Multidipole confinement of argon and potassium plasmas

Multidipole confinement of an argon discharge plasma and a potassium plasma produced by surface ionization was investigated. In both cases, a large volume of uniform density quiescent plasma was produced in the central region of low magnetic field strength. Measurements of electron and ion densities and space potentials suggest that self-consistent electrostatic fields resulted in crossfield (to B) ion confinement and that the cusp leak widths were determined by a noncollisional mechanism (e.g., Bohm diffusion). A comparison of the nondischarge potassium plasmas produced with and without multidipole confinement indicates that the ion confinement time was improved by a factor of ∼15 by the multidipole magnetic field.