Lower hybrid wave generation by a laser-produced plasma
Abstract
The expansion of a dense, laser-produced plasma (lpp) into a uniform, low-density plasma has been observed to generate a spectrum of lower hybrid waves. The experiment is conducted in the upgraded Large Plasma Device ( LaPD) at UCLA. A 3/4-inch Aluminum target rod is immersed within a background Neon plasma, with plasma parameters: n_e=2×10^12cm-3, T_e=5eV, B_0=500-1500G, length=17m, radius=30cm. The target is struck with a NdYAG laser (1J, 7ns pulse) focused to a spot size of less than one millimeter. The ions in the lpp (with energies of several keV) are initially unmagnetized and propagate across the background field. The electrons, however, remain magnetized and jet away from the point source of the laser impact in a field-aligned burst. The measured electric field spectra as a function of angle are consistent with a finite line source of lower hybrid waves, with one end fixed at the laser impact site. We present these spectra, correlation measurements, and an estimation of the coupling efficiency of laser power into wave energy.
- Publication:
-
APS Division of Plasma Physics Meeting Abstracts
- Pub Date:
- November 2002
- Bibcode:
- 2002APS..DPPGP1092V