Effects of moderate bandwidth on laser absorption and stimulated Raman sidescattering

Abstract

We report experimental results regarding laser-plasma instabilities (LPI) developed by monochromatic and broadband green lasers with moderate bandwidths (0.2% and 0.6%) at intensities of 5–7 $\times 10^{14}$ W cm ^−2 in the interest of inertial fusion energy. Angular-resolved distributions of scattered light were diagnosed, which demonstrated that the laser absorption rate is enhanced by increasing the laser bandwidth. This enhancement is primarily owing to the mitigation of stimulated Brillouin scattering. Meanwhile, the inherent temporal fluctuation of laser intensity caused by bandwidth results in more intense stimulated Raman scattering, particularly regarding the sidescattering. These findings indicate that the requirement of laser bandwidth used in inertial fusion energy should exceed the moderate level to achieve comprehensive mitigation of LPI.

Keywords

• moderate bandwidth
• laser absorption
• stimulated Raman sidescattering
• inertial fusion energy