Energy deposition in direct nuclear pumped optical cavities

Abstract

A two-dimensional, time-dependent model has been developed to determine the coupled fluid dynamic and charged particle transport behavior of a flowing gas, nuclear pumped laser cavity. Stationary results are presented for a typical cavity that uses a flowing He buffer gas pumped with charged particles produced by the 10B(n,α)7Li reaction. The boron is coated on fuel plates mounted parallel to the flow direction. The effects of changing the buffer gas inlet flow velocity and outlet pressure are investigated. For a fixed inlet velocity, the results presented show that the gradients of the charged particle energy deposition and density increase in magnitude primarily in the direction perpendicular to the gas flow, i.e., normal to the fuel plates, as the outlet pressure is increased. With increasing inlet velocity and a fixed outlet pressure, the density variations decrease, whereas the variations in energy deposition increase in the direction perpendicular to the flow and decrease in the direction parallel to the gas flow. For higher inlet velocity cases, the deposition is nearly one-dimensional, varying primarily in the direction perpendicular to the flow. Qualitatively similar results can be found with an argon buffer gas and fission fragment pumping for similar charged particle ranges. In general, for a fixed cavity geometry similar charged particle energy deposition behavior can be obtained for different laser gases by adjusting the outlet pressure and charged particle source.