Particle exchange in the plug of a thermal barrier tandem mirror

Catto, Peter J.

doi:10.1063/1.864398

Cited by 11 publications

(7 citation statements)

References 7 publications

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“…Again using the ansatz [7] that the flux for f is distributed as exp(-e) -exp(-e m ), we find with (12) (13) (14) We note that a approaches the correct large-mirrorratio limit (unity) and small-mirror-ratio limit (zero), as R approaches one and zero, respectively. In addition, we use a as an interpolation function to connect the previously derived [1][2][3][4][5] large-and smallmirror-ratio loss rates (G p and G o , respectively), and thus take…”

Section: And>mentioning

confidence: 76%

“…[6] and describe a procedure for extrapolating these to obtain expressions applicable at intermediate mirror ratios. An alternative procedure, with approximately the same degree of rigour, is described in Refs [14,15]. In Section 4, we describe a series of code runs in which the mirror ratio and electron heating power are varied in order to test the analytic formulae.…”

Section: Introductionmentioning

confidence: 99%

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Electrostatically trapped electrons in thermal-barrier tandem mirrors

Rensink

Cohen

Mirin³

et al. 1984

Nucl. Fusion

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Electron confinement in the plug regions of thermal-barrier tandem mirrors is examined. Analytical and numerical (Fokker-Planck code) approaches are presented for small-to-intermediate mirror ratios including the effects of passing particles and electron heating. Steady-state trapped-electron densities and mean energies from the theory and code agree to within 20% for mirror ratios 0 < R < 2.2 with and without passing particles. Electron heating and detrapping by strong RF diffusion is demonstrated computationally for parameters expected in the TMX-U experiment. * Work performed under the auspices of the US Department of Energy by the Lawrence Livermore National Laboratory under contract number W-7405-ENG-48.

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Section: And>mentioning

confidence: 76%

Section: Introductionmentioning

confidence: 99%

Electrostatically trapped electrons in thermal-barrier tandem mirrors

Rensink

Cohen

Mirin³

et al. 1984

Nucl. Fusion

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“…Equation (2) applies when the ratio R of the magnetic field at the edge of the potential well to that at the middle is bigger than about T e p / $ p b . Extension to smaller mirror ratios is considered in Refs [5][6][7] and is also discussed in the present paper.…”

Section: Figl Sketch Of Magnetic and Potential Profiles For A Tandem ...mentioning

confidence: 99%

“…(An alternative ansatz, obtained by specifying the shape of the level surfaces of f/fM, is used in Ref. [7] to extrapolate the results of Ref. [5] to small mirror ratio.)…”

Section: Approximate Evaluation Of Flux Expressionsmentioning

confidence: 99%

Effect of magnetically trapped electrons on the plug potential in thermal-barrier tandem mirrors

Cohen

1983

Nucl. Fusion

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The problem of potential formation in a thermal-barrier tandem-mirror machine in which the plug and barrier are combined in a single cell is considered. In particular, the effect of hot, magnetically confined barrier electrons on formation of the potential difference $ P b between the plug and barrier regions is evaluated. This is done using a fit to a portion of the hot-electron distribution function and the formalism of Cohen, Bernstein, Doming and Rowlands, which gives the collisional loss rate for particles trapped in a well in the presence of an arbitrary distribution of passing particles. The energy flux associated with the flow of particles across the separatrix dividing the passing and trapped portions of velocity space is also derived in terms of the particle and energy fluxes in the absence of passing particles. Numerical examples appropriate for MFTF-B and TMX-U are presented.

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“…(ii) On the other hand, in the weak ECH case [23,35], f p becomes Maxwellian because of collisions, and the relation is…”

Section: Comparison Between the 0 C Versus 0 B Data Plot And Cohen's ...mentioning

confidence: 99%

Observation of scaling laws of ion confining potential versus thermal barrier depth and of axial particle confinement time in the tandem mirror GAMMA 10

et al. 1988

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In the thermal barrier tandem mirror GAMMA 10, the scaling law governing the enhancement of the ion confining potential, ϕc, resulting from thermal barrier formation, is obtained experimentally, and is consistently interpreted in terms of the weak and strong ECH theories set up by Cohen and co-workers. The scaling law on the axial particle confinement time, τp‖, related to this ϕc formation, is also demonstrated in detail; it is in good agreement with the Pastukhov theory as modified by Cohen and co-workers. This scaling is verified at any radial position in the core plasma region and at any time through the various stages of a discharge; this indicates a scaling with drastic improvement of τp‖, due to the potential formation in the tandem mirror plasma.

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Particle exchange in the plug of a thermal barrier tandem mirror

Abstract: The collisional fluxes of trapped electrons escaping from the plug, and the center cell electrons passing over the thermal barrier and becoming trapped, are evaluated for a simple thermal barrier model appropriate to present tandem mirror experiments.

Cited by 11 publications

References 7 publications

Electrostatically trapped electrons in thermal-barrier tandem mirrors

Electrostatically trapped electrons in thermal-barrier tandem mirrors

Effect of magnetically trapped electrons on the plug potential in thermal-barrier tandem mirrors

Observation of scaling laws of ion confining potential versus thermal barrier depth and of axial particle confinement time in the tandem mirror GAMMA 10

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