Practical considerations for a plasma neutralizer

A beam of energetic H− or D− ions is efficiently converted to the uncharged state upon impact on a dense plasma. Neutralization efficiencies of the emerging beam can exceed 80%. This paper reports on a design approach to a plasma‐stripping cell, illucidating several practical aspects. The plasma is formed by a low‐frequency (1.4 MHz), high‐power (20–60 kW) rf discharge in a multipole ring‐cusp magnetic field. A mild steel rectangular box is used as a low‐reluctance return path for the magnetic flux, a heat‐transfer medium, and mechanical support. The working gases used in these studies are H2, He, Ar, and Xe. The central density found in the resulting plasma ranged from about 1013 to ≳1014 cm−3 with the heavier species exhibiting the higher densities. Test results performed over a pressure range of 2–10 mTorr are presented. The rf power required to achieve a given plasma density with this design should scale with the cell length for a given gas.Measurements of magnetic‐flux‐density components in the plasm...