Equilibrium of a Toroidal Plasma with a Conducting Aperture Limiter

Abstract

A conducting limiter brings about equilibrium of a toroidal plasma by anchoring magnetic field lines. Charge separation arising from the curvature effect can be short circuited by the limiter. This way of achieving equilibrium is not possible if the charge separation current exceeds the maximum ion saturation current to the limiter. Experiments with the Model C stellarator are consistent with this model. An observed instability is related to the loss of equilibrium due to the excess charge separation current.

Observation of improved behavior by electrode biasing of a toroidal plasma having no poloidal magnetic field

“…The equilibrium of this simple toroidal plasma is maintained by a vertical current in the plasma which flows along the conducting limiter. In other words, the conducting limiter substantially reduces the vertical electric field E z produced by charge separation, and is discussed in detail elsewhere [10,11]. Such hot filament produced toroidal plasmas have been used earlier for tokamak-related studies, viz., current drive [12], wave propagation, and heating [13].…”

“…4(a)] and the maximum increase is by a factor of -2. The asymmetric radial profile of the plasma density is due to the incomplete short circuit of E z (arising because of \B and curvature drift) by the limiter [11], which results in an E z x/?<» radially outward force. The unchanged shape of the radial profile by bias suggests that the convective losses due to EZ^BQ are not affected.…”

Investigation of Plasma Equilibrium in the Saskatchewan Torus‐Modified (STOR‐M) during Alternating Current Operation

“…In the absence of the rotational transform, during the current reversal phase the plasma will be lost over a time scale [16] τ ∼ 2ea…”

Low-frequency fluctuations in a pure toroidal magnetized plasma

“…This vertical electric field is short circuited by a conducting circular grounded limiter of diameter 18 cm so as to keep plasma in equilibrium. A detail of the maintenance of equilibrium of plasma by a conducting limiter is described in [11]. A similar technique of plasma production and equilibrium has been used in a few other BETA-like devices such as ACT-1 (advanced concept torus 1) [1] and Blaamann [3].…”