Physicists have been chasing antimatter technology for more than 80 years now — driven by the promise of oppositely oriented particles that explode in a burst of energy whenever they make contact with their more common counterpart. If we could tame antimatter, those explosions could be used to power a new generation of technology, from molecular scanners to rocket engines to the so-called "annihilation laser," a tightly concentrated energy beam fueled by annihilating positrons. But while scientists have seen recent breakthroughs in creating the particles, they still have trouble capturing and containing them.
Whenever a positron and an electron meet, they annihilate each other
That progress has left us closer to workable antimatter than ever before, and parallel projects are already working on novel devices to cool and trap the particles, along with new magnetic arrays to keep them stable. With the right funding, experts estimate we could see the dawn of the positron age in as few as five years. Positron Dynamics is one key player in the new wave of technology, working on an innovative method for cooling down and capturing positrons, the antimatter equivalent of the common electron. Whenever a positron and an electron meet, they annihilate each other, which presents a serious challenge for anyone working with them. It’s particularly difficult because electrons are literally everywhere, floating in clouds around essentially every atom in the universe. Right now, the best solution for cooling the positrons is running them through a block of frozen neon (called a "moderator"), which offers a minimum of stray electrons. But the system only catches roughly one in 100 positrons, and in the 30 years it’s been in use, no one’s been able to improve on it.
It's a flood of positrons, compared to the current trickle
Positron Dynamics thinks it can do better, and with seed funding from Paypal billionaire Peter Thiel’s Breakout Labs, the company has enough money to find out. "We’ve run some initial simulations, and it looks like we could be able to create as many as 10 micrograms of positrons a week with a linear accelerator," says co-founder Ryan Weed, PhD, a physicist and former cryogenic engineer for Jeff Bezos’s space flight company Blue Origin. That’s a flood compared to the current trickle that’s coming from isotope-based methods, and it could be enough to turn positron creation into a self-sustaining business.
Instead of a single block of neon ice, the company uses an array of 50 or more thinly sliced semiconducting solids. Flying through the array, particles will lose a little bit of heat to each one until they're cool enough to trap. From there, the positrons can be pulled out of the empty spaces between the layers by a magnetic field. Many of these tactics have been tried before, but never in exactly this combination. The lab also has a few new tricks up its sleeve, like keeping the entire system in a vacuum, so the positrons have a better chance of surviving the different layers of array without running into any electrons. Inevitably, most positrons will still explode before they can make it through the trap — but if Weed can get even one in ten to survive, it would be a massive breakthrough, potentially turning antimatter into an industrial product. Even better, if the Positron Dynamics-style moderator takes off, it could scale the process to even more positron-rich environments like linear accelerators, which create antimatter on a much larger scale.
A positron scanner could spot sub-microscopic flaws in metal
That’s where the real fun starts. Many positron scientists think that, as soon as five years from now, we’ll have the technology to transport positrons the same way we transport tanks of liquid nitrogen or other industrial chemicals. Positrons are already used in some medical imaging technologies, like positron emission tomography, thanks to their X-ray-like ability to identify tumors and other points of high metabolic activity in the body. Positrons also tend to nestle into atomic level gaps in metal, so Weed envisions a positron scanner that could spot sub-microscopic flaws in a semiconductor or an airplane engine. Given the right storage breakthroughs, Weed estimates the scanner might be workable in as few as three years.
Weed envisions huge engines fed by positrons
From there, things get even more ambitious. In the long term, Weed envisions huge engines fed by positrons, creating the equivalent of a jet engine thrust from electron-positron explosions. Antimatter drives are common in science fiction, but once positron storage becomes possible, scientists can begin to make real progress on the drives, turning the energetic positron-electron explosion into something that could power a submarine or a spaceship. And positrons are especially useful for creating a beam of intensely focused energy — known as an annihilation laser — along with more complex arrangements that the Positron Dynamic team believes might be useful for catalyzing fusion.
"With both positrons and antiprotons, collection is still pretty damn inefficient."
A lot needs to happen before we get there, and catching positrons is just the start of it. Researchers will also need a good way to store the particles, a project that many academic labs are currently tackling. Cliff Surko, a physicist at UC San Diego, is working on a positron storage technique that could someday store up to a trillion positrons, more than 500 times the current storage limit. That wouldn’t be enough for a propulsion engine, but it would be plenty for the first-generation scanners that the Positron Dynamics team has envisioned. And like them, Surko imagines it could be ready within the next five years. A new positron capture technique would be hugely useful to Surko, but he’s still skeptical about whether Weed can pull it off. "People have worked for 30 years on various approaches, but I haven’t heard much progress," Surko says. "It’s been a bit of an embarrassment. With both positrons and antiprotons, collection is still pretty damn inefficient."
But while doubts remain, Weed is undeterred. His lab has already applied for Department of Defense grants for the scanner, and thinks their propulsion concepts could start testing within the next 10 years. Despite the long odds, it’s hard not to be excited about the prospect of antimatter drives within the decade. And even if that particular scheme doesn’t work out, there will be plenty of other antimatter concepts waiting in the wings. "Every few years somebody will have a new idea and you try it," Surko says. "You never know quite where it’s gonna go."