Livermore Petawatt laser sets new pulsed-power record

Livermore Petawatt laser sets new pulsed-power record

The Petawatt laser at the Lawrence Livermore National Laboratory (LLNL, Livermore, CA) has broken the previous laser-power record by an order of magnitude. A series of test shots produced 1.25-PW pulses, compressing approximately 580 J of energy within 490 fs. The record has jumped in the last 18 months from 0.050 PW (50 TW), set at Commissariat a l`Energie Atomique (CEA, St. George, France), to LLNL`s 0.125 PW one year ago, and now to 1.25 PW.

The Petawatt laser uses one beamline of the Nova Nd:glass laser at LLNL. Chirped-pulse amplification enables its laser pulses to be amplified without damaging system optics. Compressed-pulse power density is on the order of 0.75 TW/cm2 in a 58-cm-diameter near-diffraction-limited beam, which means LLNL-researchers had to develo¥robust metallic and multilayer dielectric diffraction gratings for stretching and compressing the pulses by adjusting their paths within a vacuum. Transmissive optical elements cannot be used after compression because final beam irradiance may be more than 1021 W/cm2--more than 1000 times the threshold for producing relativistic plasmas. The Petawatt laser will be used to test fast ignition for inertial confinement fusion and generate high-energy x-rays and may also be used in nuclear and plasma physics experiments.