QNX raises the heat in Alcator C-Mod fusion reactor

In late 2008, researchers at MIT demonstrated for the first time that radio waves can help control the flow of plasma in a fusion reactor. Using a dipole antenna, the researchers emitted several million watts of radio waves to break up the plasma turbulence that, until now, has plagued fusion research.

Why is this a big deal? Well, to produce fusion reactions, you have to make plasma very hot and very dense. To help achieve the necessary level of heat in their Alcator C-Mod reactor, the MIT researchers use high-power microwave systems controlled by the QNX RTOS. Just one problem: as you increase heat and pressure in a fusion reactor, you also create plasma turbulence. The plasma cloud becomes unstable and loses the heat needed to maintain a fusion reaction.

According to Popular Mechanics, “plasma turbulence… is the biggest obstacle to fusion... preventing the kind of long-term reaction necessary for true power production.” Thus, the fact that MIT researchers have successfully used radio waves to propel plasma represents a milestone in the long road towards building commercially viable fusion reactors. (I say “long” because most experts believe it will be another 30 or 40 years before such reactors come online.)

Fascinatingly, Yijun Lin, the MIT physicist who co-developed the radio-wave method, states that there still isn’t a satisfying theoretical explanation for why the method works. But the fact that it does work suggests that, after decades of research, a controllable method for propelling plasma has finally been found.

The Alcator C-Mod reactor isn’t the only MIT fusion project that uses QNX technology. In November, I described the LDX project, which uses a QNX-controlled system to magnetically levitate a superconducting torus in a fusion reactor chamber. The torus generates lines of magnetic force similar to those that surround the Earth, Jupiter, and other magnetized planets. The reactor then uses pulses of microwave heating to create plasma discharges, which the torus holds in place.

The C-Mod and LDX projects represent two different approaches to fusion reactor technology. The C-Mod is a tokamak; the LDX, a levitated dipole. To find out more about these technologies, check out the MIT's Plasma Science and Fusion Center (PSFC).