What’s different about Pacific Fusion’s pulsed magnetic concept?

In a nod—or a challenge—to the bold decadal vision of the DOE’s Office of Fusion Energy Sciences, Pacific Fusion shared a technical paper written by a team including five of its employees that articulates “a set of community-developed principles and our own bold vision to develop three major advances: the demonstration of facility gain (𝑄𝑓 > 1) by the end of the decade, a subsequent commercial pilot plant, and a next-generation source for national security needs.”

While the company is now operating with private funds and a staff of 44, according to the paper some at Pacific Fusion believe the Department of Energy and the National Nuclear Security Administration might share the company's interest in proving a fusion concept based on experience gained at NIF and at Sandia National Laboratories’ Z machine—and be motivated to join Pacific Fusion in a public-private partnership.

About the technology: Pacific Fusion’s website explains the technology in simple terms. It describes a system with three components: pulser modules, a small meter-scale fusion chamber, and centimeter-scale fuel containers. The pulser modules store electricity in capacitors and release it in fast pulses that deliver that energy with help from metallic pulse tubes that speed toward the fusion chamber before imploding. The energy from multiple transmission lines is coupled into two electrodes, which drive current through the target and electromagnetically compress it to cause fusion.

Pulser technology has been around for decades. The United States has the world’s most advanced pulser in the Z machine, but the authors of the technical paper shared Friday believe a pulser using impedance-matched Marx generator (IMG) technology (invented in 2017 and “demonstrated in action at LLNL in 2022”) can deliver an intense, 100-nanosecond burst of energy by accounting for electromagnetic-wave propagation and “stacking waves,” as opposed to the “stacking voltage” approach of conventional pulser technology. With IMG, internally reflected waves cancel, leaving only forward-going waves, according to the paper.

By delivering that energy directly to deuterium-tritium fuel capsules, as in inertial confinement fusion, but with the ability to “magnetically squeeze” the fuel, Pacific Fusion’s founders believe their approach can expand the range of pressure and confinement time conditions under which fusion can be achieved in a single machine. The pulser modules can be optimized for either simultaneous or staggered arrival of pulses. With simultaneous arrival, the fuel is subject to short, intense compressions; while with staggered arrival, longer, lower-pressure compression is permitted.

Pacific Fusion's founders claim a future energy producing system—which would be at least a decade away—would be “built of small mass-manufacturable units called bricks (two capacitors and a switch), which are assembled into modules that fit into shipping containers.” The fusion chamber would be “compact and cylindrical,” and the system would be built “from widely available materials.”

Funding: Pacific Fusion announced October 25 that it has received $900 million in Series A financing led by venture capital firm General Catalyst. That funding, according to Pacific Fusion, was committed upfront but will be “unlocked” with the achievement of milestones.

General Catalyst offered its answer to the question “Why Pacific Fusion?” in an October 25 press release. It pointed to Pacific Fusion’s team, technology, and financing structure.

The team is led by Eric Lander, a scientist well known for leading the International Human Genome Project and for a stint as science advisor to President Biden and head of the White House Office of Science and Technology Policy; and it includes Will Regan, who developed the ARPA-E Accelerating Low-Cost Plasma Heating and Assembly (ALPHA) fusion program; Keith LeChien, who led pulsed magnetic fusion at LLNL and served as director of inertial confinement fusion at the NNSA and one of the inventors of IMG; and Leland Ellison, Nathan Meezan, and Alex Zylstra, all formerly of LLNL.

From the founders: Eric Lander, Will Regan, Keith LeChien, Carrie von Muench, and Leland Ellison all signed a founders’ letter released October 25. They describe confidence in a technology that is based on the achievement of ignition at NIF in December 2022 but also on less well-known work with Sandia’s Z machine, which has “used fast-rising current pulses to drive the MagLIF [magnetized liner inertial fusion] concept to achieve the highest pulsed magnetic fusion Pτ ever, second only to laser-driven concepts.”

The team’s goal now is to build a high-gain pulsed magnetic fusion driver to achieve net facility gain, defined as more fusion energy output than all stored energy input. The company also says it has started engineering the components and systems for a commercial fusion system.

Acknowledging that they’re joining a crowded field, the founders write: “We will regularly share and publish our research so others can scrutinize and build on our findings, just as we build on theirs. We are equally committed to partnering with communities, regulators, policymakers, suppliers, industry peers, and customers as we make commercial fusion a reality together.”

The paper has more to say: The paper presenting the case for Pacific Fusion’s approach, “Opportunities in Pulsed Magnetic Fusion Energy,” was submitted to the open access platform arXiv.org in August by Alex Zylstra, former lead experimentalist for NIF’s successful fusion ignition experiments and now experiments lead at Pacific Fusion. The paper captures the content of a January team meeting in San Diego, Calif., and the team’s belief that pulsed magnetic fusion is “the most attractive path forward when balancing technology maturation, cost, and complexity.”

That is in part because the team believes it’s “an underappreciated fact” that pulsed magnetic fusion has demonstrated performance “on par with laser-driven ICF and tokamaks despite receiving only a small fraction of investment relative to those concepts.”

The hybrid fusion approach offers the advantages of inertial fusion with simpler target design, according to the paper:

Pulsed magnetic driven ICF is the shortest path to ignition that takes advantage of low-cost compact pulsers while retaining the ‘ICF advantage’—the same facility can drive multiple designs and concepts, enabling rapid iteration and innovation. Pulsed magnetic targets are fabricated using the same technologies as laser targets, such as precision machining and electroplating. Pulsed magnetic targets are simpler than cryogenic hohlraum targets on the NIF, with fewer components and assembly steps, and with surface roughness requirements that are simpler to achieve—similar to that of 22-caliber bullet casings, which are made using rapid, low-cost honing processes.

Synchronizing goals: The authors of the technical paper make an argument for increasing funding for pulsed magnetic fusion which they says “has received a factor of 5 to 10 less investment than laser-based ICF and tokamaks” yet has demonstrated performance comparable to both approaches, and suggests that “focused attention, particularly to improving the distribution of resources within the publicly-funded fusion ecosystem . . . will provide a similar rapid return on that investment.”

Some areas called out for more attention include pulser architectures, energy storage and switching technologies; advanced diagnostic technologies; materials and fusion chamber design; and the sharing of publicly funded and unclassified data, codes, and models.

The authors believe that a pilot plant should be demonstrated within five years after facility gain is demonstrated. That “commercially relevant demonstrator” would be expected to yield hundreds of megajoules at shot rates relevant to energy production and to include power plant technologies such as a tritium breeding blanket and heat exchanger.

Believing the NNSA will be interested in the potential national security applications of pulsed magnetic fusion, the technical paper shared by Pacific Fusion suggests that “It is possible that the NNSA’s most critical requirements could be met by the 𝑄𝑓 > 1 facility, motivating the development of a public-private partnership during its planning phase to ensure the national security elements required of [next-generation pulsed power] were included during the initial build.”