J. F. Figueira

Plasma-breakdown retropulse isolators for the infrared

The design and performance of a passive plasma isolator for suppressing retropulses in high-power CO(2) laser-fusion systems are described. The device uses a gas-filled spatial filter designed to produce a plasma at the focal plane iris. General design criteria for these isolators are discussed, and the performance of a specific isolator is evaluated. For the unit tested, retropulse attenuations of 33 dB for focal plane intensities of 1.5 TW/cm(2) have been demonstrated.

Configuration and performance of the Los Alamos Aurora KrF/ICF laser system

Because short wavelength lasers are attractive for inertial confinement fusion (ICF) , the Department of Energy is sponsoring work at Los Alamos and the Naval Research Laboratory in KrF laser technology. The Los Alamos National Laboratory is investigating the feasibility of high-power KrF lasers as future ICF drivers. The Aurora Laser System is an end-to-end technology demonstration prototype for large-scale KrF laser systems employing optical angular multiplexing and serial amplification by electron beam driven KrF laser amplifiers. During the last year integration of the Aurora Laser System has been completed and the system has entered the initial operational phase by delivering kilojoule level shots to target. In this paper the current configuration of the system is described and its performance is reported.

Status of Inertial Confinement Fusion Research at Los Alamos National Laboratory

Los Alamos National Laboratory is engaged in a long-range program to investigate the merits of Krypton-Flouride (KrF) lasers as inertial confinement fusion (ICF) drivers. Because of their intrinsic short wavelength (0.25 μm), broad bandwidth (∼0.5%), smooth spatial beam profile, and precise and flexible temporal pulse-shaping capabilities, KrF lasers appear to be an attractive ICF driver candidate from the laser-target interaction physics standpoint. Additionally, the use of a gaseous lasing medium with the potential of high overall system efficiency preserves a direct path to energy production. Current cost pro-jections for MJ-class KrF systems show it to be affordable. The present Los Alamos KrF experimental facility, AURORA, has recently begun integrated system experiments. It has already achieved more than 100 TW/cm2 on target with >1 kJ of energy. The facility is designed to deliver 5 kJ to the target with a 5-ns pulse length and a spot size ∼200 μm. Shaped pulses from 2–20 ns can also be tested. The system employs angular multiplexing, where 96 beam pulses are overlapped into a single, 500-ns beam train. The 96 beam paths are offset and staggered thorough the amplifier chain to provide spatial and temporal separation of the individual beams. The energy from each amplifier is extracted continuously over the 500-ns electron-beam pumping duration. The appropriate time delay is then removed from each beam segment so that they are simultaneously recombined at the target plane. The first target physics experiments will be x-ray conversion experiments, followed by experiments on the effects of laser pulse shaping and bandwidth on target performance.

Development Of KrF Lasers For Inertial Confinement Fusion

High peak power rare gas halide lasers for applications in Inertial Confinement Fusion are being developed at laboratories across the world. The United States Department of Energy sponsors a program conducted at the Los Alamos National Laboratory and the Naval Research Laboratory. The Los Alamos laser development program is composed of three major elements; the Aurora Laser Facility is a 1 terawatt KrF laser designed as an integrated performance demonstration of a target qualified excimer laser system; an advanced design effort evaluates concepts that offer the improved performance and lower cost that will be essential for the construction of future lasers in the 0.5 to 10 MJ class; and a laser technology program that addresses both performance and cost issues that will be important in advanced laser system designs.