PINHOLE CLOSURE BY LASER-TARGET INTERACTION PRODUCED PLASMAS

A set of gold planar pinhole targets were irradiated with1.06μm Nd:glass laser pulse.I,the laser power density at pinhole edge,was from 8.8 × 10¹² W/cm² to 4.8 × 10¹³ W/cm².According to a lot of high speed photography images of closure effect,the closure speed c1 was inferred to be in the range of 4.5 × 10⁶ to 1.0× 10⁷cm/s with a scaling formula of c₁=10 I^0.3.Also,the ratios of the laser energy transmitted through pinholeswere investigated,as a function of hole diameter,laser pulse duration,laser energy and.so on.In addition,it was discovered that the x rays radiated from the pinhole plasmas,showed double-Peaked temporal profiles and o-like spatial distribuctions.