Population inversions in ablation plasmas generated by intense electron beams. Final report, 1 November 1985-31 October 1988

Technical Report · Tue Nov 01 00:00:00 EST 1988

OSTI ID:5921057

Gilgenbach, R M; Kammash, T; Brake, M L

Experiments during the past three years have concerned the generation and spectroscopic study of electron beam-driven carbon plasmas in order to explore the production of optical and ultraviolet radiation from nonequilibrium populations. The output of MELBA (Michigan Electron Long Beam Accelerator), has been connected to an electron-beam diode consisting of an aluminum (or brass) cathode stalk and a carbon anode. Magnetic-field coils were designed, procured, and utilized to focus the electron beam. A side viewing port permitted spectroscopic diagnostics to view across the surface of the anode. Spectroscopic diagnosis was performed using a 1-m spectrograph capable of operation from the vacuum-ultraviolet through the visible. This spectrograph is coupled to a 1024-channel optical multichannel analyzer. Spectra taken during the initial 400-ns period of the e-beam pulse showed a low effective-charge plasma with primarily molecular components (C/sub 2/, CH) as well as atomic hydrogen and singly ionized carbon (CII). When the generator pulse was crowbarred after the first 400 ns, the spectra revealed a continuation of the low-charge-state plasma. At times greater than 400 ns in non-crowbarred shots, the spectra revealed a highly ionized plasma with a very large intensity line at 2530 Angstroms due to CIV (5g-4f), and lower-intensity lines due to CIII and CII. This CIV line emission increased with time, peaking sharply between 750 and 900 ns, and decayed rapidly in less than 100 ns. Emission from these high ionization states may be due to electron beam-plasma instabilities, as this emission was accompanied by high levels of radio frequency and microwave emission.

• Research Organization: Michigan Univ., Ann Arbor, MI (USA). Dept. of Nuclear Engineering
• OSTI ID: 5921057
• Report Number(s): AD-A-205716/4/XAB
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ABLATION
BEAM-PLASMA SYSTEMS
ELECTRON BEAMS
SURFACES
THERMIONIC DIODES
ALUMINIUM
ANODES
BRASS
CARBON
EMISSION SPECTRA
HYDROGEN
IONIZATION
MAGNET COILS
MAGNETIC FIELDS
MICROWAVE RADIATION
POPULATION INVERSION
PRODUCTION
PROGRESS REPORT
PULSES
SPECTROSCOPY
ULTRAVIOLET RADIATION
ALLOYS
BEAMS
COPPER ALLOYS
COPPER BASE ALLOYS
DIODE TUBES
DOCUMENT TYPES
ELECTRIC COILS
ELECTRICAL EQUIPMENT
ELECTRODES
ELECTROMAGNETIC RADIATION
ELECTRON TUBES
ELEMENTS
EQUIPMENT
LEPTON BEAMS
METALS
NONMETALS
PARTICLE BEAMS
RADIATIONS
SPECTRA
THERMIONIC TUBES
ZINC ALLOYS
640410* - Fluid Physics- General Fluid Dynamics