Last week scientists at the U.S. Department of Energy’s Lawrence Livermore National Laboratory in California achieved a net energy gain for the first time, in a fusion experiment using lasers.
The researchers say the reaction at the Livermore laboratory produced around 3 megajoules of energy, or around 150 percent of the 2 megajoules that were needed to start the reaction — a 50 percent net gain. A small capsule of deuturium-tritium fuel about half the size of a BB was struck by the ravening beams1 from 192 ultraviolet lasers all aimed at a small ampule containing the pellet in the exact center of the ignition chamber. All this happened in less time than it takes light to move 10 feet. X-rays from the wall impinged on the spherical capsule. The fuel inside the capsule got squeezed by the X-rays., squeezing the pellet.
They’ve done this experiement a hundred times before, but according to Dr. Marvin Adams, the NNSA Deputy Administrator for Defense Programs, what happened this time was that the capsule stayed hot enough, dense enough, round enough, for long enough, that the reaction was triggered. The energy production took less time than it takes light to travel one inch.
I have a special message for listeners who want to work on exciting, challenging, and important problems: we’re hiring!— Dr. Marvin Adams, he NNSA Deputy Administrator for Defense Programs
To put this in perspective, we’re still a long way from doing anything useful with the energy produced. The 0.5 megajoules of energy produced is really only only about enough to boil two or three kettles of water. While the results are a milestone in a scientific quest that has been developing since at least 1958, the ratio of energy going into the reaction at Livermore versus the energy coming out needs to be about 100 times bigger to be a practical source of energy.
The type of reactor used in the experiment is also problematic. It’s a laser-triggered ignition system, with a reaction chamber essentially lined with high powered ultraviolet lasers, all focused on a single pellet of deuterium-tritium alloy in the center. Some drawbacks of such a configuration in terms of continous operation should be apparent even to the casual observer: how does one feed a continous supply of these pellets into the reactor, how does one collect the energy produced in a useful manner, and what happens to all the heat from the reaction? These problems and a thousand others have to be solved before a reactor based on this design could be put to commercial use, and it may take decades more work to solve them.
Fusion works when nuclei of two atoms are subjected to extreme heat of 100 million degrees Celsius (180 million Fahrenheit) or higher leading them to fuse into a new larger atom, giving off enormous amounts of energy. Unfortuinately it takes a lot of energy to make that happen. The trick has always been to more energy out than you put in. You know that thing where the news headlines keep saying “Fusion is Just 10 Years Away”, and they’ve been saying that for decades now? The net loss reactions humans have managed so far is one of the big reasons why it’s been so elusive.
All those caveats aside, this is the first time anyone, anywhere in the world, has achieved net gain nuclear fusion. Now that we have this, the ramifications are profound. We can now recreate conditions here on the planet’s surface that were previously only possible in the sun and stars, and we can do it without setting off traditional nuclear explosions. This opens broad new vistas of scientific research that were previously inaccessible to humankind.
Lawrence Livermore focuses mainly on national security issues related to nuclear weapons and the fusion experiment could lead to testing safer testing of the nation’s arsenal of such bombs.
Investors including Bill Gates, Jeff Bezos and John Doerr have poured money into companies building fusion. Private industry secured more than $2.8 billion last year, according to the Fusion Industry Association for a total of about $5 billion in recent years.