AVS 57th International Symposium & Exhibition
    Plasma Science and Technology Tuesday Sessions
       Session PS-TuP

Paper PS-TuP13
Warm Magnetized Vlasov Emission Equilibria

Tuesday, October 19, 2010, 6:00 pm, Room Southwest Exhibit Hall

Session: Plasma Science and Technology Poster Session
Presenter: R.E. Terry, Naval Research Laboratory (retired)
Correspondent: Click to Email
A Vlasov equilibrium is developed for steady state emission into a magnetized gap in coaxial geometry. The cathode boundary conditions are those of a perfect conductor that emits a Maxwellian electron flux radially, azimuthally, and axially. The anode boundary conditions are those of a perfectly absorbing conductor. The cathode carries a fixed current and the radial gap is set to a fixed voltage. The angular momentum of emitted electrons around the cathode is found to materially change the orbit turning points. When energy conserving solutions are examined it is found that axial velocities must remain bounded above by a well defined function of radius, magnetic field, and voltage. A fully nonlinear and self consistent Vlasov-Poisson problem is formulated and solved for the space charge distribution implied by the Vlasov equilibrium. Moments of the Vlasov distribution then determine the shunt impedance of the gap and the criteria for "warm" magnetic insulation of the coaxial line. The theory limits to Ottinger's critical current magnetization picture for cold electrons, but shows a properly non-singular behavior in the electron density profile at the radial turning points and so properly reduces the enhacement of ion flux across the gap. Extensions of the model to include electron impact ionization of neutrals in the gap are also developed.