Stimulated Brillouin scattering of laser radiation in an expanding plasma during compression of a spherical target can significantly reduce the fraction of absorbed energy. A model of CBET (crossed-beam energy transfer) stimulated scattering under multi-beam irradiation of a spherical target has been developed. The model does not contain empirical factor, unlike the model known in the literature. This makes it possible to use it in calculations for the conditions of planned experiments. Calculations of the fraction ΔCB of energy released from the plasma due to CBET scattering for experimental conditions at the OMEGA installation have been carried out. It is shown that this fraction depends on the factor fe of the electron heat flux limitation. With fe values in the range 0.04–0.06, the calculated values of ΔCB (0.12–0.084) are close to the value 0.1 obtained in the experiment and in numerical simulation at fe = 0.06.
Bayesian modelling of a thermal helium beam for measurement of electron density and temperature in the W7-X divertor plasma