There is big news in the field of fusion science, from the physicists at the Lawrence Livermore National Laboratory in Alameda County, California. At the lab's National Ignition Facility (NIF), researchers say they are closing in on a milestone where their extremely bitchin' device successfully creates a "burning plasma" that is sustained by its own heat. A self-sustaining plasma capable of generating significant energy that can then be converted to electrical power would be an energy breakthrough of historic proportions. Could it also reduce our planet to a cloud of ash, wafting sadly through the solar system? Scientists say no. I say they are simply not trying hard enough.
NIF takes a different approach to fusion than the one taken by the MIT scientists working on the SPARC tokamak. You may recall that the tokamak magnetically suspends a deuterium-tritium cocktail in a donut-shaped torus and then bombards it with various science things until a plasma is formed. The trick, there, is getting a hot enough and dense enough plasma to emit more thermal energy than it uses, but scientists working on tokamak experiments believe they are very close to energy breakeven, and that tokamaks offer a very realistic chance at eventual commercial energy production. The NIF may seem to be several steps behind in its pursuit of energy breakeven, but its angle of attack is steeper, it deploys much more violence, and it features many, many more lasers, any one of which could do truly awesome and destructive things to a human thorax.
The science of this NIF reactor is very cool. They soak a little blob of foam in fusion fuel and encase it in a diamond capsule, then sock that capsule inside a little gold can the size of a thimble, called a hohlraum. Then they point 192 super-intense lasers at this little hohlraum and fire away. The hohlraum, thus bombarded by energy, emits x-rays which generate truly incredible heat inside the diamond capsule and compress the fuel "to billions of atmospheres" of pressure. As researchers refine this process—adapting certain of the lasers for specific science things, cleaning up "imperfections of just a millionth of a meter" in the capsule shell, enlarging the hohlraum—the NIF generates greater and greater energy yields, recently topping 60 kilojoules. I do not know what that means, but I am told in this excellent explainer from Daniel Clery of the magazine Science that the target for burning plasma is 100 kilojoules. They're on their way.
Apparently it was the opinion of the Trump administration that all this awesome laser power should be directed at tasks relevant to the maintenance of America's stockpile of nuclear weapons, which slowed and imperiled the much more significant goal of unlocking fusion energy for all of mankind:
The proportion of NIF shots devoted to the ignition effort has been cut from a high of nearly 60% in 2012 to less than 30% today to reserve more shots for stockpile stewardship—experiments that simulate nuclear detonations to help verify the reliability of warheads. Presidential budget requests in recent years have repeatedly sought to slash research into inertial confinement fusion at NIF and elsewhere, only to have Congress preserve it. NIF’s funder, the National Nuclear Security Administration (NNSA), is reviewing the machine’s progress for the first time in 5 years. Under pressure to modernize the nuclear arsenal, the agency could decide on a further shift toward stockpile stewardship. “Will the ignition program be squeezed out?” asks Mike Dunne, who directed Livermore’s fusion energy efforts from 2010 to 2014. “The jury’s out.”
Daniel Clery, Science
It is imperative that President-elect Joe Biden commit the United States to firing the NIF's 192 lasers at hohlraums loaded up with diamond-coated pellets of fusion fuel, in order to achieve their goal of producing a self-sustaining plasma with the awesome heat and singular beauty of the very stars of the night sky. And it is absolutely essential that I then be allowed to swallow a hohlraum and stand at the center of this apparatus, so that the 192 lasers may be fired in sequence at the exact moment when the hohlraum passes through my esophagus directly behind my solar plexus. I am willing to endure a few nanoseconds of searing pain as the lasers penetrate my flesh in order to be consumed utterly by the unfathomably hot plasma cloud emanating from the very core of my being.
There are encouraging signs that my bodily destruction would proceed in just such a manner. Researchers recently observed conditions in the reaction that suggest that a few more bumps in energy input may produce runaway fusion spreading from the center of the fuel capsule:
Even at maximum compression, the NIF researchers believe only the very center of the fuel is hot enough to fuse. But in an encouraging finding, they see evidence that the hot spot is getting a heating boost from frenetically moving helium nuclei, or alpha particles, created by the fusion reactions. If NIF can pump in just a bit more energy, it should spark a wave that will race out from the hot spot, burning fuel as it goes.
You can bet they are working on tricks for boosting the reaction, including possibly "boosting the laser energy." The list does not yet include suspending the hohlraum inside the chest cavity of a sports blogger, but scientific breakthroughs often require just this sort of outside-the-box thinking. If igniting a star inside my torso is not feasible, I am willing to wait until the plasma cloud is already burning and expanding at the center of the reactor, and then take a running head-long leap into the inconceivably brilliant star juice, and be thus eradicated from this plane of existence.
H/t Paul
