Interaction of an intense relativistic electron beam with preformed channels. Interim report

Technical Report · Thu Jun 12 04:00:00 EDT 1986

OSTI ID:5146264

Murphy, D P; Raleigh, M; Pechacek, R E; Greig, J R

The interaction of an intense relativistic electron beam (REB) with preformed channels in gaseous atmospheres demonstrates the effects of reduced density, avalanche ionization, preexisting conductivity, and channel currents. The intense REB for these experiments was produced from a field-emission diode driven by the approx. 1.4-MV pulse from a pulse-forming line. Peak REB currents up to approx. 16 kA, and current densities up to approx. 2 kA/cm/sup 2/ were achieved. The time history of the REB was approximately a half-sinewave of width 27 ns (FWHM). Channels in the atmosphere were created using laser-guided electric discharges. Current-carrying reduced density channels were produced by applying a second discharge to the reduced density channel produced by the first discharge. Reduced density (< or = (pho sub 0/80), non-conducting channels were produced by the absorption of radiation from a pulsed CO/sub 2/ laser in ammonia gas at background pressures of approx. 40 Torr (approx. (pho sub 0/20). Results showed that reduced density had little effect of REB propagation except for the decreased scattering, until it was reduced so much that the generation of conductivity changes. Avalanche ionization in a uniform atmosphere increased the growth of instabilities but, when avalanche ionization was confined to a reduced density channel, the REB was always repelled or expelled from the channel. Pre-existing conductivity in the form of a conducting channel with conductivity, sigma > or = 0.1 S/m, also caused the REB to be repelled or expelled from the channel. However, the presence of a parallel channel current permitted the REB to be readily injected into the channel and guided along it with minimal losses.

• Research Organization: Naval Research Lab., Washington, DC (USA)
• OSTI ID: 5146264
• Report Number(s): AD-A-169099/9/XAB; NRL-MR-5798
• Country of Publication: United States
• Language: English

Related Subjects

640420* -- Fluid Physics-- Properties &amp; Structure of Fluids-- (-1987)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ATMOSPHERES
BEAMS
ELECTRIC DISCHARGES
ELECTRON BEAMS
ELECTRON DENSITY
EMISSION
ENERGY RANGE
FIELD EMISSION
INTERACTIONS
IONIZATION
LASER GUIDANCE
LEPTON BEAMS
PARTICLE BEAMS
PULSES
RELATIVISTIC RANGE