A local high school student has been selected as a semi-finalist in the Intel Science Talent Search for his work on the University of Rochester's Omega laser, the most powerful fusion laser in the world. Ronen Mukamel of Brighton High School showed how a certain configuration of optics will make a fusion laser more flexible with little sacrifice in performance. His calculations are likely to have an impact on the design of the National Ignition Facility (NIF) in California, which will be the world's most powerful laser when its construction is finished.
"Ronen's work is providing an answer that will be relevant to the final decisions at NIF," says R. Stephen Craxton, a physicist in the Theory Division at the University's Laboratory for Laser Energetics and Mukamel's mentor last summer.
Mukamel wrote a program that would model how the NIF laser would perform if certain optical components were arranged in various orders. Each of the NIF's 192 laser beams must pass through a phase plate, a piece of glass that slightly diffuses the beam, and a series of frequency conversion crystals that turn the infrared laser to a more potent ultraviolet one. If the beam passes through the phase plate first, it is dispersed in such a way that the crystals don't convert the beam to ultraviolet as effectively as they could-but if the beam passes through the crystals before they pass through the plate, the intensity of the beam becomes so great that it would damage the plate. Mukamel discovered that only about 5 to 7 percent of the laser's potency would be lost if the plate were placed first.
Craxton notes, "We knew that some of the laser's power would be lost, but we speculated the losses would be greater than what Mukamel calculated.. His data means this configuration is quite feasible."
Keeping the phase plate before the conversion crystals has another advantage: Both kinds of laser-driven fusion can be performed in this configuration. Direct-drive fusion, which is the kind of fusion undertaken at Omega, blasts the target directly with laser energy, whereas indirect-drive fusion requires the lasers to fire on the inside of a cylinder that radiates X-rays which strike the target. Having both types of fusion experiments available in the NIF will broaden the kinds of experiments the giant laser will be able to perform.
Mukamel, 17, has won several awards for research he's done in the past. He's also been an exceptional scholar, taking a graduate-level college course in number theory while still a freshman in high school. Mukamel has worked with several researchers at the University, as well as with others in a summer program at Ohio State University. He is one of several Rochester-area students who have been honored in national science competitions during the last decade for work done at the Laboratory for Laser Energetics.
In the latest competition, more than 1,500 students from around the country entered the competition, and only 300 were chosen as semifinalists. Mukamel is the only semifinalist from the Rochester area. For his accomplishment, Mukamel and his school will each receive $1,000. Forty finalists will be chosen to attend the Science Talent Institute in Washington, D.C., in March, where one winner will receive a prize of $100,000.