Experimental and modeling tests of a spherically convergent ion focus
- Univ. of Wisconsin, Madison, WI (United States). Dept. of Nuclear Engineering and Engineering Physics
Convergent ion focus devices have been considered as sources of fusion reactivity since early studies in the late 1960`s. In general, these devices rely on the confinement and acceleration of plasma ions in a spherically or cylindrically symmetric electrostatic potential well. Ions at the edge fall into the well and converge to the central core region. This leads to a strongly increasing central density and central ion energies comparable to the depth of the potential well, resulting in considerable fusion reactivity with modest device parameters. Several schemes have been proposed for creating the potential well, with simple transparent spherical grids being the usual experimental realization. Potential applications of these fusion devices range from small low-intensity fusion-product particle sources for nuclear assaying to more intense sources for isotope generation and waste processing. Even more optimistic projections have led to discussions of fusion power generation through electrostatic confinement. Recent experiments and modeling efforts are developing a deeper understanding of the operation of these devices. Operation of a gridded spherical focus at low density has verified the classical ion flow model and demonstrated a core density enhancement factor of > 10. Probe measurements with applied potentials of {le} 10 kV indicate a space potential distribution which is much steeper than that expected from simple space-charge-limited flow. The highest gradients are in the near-field region of the grid where the angular asymmetries of the potential distribution are also highest. Even so, central core radii of < 0.6 cm have been observed, considerably below the radius expected from single ion orbit models. Near-term future experiments are concentrating on development of nonperturbing diagnostics of the energetic ion core, achieving high core density operation, and testing predictions of flow instabilities.
- OSTI ID:
- 178234
- Report Number(s):
- CONF-950612-; ISBN 0-7803-2669-5; TRN: 96:006718
- Resource Relation:
- Conference: 22. international conference on plasma science, Madison, WI (United States), 5-8 Jun 1995; Other Information: PBD: 1995; Related Information: Is Part Of IEEE conference record -- abstracts: 1995 IEEE international conference on plasma science; PB: 312 p.
- Country of Publication:
- United States
- Language:
- English
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