The role of the electrical polarization field in magnetic plasma confinement

E. Gidalevich, S. Goldsmith, R. L. Boxman

Research output: Contribution to journalArticlepeer-review

Abstract

The radial expansion of an axially flowing plasma column in a constant axial magnetic field is considered for the following cases: (a) magnetized electrons and unmagnetized ions, and (b) magnetized electrons and partially magnetized ions. In case (a), radially escaping ions produce a radial electric polarization field. For a directed axial ion velocity of v0 = 1.5 × 104 m s-1, particle concentration n0 = 1018 m-3 and magnetic field B = 0.02 T, the azimuthal electron drift velocity in the crossed electric and magnetic fields is 4 × 105 m s-1, i.e. near to their thermal velocity with Te = 3 × 104 K: √kTe/me ≈ 5 × 105 m s-1 and it together with the thermal velocity determines the electron collision frequency. With a neutral gas pressure of 1.3 Pa and a magnetic field strength of B = 0.01 T, the radial electron velocity reaches the radial ion expansion velocity within a time of ≤8 × R/v0, where R is the plasma column radius. If the ions are partially magnetized, the electric polarization field is caused by radially escaping unmagnetized ions, while the electrons, and magnetized ions drift in the crossed electric, and magnetic field. The thermal, and axially directed ion velocities are much less than their azimuthal drift velocity, and thus the azimuthal velocity determines the collision frequency.

Original languageEnglish
Pages (from-to)653-660
Number of pages8
JournalJournal of Physics D: Applied Physics
Volume36
Issue number6
DOIs
StatePublished - 21 Mar 2003

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