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Nuclear Fusion Reactor

The heart of the National Ignition Facility (NIF) at Lawrence Livermore National Labs. This is where it all comes together.


Project Director Ed Moses (far left) is confident that they will ignite fusion in the next 3 to 6 months.


In the neighboring rooms are 192 lasers, each of which is the most energetic in world (100x any predecessor). Their meter-wide beams enter through the shiny rectangular lens arrays to focus down on a precise spot (aligned to 30 micron spatial and picosecond temporal accuracy) in the center of this blue spherical chamber. Therein lies a gold tic-tac shaped pellet, that will absorb the laser energy and emit x-rays internally, like the evenly distributed warmth of an oven. At the center of the gold pellet is a tiny red droplet of frozen hydrogen isotopes (deuterium and tritium near absolute zero, 20°K) encased in plastic. It will take a wild ride, whipping from zero to 3 million degrees in just 20 billionths of a second. As the plastic explodes, it also implodes, driving the hydrogen inward at 1 million MPH to fuse into helium, hopefully igniting a chain reaction of fusion in the droplet.


A tiny brown dwarf star will be born.


That colorful comparison comes courtesy of SETI Director Jill Tartar (floral centerpiece above).


The hot neutrons released in the fusion reaction can be captured by a molten salt blanket, driving an energy plant much like a solar thermal facility. “Syn-solar” in this case. This was a name Danny Hillis (beard-masked-man above) suggested while we were brainstorming better names for this reactor. I kicked off the renaming discussion with the observation that for most people, fusion and fission are a confused blur, like stalagmites and stalactites. Even calling it a “helium fusion engine” might help pseudo-scientists remember the distinction. It’s continuous baseload power, like the atomic energy plants of today, but without the nasty bits.


Anyway, including lithium in the salt bath can generate more tritium fuel, and so the only fuel needed is deuterium, which Ed Moses estimates is available in such abundance that we could power all of the Earth’s energy needs for 10x the expected lifespan of our sun, at which point we will have a bigger climate problem. =)

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Taken on July 29, 2010