NRL Nike Laser focuses on nuclear fusion

Mar 20, 2013
This is the Nike Laser -- focal zooming. Credit: U.S. Naval Research Laboratory

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.

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 physics.

"The development of an energy production system that utilizes 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 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.

In an ICF implosion, a progressively diminishing portion of the beams will engage the shrinking pellet if the focal spot diameter of the laser remains unchanged. For optimal coupling, it becomes desirable to decrease the laser focal spot size to match the reduction in the pellet's diameter, minimizing wasted energy.

"Matching the focal spot size to the pellet throughout the implosion process maximizes the on-target ," Kehne said. "This experiment validates the engineering of focal zooming in KrF lasers to track the size of an imploding pellet in ."

With single-step focal zooming implemented, the Nike laser provides independent control of pulse shape, time of arrival, and focal diameter allowing greater flexibility in the profiles and pulse shapes that can be produced. The flexibility in pulse shaping provides promising uses in both future experiments and laser diagnosis.

Explore further: Scientists propose an enhanced new model of the source of a mysterious barrier to fusion known as the 'density limit'

Related Stories

World’s largest laser picks up the pace

Nov 29, 2007

With their target completion date just a year and a half away, scientists and technicians at the National Ignition Facility (NIF) are quickening their pace to install and test the rest of NIF’s 192 lasers ...

Recommended for you

To conduct, or to insulate? That is the question

Jul 02, 2015

A new study has discovered mysterious behaviour of a material that acts like an insulator in certain measurements, but simultaneously acts like a conductor in others. In an insulator, electrons are largely stuck in one place, ...

Soundproofing with quantum physics

Jul 02, 2015

Sebastian Huber and his colleagues show that the road from abstract theory to practical applications needn't always be very long. Their mechanical implementation of a quantum mechanical phenomenon could soon ...

Extreme lab at European X-ray laser XFEL is a go

Jul 02, 2015

The Helmholtz Senate has given the green light for the Association's involvement in the Helmholtz International Beamline (HIB), a new kind of experimentation station at the X-ray laser European XFEL in Hamburg, ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.