Large increase in the electron capture and excitation cross sections for Li+ colliding with atomic H under UV laser assistance

Abstract

Neutralization and ash products due to electron capture processes in plasmas reduce the efficiency of energy generation in fusion Tokamak reactors. Therefore, lithium ions have been used to improve the efficiency of energy generation where good control of the electron capture process is required. Here, we show that an intense ( W cm−2), ultra-short (1 fs at full width half-maximum) Gaussian laser pulse in the UV region can enhance the electron capture process on in the low collision keV energy region. We find a factor of 10 enhancement in electron capture cross-section at impact energies lower than 10 keV amu−1 for an 80 nm wavelength laser and a factor of 2 for the excitation process in the hydrogen atom as compared to the laser-free case. In contrast, for a 200 nm wavelength laser the increase of the electron capture cross-sections takes place around 1 keV amu−1 by a factor of 3 and no enhancement for the excitation process. Our results show that the UV assisted production of Li can be controlled, particularly for short UV wave-length for a specific collision energy range. We anticipate that our findings will facilitate UV laser control of the Li production in Tokamak reactors and encourage further experimental work in this system.