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X-Ray Measurements from the Tandem Mirror Experiment-Upgrade (TMX-U)*

Published online by Cambridge University Press:  12 April 2016

E.H. Silver ,
J.F. Clauser  and
B.H. Failor
E.H. Silver
Affiliation:
Lawrence Livermore National Laboratory, University of California Livermore, CA 94550
J.F. Clauser
Affiliation:
Lawrence Livermore National Laboratory, University of California Livermore, CA 94550
B.H. Failor
Affiliation:
Lawrence Livermore National Laboratory, University of California Livermore, CA 94550

Extract

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We report the results of X-ray emission measurements made at various plasma locations in the Tandem Mirror Experiment-Upgrade (TMX-U). By manipulating the electron and ion density profiles within the magnetic mirror end cells, a local minimum in the axial electrostatic potential creates a barrier that thermally isolates central cell electrons from those in the end cells. This thermal barrier makes it possible to heat end cell electrons to a temperature (~1.6 keV) that is significantly higher than the central cell value (30 to 200 eV), thereby increasing the ion confining potential. Formation of this potential peak is attributable, in part, to mirror-trapped hot ions (8 keV) that are injected as beams of neutral particles. The resulting ion density profile exhibits two symmetric peaks at the locations of the ion turning points and a depression where the magnetic field is a minimum. Electron cyclotron resonance heating (ECRH) is applied at the density minimum and produces a population of hot, mirror-trapped electrons (20 to 200 keV). It reduces an already depressed electrostatic potential to establish the thermal barrier. In addition, ECRH applied at the outer density peak raises the -ion confining potential and enhances central cell ion confinement by increasing the end cell electron temperature. X-ray measurements are made with solid state and scintillation detectors at the ECRH locations. Medium resolution spectra are obtained over a broad energy band and have proven to be an important tool for determining the efficiency of thermal barrier formation. We present our initial findings from these non-Maxwellian plasmas.

Type
Session 6. Poster Papers
Information
International Astronomical Union Colloquium , Volume 86: Eighth International Colloquium on Ultraviolet and X-ray Spectroscopy of Astrophysical and Laboratory Plasmas , 1984 , pp. 219
Copyright
Copyright © Naval Research Laboratory 1984. Publication courtesy of the Naval Research Laboratory, Washington, DC.

Footnotes

*

Work performed under the auspices of the U.S. Department of Energy by the Lawrence Livermore National Laboratory under contract number W-7405-ENG-A8.

References

* Work performed under the auspices of the U.S. Department of Energy by the Lawrence Livermore National Laboratory under contract number W-7405-ENG-A8.