Fluid dynamics calculation of sputtering

The sputtering yields from hot, cylindrical spikes are calculated. To this end, the evolution with time of the energy deposited in a Lennard-Jones target is assumed to be described by the fluid dynamics equations. Furthermore, a crystal pressure is introduced that provides the forces which keep the target around normal density at low temperature. The results of these calculations show that, contrary to predictions of the standard thermal spike theory, the sputtering yield increases with excitation energy in a less-than-quadratic manner. The origin of such a discrepancy relates to the elastic wave resulting from the high-pressure built up in the hot spike. This wave appears to be more efficient than thermal conduction in carrying energy away from the hot core of the spike. The sensitivity of the sputtering yield upon viscosity, the speed of sound and other thermodynamics properties of the target are investigated