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witherspoon_icc2007_poster.pdf2007-02-27 12:30:32Franklin Witherspoon

Pulsed Injector Development for Dense Plasma Jets

Author: Franklin D Witherspoon
Requested Type: Poster Only
Submitted: 2006-12-18 15:32:49

Co-authors: A.Case, S.J.Messer, D.N.vanDoren, M.W.Phillips

Contact Info:
HyperV Technologies Corp.
13935 Willard Road
Chantilly, VA   20151

Abstract Text:
High velocity dense plasma jets are under development for a variety of fusion applications, including plasma refueling, magnetized target fusion, injection of angular momentum into centrifugally confined mirrors, HEDP, and others. The approach utilizes symmetrical pulsed injection of very high density plasma into the breech of a coaxial EM accelerator having a tailored cross-section geometry to prevent formation of the blow-by instability. Key to this approach is the mini-injectors used to produce the initial working plasma. We are following two parallel development paths to accomplish this initial injection. One uses a large number (ultimately up to 64) of electrothermal capillary discharges, while the second uses an even larger number of sparkgaps arranged in a toroidal configuration. Experiments are performed on two test fixtures; one is a 2pi configuration with 64 capillary injectors, and the second is a sparkgap array, which currently has 50 sparkgaps, but which is soon to be expanded to 112 in a new accelerator being fabricated using the sparkgap approach. Both systems have recently had their power supply circuits upgraded to increase the energy dissipated in the discharge. We will present results from both experiments and examine the advantages and disadvantages of each approach in the context of the desired plasma pulse generated and the practical issues revolving around fabrication, vacuum sealing, and HV initiation, including practical constraints presented by the HV driving circuit. We will also present analysis and test results for a circuit configuration which may reduce the required ballast resistance. Diagnostics used include Rogowski coils, a fast gated PI-MAX camera, (which allows imaging of the plasma jets and their subsequent merging/interaction), and time resolved spectroscopy.

*Research funded by the DOE Office of Fusion Energy Science through Grants DE-FG02-04ER83978, DE-FG02-05ER54810, DE-FG02-05ER84189

Characterization: B2

Please place next to HyperV's other two posters:

1)A.Case etal, "A Plasma Jet Accelerator for the Maryland Centrifugal Experiment"

2)M.Phillips etal, "Numerical Studies of Pulsed Plasma Jets"

University of Maryland

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

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