Experimental and modelling tests of a spherically convergent ion focus

Summary form only given. 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 modelling efforts are developing a deeper understanding of the operation of these devices. 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.