LASER LIGHT SCATTERING FROM DENSITY FLUCTUATIONS IN THE CULHAM FOCUS
The ion feature S (kappa,omega) in the spectrum of laser light scattered from a dense plasma focus is recorded synchronously for three different scattering vectors kappa and two values of the scattering parameter alpha = (kappa-lambda-D)**-1. The kappa vectors in the scattering geometry kappa = (kappa-scat- KAPPA-inc) are chosen so that density fluctuations in the ion current direction kappa-10 degrees (antiparallel) can be compared with those in the orthogonal plane, kappa-10 degrees (orthogonal). The irradiated and viewed volume of the plasma is 4mm long axially with a mean orthogonal diameter of 5mm. Light scattered over a 20ns interval from all the electrons contributed to the cooperative ion feature S-i (kappa, omega). In order to interpret the spectrum, the density structure and the magnetic field structure have been evaluated as a function of time using holographic interferometry and Faraday rotation polarimetry. A thin outer skin, sigma = 2r-ci is indicated, carrying most of the current during the collapse phase. Complete redistribution of the current flow occurs during the 10 ns or so following peak compression and allows 30% of the current to diffuse into the core. It seems plausible, therefore, to base the analyses of the S-i(kappa,omega) spectra during the compression phase on contributions from two spatially separate regions viz. a thin, outer current carrying shell and an inner core, both with quite distinct plasma parameters.
Bibliographic Reference: 3RD INTERNATIONAL WORKSHOP, STUTTGART (GERMANY), SEPT. 12-13, 1983 WRITE TO CEC LUXEMBOURG, DG XIII/A2, POB 1907 MENTIONING PAPER E 31912 ORA
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Record Number: 1989124029900 / Last updated on: 1987-01-01
Available languages: en