Numerical modeling of droplets growth and their thermal radiation from metallic targets heated by heavy ion beams

Summary form only given. We investigate thermal radiation of a thin metallic foil heated by an intense heavy ion beam. It is supposed that the energy absorbing is volumetrically uniform. The foil dynamics is described by 1D-equations of gasdynamics which are written down in mass coordinates. The system of equations is added by equations of state [1]. Droplets of metastable vapor-liquid medium provide the main contribution to thermal radiation. This medium is formed at adiabatic expansion of a target heated by an ion beam. The method of calculation of dependence of optical properties (complex index of refraction) of liquid metals on temperature and radiation wavelength is offered. Experimental data are used in this method. Absorbing and scattering sections of separate drops are calculated according to Mie theory [2]. In present work different nucleation models [3-6] are considered. Appropriate mathematical problems are solved by numerical methods. Using of implicit finite-difference schemes allows reaching of quasi-stationary nucleation regimes. Comparison results for different solutions of nucleation models are presented. Workability regions of these models are determined. The number of the droplets which are formed in unit of volume is large. The radiating vapor-liquid medium can be considered continuous. Coefficients of absorbing and scattering of the continuous medium determined by means of integration by drops radiuses for each target point. Results of calculations of change of effective brightness temperature for lead foils heated by heavy ion beams are given. Comparison with the available experimental data [7] is carried out. As a result of extensive numerical studies, it has been shown that for a lead foil having a thickness of 300 μm, intensive radiation of hot droplets takes place at the specific absorbed energy of about 2kJ/g.