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PODCAST: Fusion Energy

On this week's podcast, we talked about two of the leading fusion energy experiments, the National Ignition Facility and ITER. It's hard to get a real idea of these facilities without seeing them.

Located at the Lawrence Livermore National Labs in California, the National Ignition Facility shoots powerful lasers at a tiny pellet of hydrogen in hopes of getting it to "ignite." This technique is called the Inertial Confinement, because the intense heat and pressure of the lasers to crush the hydrogen together from all angles. In a building the size of three football fields, workers prepare the 192 lasers aimed at the their targets. Each laser has to fire with better than millisecond precision so that each beam hits the fuel pellet at exactly the same time. (Image: DoE)

The target chamber is round because all the laser beams have to hit the target evenly from every direction. The shots have to be even or else one side will be squeezed either too much or not enough and the target hydrogen nuclei won't fuse together. (Image: DoE)

All that for a the tiny little target at the end of the cone. Inside the silver spool-shaped holder is a plastic pellet that holds the hydrogen about the size of a ball bearing. So far, the lasers at the NIF have been able to annihilate the pellet just fine, but they haven't been able to get more energy out of the explosion than they put in, the holy grail of fusion research. (Image: DoE)

The NIF improved on the older NOVA laser, also at Lawrence Livermore. The NOVA experiment ran from 1984 through 1999 and used ten lasers. It laid the groundwork for almost all the research being done today at the NIF. (Image: DoE)

ITER is a totally different method, one that uses magnetic fields to get the high temperatures and pressures needed for fusion. It's still being constructed so all that really exists right now are some empty buildings in the south of France, parts being built all around the world and some impressive looking designs. (Image: ITER)

ITER is a tokamak and while it has yet to be fully assembled, there have been dozens of others built around the world to test the design. None have gotten close to producing more energy than they take in, but they've been crucial to learning how to build ones that might. This is the Alcator C-Mod at MIT's Plasma Physics laboratory. It looks a little familiar...

Inside the C-Mod. The donut-shaped chamber is about 1.5 meters across. When its running powerful magnetic fields would pinch the burning plasma into a thin purplish ring. The plasma gets astoundingly hot, tens of millions of degrees, which is why this photo was taken when the machine was off. (Image: Mike Garrett)

The National Spherical Torus Experiment (NTX for short) at the Princeton Plasma Physics Lab is taking a slightly different approach. Instead of the donut shaped plasmas you see in most tokamaks, the NTX shapes it into almost a perfect sphere, with a much smaller hole going down through the middle. (Image: DoE)

Fusion research has been around in some capacity since the end of World War II, and lots of other designs have come and gone. This is a schematic for the Mirror Fusion Test Facility, a "Magnetic Mirror" system. It works just like a tokamak, just stretched out into a straight line. The Department of Energy actually built this machine, but the day it was completed in 1986, the project was canceled by Congress and the experiment never ran. (Image: DoE)


  1. What about the work being done at Tri Alpha Energy?

  2. I would add that the Magnetic Test Facility was never turned on.

    They spent 372 million on it, it was the most expensive project at the Livermoore National Labs to that point.

    It was killed by the Reagan Administration. The reason given was to balance the US budget.


    Source: Booth, William. "Fusion's $372-Million Mothball." Science [New York City] 9 Oct. 1987, Volume 238 ed.: 152-55. Print.

  3. What about the research being done about the aneutronic reactor concept?

  4. "The reason given was to balance the US budget."

    Uhh, no.

    No one had built a large tandem mirror before, so while MFTF was being designed they decided to make a smaller version, TMX. TMX existed to test the MFTF concepts.

    And that it did - it tested them and found they didn't work. It was pretty clear that MFTF-B was simply not going to get anywhere near breakeven.

    At the time, the entire US program was based on reaching breakeven - MFTF was a backup in case TFTR didn't work. But now that MFTF looked like it wouldn't work, and TFTR had no similar red flags, killing MFTF was a no brainer.


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