Flux Tailoring of a Permanent-Magnet Field With a High-Temperature Superconducting Tube for a Helicon Plasma Source

In this paper, we explore modifying the field of a permanent magnet through the use of the Meissner effect, motivated by application to a helicon plasma source. The use of a high-temperature superconducting material is more practical for maintaining a system-wide critical temperature, and it is therefore the focus of our investigation. The field supplied by a permanent magnet is confined to the inside of the tube to obtain a uniform field solution analogous to that of an inviscid incompressible fluid. Discussed are both the theoretical results, which neglect flux pinning and experimental results that show its effect. The experiment to assess the approach uses a tube of Bi-2223 cooled with liquid nitrogen inside of a vacuum chamber. Further analysis shows that the experimental and theoretical results agree and that shaping of the magnetic fields is in fact possible.