First results from plasma edge biasing on SPECTOR

Carl Dunlea; General Fusion Team; Chijin Xiao; Akira Hirose

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arXiv · 1909.07463

First results from plasma edge biasing on SPECTOR

Carl Dunlea·General Fusion Team·Chijin Xiao·Akira Hirose

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Abstract

A description of an edge-biasing experiment conducted on the SPECTOR (Spherical Compact Toroid) plasma injector is presented, along with initial results. The insertion of a disc-shaped molybdenum electrode (probe), biased at up to +100V, into the edge of the CT (Compact Torus), resulted in up to 1kA radial current being drawn. Core electron temperature, as measured with a Thomson-scattering diagnostic, was found to increase by a factor of up to 2.4 in the optimal configuration tested. H_alpha intensity was observed to decrease, and CT lifetimes increased by a factor of up to 2.3. A significant reduction in electron density was observed; this is thought to be due to the effect of a transport barrier impeding CT fueling, where, as verified by MHD simulation, the fueling source is neutral gas that remains concentrated around the gas valves after CT formation.

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Carl Dunlea, General Fusion Team, Chijin Xiao, Akira Hirose. 2020-02-29. First results from plasma edge biasing on SPECTOR. https://arxiv.org/abs/1909.07463

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