Characteristics of Soft X-ray Emission from the Plasma Produced by Long Pulse Width Laser Beam

Abstract

Iodine photodissociation laser pulse (λ=1.32μm, pulse width=13.3ns) is focussed to various targets (C, Al, Ti, Fe, Cu, Mo) and laser plasma is produced. Two electron temperatures are obtained from the two slopes of continuous x-ray spectra over the region (0<μ<19.84A). Zdependence of two electron temperatures (6≤Z≤42) are discussed from the characteristics of the plasma heating processes to which the long pulse laser beam is involved. One dimensional hydrodynamic model for the plasma electrons is used and the time-averaged temperature is derived theoretically to explain the cold electron temperature T_c obtained experimentally. Also, the hot electron temperature T_h obtained experimentally is explained by the effect of parametric instability.