James P. Armstrong

High-average-power femto-petawatt laser pumped by the Mercury laser facility

The Mercury laser system is a diode-pumped solid-state laser that has demonstrated over 60 J at a repetition rate of 10 Hz (600 W) of near-infrared light (1047 nm). Using a yttrium calcium oxyborate frequency converter, we have demonstrated 31.7 J/pulse at 10 Hz of second harmonic generation. The frequency converted Mercury laser system will pump a high-average-power Ti:sapphire chirped pulse amplifier system that will produce a compressed peak power > 1 PW and peak irradiance > 1023W/cm2.

MICRON-SCALE DEEP HOLE DRILLING FOR BERYLLIUM CAPSULE FILL APPLICATIONS

Abstract A laser processing system has been developed to drill high aspect ratio holes through the impermeable beryllium capsules envisioned for ignition shots on NIF. The drilling system was designed to produce holes with an entrance and exit diameter of approximately 5 μm through the full 175 μm thickness of the capsule. To meet these requirements, a frequency doubled femtosecond-class Ti:Sapphire laser is directed through a high numerical aperture lens to provide the spot geometry needed to drill the hole. The laser pulse is confined by the metallic walls of the hole, thereby maintaining the diameter of the channel well beyond the Rayleigh range of the optical system. Presented is the current state of this work-in-progress, including descriptions of the device and the technique used to produce the holes. The various means of characterizing the laser-drilled channels are also discussed.

HIGH AVERAGE POWER PETAWATT LASER PUMPED BY THE MERCURY LASER FOR FUSION MATERIALS ENGINEERING

A high average power diode pumped solid state laser is used to pump large aperture Ti:sapphire enabling high average power chirped pulse amplification. After compression, over a petawatt of peak power will be used to generate fusion ions and neutrons for materials testing of first wall and final optics candidates.

Recent progress in the development of capsule targets for the National Ignition Facility

The capsule targets for ignition experiments at the National Ignition Facility must meet very exacting requirements. Primary among them is an extremely high degree of symmetry at all length scales for the 2-mm-diameter 150-μm-walled capsule. At LLNL work is in progress to produce both polyimide and sputtered beryllium targets that meet these specifications. Both of these targets require a thin-walled spherical-shell plastic mandrel upon which the beryllium or polyimide ablator is deposited. In this paper we report on recent progress in developing NIF capsules that meet the demanding design requirements.

Power scaling of Ti:Sapphire amplifiers: Design of a high average power Temto-Petawatt laser

A large-aperture high-average-power gas-cooled Ti:sapphire slab pumped by the Mercury laser is the final amplifier in a chirped pulse amplification chain capable of producing a compressed peak power >1 petawatt and peak intensity >1023 W/cm2.

Activation of a Temporal, Spectral, and Spatially-Shaped Front End for the Mercury Laser

Hybrid fiber-based master-oscillator power amplifier system coupled with a Yb:SFAP power amplifier will produce 500mJ at 10Hz with 100:1 temporal contrast over 3-10ns and 300GHz spectrally shaped bandwidth allowing broadband amplification corrected for gain narrowing.

Full System Operations of Mercury: A Diode-Pumped Solid-State Laser

Laser operations with two amplifiers activated produced 35 Joules at 1 Hz, 12 Joules at 10 Hz, and 8x104 total system shots. Static distortions in the Yb:S-FAP amplifiers were corrected by magneto rheological finishing technique.

High energy hybrid fiber - Yb:SFAP laser with dynamic spectral and temporal pulse shaping

We have commissioned a turnkey 500 mJ, 10 Hz front end laser. The system delivers temporally and spectrally tailored pulses to correct signal distortions within itself or subsequent amplifiers from single longitudinal mode to 250 GHz RF bandwidth.

Activation of a Spatial, Temporal, and Spectrally Sculpted Front End for the Mercury Laser

We have produced over 500 mJ using a hybrid fiber-based master-oscillator system coupled with a Yb:S-FAP power amplifier. This system is designed with spatial, temporal, and spectral sculpting enabling broadband amplification correctable for gain narrowing.