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Based on two constants of motion, H and P?, where H is the total energy of a particle and P?is its canonical angular momentum, particle confinement criteria are derived which impose constraints on H and P?. With no electric field at the ends of field-reversed magnetic configurations, confinement criteria for closed-field and absolute confinements are obtained explicitly, including both lower and upper bounds of P?/q, where q is the charge of the species considered, for a class of Hill's vortex field-reversed magnetic configurations. The commonly used criterion for the Hamiltonian, H < ??0P?, where ?0? qB0/mc, is deduced from a more general form as a special case. In this special case, it is found necessary to impose a new criterion, , where Rwis the wall radius and B0is the vacuum field, which reduces the confinement region in (H, P?) space. With the presence of electric fields at the ends of field-reversed magnetic configurations, confinement criteria are obtained for two interesting cases. In addition to lower and upper bounds of H, both lower and upper bounds of P?/q are found. For axially confined particles, the lower bound of P?/q reduces the confinement region in (H, P?) space and represents a new criterion. These results can be applied to calculations for field-reversed mirrors and field-reversed theta pinches.

As a result of certain experimental observations, interest in the bootstrap current arising from neoclassical transport in tokamaks has increased recently. In this study, the bootstrap current is calculated for a number of radiofrequency (RF) current driven tokamaks. Two-dimensional, self-consistent, steady state tokamak MHD equiJibria are obtained by including both the transport driven bootstrap current and the externally driven RF current. Self-consistency is accomplished by iterating the two-dimensional MHD equilibrium calculation and the current calculation (including bootstrap current and RF ray tracing). The parameter ? = 1 ?(?/?B) is defined as a measure of the RF current drive power reduction achieved when bootstrap currents are included in the calculation (? = eR0I/PCDis the current drive efficiency without the benefit of bootstrap current and ?B= eR0I/PCDis the higher efficiency obtained when bootstrap effects are included). For INTOR-type reactor parameters with e= (0.7?1.4) × 1020m?3, ? ? 0.4?0.9 (40-90% reduction of RF power) is obtained. Calculations for other reactor parameters of interest are also carried out. It is found that for reactor-grade plasmas, the bootstrap current contribution to the toroidal current is, in general, important. In some cases, it is even found that the bootstrap current density locally exceeds the required current density of the initial target equilibrium. An approximate scaling law for P, based on the parametric survey performed, is also obtained.