Cylindrical Liquid Jet Grids for Beam-Port Protection of Thick-Liquid Heavy-Ion Fusion Target Chambers

Thick-liquid pockets have the potential to protect structural materials and increase power density in heavy-ion fusion chambers. Here we show that cylindrical liquid jets have interesting advantages for creating shielding grids for heavy-ion beam lines. A cylindrical nozzle design with a very low convergence ratio was developed, and the fabrication methods needed for inexpensive numerically-controlled machining of large nozzle arrays demonstrated. Cylindrical jets were studied because they give the highest surface smoothness for a given degree of turbulence suppression, allow flow control to individual nozzles for control of jet pointing, and attenuate target-induced shocks effectively. Improved control of the grid geometry allows the driver energy to be delivered by a larger number of beams. These smaller beams–up to 160 in the example here–improve focusing and reduce neutron collimation up beam lines.