SOONER USING FUSION?

Fusion is one of those future energies: Like hydrogen, it is always somewhere off in a distant utopian future. Meanwhile, we've got to plug into the sun and wind.

A Step Toward Fusion Energy
March 10, 2007 (Science Daily)

- …one step closer to…fusion energy…The [University of Wisconsin-Madison] research team, headed by electrical and computer engineering Professor David Anderson and research assistant John Canik, recently proved that the Helically Symmetric eXperiment (HSX), an odd-looking magnetic plasma chamber called a stellarator, can overcome a major barrier in plasma research, in which stellarators lose too much energy to reach the high temperatures needed for fusion.
- Published in a recent issue of Physical Review Letters, the new results show that the unique design of the HSX in fact loses less energy, meaning that fusion in this type of stellarator could be possible.
- Plasma is very hot, ionized gas that can conduct electricity - essentially, it's what stars are made of. If heated to the point of ignition, hydrogen ions could fuse into helium, the same reaction that powers the sun. This fusion could be a clean, sustainable and limitless energy source.

- Current plasma research builds on two types of magnetic plasma confinement devices, tokamaks and stellarators. The HSX aims to merge the best properties of both by giving a more stable stellarator the confinement of a more energetically efficient tokamak…
- Tokamaks, the current leader in the fusion race, are powered by plasma currents, which provide part of the magnetic field that confines the plasma. However, they are prone to "disruptions."
- …Stellarators do not have currents, and therefore no disruptions, but they tend to lose energy at a high rate, known as transport…
- The HSX is the first stellarator to use a quasi-symmetric magnetic field. The reactor itself looks futuristic: Twisted magnetic coils wrap around the warped doughnut-shaped chamber, with instruments and sensors protruding at odd angles. But the semi-helical coils that give the HSX its unique shape also direct the strength of the magnetic field, confining the plasma in a way that helps it retain energy.

- The team designed and built the HSX with the prediction that quasisymmetry would reduce transport. As the team's latest research shows, that's exactly what it does…
- These results excited and relieved the researchers who have spent years working on the project…
- The next step for the project is to establish how much symmetry in the coils is necessary to achieve low transport rates. They hope to make the coils easier to engineer…HSX could someday be incorporated into fusion generators…