Image: Sandia National Laboratories
Researchers at Sandia National Laboratories have announced a breakthrough that could lead to break-even nuclear fusion reactions within 2-3 years. The goal of nuclear fusion research is to make energy from sea water, producing only the harmless gas helium as a result of the fusion reaction. It is the holy grail of clean, sustainable energy, the same process that powers our sun.
The nuclear fusion efforts involve research at the cutting edge of physics, where one of the avenues of exploration goes by the name "Z-pinch" (which should gain the technique immediate street cred should it be successful). So what is a Z-pinch? And how could it power the future?Pinching Atoms
The name Z-pinch derives from the early experiments in plasma pinch technology, in which the "pinch" occurred in a tube running along what physicists refer to as the Z-axis. The driver for the pinch is the Lorentz force, a phenomenon which can be seen in the example of two wires carrying electrical current in the same direction: the wires will pull towards one another. Instead of two wires pulling together, imaging a cylinder of charged plasma, in which the entire cylinder pinches at once. The "pinch" is the force that pushes the starting fuel, hydrogen isotopes, so close together that they actually fuse together into helium, releasing a nice dose of energy in the process.
While sounding good in theory, the Z-pinch method ran into a major obstacle: the faster you squeeze the plasma together, the faster it becomes unstable and breaks up. Further studies demonstrated that this effect is unavoidable. The instabilities, named "magneto-Rayleigh-Taylor [MRT] instabilities", are the target of the recent breakthrough at Sandia.
The Sea Monster of Nuclear Fusion
In their press release, Sandia refers to the MRT instabilities as the "sea monster of nuclear fusion." The image is telling. Mankind has finished braving the unknown seas, adventurously exploring distant continents, and ultimately learning that no sea monsters dot the map. Sandia researchers surely envision a day when the specters currently haunting the goal of safe, clean, fusion energy are mapped and understood.
The basis for the breakthrough by Sandia is the use of a solid aluminum cylinder, instead of a plasma cloud, to compress the fuel. Without going into all the complexities, older methods relied on a web of wires to initiate the pinch. Small imperfections in the surfaces of the wires were known to be a source of the MRT instabilities. But there was no way to controllably reproduce the imperfections, inhibiting study of the MRT instabilities. The aluminum cylinder can be etched to deliberately and predictably destabilize the system during the pinch.
The knowledge gained from studying the instabilities will be used to better simulate the pinch process in computer models, which will help physicists to better control the conditions of future Z-pinch experiments. The leader of the study, Daniel Sinars, believes that this could open the path to achieve a break-even fusion reaction in the next two to three years. Break-even is the point at which as much energy is generated by the fusion reaction as must be used to create the fusion conditions.
Currently, Sandia National Laboratory's Z-machine is the only facility seriously attempting to demonstrate nuclear fusion using the Z-pinch method. However, several facilities around the world continue research into other nuclear fusion methods. It is not time to give up on wind and solar yet, but the future of fusion is one step closer.
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