Laser light scattering from density fluctuations in the Culham focus
Abstract
The ion feature in the spectrum of laser light scattered from a dense plasma focus was recorded synchronously for three different scattering vectors and two values of the scattering parameter. The electron drift parameter derived from the relative blue shift of the spectrum from the sheath region is significant and can approach the electron thermal velocity Polarimetry however indicates that the ratio of electron drift to thermal velocity is 1 during the collapse phase. These contradicting conclusions can be reconciled by postulating filamentation of the current in the sheath region. During the period t = 0 to + 15 nsec there is rapid, anomalous diffusion of the poloidal magnetic field into the core region. During the period following anomalous field diffusion polarimetry shows very clear evidence for short-lived beam currents flowing within a diameter 250 microns. These beams are correlated with the very strong enhancement of the ion feature.
- Publication:
-
Plasma Focus Research
- Pub Date:
- September 1983
- Bibcode:
- 1983pfr..work..119K
- Keywords:
-
- Laser Beams;
- Laser Spectroscopy;
- Light Scattering;
- Plasma Density;
- Plasma Focus;
- Polarimetry;
- Electron Diffusion;
- Ion Distribution;
- Plasma Currents;
- Plasma Sheaths;
- Thermal Plasmas;
- Plasma Physics