or a spheromak and a component of energetic large orbit ions to provide heating energy as well as improved stability. This paper treats first the injection, trapping, and formation of electron and ion rings from a theoretical standpoint as well as presenting the principal experimental results. The equilibria and the characteristics of the particle orbits are discussed in some detail including conditions under which the orbits cease to be integrable and pass to a stochastic description. The theory of magnetic compression of rings and the classical transport of heat and particles of the plasma confined in the closed-poloidal-field-line region is presented. The bulk of the review is concerned with low-frequency stability of such configurations by means of a generalized energy principle for treating the large-orbit particles in the Vlasov limit. The pathology of all possible unstable modes is discussed at some length. We conclude with an exhaustive survey of microinstabilities driven by the energetic particle current for a special model and conclude that most of them are stabilized by strong gradients in density and magnetic field. A brief discussion on drift modes follows. Our present theoretical understanding of these systems, although still incomplete in some respects, nevertheless leads to the view that the promise of the very favourable features of fusion reactors based on these concepts is a sufficient impetus for their continued experimental and theoretical study.

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