U.S. scientists achieve nuclear fusion “breakthrough”

PHOTO BY JAKE LONG FROM NIF 

In a historic success on Dec. 5, 2022, a nuclear fusion lab achieved ignition in a fusion reaction and produced a net energy gain. The Falconer spoke to Dr. Daniel Jassby, a retired principal research physicist at the Princeton Plasma Physics Lab, to understand the physics and engineering of this achievement and its potential contribution to the development of fusion energy.

Q: What did NIF achieve and how is it different from past experiments?

A: They achieved ignition of a thermonuclear plasma and instigation of a propagating thermonuclear burn. That’s what’s required in order to get significant energy output…The only time that’s been done previously is with large-scale thermonuclear explosives, colloquially called hydrogen bonds. [This is] the first time it’s ever been done in the laboratory.

Q: How does this reaction contribute to fusion energy technology?

A: It shows that it’s possible to have a system fueled by deuterium and tritium that can generate an infinite amount of energy, [or] at least it’s on a track to producing much more energy. Imagine somebody starting a fire with dry wood for the first time in history. But, it represents only the so-called scientific feasibility of fusion. There’s a large number of difficult technologies that have to be developed, in some cases invented, to make it practical.

Q: How far off are we from having fusion energy as an energy source?

A: If you’re talking about power sources that can be put on a grid that people can readily utilize, [it will be] at least 50 years because of all the technologies that need to be developed. There are a host of private fusion companies out there that say they’re gonna do this in the 2030s. That is completely crazy. Their plans are all based on fusion systems that have not even been demonstrated and they haven’t come anywhere close to achieving what Livermore achieved at the NIF.

Q: What are the engineering obstacles to producing fusion energy?

A: The Livermore experiments at the NIF are using phases that are very inefficient, as the electrical energy requirement is huge. You have to have a laser that has much higher efficiency and they do exist, but with much lower power levels than the Livermore lasers. Also, the Livermore laser only pulses once or twice a day as everything needs to heat up and they have to wait until it cools down. But for practical reactors, it has to pulse about once a second. Also, the target that they’re using … is extremely expensive to make. The price of those targets has to be reduced by at least $1,000, probably $10,000. And there has to be efficient ways of capturing the energy that’s produced by the fusion reactions and converting it to electricity.

Q: If I gave you a blank check, where you could spend any amount of money on some aspect of fusion research and development, what would you spend it on and why?

A: If I had this infinite amount of money, I would develop either a laser beam or a particle beam with the characteristics that are required for a practical reactor. The laser at the NIF is great for doing experiments, but it’s completely unsuitable for any practical power production for two main reasons. One, it’s very inefficient, as it consumes so much electrical energy. And second, it only fires once or twice a day.