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Inertial Electrostatic Confinement (IEC) Fusion

The first time I actually learned how nuclear power plants worked, I was so disappointed to find out that we have this crazy atomic reaction all just to heat up some water to spin turbines. So, until recently, I haven't taken much interest in nuclear physics, also partly due to being scared of radiation, but eventually I learned about Fusion and the prospects of it and it sucked me in. Now I'm working on a particle simulator to test reactor designs, which I hope will someday lead me to a good design I can build.

So, What is Fusion?

 Fusion is when the nuclei of two atoms (made up of protons and neutrons) collide with each other and combine or "fuse" into heavier atoms and release energy. This is unlike fission where unstable atoms split apart on their own releasing energy.

You might recall from high school chemistry/physics that an atom is made up of neutrons (which have nuetral charge), protons (which have a charge of +1), and electrons (which have a charge of -1). Ions are just atoms with fewer electrons than there are protons, and thus have a net positive charge. Also remember that like charges repell and opposite charges attract.

Thermonuclear fusion is when you heat an area up really hot, and thus the atoms are moving around so fast that they can overcome the mutual repulsion from each other and random collisions can occur that produce fusion reactions.

IEC is a method for producing fusion where concentric spherical grids are arranged in such a way that the outter grid has a strong positive charge (which repells ions), and an inner grid is negatively charged (attracting ions).

So basically the ions will accelerate towards the inner grid, and in most cases zoom right past the grid wires, all converging at near a single point in the middle, often slamming into each other at high enough speeds to fuse. If they don't hit each other they fly right past the middle and climb back up the otherside coming back up to about the same potential they started at, and then zoom back in towards the center again.

Wait a minute, I thought Fusion wasn't possible yet?

No, it's possible. Filo T. Farnsworth who invented the TV, and his assistant Robert Hirch made this style IEC Fusor in the 1950's and the design is still used today as a nuetron source from the fusion reactions. However, as it takes a lot of energy to produce the reaction, it has not yet been made efficient enough for the reaction to provide enough energy to power itself. This is what we're currently racing to achieve.

Doesn't it have to be really hot to get Fusion?

Sometimes people talk about having to have a certain temperature for Fusion to occur. This is kind of misleading when talking about IEC, because temperature is basically a function of the speed of particles moving around in an area, and it's true you need the particles to be moving fast enough to overcome their mutual repulsion in order to fuse. A Maxwellian Distribution is the reverse of that, describing the speed of particles moving with an area at a specific temperature. The reason this is misleading is because with IEC the speed of all of the particles is greatest at the center and diminishes the closer you get to the outter grid. So, at the very center, where you're concerned with whether or not you can get fusion, we shouldn't have, or at least don't want to have a distribution of various particle speeds, instead, hopefully, practically all of the particles at the middle will be moving at the fully accelerated speed.

So IEC isn't "cold fusion", it's definitely "hot" at the center, but it's not a Maxwellian Distribution.

Current evolution of the IEC design

Dr. Robert Bussard took the Farnsworth/Hirsch fusor, and realized that since so much of the loss that made it impractical was from ions colliding with the inner grid and being lost to the electronics of the system, that he should find a way to get rid of the grid. So, he developed the polywell fusor, which operates on the same principles I've described above, but instead of using a metallic grid in the center to attract the ions, he injects electrons into the system, and uses an special arrangement of magnetic fields to reflect the electrons that are trying to escape back to the middle. He found funding to build prototypes of his idea under DoD contracts, which also forced him to keep everything a secret for a major part of the development. His most promising results weren't even realized until after the last day of the contract and they had to tear everything down. The results were promising enough to continue the development and so Bussard sought new funding which lead him to give a presentation to Google you might have even seen: Should Google go Nuclear. The first time I watched this video I had no idea what the heck he was talking about, and it wasn't until I finally got into Fusion and watched the video a few times until I realized how amazing the project he was working on really was. Bussard has since died, and his team has continued development under navy funding (EMC2 Fusion Development Corporation).

The simulation I've been working on is still a work in progress, but I'll post information about the project as I go in the projects section: Projects: IEC Simulation.

References:

There are some great resources you can check out on the subject.
First there's several resources on the simple fusor:
http://www.fusor.net/
http://en.wikipedia.org/wiki/Fusor

Check out this gallery:
http://fusion.wsyntax.com/gallery/

I like to link this video too :) (the whole video is pretty interesting, but I linked to the middle so you can get right to the good stuff)

And for the polywell check out:
Should Google go Nuclear (video)
Should Google go Nuclear (pdf)
http://en.wikipedia.org/wiki/Polywell
http://en.wikipedia.org/wiki/Inertial_electrostatic_confinement
http://www.emc2fusion.org/ (Bussard's legacy -- the company)

And in general, just google IEC Fusion.

Comments

John Logie Baird invented the TV ! Philo Farnsworth made it all electronic. I had to point this out because i, like Baird, am Scottish.

The simulation screens are throwing up very interesting patterns. Thanks for this article it's enlightened me :)