Convergence, electrostatic potential, and density measurements in a spherically convergent ion focus
- University of Wisconsin---Madison, 1500 Engineering Drive, Madison, Wisconsin 53706 (United States)
Unique measurements of the basic plasma-flow characteristics in a low pressure ({le}53 mPa H{sub 2}) spherically convergent ion focus are obtained using high-voltage ({le}5 kV) emissive and double probes. The radial plasma potential distribution agrees with a collisionless, recirculating, space-charge-limited current model. Flow convergence increases with voltage and neutral pressure and decreases with cathode grid wire spacing and current. Core radii within 4{endash}5 times the ideal geometric limit are measured, and the observed core sizes are consistent with predictions from a multipass orbit model which includes asymmetries in the accelerating potential well. A virtual anode is observed in the converged core region, and no evidence for multiple potential well structures in the core is found. Measurements of the core ion density (n{sub ic}{approximately}10{sup 15} m{sup {minus}3}) are consistent with simple flow convergence models. {copyright} {ital 1997 American Institute of Physics.}
- OSTI ID:
- 432510
- Journal Information:
- Physics of Plasmas, Vol. 4, Issue 1; Other Information: PBD: Jan 1997
- Country of Publication:
- United States
- Language:
- English
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