The invention of Sirius and what we’ve learned from 3,000 shots at Lawrence Livermore National Laboratory

The U.S. national laboratories built the foundation for America’s fusion industry. Many of us at Pacific Fusion spent years working at those labs before starting the company in 2023. That experience is why we place such a high value on government-industry partnerships.

I was proud to share the results this week of a research campaign conducted through our Cooperative Research and Development Agreement (CRADA) with Lawrence Livermore National Laboratory. Sirius, a pulsed-power prototype at LLNL, has now surpassed 3,000 full-power shots, representing an important milestone for the novel impedance-matched Marx generator (IMG) architecture that underpins Pacific Fusion’s fusion system.

For more than a century, terawatt-class pulsed-power machines have relied on conventional Marx banks, which inductively stack voltage from discharging capacitors. An IMG works differently, synchronizing electromagnetic waves directly onto a common transmission line in a single step and creating a system that is simpler, more efficient and easier to scale. I co-invented the IMG architecture with Bill Stygar, now a researcher at LLNL, when we were both at Sandia National Laboratories in Albuquerque. This pulsed, unipolar, line-synchronized, electromagnetic radiator or pulser is a fundamental enabling technology that makes possible repetitive pulsed power at fusion energy scale.

During the Sirius campaign, the four-stage pulser prototype delivered 60 gigawatts in a 100-nanosecond pulse, with 95 percent energy efficiency. More importantly, the 3,000-shot campaign gives us one of the world’s most advanced empirical datasets on compact, fast and modular pulser systems. The data are used to validate our simulation models and improve our ability to predict the performance of much larger fusion systems.

This matters because the same government-industry partnership that developed and validated the IMG is now scaling it into fusion infrastructure that can strengthen U.S. leadership in clean energy and national security, at a moment when China is investing billions to do the same.

As Kumar Raman, LLNL’s project manager for Sirius, put it in LLNL’s blog: “The implications of the results are quite significant.”

Pacific Fusion is building rapidly

We founded Pacific Fusion to scale this new pulser architecture into an affordable, practical and scalable commercial fusion system.

Our pulser-driven system works by taking electricity from the wall plug, storing it briefly, and directly releasing it in an enormous burst — like a lightning bolt — in about 100 nanoseconds. For fusion, we focus that burst onto a fusion target and create the extreme conditions needed to compress it and release enormous amounts of energy.

In June we announced a successful demonstration of Pacific Fusion’s scaled prototype pulser that expands the Sirius platform by roughly 11x, delivering about 440 GW of peak output power and about 1.1 MV peak voltage in 80 nanoseconds. It's the highest-power, single-step pulsed-power driver ever demonstrated, and it is designed with some conservatism for production-scale build up. We’re now building a full scale pulser prototype that is roughly 40x the size of Sirius with schedule completion projected in the coming months.

And this August we will break ground on the world’s first net facility gain, high-yield (100+ megajoules) fusion system in Albuquerque, New Mexico. This facility will be the most advanced high-energy-density environment generator on the planet. It will be capable of achieving net facility fusion gain and creating some of the most intense bursts of neutrons, x-rays, gammas, and multi-megabar pressures with unique opportunities for a range of fusion energy research, commercial applications, fundamental high-energy-density (HED) science and national security.

High stakes in the pursuit of high-gain

As former lab directors of Sandia National Laboratories and Los Alamo National Laboratory opined recently in the Exchange Monitor, American technological superiority has always come from pairing public mission with private agility. We’ve seen the playbook work successfully before and fusion is the next place to run that model. 

China understands this and is moving rapidly to advance its capabilities. They are making enormous investments in infrastructure across their economy, especially in fusion, where public sources indicate that government funding has eclipsed U.S. fusion investment in recent years.

For more information, read our press release here. Read about it on LLNL’s blog here.