A private company has built a machine that’s breaking records in the journey towards generating power by nuclear fusion.
Nuclear fusion, the reaction that powers the sun and provides all the heat and light that sustains life on Earth, may provide the solution to our energy crisis. While we have been using nuclear fission reactors to generate electricity for decades, the process is far from ideal. Any failure in containing the radioactive waste products has catastrophic repercussions on human health and the environment.
In comparison, nuclear fusion seems like a godsend. Instead of splitting a uranium atom apart, fusion would combine hydrogen atoms into helium, producing fewer radioactive waste particles. Hydrogen is much more abundant than uranium, so nuclear fusion represents a nearly unlimited fuel supply. It also releases several times as much energy as does nuclear fission.
So why isn’t the landscape dotted with nuclear fusion reactors, instead of power plants that belch depleted fossil fuels into the air? The problem with nuclear fusion is that atoms don’t like to snuggle, and so a massive amount of energy is required to overcome the repulsive forces between their positively charged centres (“nuclei”). The hydrogen gas must be heated up high enough that the atoms lose their electrons and melt into a plasma of ions and electrons. Fusion happens once those ions collide with enough force to stick together, releasing some of their mass in the form of energy.
That’s what happens in the core of the sun, which averages around 15 million degrees Celsius. So it’s easy to understand why scientists are still figuring out how to induce nuclear fusion in a laboratory setting, not to mention maintaining the reaction in a commercially viable method.
But Tri Alpha Energy has come tantalizingly close. The L.A.-based company has built a machine that can heat a ball of plasma to about 10 million degrees Celsius, and keep it that way for 5 full milliseconds without decaying. This is a huge milestone and brings us closer than ever to achieving controlled fusion.
Tri Alpha Energy succeeded where larger, government-funded projects have stalled by refusing to settle for standard methods. Instead of using deuterium and tritium (D-T), two isotopes for hydrogen that have different masses, they plan to use a different fuel that’s simpler and cheaper: a mixture of hydrogen and boron. Hydrogen-boron reactions only produce three harmless alpha particles, or helium atoms minus their electrons, as opposed to the radioactive neutrons released by D-T reactions. Consequently, hydrogen-boron fusion actually releases less radiation than burning coal! Boron is also much more abundant than tritium, which does not occur naturally.
Unfortunately, hydrogen-boron requires temperatures above 3 billion degrees Celsius, so the Tri Alpha Energy team had to figure out how to confine the super-heated plasma without melting its container. They used an approach called a field-reversed configuration (FRC), which causes the plasma particles to generate magnetic fields that hold it in a doughnut shape.
The result is a machine called C-2, a 23-meter long tube rigged with magnets, controllers, diagnostic instruments, and particle beam generators. The machine fires two rings of plasma from the edges of the tube to the center, where they merge and release their energy as heat. By stabilizing the FRCs and reducing heat loss, the machine accomplished a 5 millisecond lifespan without decay.
Next year, Tri Alpha Energy plans to rebuild the machine in a larger, more powerful incarnation that will achieve longer-living, higher-temperature FRCs. The company is well on its way to developing technology for safe and sustainable nuclear fusion power.