Self-Consistent Calculation of Half-Harmonic Emission with an Electromagnetic Zakharov Model

Half-harmonic emission has been regarded as a signal of two-plasmon decay or stimulated Raman scattering (SRS). Experimental observations at the Omega Laser Facility show both blue and red shifts of half-harmonic light. The red shift might be a powerful diagnostic tool to measure electron temperature near quarter-critical density.\footnote{W. Seka \textit{et al}., Phys. Fluids \textbf{28}, 2570 (1985); W. Seka \textit{et al}., Phys. Rev. Lett. \textbf{112}, 145001 (2014).} However, the interpretation of the half-harmonics spectrum is difficult because of its complicated generation mechanism. To resolve this problem, a self-consistent electromagnetic Zakharov code that is able to calculate half harmonics emission has been developed, including all the possible generation mechanisms such as absolute SRS, Thomson down-scattering, linear mode conversion, and nonlinear mode conversion.\footnote{D. F. DuBois, D. A. Russell, and H. A. Rose, Phys. Rev. Lett. \textbf{74}, 3983 (1995); D.~A. Russell and D. F. DuBois, Phys. Rev. Lett. \textbf{86}, 428 (2001).} This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.