Time-dependent plasma behavior triggered by a pulsed electron gun under conditions of beam-plasma-discharge
Abstract
We have conducted a number of experiments intended to simulate spaceborne applications of energetic electron guns while exploring the 'in situ' diagnostics of time-dependent beam-plasma behavior under pulsed electron gun conditions. The conditions include the beam-plasma-discharge (BPD) and the BPD afterglow that exists after gun-pulse termination. With electron gun characteristics set at (I(g), V(g), T(on)/T(off) _ (34 ma, 1.9 keV, 80 ms/270 ms) and a superimposed magnetic field at 1.5 gauss, the results show that: (1) There is a three order-of-magnitude increase in plasma density within 5 ms of gun turn-on; (2) During the pulse-ON time a quasi-steady-state BPD is maintained with characteristics identical to dc-BPD conditions; (3) Plasma losses appear to be dominated by Bohm-like diffusion processes; and finally (4) The afterglow can be characterized by an isodensity radial profile that decays with a 36 msec time constant and cools at a 3800 K/sec rate.
- Publication:
-
Naval Research Lab. Report
- Pub Date:
- July 1981
- Bibcode:
- 1981nrl..reptT....S
- Keywords:
-
- Electron Guns;
- Plasma Diagnostics;
- Time Dependence;
- Electric Discharges;
- Electrostatic Probes;
- Geomagnetism;
- Plasmas (Physics);
- Plasma Physics