Dynamics of a laser produced plasma and its properties for microwave reflection

Abstract

Summary form only given, as follows. A large plasma sheet is created by a 193 nm laser ionizing a low ionization potential molecule tetrakis-(dimethylamino)ethylene (TMAE). The plasma density is diagnosed by a fast response single Langmuir probe, and special features of the probe measurements at early times in the laser produced plasma are discussed. On microsecond time scales, the plasma decay is dominated by a two-body recombination process, and other plasma decay processes, such as plasma diffusion, electron attachment, three-body recombination with either another molecule or an electron as the third body, can be neglected. The initial plasma densities vary for different experimental conditions, but all the density traces at later times approach a same limit, which is only sensitive to the two-body recombination coefficient. Based on plasma density measurements, a dielectric model is developed to calculate the properties of microwave reflection from the plasma sheet. The critical reflection angles for different plasma densities, as well as the polarization effects on the microwave reflection are discussed. The calculations of microwave reflection from the plasma density measurements agree well with those obtained by direct microwave measurements.