Applicability of semiclassical methods for modeling laser-enhanced fusion rates in a realistic setting

Abstract

In the context of the potential laser-induced enhancement to the rates of ${\mathrm{DHe}}^{3}$ and DT fusion, we discuss the frequently-used Wentzel-Kramers-Brillouin (WKB) method and the imaginary-time method (ITM). For static external electric fields, we find that these methods predict significant enhancement to the fusion cross section for electric-field strengths $>{10}^{14}$ V/m, especially at low values ($\ensuremath{\approx}$ keV) for the enter-of-mass (CoM) energy. When considering dynamic electric fields, this enhancement can be amplified by considering increased photon frequencies. However, we also provide a review of the region of laser-parameter phase space where these semiclassical methods are applicable. We conclude that this allowable region decreases for higher photon frequencies in conjunction with lower values for the electric-field strength, motivating the need for future experiments to test the predictions of these methods and their ranges of validity.