Cross beam energy transfer (CBET) is an important process in indirect-drive inertial confinement fusion (ICF) research, since it has been routinely applied to control the implosion symmetry of the fusion capsule. To study CBET, an experiment was carried out recently on the Shenguang laser facility, by injecting 24 laser beams through a laser entrance hole into a shortened gas-filled hohlraum. Two of the inner beams (28.5° and 35° relative to the hohlraum axis, respectively) hit a gold witness plate after transmitting through the hohlraum. The generated x-ray spots, together with several additional spots produced by calibration beams with known intensities on another neighboring plate, were recorded by an x-ray frame camera, which provided a way to infer the powers of the transmitted inner beams. The results displayed a prominent CBET process as the wavelength difference between the inner and outer beams was increased. A maximum enhancement of ~80% in the peak power of inner beams was recorded, corresponding to an enhancement of ~60% in the x-ray flux of the spot, which was measured by a space-resolving flux detector. These results were favorably reproduced by simulations.

Cross beam energy transfer,Indirect-drive,gas-filled hohlraum