Fast ignition integrated experiments on GEKKO-LFEX laser facility

Abstract

Fast ignition realization experiments were carried out on GEKKO-LFEX laser facility. Present LFEX laser delivers 1.4 kJ of laser energy with 1.5 ps of pulse duration by two of four beams. This laser facility will be completed until the end of FY20111. Pedestal intensity of the LFEX laser is a critical parameter to determine coupling efficiency between the LFEX laser energy and compressed fuel core temperature, two new schemes have been successfully installed in the front end system of the LFEX laser to reduce the pedestal intensity. All diagnostics should be operated in the presence of intense background signal generated by intense LFEX laser and material interactions. Photodisintegration of iron atoms in the target chamber wall was found the dominant source of the background signal especially in the neutron time-of-flight measurement. Neutron yield were carefully evaluated with the consideration of the photodisintegration neutrons. A well-shielded x-ray streak camera measured the LFEX injection timing relative to the fuel compression timing with an accuracy of 10 ps. In the fast ignition integrated experiment, neutron yield was enhanced up to 3.5 × 107. The comparison between the simple modeling and experiment results reveals 20% of coupling efficiency was achieved.