Sunday, May 27, 2018

Fusion

I have long wondered what the point of Inertial confinement fusion (ICF) is but I'm starting to really come around. Unlike magnetic confinement fusion (MCF), ignition is not sustained with ICF, so each fusion ignition has to be started with massive input of energy only to have blow itself out a short time later. It seems very inefficient since like a star MCF is ignited and just keeps burning as long as confinement remains. However, sustained fusion is likely a long way away, since confinement failure destroys  or damages the tokomak, so ICF which runs like tiny H-bombs in semi-disposable containers could be the way to go. Also, the risk of an "event" from ICF is low since there is no sustained fusion, if the laser stops firing there is no fusion and with a carbon/carbon reactor housing cooled by lithium salts even a massive containment failure wouldn't be uncontainable.

The choice of fuel is what I question. The use of cryogenic fuel could be a problem since even if the lasers get cheaper and smaller having to make, store, and dispense perfectly round spheres of hydrogen isotope ice doesn't seem like the easiest thing especially since the reactor vessel would have a significant neutron flux once it had been used for a while.
The solution could be to use a solid Lithium Hydride/Deuteride blend fuel something like Teller Ulam H-bombs. The ignition temperature of lithium7/hydrogen fusion is lower than hydrogen fusion and the product Li/H fusion is two alpha particles that would ignite additional fusion. The increased mass of the lithium would also increase the compressed density, and act like a tamper.

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