STUDY OF K-ALPHA ABSORPTION STRUCTURES IN A SUBCRITICAL-DENSITY LASER-PRODUCED PLASMA

The study of K alpha line absorption by point-projection backlighting is presented for a laser-produced aluminum plasma at electronic densities below 5 X 10(21) cm-3. The appearance of ionic species as a function of distance from the target is measured absolutely by the use of a knife edge as a spatial fiducial. These data are used to determine the gradient of the average charge as a function of space. A non-local-thermodynamic-equilibrium ionization model has been developed to determine temperature and densities consistent with this measure. Comparisons with hydrodynamic codes are presented, along with a discussion of the inferred temperature.