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Recent results from a neutral particle analyzer on the SSPX spheromak

Author: Ephrem D Mezonlin
Requested Type: Poster Only
Submitted: 2006-12-18 21:40:21

Co-authors: J.A. Johnson III, V.I. Afanasyev, J.M. Moller, D.N. Hill, E.B. Hooper, H.S. McLean, R.D. Wood

Contact Info:
Florida A&M University
1800-3 E. Paul Dirac Drive
Tallahassee, FL   32310

Abstract Text:
We report measurements of charge-exchange power loss in the Sustained Spheromak Physics Experiment (SSPX) using a newly installed compact neutral particle analyzer (CNPA). The SSPX CNPA measures the neutral particle energy spectrum between 50-1000 eV in 25 energy channels at a rate of 10 KHz during SSPX plasma discharges. Total power loss is estimated by assuming the energy flux calculated for the small area viewed by the instrument applies to the entire plasma surface. Initial results indicate charge exchange power loss represents only 2 percent of the total the input gun power during the sustainment phase of the discharge. It has also been useful to calculate an effective temperature for the high and low energy regions of the measured energy spectra with low energy (< 300 eV) corresponding to edge ion temperatures and high energy regions (> 300 eV) corresponding to core ion temperatures. Effective temperatures in the core (up to 300 eV) are observed to correlate with magnetic fluctuations, especially at the beginning and end of the shot when fluctuation levels are highest. Edge temperatures (~50 eV) tend to stay constant throughout the shot and regardless of fluctuation level. Computational methods with various neutral particle analysis codes are being explored to estimate the ion temperature profile.

* Work performed under the auspices of the US DOE by University of California Lawrence Livermore National Laboratory under contract W–7405–ENG–48.

Characterization: A1,E3

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