A system for generating and maintaining a magnetic field with a field reversed configuration comprising a confinement chamber, first and second diametrically opposed FRC formation sections positioned adjacent opposing ends of the confinement chamber, first and second divertors coupled to the first and second formation sections, one or more of a plurality of plasma guns, one or more biasing electrodes (905, 900, 910, 920) and first and second mirror plugs, wherein the plurality of plasma guns includes first and second axial plasma guns operably coupled to the first and second divertors, to the first and second formation sections and to the confinement chamber, wherein the one or more biasing electrodes are positioned within one or more of the confinement chamber, the first and second formation sections, and the first and second divertors, and wherein the first and second mirror plugs are positioned between the first and second formation sections and the first and second divertors, a gettering system (810,820) coupled to the confinement chamber and the first and second divertors, a plurality of neutral atom beam injectors coupled to the confinement chamber and angled toward a mid-plane of the confinement chamber, a magnetic system comprising a plurality of quasi-dc coils (412, 414, 416) positioned around the confinement chamber, the first and second formation sections, and the first and second divertors, and first and second set of quasi-dc mirror coils (412,414) positioned between the first and second formation sections and the first and second divertors, and characterized in that the plurality of neutral atom beam injectors are tunable in a continuous manner between a first beam energy and a second beam energy, wherein the second beam energy differs from the first beam energy, and in that the system further comprises an active feedback plasma control system, wherein the system is configured to control the beam energies of the plurality of neutral beams by a feedback signal received from said active feedback plasma control system to enable optimal matching of the orbital parameters of the injected and then trapped fast ions from the neutral beams relative to the instantaneous magnetic pressure profiles during a field reverse configuration +he- ramp-up process. a confinement chamber, first and second diametrically opposed FRC formation sections positioned adjacent opposing ends of the confinement chamber, first and second divertors coupled to the first and second formation sections, one or more of a plurality of plasma guns, one or more biasing electrodes (905, 900, 910, 920) and first and second mirror plugs, wherein the plurality of plasma guns includes first and second axial plasma guns operably coupled to the first and second divertors, to the first and second formation sections and to the confinement chamber, wherein the one or more biasing electrodes are positioned within one or more of the confinement chamber, the first and second formation sections, and the first and second divertors, and wherein the first and second mirror plugs are positioned between the first and second formation sections and the first and second divertors, a gettering system (810,820) coupled to the confinement chamber and the first and second divertors, a plurality of neutral atom beam injectors coupled to the confinement chamber and angled toward a mid-plane of the confinement chamber, a magnetic system comprising a plurality of quasi-dc coils (412, 414, 416) positioned around the confinement chamber, the first and second formation sections, and the first and second divertors, and first and second set of quasi-dc mirror coils (412,414) positioned between the first and second formation sections and the first and second divertors, and characterized in that the plurality of neutral atom beam injectors are tunable in a continuous manner between a first beam energy and a second beam energy, wherein the second beam energy differs from the first beam energy, and in that the system further comprises an active feedback plasma control system, wherein the system is configured to control the beam energies of the plurality of neutral beams by a feedback signal received from said active feedback plasma control system to enable optimal matching of the orbital parameters of the injected and then trapped fast ions from the neutral beams relative to the instantaneous magnetic pressure profiles during a field reverse configuration +he- ramp-up process.