Pictures of Tri-alpha energy's nuclear fusion prototype in Time magazine and NY Times

Tri Alpha’s reactor is very different from the towering tokamaks that dominate the fusion skyline, or the supervillain lasers of the NIF. You could think of it as a massive cannon for firing smoke rings, except that the smoke rings are actually hot plasma rings, and the gunpowder is a sequence of 400 electric circuits, timed down to 10 billionths of a second, that accelerate that plasma ring to just under a million kilometers an hour.

And there are actually two cannons, arranged nose to nose, firing two plasmas straight at each other. The plasmas smash into each other and merge in a central chamber, and the violence of the collision further heats the combined plasma up to 10 million degrees Celsius and combines them into a single plasma 70 to 80 centimeters across, shaped more or less like a football with a hole through it the long way, quietly spinning in place.

But a fusion reactor’s work is never done. Positioned around that central chamber are six massive neutral beam injectors firing hydrogen atoms into the edges of the spinning cloud to stabilize it and keep it hot. Two more things about this cloud: one, the particles in it are moving in a much wider orbit than is typical in, say, a tokamak, and hence are much more stable in the face of turbulence. Two, the cloud is generating a magnetic field. Instead of applying a field from outside, Tri Alpha uses a phenomenon called a field-reversed configuration, or FRC, whereby the plasma itself generates the magnetic field that confines it. It’s an elegant piece of plasma-physics bootstrappery. “What you get within forty millionths of a second from the time you unleash your first little bit of gas,” Binderbauer says proudly, “is this FRC sitting in here, fully stagnant, no more moving axially, and rotating.”

The machine that orchestrates this plasma-on-plasma violence is something of a monster, 23 meters long and 11 meters wide, studded with dials and gauges and overgrown with steel piping and thick loose hanks of black spaghetti cable. Officially known as C-2U, it’s almost farcically complicated–it looks less like a fusion reactor than it does like a Hollywood fantasy of a fusion reactor. It sits inside a gigantic warehouse section of Tri Alpha’s Orange County office building surrounded by racks of computers that control it and more racks of computers that process the vast amounts of information that pour out of it–it has over 10,000 engineer control points that monitor the health of the machine, plus over 1,000 physics diagnostic channels pumping out experimental data. For every five millionths of a second it operates it generates about a gigabyte of data.

In June the reactor proved able to hold its plasma stable for 5 milliseconds.

That’s not a very long time, but it’s an eternity in fusion time, long enough that if things were going to go pear-shaped, they would have. The reactor shut down only because it ran out of power–at lower power, and hence with slightly less stability, they’ve gone as long as 12 milliseconds. “We have totally mastered this topology,” Binderbauer says. “I can now hold this at will, 100% stable. This thing does not veer at all.”