3 Laser Fusion Research Hubs selected by the Energy Department

The U.S. Department of Energy is creating three research centers in hopes of harnessing miniature laser-powered thermonuclear explosions for future power plants, officials announced Thursday.

The three hubs – located at Lawrence Livermore National Laboratory in California, Colorado State University and the University of Rochester in upstate New York – will share a total of $42 million over four years.

The research efforts will be “more focused on the underlying technologies required for any inertial fusion system,” said Scott Hsu, the chief fusion coordinator at the Department of Energy.

Combining two small atoms – usually hydrogen – into a heavier one produces energy. This process, known as fusion, is the driving force behind the Sun and other stars. If controlled fusion could be recreated on Earth, it could lead to an abundant energy source that doesn’t generate planet-warming carbon dioxide or long-lived radioactive waste.

Most fusion energy research to date, and most of the department’s fusion science budget, has focused on reactors that use powerful magnetic fields to trap super-hot hydrogen until the nuclei collide and come together. But a successful experiment last year at the National Ignition Facility (NIF) in Livermore put forward a different approach: firing high-powered lasers at a single grain of hydrogen, squeezing the atoms together to generate a fusion flash.

NIF was not designed as a prototype for fusion energy generation. It has been used primarily to maintain US nuclear weapons since the cessation of nuclear testing in 1992.

The NIF science experiment fired one laser pulse at one hydrogen fuel pellet. A practical power plant would need to fire laser pulses repeatedly – ​​at a cadence of perhaps 10 per second – with a new fuel pellet deposited for each pulse.

These lasers should be more powerful, more reliable and much more energy efficient than those at NIF. The targets for hydrogen fuel should be cheap and easy to produce. A single power plant would require a constant supply of millions of pellets. The new research hubs will help address these barriers.

The Energy Department received many applications and a review panel chose Livermore, Rochester and Colorado State, said Kramer Akli, who manages the government’s inertial fusion energy science program. Each of the winning proposals includes collaborations with other universities, national laboratories and private companies.

“You want to bring together the brightest in your field so that you can innovate and tackle some of the challenges in inertial fusion energy,” said Dr. Akli.

One of the main goals of the University of Rochester hub would be to test a new laser that would fire directly into hydrogen fuel. This approach is more energy efficient than that used in the NIF experiment in Livermore. But if small variations in the laser light cause instabilities, this prevents the fusion.

The instabilities can be tamed if the laser light is spread over a range of wavelengths. Scientists at the University of Rochester have been following this approach, known as direct propulsion, for years, and the hub’s research money will go toward experiments testing whether a new high-powered laser can solve this problem. “This really opens up the direct propulsion path,” said Dustin Froula, the physicist leading the Rochester hub.

The Colorado State Hub will study multiple types of lasers proposed for different inertial fusion concepts and also explore different designs for the fuel targets. Carmen Menoni, a professor of electrical and computer engineering who led the hub proposal, said she would look at new materials for the coatings used on laser optics so they could better survive the ongoing high-energy laser barrage.

Tammy Ma, the plasma physicist leading the Livermore hub, said the focus would extend beyond the indirect drive approach used by NIF and start addressing what would be needed to build a real power plant . “It’s not just: you have a target, and you shoot it, and you create energy,” said Dr. Mon.

The $42 million – $16 million each for Livermore and Colorado State, and $10 million for Rochester – is the first of a series of modest initial investments to be made in laser fusion over the coming years. It represents a small portion of the Energy Department’s fusion energy science budget, which is spending well over half a billion dollars this year.

“These hubs are just the seed of a U.S. program at this point,” said Dr. Mon.

The initial research should help clarify which approaches are the most promising. “It’s not enough investment to really get to those answers,” said Dr. Mon. “But I think after four years we can chart a promising path for the U.S. to really demonstrate a full-scale pilot plant.”