Equilibrium of Electron Clouds in Toroidal Magnetic Fields

Daugherty, J. D.

doi:10.1063/1.1761966

Cited by 57 publications

(27 citation statements)

References 4 publications

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“…This is the opposite of what occurs in non-neutral plasmas confined by pure toroidal fields which shift inward, such that the resulting attraction of the plasma to the inboard side of the conducting boundary balances the hoop force. [9][10][11] When the conducting boundary is shifted vertically with respect to the magnetic surfaces, the plasma density builds up near the conductor. This is equivalent to a negatively charged plasma being attracted to a positive charge.…”

Section: Discussionmentioning

confidence: 99%

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Numerical investigation of three-dimensional single-species plasma equilibria on magnetic surfaces

et al. 2005

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Presented for the first time are numerical solutions to the three-dimensional nonlinear equilibrium equation for single-species plasmas confined on magnetic surfaces and surrounded by an equipotential boundary. The major-radial shift of such plasmas is found to be outward, qualitatively similar to the Shafranov shift of quasineutral plasmas confined on magnetic surfaces. However, this is the opposite of what occurs in the pure toroidal field equilibria of non-neutral plasmas (i.e., in the absence of magnetic surfaces). The effect of varying the number of Debye lengths in the plasma for the three-dimensional (3D) model is in agreement with previous 2D calculations: the potential varies significantly on magnetic surfaces for plasmas with few Debye lengths (a≲λd), and tends to be constant on surfaces when many Debye lengths are present (a≳10λd). For the case of a conducting boundary that does not conform to the outer magnetic surface, the plasma is shifted towards the conductor and the potential varies significantly on magnetic surfaces near the plasma edge. Debye shielding effects are clearly demonstrated when a nonuniform bias is applied to the boundary. Computed equilibrium profiles are presented for the Columbia Non-Neutral Torus [T. S. Pedersen, A. H. Boozer, J. P. Kermer, R. Lefrancois, F. Dahlgren, N. Pomphrey, W. Reiersen, and W. Dorland, Fusion Sci. Technol. 46, 200 (2004)], a stellarator designed to confine non-neutral plasmas.

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Section: Discussionmentioning

confidence: 99%

“…This outward shift of density is the opposite of what is observed for pure toroidal field equilibria, 9 where the plasma contracts. 10,11 In the case of a pure toroidal field, there is a bulk force balance between the attraction of the plasma to the inner conducting wall and the hoop force pushing the plasma outward.…”

Section: Conforming Boundarymentioning

confidence: 99%

Numerical investigation of three-dimensional single-species plasma equilibria on magnetic surfaces

et al. 2005

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“…The impact of electric rotation in various toroidal configurations was also analyzed 13 . Electric rotation to overcome drifts was likewise analyzed, both theoretically and experimentally, within the context of particle accelerators [14][15][16][17] and non-neutral plasma confinement [18][19][20] .…”

Section: Introductionmentioning

confidence: 99%

Efficiency of wave-driven rigid body rotation toroidal confinement

2017

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The compensation of vertical drifts in toroidal magnetic fields through a wave-driven poloidal rotation is compared to compensation through the wave driven toroidal current generation to support the classical magnetic rotational transform. The advantages and drawbacks associated with the sustainment of a radial electric field are compared with those associated with the sustainment of a poloidal magnetic field both in terms of energy content and power dissipation. The energy content of a radial electric field is found to be smaller than the energy content of a poloidal magnetic field for a similar set of orbits. The wave driven radial electric field generation efficiency is similarly shown, at least in the limit of large aspect ratio, to be larger than the efficiency of wave-driven toroidal current generation.

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“…Theory supports the expectation that equilibria exist for nonneutral plasmas in a toroidal magnetic field [ 1,2,3,4]. Under certain restrictions, the equilibria are also expected to be stable [5,6,7].…”

Section: Introductionmentioning

confidence: 60%

Electron plasma confinement in a partially toroidal trap

Stoneking¹,

Fontana²,

Sampson³

et al. 2002

AIP Conference Proceedings

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Abstract. A new experiment seeks to examine equilibrium, stability, and confinement properties of toroidal electron plasmas. Electron plasmas with density about 3 x 106 cm-3 are trapped for S ps in a "partially" toroidal (or 'C'-shaped) trap (B z 200 G). Large amplitude oscillations are observed in the 100 kHz frequency range. The oscillation frequency is proportional to 1IB and depends on the applied horizontal electric field, but not on the amount of charge in the trap. Some evidence points toward the ion resonance instability as the cause of these oscillations.

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Equilibrium of Electron Clouds in Toroidal Magnetic Fields

Cited by 57 publications

References 4 publications

Numerical investigation of three-dimensional single-species plasma equilibria on magnetic surfaces

Numerical investigation of three-dimensional single-species plasma equilibria on magnetic surfaces

Efficiency of wave-driven rigid body rotation toroidal confinement

Electron plasma confinement in a partially toroidal trap

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