Stimulated Raman Backscatter from a Magnetically Confined Plasma Column

Stimulated Raman backscatter from long-scale-length, magnetically confined, underdense plasma has been studied for incident C${\mathrm{O}}_2$ laser intensities up to 2.5×${10}^{11}$ W/${\mathrm{cm}}^2$. Above an incident threshold of 4×${10}^{10}$ W/${\mathrm{cm}}^2$ the reflectivity rapidly rises to a saturated value of 0.7%. The measurements are in good agreement with a theoretical model of absolute instability which includes both collisional and Landau damping due to hot-electron production.