The Technology Enabling Role of Magnetic Cusps in Plasma Science

Plasma transport in magnetic cusps remains not well understood. The problem of plasma transport in magnetic cusps was a particular problem that Noah Hershkowitz studied experimentally throughout his career. Indeed, his seminal leak width work established a basis for assessing plasma losses in multipole plasma sources. Interestingly, Noah also utilized cusp confinement to probe other plasma physics phenomena as well such as sheaths.  It was his multipole, magnetic cusp sources that provided the uniform, field-free region required to carry out his numerous plasma sheath measurements and basic probe studies.  The insight gained however from his direct study of transport through magnetic cusps has impacted a range of seemingly disparate research communities ranging from space propulsion to plasma processing to even nuclear fusion.  Here, we review some of the recent magnetic cusp work ongoing in these exciting research areas with ties to and influenced by Noah’s research.