Final compression beamline systems for heavy ion fusion drivers

Abstract

We have identified a general final compression section for HIF drivers, the section between accelerator and the target. The beam are given a head to tail velocity tilt at the beginning of the section for longitudinal compression, while going through bends which direct it to the target at specific angle. The aim is to get the beams compressed while maintaining a small centroid offset after the bends. We used a specific example 1MJ driver with 500MeV Rb+1 ion beams. We studied the effect of minimizing dispersion using different bend strategies, and came up with a beamline point design with adiabatic bends. We also identified some factors that lead to emittance growth as well as the minimum pulse length and spot size on the target.

The hydrodynamic and radiative properties of low-density foams heated by x-rays

“…Heating of polymer foam layers by an external x-ray source has been simulated using the 1D hydrodynamic code RADIAN, which includes transport of radiation of the external source and self radiation of the created plasma. Results of the simulations [21][22][23][24][25] have been used for optimization of the combined target design and for the interpretation of experimental results obtained at the PALS laser system.…”

“…In this sense, correct optical constants, which take into account a chemical composition of heated matter, are of crucial importance. The optical constants for the TAC chemical composition have been calculated in a context with the 'ion model' described in [22][23][24] for plasma temperatures and densities typical for the discussed experiments. Using these constants provides the best agreement between experimental results and simulations [21,22].…”

“…In some cases, at the beginning of the x-ray heating process, the plasma layer is optically thick for external radiation. But at later times, when the plasma temperature increases, it starts to be partially transparent since the plasma absorption coefficients drop with the temperature [23][24][25].…”

“…Over a few years, extended numerical simulations for different parameters of the hohlraum-based x-ray source and polymer foam layers have been performed [21][22][23][24][25] and were used for optimization of the conversion efficiency of the foam indirect heating process. In section 4 we present results of the simulations, which are relevant for experiments carried out at the PALS laser facility and can be helpful for better understanding of the indirect matter heating process.…”

Direct drive fuel target optimization in HIF

“…In target implosion, ICF has two ways of implosion schemes, that is, indirect-driven scheme and direct-driven implosion scheme [1][2][3][4][5][6][7][8].…”