Courtesy Mark RyanOld Sol could be stirring up the atmosphere this evening with a display of northern lights (aurora borealis). Scientists have recorded a significant burst of plasma shooting from the Sun’s surface that could mean we earthlings are in for a light show tonight or early Wednesday morning. The solar wind particles are headed right toward us, and when they reach the Earth’s magnetic field they’ll interact with atoms of nitrogen and oxygen in the atmosphere and - hopefully - produce glowing sheets and fingers of green, red, blue, or even yellow in a wonderful display in the northern skies. The southern hemisphere experiences the same phenomenon but down there it’s known as the aurora australis (southern lights).
Lately, here in the Twin Cities, the air has been supersaturated with humidity so I don’t know how crisp a view we’ll get but it could be worth stepping outside tonight to see what’s up.
Professor David Anderson and his assistant John Canik have constructed a new type of stellarator that they claim will overcome the problem of energy loss that is inherent in the machines.
A stellarator is strange-looking toroidal (doughnut-shaped) device comprised of a chamber wrapped in magnetic coils and used to confine a hot plasma so as to sustain a controlled nuclear fusion reaction. A similar machine, called a tokamak, is also used in the quest for fusion energy. But both machines have their problems. A tokamak uses plasma currents to confine the plasma inside magnetic fields and, because of this, can experience “disruptions”. A stellarator, on the other hand, uses no currents so disruptions don’t occur, but the machine tends to lose energy at a high rate –a process known as transport-which makes it unable to reach the high temperatures necessary for nuclear fusion .
So Anderson and Canik set out to come up with a new configuration utilizing the best features of both machines. The result was the Helically Symmetric eXperiment (HSX), a new type of stellarator that uses a quasi-symmetric magnetic field to confine the plasma.
Essentially the stuff of stars, plasma is a hot ionized gas that- if heated to a high enough temperature- can cause hydrogen atoms to fuse themselves into helium atoms, the very process that powers the sun’s energy. If fusion can be achieved in the lab, it would mean a limitless new source of energy.
Anderson and Canik’s idea was to design and construct a machine using quasisymmetry that would effectively reduce transport, and according to their recent research, that’s exactly what the HSX does.
"This is the first demonstration that quasisymmetry works, and you can actually measure the reduction in transport that you get," says Canik.
The research results appeared in a recent issue of Physical Review Letters, and for Prof. Anderson the results couldn’t have been better.
"We all thought the machine would do what it's turning out to do, but there are a million reasons why it might not: the theory might be wrong, (or) we might have built it badly," Anderson said. "But everything is panning out and supporting the fact that the ideas on which it was based were correct, and really points the way of the future for the stellarator."
The seventeen years of work seems to be paying off for the team, which now hopes to determine how much symmetry in the coils is necessary to attain low rates of transport.
"It's an exciting field. It's something where one can contribute positively to mankind with an energy source that's completely sustainable, doesn't involve nuclear proliferation or radioactive waste, with a limitless fuel supply," says Anderson. "Plus, the machines look cool."