|
|
| Fig. 1: Nuclear fusion is the holy grail of energy production. (Source: Wikimedia Commons) |
Late in 2015, after almost 2 decades of hiding from the public eye as a stealth company, Tri Alpha energy revealed itself, as a bold and ambitious nuclear fusion upstart that's been hard at work for many, many years on one of the more unique and novel methods for nuclear fusion. Based south of Los Angeles, Tri Alpha is a privately held company employing a 150 scientists in the goal of creating plasma hot enough for fusion, such that one could potentially produce more energy from fusion than the energy put into the system to get that temperature. Tri Alpha is unique in using a linear plasma collider, and then using beams of high energy particles aimed tangentially to keep the plasma stable for longer. In a significant step on the path to nuclear fusion, Tri Alpha announce last August that they were able to form a ball of plasma at 10 million degrees Celsius and held it steady for 5 milliseconds without decaying away. This is significant as previously scientists struggled to hold a plasma at this temperature for more than 0.3 milliseconds, and Tri Alpha showed for the first time that they could hold it for far longer, about 17x longer, in a steady state.
Nuclear fusion has always been an incredibly attractive energy as operating by the same principles of the Sun, is basically a limitless source of producing energy. Fusion requires different atomic nuclei fusing together to create new nuclei, releasing huge amounts of energy in the process. (Fig. 1) However tremendously high pressures - about 3 Billion degrees Celsius - are required to initiate the fusion reaction process. Thus the central question in nuclear fusion is how to build a machine that can make plasma hot enough and long enough, to make temperatures hot enough for potential fusion, and long enough for fusion to actually take place. And for many decades, the primary research approach to fusion has involved building "large, doughnut-shaped" machines called tokamaks, which exert powerful magnetic fields to compress the super-hot plasma that contains the atoms to be fused in the process. [1] However the tokamaks approach has been met with little success but huge cost overruns due to the technical challenges and difficulty of the method. The International Thermonuclear Experimental Reactor or ITER is the world's biggest fusion project with over $17 billion of spending so far, uses a tokamak design and is now already years behind schedule, having announced that their fusion reactor won't be turned on until 2025. The National Ignition Facility in Livermore, CA has cost $4B so far and also has yielded no success so far. [2]
Compared to the tokamak approach taken by the much bigger government funded projects mentioned above, Tri Alpha is chasing a different approach that promises to be a lot simpler, a lot less expensive, and actually already has early results. Tri Alpha's system is in many ways analogous to high energy particle accelerators, like the Large Hadron Collider - in Tri Alpha's case beams of plasma are accelerated into collision in a central vessel where the fusion is supposed to take place. The Tri Alpha machine produces a toroid of plasma, but rather than external, the flow of the particles in the plasma itself produces all the magnetic field holding the plasma together, in an approach called "field-reversed configuration (FRC)". However it was difficult with this approach to maintain a plasma for any meaningful time at all. Started by UC-Irvine Professor Norm Rostoker in 1997, Tri Alpha had a unique approach: using two congruent machines that form two rings of plasma, that are then fired at each other in a proprietary process at almost a million km/hour, where they collide at the center of the fusion vessel to merge into a larger FRC, turning all that kinetic energy into heat in the collision. However this approach fails due to turbulence and instability of the plasma. The insight behind Tri Alpha was a way to tackle both these problems, such that the high temperature plasma could be maintained stably for a longer period of time. Turbulence of the plasma is when the high temperature particles of the plasma reach the outermost edge and thus heat is lost. Instability is the fact that it is very difficult to confine a hot plasma, as the plasma bulges and squirms breaking up from on continuous plasma eventually. This crown jewel insight of Tri Alpha to tackle both turbulence and instability was to fire high-speed particles tangentially into the edge of the plasma. These tangentially fired, fast particles would provide a protective shell around the plasma as it would provide much larger orbits in the plasma's magnetic field than the actual plasma particles, and thus acting like a protective shell against the plasma instability and turbulent heat-loss. [3]
Tri Alpha in August of 2015 with the machine mentioned above was able to sustain a heated plasma for 5 milliseconds stably at about 10 million degrees. However fusion reactions require temperatures of about 3 billion degrees Celsius so still much progress is needed to achieve such temperatures, however Tri Alpha is actively trying to scale up their system such that it could output higher temperatures. Also continued progress from 5 milliseconds of suspended plasma would also be necessary for fusion and would also require a larger, scaled up system. However given that Tri Alpha has been able to achieve one of the most positive steps in the progress of nuclear fusion out of all major projects in the last 2 decades, even though it only had financing of hundreds of millions of dollars, versus many multiples of billions of dollars for ITER or NIF, it seems like a very promising and most cost effective way to continue to scale potential nuclear fusion technologies. As a September MIT Tech review article put it, while Tri Alpha has only succeeded in keeping the plasma stable for 5 milliseconds, "much less than the blink of an eye, but [it's] half an eternity on the scale of fusion reactions." [4]
© Anjan Katta. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
[1] A. A. Harms, D. R. Kingdon, and K. F. Schoepf, Principles of Fusion Energy (World Scientific, 2000).
[2] K. Chang, "Machinery of an Energy Dream," New York Times, 17 Mar 15.
[3] L Grossman, "Inside the Quest for Fusion, Clean Energy's Holy Grail," Time, 22 Oct 15.
[4] R. Martin, "Finally, Fusion Takes Small Steps Toward Reality," Technology Review, 14 Sep 15.
