Efficient lasing in mixtures of helium and fluorine in diffuse discharges formed by runaway electrons

The parameters of stimulated lasing in diffuse discharges formed in mixtures of helium and fluorine in a strongly inhomogeneous electric field are investigated. Lasing is obtained in the visible and VUV spectral regions on the transitions of fluorine atoms and molecules. It is shown that lasing in He – F₂ mixtures at a wavelength of 157 nm continues for several half-periods of the discharge current. Due to the homogeneity of the diffuse discharge, the maximum lasing efficiency of the F₂ laser is 0.15%, which corresponds to the efficiency of this type of lasers pumped by pre-ionised transverse volume discharges.