Engineering topics

Bekefi, G.

Publications and source records attributed to Bekefi, G..

4 records

NASA NTRS1972

Stark profiles of forbidden and allowed transitions in a dense, laser produced helium plasma.

Comparisons of experimental and theoretical Stark profiles of the allowed 2(1)P-3(1)D helium line at 6678 A and of the forbidden 2(1)P-3(1)P component at 6632 A in a dense plasma were carried out. The plasma was produced by optical breakdown of helium by means of a repetitive, high power CO2 laser. The allowed line shows good agreement with conventional theory, but discrepancies are found around the centre of the forbidden component. When normally neglected ion motions are taken into consideration, the observed discrepancies are partially removed. Tables of the Stark profiles for the pair of lines are given.

Ya'akobi, B.↗

NASA NTRS1971

Structure of the plasma fireball produced by a CO2 laser.

Study of the space and time resolved structure of a helium plasma produced with a repetitive CO2 laser during the first 15 microsec of the afterglow period. The spectra of several neutral and ionized helium lines are used in the determination of the density and temperature profiles of the luminous fireball. It is found that the plasma is comprised of a dense hot core, which emits primarily ionic lines, and a well-defined tenuous outer shell, which is primarily the source of neutral emission lines. This ?two-component' plasma structure develops at about 0.4 microsec after breakdown, at about the time when the luminous fireball dissipates its expansion energy and comes to a virtual standstill.

George, E. V.↗

NASA NTRS1967

Plasma physics

Far infrared spectrophotometer and electron plasma oscillations

PLASMA OSCILLATION↗

NASA NTRS1967

Gaseous electronics

Electron-electron relaxation rates determined from time-dependent electron velocity distribution

VELOCITY DISTRIBUTION↗