Fusion News: Newsweek- Shine On, Tiny Little Star
The Lawrence Livermore National Laboratory, founded in 1952, contains 192 laser beams. It was created during the cold War to dream up weapons but now their mission has changed to nuclear “stewardship.”
The NIF concentrates 192 laser beams (the world’s most powerful; Livermore loves superlatives) on a pellet of hydrogen fuel two millimeters in diameter, suspended in a hollow chamber 10 millimeters in length called a hohlraum made out of gold and depleted uranium. The laser beams travel 4,900 feet, through a series of amplifying mirrors, into an enormous aluminum orb, the target chamber, where the hohlraum is suspended in a vacuum cooled to a brisk minus 426 degrees. The laser beams first hit the walls of the hohlraum, turning into x-rays that then travel (hopefully) toward the fuel pellet whose interior is lined with tritium and deuterium, isotopes of hydrogen.
The recent success of the NIF was published last month in Nature which revealed more energy released by the fusion of the hydrogen atoms than the energy that went into the pellot.
In the recent Nature article that made so much news, Livermore scientists wrote that their latest shots “show an order-of-magnitude improvement in yield performance over past deuterium-tritium implosion experiments.” Successful ignition has been repeated since (the lasers “shoot” about 200 times a year) with even greater yields, but the fusion yield remains modest so far, partly because while hydrogen nuclei are fusing, energy-rich helium nuclei known as alpha particles escape. If the force of the fusion were great enough to incorporate the alpha particles, a process known as alpha-particle bootstrapping, far more tritium and deuterium nuclei would consequently be incited to get in on the subatomic orgy. So while the reaction does yield energy, there is a huge qualification to that goal: only 1 percent of the lasers’ original 1.9 megajoules of energy even reaches the fuel, since most of it dissipates along the way. The victory, with its 17 kilojoule yield, is a modest one.
Peter J.K. Wisoff, one of the directors of the Livermore’s fusion project, believes that the nuclear fusion reaction, what he calls the “tiny little star,” will be enormously beneficial in the future. As reported by the New York Times in the article, “Shine On, Tiny Little Star:”
That energy could either be deployed to, say, obliterate Tehran or power San Francisco with cheap, non-polluting energy. “By investing in our nuclear security,” Wisoff says, the federal government is “enabling us to have the conversation over whether fusion would be able to be a power source in the future.” He says that funders like the NNSA have a clear-cut goal in mind: “Let’s get ignition, and then the decision-makers in Washington will decide whether they want an emphasis on getting fusion energy for the world at large.”
