Intense ion beam research for magnetic fusion

The application of intense pulsed ion beams to magnetic fusion requires (1) the development of multikilojoule sources of 100–500 keV ions, (2) an understanding of the physics of intense ion beam propagation transverse to magnetic fields, and (3) the ability to inject and merge these beams with an existing plasma configuration, such as Spheromak or FRC. The first two issues are being addressed by the IREX and LONGSHOT experiments which both inject beams through cusp-shaped magnetic fields. In IREX, puffed and static gas fills and preionized plasma in the cusp region have produced effective space-charge suppression for efficient beam injection. In LONGSHOT, improvements in beam transport by minimizing the propagation distance in transverse field are incorporated into a scaled-up injector, LONGSHOT II, which so far has delivered a proton pulse of 600 J. A 2-1/2 D hybrid simulation code CIDER has been employed to study the merging of a partially field reversed ion ring with a spheromak in a weakly collisional plasma regime which supports electron Hall currents.