NIF produces excess power
This image shows one of the most ambitious physics experiments ever conducted, the National Ignition Facility (NIF) in Livermore California. The NIF project is a $3.5 billion, U.S. government-funded research facility designed with the goal of investigating fusion.
The NIF system attempts to create fusion by focusing rapid-fire bursts from 192 lasers on a small, hydrogen-containing target known as a hohlraum. The laser bursts are intended to cause rapid-heating of the sample to temperatures upwards of a million degrees; temperatures seen in the interior of stars. The combination of lasers and heating of the hohlraum exterior generates pressures on the hydrogen isotopes large enough to, hopefully, cause them to fuse together into helium.
The NIF project has several goals, including military ones (allowing experimentation with fusion without having to detonate a nuclear weapon), but the term “ignition” in its name has a specific meaning. Ignition would be reached if the facility is able to generate a self-sustaining fusion reaction.
Enormous amounts of energy are released when hydrogen nuclei fuse together to make helium. If enough energy is produced by the reaction to power the lasers and supporting equipment, then the facility would have been able to generate a self-sustaining fusion reaction. This step, a fusion reaction that can sustain itself, is termed “ignition”, and is the step required before fusion could ever be considered as an energy source for society.
The NIF project has struggled for years with cost issues, politics, and delays, but in late September they reached a major milestone. They have not yet achieved “ignition”, but they accomplished something never before done in any fusion experiment on Earth.
In a firing of the lasers, they produced a reaction that released more energy than the lasers put into the sample. NIF has now produced a fusion reaction that has released a significant amount of energy. That’s a major accomplishment and a major step towards ignition.
The form of the reaction is likely a very complicated function of the exact arrangement and timing of the lasers and the exact makeup of the hohlraum. Consequently, it’s not just as simple as firing all the lasers; an enormous number of variables have to be tested and accounted for, but clearly NIF is making progress on the larger goal of ignition.
Of course, immediately after this success in late-September, the workers at NIF were furloughed as a consequence of the U.S. government shutdown and work on the project has temporarily stopped, temporarily preventing replication or improvement upon this success.
Image credit: Lawrence-Livermore National Lab