Researchers at the U.S. Naval Research Laboratory have successfully demonstrated pulse tailoring, producing a time varying focal spot size known as ‘focal zooming’ on the world’s largest operating krypton fluoride (KrF) gas laser. NRL reports:
The Nike laser is a two to three kilojoule (kJ) KrF system that incorporates beam smoothing by induced spatial incoherence (ISI) to achieve one percent non-uniformity in single beams and 0.16 percent non-uniformity for 44 overlapped target beams. The facility routinely conducts experiments in support of inertial confinement fusion, laser-matter interactions, and high energy density physics.
“The development of an energy production system that utilizes thermonuclear fusion is an ongoing process of important incremental steps,” said David Kehne, research scientist, NRL Plasma Physics Division. “As such, the use of focal zooming in an inertial fusion energy system is expected to reduce the required laser size by 30 percent, resulting in higher efficiency and lower construction and operating costs.”
In the direct-drive inertial confinement fusion (ICF) concept, numerous laser beams are used to implode and compress a pea-sized pellet of deuterium-tritium (D-T) to extreme density and temperature, causing the atoms to fuse, resulting in the release of excess energy.
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