Interview with Xcimer Energy: NIF-Style Inertial Confinement is Alive and Well in Denver!

Earlier this week, we interviewed Conner Galloway (CEO and Founder) and Alex Valys (President and Founder) of Xcimer Energy Corporation. Xcimer, which was founded in 2021 and is headquartered in Denver, CO, has raised roughly $100 million dollars since their founding four years ago. Their focus is on generating energy from inertial confinement fusion (ICF), specifically by utilizing the approach pioneered at the Lawrence Livermore National Laboratory (LLNL) National Ignition Facility (NIF). Xcimer’s investors include Breakthrough Energy Ventures, Lowercarbon Capital, Prelude Ventures, Emerson Collective, Gigascale Capital, and Starlight Ventures. Additionally, Xcimer was the recipient of a large Department of Energy (DoE) milestone grant of $9 million (the second largest of that year) early in the company’s history, while they were still a seed-funded startup.

Inertial Confinement Fusion – It’s All About The Lasers

The thing that really inspired Conner and Alex was one of the earlier ICF tests at NIF, which showed that the energy gain of the fuel capsule itself was roughly 34 (note that this was not the NIF test where Q>1). What they saw as the inherent weakness of the NIF approach was the lasers themselves. Galloway and Valys saw several specific weaknesses with the NIF lasers:

• NIF’s approach utilized too many lasers which are too expensive: NIF uses 192 lasers that converge on the fuel pellet in the center of the NIF chamber. These lasers, which are housed in a 10-story building which is 300 meters long, utilize 120 tons of precision glass, and had a total cost to build of $3.6 billion. This is one of the greatest problems with solid-state lasers – the neodymium-doped phosphate glass for them, while more plentiful than 20 years ago, is still very expensive.
• NIF’s lasers are not powerful enough: The total power of the 192 NIF lasers is 2 megajoules (MJ) in a billionth of a second, which causes issues for ICF. Primary among these issues is the NIF lasers are infrared (IR) lasers, while the best wavelength to generate X-rays to compress and heat the fuel pellet are ultraviolet (UV) rays; frequency shifting cuts the power in the UV beams to a third of that in the IR beams.

Refining the NIF Approach to Lasers

To improve the performance and economics around ICF, Xcimer knew that they needed to refine the approach taken by NIF. The key changes include the following:

1. Switching to a UV-native laser with a lower cost lasing medium: The first improvement that Xcimer undertook was to switch to a laser that natively emitted UV light, avoiding the 67% power loss that NIF was seeing by shifting the laser frequency. They also wanted a laser that had a cheaper lasing medium than neodymium-doped phosphate glass. The answer was Krypton Flouride (KrF) gas excimer lasers. These have a very high power output, are natively UV-emitting, and are much cheaper to build and operate than solid-state glass lasers.
2. Significantly reducing the number of laser beams: As stated above, the 192 laser beamlines in NIF include not only expensive glass, but expensive optics, alignment systems, and other components. Xcimer made the decision to switch to just two (2) lasers. These lasers utilize beam-front shaping to ensure that the fuel capsule is heated uniformly, even though it is only being impinged upon by two laser beams.
3. More power: By going to two ten megajoule (10 MJ) lasers, Xcimer significantly increases the power that is hitting the target. This also lets them go to a lower one-half Hertz powerplant injection rate for fuel pellets (one pellet every two seconds).
4. Don’t do everything with a single pulse: Xcimer’s approach utilizes a multiple pulse train to heat and compress the fuel pellet, increasing the total amount of energy injected into the fuel pellet.

The other side benefit of a slower fuel pellet injection rate is that it allows Xcimer to utilize a liquid metal first wall “waterfall” approach, as shown below. 

As the pellet is injected into the chamber, fluorine lithium beryllium liquid salts are “poured” down the inner side of the chamber. This protects the structural wall of the fusion chamber, absorbs the high-energy neutrons and converts them to heat, and converts some amount of the lithium to tritium. This can easily be done at the 0.5 Hz pellet injection rate. It also reduces the cost of operating Xcimer’s fusion machine by eliminating the periodic replacement of the costly first wall.

What Would an Xcimer Power Plant Look Like?

Xcimer stated that their goal is to build electrical power plants with a minimum electrical net output of 300 MW. From their perspective, the more power the fusion plant outputs, the more economical it is; a plant with 1GW or more of electrical output would be optimal, from the perspective of economics, power demand, and producing enough power to “make a difference”. The image below shows what a typical Xcimer power plant would look like.

The greatest challenge to realizing these plants, which Xcimer thinks could happen by 2035, is scaling up the supply chain for some of the critical components in their design. From their perspective, the supply chain existed in the U.S. in the 1980s, but increased globalization of supply chains means that much of it has moved overseas. Xcimer’s desire is to have a U.S. or ally-based supply chain, reducing the risks of supply chain “impairment” such as we have seen in other energy technologies like photovoltaic solar, wind energy, and similar technologies where the bulk of the components are built in China.

The Race for Fusion – A Race That Is the U.S.’s To Lose

Speaking of China, Xcimer believes that they are our real competition in the race to achieve fusion energy, whether via ICF, MCF, or other hybrid techniques. The Chinese focus on human capital, where they are graduating 10X the PhDs focused on fusion that the U.S., is not the only troubling factor there. The Chinese government is also investing more money into fusion than the U.S., and they are building credible programs in both ICF and MCF – China’s EAST tokamak is just one example of this. Xcimer’s founders are confident that the U.S. can still win, but increased U.S. investment in fusion, particularly at the government level (especially in reshoring the supply chain) will be critical in doing so.