Effect of irradiation on nonlinear optical recirculation cavity performance

In applications such as the production of hydrogen ions for accelerators in spallation neutron sources, charge stripping of hydrogen ions using high-power lasers represents an attractive technical approach. The use of laser–ion interaction in conjunction with a laser recirculation cavity holds promise for improved efficiency, but the high-radiation environment raises concerns about the longevity of the key components of such a system, especially the nonlinear crystal used for frequency conversion. We present the results of an in-reactor irradiation experiment in which a sample beta-barium borate crystal has been irradiated with fast neutrons and gamma-rays, accompanied with the Monte Carlo analysis of the irradiation dose and its comparison with typical conditions at the Spallation Neutron Source at Oak Ridge National Laboratory. The results suggest that our design of the laser recirculation cavity exhibits a radiation hardness consistent with maintaining enhancement factors of the order of 10 over > 10 years, but a more detailed experimental study is needed to investigate the radiation hardness of cavity designs exhibiting greater enhancement factors.