Equivalence of energy deposition profile in target between electron beam of multi-energy composite spectrum and X-ray

Abstract

It has great significance to study the thermal-mechanical effects of X-ray in assessing the viability of space-crafts, the penetration ability of missiles and testing the effectiveness of the anti-nuclear reinforcement measures. However, it is rather difficult to construct a suitable X-ray source in laboratory. During recent decades, pulsed electron beam with multi-energy composite spectrum has become a most important simulation source of X-ray to study its thermal-mechanical effects. And energy deposition profile in target material is the basis for studying the thermo-mechanical effects. However, under the same incident conditions, the energy deposition profile of pulsed electron beam with multi-energy composite spectrum in target material is extremely different from X-ray's, and the equivalence between the two beams is quite low. Thus, it is very important to adjust the energy spectrum and the incident mode of pulsed electron beam so as to improve their equivalence. In this paper, we use the energy deposition profiles of electron beam and X-ray in different kinds of material. MCNP is used to calculate their energy deposition profiles in target materials. Two kinds of blackbody X-rays with the equivalent temperatures of 3 and 5 keV and energy density of 200 J/cm2 are chosen for an optimization target. Aluminum, copper and titaniumare chosen as the target materials. Based on the change law of electron beam's energy deposition profile when the electron beam hits the target material at different incident angles, a theoretical model is established. Then, taking advantage of simulated annealing algorithm, we use the MATLAB to carry out numerical calculation and finally the numerical optimization results about the incident angle spectrum and energy density of electron beam are obtained. After optimization, the energy deposition of pulsed electron beam with multi-energy composite spectrum is well adjusted. The peak energy deposition and change of gradient of electron beam are of wonderful consistency with X-ray's. The equivalence of pulsed electron beam with multi-energy composite spectrum in simulating X-ray is also effectively improved. However, the energy density of adjusted pulsed electron beam should be much higher than 200 J/cm2. Electron beam designed by this paper can be used to better simulate the thermal-mechanical effects of X-ray in different kinds of materials.