INTERNAL EXPLOSION IN LASER ABLATION OF SUPERCONDUCTING TARGETS

The temperature profile inside a superconducting target in laser ablation is calculated for laser pulses of various shapes. The calculation is based on the equation of heat conduction. All parameters characterizing the target material are assumed to be temperature dependent and are determined empirically by extrapolating experimental data to the melting point. The receding velocity of the vapor-solid interface is determined by the dynamical balance of energy. Our calculation shows that, in general, there exist subsurface overheating spots at different instants as long as the laser pulse intensity is strong enough. The dependence of their occurrence on the pulse shape is analyzed, and conditions to avoid them without jeopardizing the deposition process are discussed.