DETERMINATION OF THE VELOCITY DISTRIBUTION IN PLASMA WITH LASERS BY THOMSON AND BY RESONANT SCATTERING.
Abstract
Laser scattering methods that appear promising for deducing the single-particle electron-velocity distribution (as well as density and temperature) are described and compared. Single laser Thomson scattering with kl sub D>>1 and a frequency shift greater than the plasma frequency, is reviewed and shown to be feasible for the velocity range between thermal to three times thermal velocity. Also analysed are methods involving Thomson scattering off the electron plasma or ion plasma resonance with kl sub D<1. A new method is described using the double-laser method of Kroll et al. to scatter off induced plasma oscillations. The detailed theory is presented for arbitrary distribution functions and with fewer assumptions than in other work. Based on Landau damping, this method is suited for the high-velocity range between 2.4 and 4 times thermal velocity, the upper limit given by collisional damping and hence dependent on density. The best density range is between 10 to the 12th power and 10 to the 13th power/cc. With a N2 + CO2 + He laser at 10.6 microns, the scattering angles are between 10 - 20 degrees. For an appreciable scattering angle at lower densities, one requires sources between 126 and 1450 times the plasma frequency, when the electron temperature is 3000K. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 01, 1966
- Accession Number
- AD0649664
Entities
People
- Issie P. Shkarofsky