Nonuniform density distribution model in an investigation of nonneutral electron plasma columns supported by a Penning discharge
Study of the electron plasma in the plasma lens in a continuation of Lefevre and Connolly's work. The lens tube with tapered electrodes was designed so that the ends of the electrodes are all located on the same magnetic flux tube with diameter of 2.6 cm at the center. The electron plasma is confined axially by electrode potentials and radially by a nonuniform magnetic field. The nonuniform magnetic field is necessary to achieve an almost pure electron plasma. The nonuniform magnetic fields cause the plasma density distribution to be nonuniform not only radially, but also axially. The electrode potentials impose a boundary condition to the plasma and dictate the plasma shape. For a stable plasma mode, the plasma surface follows a flux tube in some range of the z axis and gradually shrinks towards the end. Plasma modes whose surfaces almost follow flux tubes were found. Configuration instability is discussed for the plasma whose surface expands outward from the flux tube. Positive ions are dynamically concentrated near the plasma axis. An estimate of the order of magnitude of the dynamic ion concentration is given based on the experimental data and the nonuniform model. The estimated dynamic ion concentration near the axis is about 1-3% of the electron density there at a gas pressure of about 9 x 10/sup -8/ Torr. The ion concentration will vary with plasma mode and gas pressure.
- Research Organization:
- Oregon Univ., Eugene (USA)
- OSTI ID:
- 7167239
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700103 -- Fusion Energy-- Plasma Research-- Kinetics
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
BOUNDARY CONDITIONS
CONFINEMENT
ELECTRIC DISCHARGES
ELECTROMAGNETIC LENSES
LENSES
PENNING DISCHARGES
PLASMA CONFINEMENT
PLASMA DENSITY
STABILITY