Of all the things with a ‘big promise,’ energy derived from controlled atomic fusion is the biggest. It’s been promised for, oh, twenty or thirty years, at least. Atomic fusion is what drives our Sun. All we need is an ever-so-small piece of that fusion energy to electrify the world, forever, more or less. Much easier said than done. At the moment, there are two major scientific initiatives underway to find a path to commercially viable fusion energy. One, called ITER (International Thermonuclear Experimental Reactor), located in Cadarache (France), uses a dense containment field of magnetism in a device called a tokamak to (eventually, it is hoped) create the atomic implosion that starts a fusion reaction. The other project, at the National Ignition Facility in California (USA), is attempting to start fusion with the force of 192 super-X-ray lasers. Those lasers have just been fired for the first time.
They were fired successfully, although short of generating enough pressure to begin a fusion reaction. That was intentional; this was just a step in the direction of final testing – a warm-up, so to speak. Warm as in 6 million degrees Fahrenheit (about 3 million degrees Centigrade), which is about 200 million degrees short of the fusion reactions that can be found in the Sun.
The extreme temperature and pressure created by the focused lasers, forces atomic structures to collapse. When they do, they release tremendous amounts of energy. That energy needs to be absorbed (instead of exploding, literally), which is the biggest technological hurdle to any kind of controlled nuclear reaction. In the NIF project, that is the job of the ‘hohlraum’ (German, ‘whole space’, pronounced hole rah-um), the space in which the reaction is contained. Some scientists have predicted that the reaction plasma (super-hot atomic material) would block the fusion energy from being absorbed. In the event, it didn’t. The hohlraum held and, in fact, managed to absorb 95% of the energy.
This was a very critical step for the NIF, demonstrating both the functionality of the laser equipment and the theoretical properties involved at this level of pressure and heat. Having passed this test, it’s on to higher levels of energy until, hopefully, one day relatively soon the lasers will be cranked up enough to begin a true fusion reaction. At that point, the project can be assessed for the feasibility (doesn’t cost too much) of using similar techniques for commercial production of fusion energy.
Fusion energy is still years, many years, down the road…if at all.