Conversion efficiency for producing thermal radiation using high-energy heavy-ion beams

Using numerical simulations of radiation transport in homogeneous cylindrical targets heated by heavy-ion beams, we have explored the dependence of the conversion efficiency η on beam power and target radius. The parameter region included specific deposition powers between 10 and 103 TW/g and target radii r between 200 μm and 1 mm. We find the results can be roughly expressed as η=x/(x+a), where x is the specific deposition power multiplied by the radius and divided by the initial target density, and a is a constant depending on the target material. The targets are chosen to make a transition from optically thick to optically thin when the maximum target temperature is reached. For Xe gas we find a=400 TW/(g/cm)2. (orig.)