Featured Research

from universities, journals, and other organizations

Punch Of World's Most Powerful Laser Ratchets Up A Notch

Date:
November 8, 2000
Source:
University Of Rochester
Summary:
The first full-scale test of a technique to improve laser-driven fusion has been successfully completed by researchers at the University of Rochester's Laboratory for Laser Energetics (LLE). Implosions using this technique, called polarization smoothing, generated 70 percent more fusion neutrons than without and moves researchers closer to self-sustaining fusion.

The first full-scale test of a technique to improve laser-driven fusion has been successfully completed by researchers at the University of Rochester's Laboratory for Laser Energetics (LLE). Implosions using this technique, called polarization smoothing, generated 70 percent more fusion neutrons than without and moves researchers closer to self-sustaining fusion. These test results are being presented at the American Physical Society Division of Plasma Physics annual meeting in Quebec City this week.

The Laboratory of Laser Energetics houses the world's most powerful laser: the 60-beam Omega. Omega is often used as a testing ground for technologies that are planned for the National Ignition Facility (NIF) under construction in California. Since the process shows such promise, it will be incorporated into each of the NIF's 192 laser beams for direct-drive implosions.

Omega fires its energy on a millimeter-sized pellet, causing the pellet to implode, crushing in on itself and triggering nuclear fusion. Initiating this implosion with 60 beams, however, is like trying to crush a balloon in your hands: though you exert force with your fingers, the balloon bulges out between them. Likewise, if the energy from each beam of the laser pushes harder in one spot than another, the pellet will implode unevenly, losing some potential to trigger fusion.

To combat this uneven pressure, scientists develop ways of "smoothing" the beams so they strike the pellet evenly. Imagine the shadow rings a flashlight shines on a wall smoothing out to a perfectly even circle of light. The more smoothing, the more wallop the laser can throw at the target. Scientists look to polarization-the tendency of light waves to vibrate in only one plane-to find a way to smooth the beams even more.

"The idea of polarization smoothing has been around for some time, but this is the first time it's been used on a laser of this scale," says scientist David Meyerhofer, professor of mechanical engineering at the University of Rochester.

The technique requires that each of Omega's 60 beams (which in sum release more than 100 times the total power output of the nation in a billionth of a second) be split into two. Each beam shines on a prism-like crystal wedge that refracts about half of the beam, while letting the other half pass straight through. The "half-beams" are then recombined and focused on the target. This recombination smooths the beam because the polarizations of the individual half-beams cancel some of each other's irregularities, somewhat like the way merging cars on a freeway fill in the free space between each other and create a more solid stream of cars. The 60 recombined beams then strike the pellet from all sides, crushing it with far few "gaps between fingers."

Though the entire polarization smoothing system was first fully implemented in August, the process for its creation began in 1996. The scientists at the laboratory had to install 240 of the refracting crystals, each more than a foot in diameter, onto the laser one beam at a time. Flawless crystals of such a size are extremely rare, and can only be manufactured at two plants in the world.

"We saw a significant increase in performance," says Meyerhofer. "As we fine tune the system, we should be able to get even more than the 70 percent increase in neutron yield."

Scientists at LLE hope to improve the system's performance even more by cooling the target pellets below minus 400 degrees Fahrenheit to pack more material into the tiny space. Tests have begun on the freezing method and scientists are already experimenting with a combination of the two techniques.

The research was funded by the U.S. Department of Energy.


Story Source:

The above story is based on materials provided by University Of Rochester. Note: Materials may be edited for content and length.


Cite This Page:

University Of Rochester. "Punch Of World's Most Powerful Laser Ratchets Up A Notch." ScienceDaily. ScienceDaily, 8 November 2000. <www.sciencedaily.com/releases/2000/10/001031065626.htm>.
University Of Rochester. (2000, November 8). Punch Of World's Most Powerful Laser Ratchets Up A Notch. ScienceDaily. Retrieved July 25, 2014 from www.sciencedaily.com/releases/2000/10/001031065626.htm
University Of Rochester. "Punch Of World's Most Powerful Laser Ratchets Up A Notch." ScienceDaily. www.sciencedaily.com/releases/2000/10/001031065626.htm (accessed July 25, 2014).

Share This




More Matter & Energy News

Friday, July 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Europe's Highest Train Turns 80 in French Pyrenees

Europe's Highest Train Turns 80 in French Pyrenees

AFP (July 25, 2014) Europe's highest train, the little train of Artouste in the French Pyrenees, celebrates its 80th birthday. Duration: 01:05 Video provided by AFP
Powered by NewsLook.com
TSA Administrator on Politics and Flight Bans

TSA Administrator on Politics and Flight Bans

AP (July 24, 2014) TSA administrator, John Pistole's took part in the Aspen Security Forum 2014, where he answered questions on lifting of the ban on flights into Israel's Tel Aviv airport and whether politics played a role in lifting the ban. (July 24) Video provided by AP
Powered by NewsLook.com
Creative Makeovers for Ugly Cellphone Towers

Creative Makeovers for Ugly Cellphone Towers

AP (July 24, 2014) Mobile phone companies and communities across the country are going to new lengths to disguise those unsightly cellphone towers. From a church bell tower to a flagpole, even a pencil, some towers are trying to make a point. (July 24) Video provided by AP
Powered by NewsLook.com
Algonquin Power Goes Activist on Its Target Gas Natural

Algonquin Power Goes Activist on Its Target Gas Natural

TheStreet (July 23, 2014) When The Deal's Amanda Levin exclusively reported that Gas Natural had been talking to potential suitors, the Ohio company responded with a flat denial, claiming its board had not talked to anyone about a possible sale. Lo and behold, Canadian utility Algonquin Power and Utilities not only had approached the company, but it did it three times. Its last offer was for $13 per share as Gas Natural's was trading at a 60-day moving average of about $12.50 per share. Now Algonquin, which has a 4.9% stake in Gas Natural, has taken its case to shareholders, calling on them to back its proposals or, possibly, a change in the target's board. Video provided by TheStreet
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins