RF plugging of multi-mirror machines

Miller, Tal; Be'ery, Ilan; Gudinetsky, Eli; Barth, Ido

doi:10.1063/5.0147925

Cited by 8 publications

(2 citation statements)

References 66 publications

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“…Note that the strategy discussed here results in large rotation in a simple mirror geometry; there remains the opportunity to sequence multiple such rotating mirrors much in the same way that has been approached for simple non-rotating mirrors 62 . Also, note that the strategy described in this paper is not the only possible way to reduce the fields across the material boundary of a plasma device.…”

Section: Discussionmentioning

confidence: 99%

Massive, long-lived electrostatic potentials in a rotating mirror plasma

Kolmes,

Ochs,

Rax

et al. 2024

Nat Commun

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Hot plasma is highly conductive in the direction parallel to a magnetic field. This often means that the electrical potential will be nearly constant along any given field line. When this is the case, the cross-field voltage drops in open-field-line magnetic confinement devices are limited by the tolerances of the solid materials wherever the field lines impinge on the plasma-facing components. To circumvent this voltage limitation, it is proposed to arrange large voltage drops in the interior of a device, but coexist with much smaller drops on the boundaries. To avoid prohibitively large dissipation requires both preventing substantial drift-flow shear within flux surfaces and preventing large parallel electric fields from driving large parallel currents. It is demonstrated here that both requirements can be met simultaneously, which opens up the possibility for magnetized plasma tolerating steady-state voltage drops far larger than what might be tolerated in material media.

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Section: Discussionmentioning

confidence: 99%

Massive, long-lived electrostatic potentials in a rotating mirror plasma

Kolmes,

Ochs,

Rax

et al. 2024

Nat Commun

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“…2010; Fowler, Moir & Simonen 2017; White, Hassam & Brizard 2018; Miller et al. 2023). Following Pastukhov (1974) and Schwartz et al.…”

Section: Introductionmentioning

confidence: 99%

Guiding centre motion for particles in a ponderomotive magnetostatic end plug

Rubin,

Rax,

Fisch

2023

J. Plasma Phys.

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The Hamiltonian dynamics of a single particle in a rotating plasma column, interacting with an magnetic multipole is perturbatively solved for up to second order, using the method of Lie transformations. First, the exact Hamiltonian is expressed in terms of canonical action-angle variables, and then an approximate integrable Hamiltonian is introduced, using another set of actions and angles, which describe the centre of oscillation for the particle. The perturbation introduces an effective ponderomotive potential, which to leading order is positive. At the second order, the pseudopotential consists of a sum of terms of the Miller form, and can have either sign. Additionally, at second order, the ponderomotive interaction introduces a modification to the particle effective mass, when considering the motion along the column axis. It is found that particles can be axially confined by the ponderomotive potentials, but acquire radial excursions which scale as the confining potential. The radial excursions of the particle along its trajectory are investigated, and a condition for the minimal rotation frequency for which the particle remains radially confined is derived. Last, we comment on the changes to the aforementioned solution to the pseudopotentials and particle trajectory in the case of resonant motion, that is, a motion which has the same periodicity as the perturbation.

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Electromagnetic oscillations and anomalous ion scattering in the helically symmetric multiple-mirror trap

Tolkachev,

Inzhevatkina,

Sudnikov

et al. 2024

J. Plasma Phys.

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The paper presents an investigation of the plasma fluctuation in the SMOLA helical mirror, which is suspected to be responsible for anomalous scattering. The helical mirror confinement is effective when the ion mean free path is equal to the helix pitch length. This condition can be satisfied in hot collisionless plasma only by anomalous scattering. The wave, which scatters the passing ions, is considered to receive energy from the trapped ions. The oscillations of the electric field in the helically symmetric plasma were observed in experiment. The oscillations have both regular highly correlated and chaotic components. The dependency of the regular component frequency on the Alfvén velocity is linear for $V_{\rm A} < 2.8 \times 10^6\ \text {m}\ \text {s}^{-1}$ and constant for higher values. It is shown experimentally that the condition for the wave to be in phase resonance with the trapped ions is satisfied in a specific region of the plasma column for the highly correlated component. The amplitude of the chaotic component (up to $3\ \text {V}\ \text {cm}^{-1}$ ) is higher than the estimated electric field required for the ion scattering.

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RF plugging of multi-mirror machines

Cited by 8 publications

References 66 publications

Massive, long-lived electrostatic potentials in a rotating mirror plasma

Massive, long-lived electrostatic potentials in a rotating mirror plasma

Guiding centre motion for particles in a ponderomotive magnetostatic end plug

Electromagnetic oscillations and anomalous ion scattering in the helically symmetric multiple-mirror trap

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