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The Pulsed High Density Experiment: Initial Results from the Dynamic Formation of High Flux FRCs

Author: Samuel P. Andreason
Requested Type: Consider for Invited
Submitted: 2006-12-18 22:08:56

Co-authors: Hiroshi Gota, Chris Pihl, and John Slough

Contact Info:
University of Washington
AERB, RM 120 BX 352250
Seattle, WA   98195-2

Abstract Text:
The goal of the Pulsed High Density (PHD) experiment is to reach break-even conditions through the magneto-kinetic compression of the Field Reversed Configuration (FRC). The simply-connected closed field, high β, and linear geometry of a FRC make it highly attractive for fusion reactor concepts in general. The PHD experimental program takes full advantage of the linear geometry by forming the FRC in translation. This “dynamic formation” makes a very high flux FRC possible. It is anticipated that dynamic formation results in large sheared axial flows with significant toroidal flux. In addition, the ability to translate the FRC allows for the efficient coupling of bank energy into FRC kinetic energy. This translation allows all the banks to be in close proximity to the FRC; thus alleviating the engineering issues associated with high bank energy storage and transmission. Finally, the translating FRC is compressed and decelerated into a small, high β, burning plasmoid. Allowing the plasmoid to continue translating after compression spreads the neutron loading along a large first wall surface. An expansion phase after the burn section allows the recovery of direct electrical energy from the FRC through induction. Because of the efficiency of coupling electrical energy into mechanical motion (and the reverse process) this concept can be a cycled approach, the electrical energy generated can be used to recharge the partially depleted banks and initiate the next cycle. There is no need for flux sustainment.

Initial experimental work on PHD has been focused on generating a FRC that is stable, has a long lifetime, and has sufficient flux and particle inventories to be accelerated and compressed to fusion conditions. In this mode of non-translated operation some of the basic results from the Large S experiment (LSX) have been repeated. Experiments with the device operating at half power show equilibrium temperatures of 300 eV and excluded fluxes of 15 mWb. Decay times >100 us have been observed. The switches on the formation bank are currently being retrofitted to allow full power operation.

This experiment was built for dynamic formation and translation. All the reversal banks on PHD are individually triggered, allowing for the successive firing of sequential reversal coils. Initial experimental results show dynamic excluded fluxes >70 mWb at the last stage. This first dynamically formed FRC translated into an end cone and persisted for some time outside the instrumented section of the machine. MOQUI simulations of this operating mode indicate >400 eV temperatures with 12 mWb of trapped flux. Currently, the first pure acceleration section of the experiment is under construction to allow further studies in this operating mode.

Characterization: A1,A4


University of Maryland

Innovative Confinement Concepts Workshop
February 12-14, 2007
College Park, Maryland

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