The ZaP Flow Z-Pinch: Plasma Flow Shear and Stability
- University of Washington (United States)
The ZaP Flow Z-pinch plasma device at the University of Washington produces a small diameter (20-30 mm) dense Z-pinch plasma with typical electron density 10{sup 22}-10{sup 23} m{sup -3} and ion plus electron temperature 100-200 eV. The plasma is stable, with relatively low magnetic mode activity, for tens of microseconds. This is orders of magnitude longer than predicted by a simple ideal magnetohydrodynamic calculation. The probable stabilizing mechanism is radial shear in the axial plasma flow. The axially flowing Z-pinch is generated with a coaxial accelerator coupled to a pinch assembly chamber. After the pinch assembles a quiescent period occurs, during which the mode activity is significantly reduced. Multichord Doppler shift measurements of impurity lines show a large, sheared flow during the quiescent period and low, uniform flow profiles during periods of high mode activity. The plasma has a sheared axial flow that exceeds the theoretical threshold for stability during the quiescent period and is lower than the threshold during periods of high mode activity. The Z-pinch plasmas are globally stable for 700-2000 times the theoretically predicted kink growth time of a static Z-pinch. The end of the quiescent period corresponds to a decrease in acceleration of plasma and possibly suggests a means to extend the experiment to quasi-steady-state operation.
- OSTI ID:
- 20849803
- Journal Information:
- Fusion Science and Technology, Vol. 47, Issue 1T; Other Information: Copyright (c) 2006 American Nuclear Society (ANS), United States, All rights reserved. http://epubs.ans.org/; Country of input: International Atomic Energy Agency (IAEA); ISSN 1536-1055
- Country of Publication:
- United States
- Language:
- English
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