No abstract

The high flux source for the Pulsed High Density Experiment (PHDX) has been constructed, and fieldreversed configuration (FRC) plasmas are being produced. To diagnose FRC plasma temperatures three kinds of diagnostic systems have been set up on PHDX; λ = 632.8 nm He-Ne laser interferometer system at the midplane for total temperatureT total , 16 channel spectrometer for ion temperature T i and soft x-ray (SXR) measurement system for electron temperature T e viewed along z-axis, respectively. The SXR measurement system consists of five sets of collimators and AXUV100 photodiodes with directly deposited filters which have different bandpass regions. As a result of preliminary temperature diagnostics, the following plasma parameters are estimated during a relatively quiescent phase of FRCs; T total ∼ 50 eV, T i ∼ 50 eV and T e ∼ 25 eV. This result does not agree with the equilibrium relation of T total ≈ T i + T e , and it must be caused by plasma condition and our assumptions in the spectral analysis.

An experimental program has been initiated that will explore the very compact, high energy density regime of fusion based on the magneto-kinetic compression of the FRC. Of all fusion reactor embodiments, only the FRC has the simply-connected closed field, linear confinement geometry, and intrinsic high b required for magnetic fusion at high energy density. PHD takes advantage of the linear confining geometry by incorporating a traveling, burning plasmoid, significantly reducing the wall loading as well as keeping the formation well separated from the burn chamber. Being small, compact, and at high b greatly improves the exposed surface to reacting volume ratio. Being pulsed eliminates the need for flux sustainment, and provides for regulation of the average wall loading. A wide range of reactor scenarios are compatible with PHD including liquid metal walls with the prospect of direct energy conversion through cyclical wall compression/expansion.

This article describes the design and operation of an experimental apparatus that was constructed for studying rotating magnetic field (RMF) current drive in plasmas formed in a metal vacuum chamber. The device was designed to enable the study of various RMF coil geometries that are fully enclosed inside the vacuum chamber. To date, the apparatus has been used with three distinct RMF coil geometries, one of which was fully immersed in the RMF-driven plasma.