CHARACTERIZATION OF A LASER PLASMA IN A PULSED MAGNETIC-FIELD .2. TIME-RESOLVED EMISSION AND ABSORPTION STUDIES

Temporally resolved emission and absorbance measurements were made in order to investigate the dynamic effects of a high-intensity pulsed magnetic field on a laser plasma. Temporally resolved emission studies were spatially resolved so that the effects of the magnetic field on plasma propagation both along and normal to the magnetic field could be probed. The mechanism of interaction of the field was investigated by observing plasma emission in spatial zones most likely to be influenced by an induced secondary current in the plasma. Spatial and temporal discrimination of emission enhancements indicated that radial compression was due to static magnetic field interactions with the laser plasma and that mild Joule-heating from the small induced current was most likely responsible for emission enhancements later in time. Spatially integrated absorbance measurements in the decaying plasma showed a decrease in absorbance as a result of the magnetic confinement; this is attributed to an increased rate of condensation of the atoms in the vapor cloud produced by the pinched plasma. More efficient coupling of energy from the magnetic field to the plasma would require low-pressure operation in a controlled atmosphere and/or a pulsed magnetic field having a greater dB/dt.