Velocity-space particle loss in field-reversed configurations

From particle confinement criteria for field-reversed configurations it is found that only a portion of (H,P/sub theta/) space, or equivalently, of velocity space, provides confinement. A loss region in velocity space is found. The effects of this loss region in velocity space are investigated. The velocity-space particle loss, i.e., particle loss caused by the existence of a loss region in velocity space, because of collisions is calculated from the Fokker--Planck equation. The corresponding scaling law for particle confinement is obtained. In collisional equilibrium, a simple analytical expression is verified to be a good representation of the actual velocity distribution in the presence of the loss region in velocity space. It is shown that velocity-space particle loss in field-reversed configurations is an important mechanism for particle loss, as well as the occurrence and spin-up of plasma rotation