Magnetic Inertial Confinement Fusion

GoogleNaut · Guru

Magnetic Inertial Confinement Fusion

10kBq Jaro · Senior Member

Interesting indeed.

This article also gives an overview, though a bit dated....

http://web.archive.org/web/20060502042348/http://torsatron.tripod.com/fusor/fusor.html

"The World's Simplest Fusion Reactor: And How to Make It Work"

Tom Ligon - Analog Science Fiction & Fact New York Vol. 118 Issue 12 Dec 1998

GoogleNaut · Guru

I have always been intrigued by the idea of Philo Farnsworth's "Star Fusor," which because of the scattering losses on the grid, could not even get close to breakeven--however, it has been commercially applied as a source of fusion energy neutrons. Available in pulses, such devices have been used successfully in petroleum industry as a 'downhole' analysis tool for detecting hydrocarbon baring rock.

Dr. Bussard's project seems to alleviate this to a certain extent by using an interesting magnetic field geometry--it looks kind of like a nested 3-axis magnetic mirror? Anyways, I thought it was also interesting because they seriously looked at proton-boron11 (P-B11) fusion as a potential energy source...

-- Edited by GoogleNaut at 01:17, 2006-11-25

10kBq Jaro · Senior Member

Bussard's concept seems to me to be similar to Bogdan Maglich's "Migma" inertial electrostatic confinement fusion reactor : http://en.wikipedia.org/wiki/Migma

Both schemes suffer from bremsstrahlung losses, and its unclear to me why either version of IEC should be better in this respect.

Moreover, the temperature necessary for an "aneutronic" reaction is 100 times greater than that needed for thermal fusion -- some 10 billion degrees ( or 1GK = 1 Giga-Kelvin).

Curiously enough, at http://sci-phys-plasma.caeds.eng.uml.edu/2001/11-01-012.htm , I read the following :

".....this argument rules out all non-equilibrium schemes, such as Maglich's Migma, or Bussard's reincarnation of the Farnsworth Fusor. (One of Rider's papers was entirely devoted to a critique of Bussard's work on electrostatic confinement)."

I can't check the veracity of those arguments (the links are busted), but at least its clear that others see Bussard's IEC and Maglich's "Migma" as similar fusion concepts.

GoogleNaut · Guru

...and this seems to point to the bremsstruhlung radiation loss as the main damping mechanism--which is entirely reasonable given the higher z value of boron (z=5) versus hydrogen (z=1) The only way to limit this kind of loss is to decrease the mean-free path of the photons 'sea.' And the only way to do that is to crank up the plasma density by many orders of magnitude--and there are only two places where such extreme plasma densities can exist (only one of those can be on Earth:) inside a star near the core, or inside a thermonuclear detonation.

Still, it's an interesting experiment with lots of interesting physics. I would love to see a copy of Dr. Bussard's paper--but I haven't been able to locate anything quite like what he talks about, so I wonder if he has written it yet? I hope he does--it would be a shame to do all those experiments and not fully document the results no matter what they may be...

Andrew · Senior Member

I've been following Bussard's activity online as much as I can. I am sceptical of his claims, but I also doubt that he is pulling a scam. He is too old and with a too good history (well, except that bit with the Riggatron) for that.

Last I heard about him, he is working with SpaceDev founder to do a demonstration Polywell reactor up-scaled enough so that it should archive breakeven. If that is successful, then they will try working on D-D or p-B11 reactors. I recall that his first designs use neutrons from D-T reactions.

I don't know why he didn't make papers regarding the mathematics of Polywell. There is this paper: http://www.askmar.com/ConferenceNotes/2006-9%20IAC%20Paper.pdf but nothing beyond that. I've found some forum posts, but none of them telling much more then already stated in his video.

10kBq Jaro · Senior Member

Andrew wrote:
I also doubt that he is pulling a scam. He is too old and with a too good history (well, except that bit with the Riggatron) for that.

He also came up with the famous Bussard interstellar nuclear ram jet, which was proven to be unworkable, from an energy-balance point of view.
But others took that idea and came up with the fuelled runway interstellar ram jet concept.....

GoogleNaut · Guru

Yeah, it's an interesting idea. If I was a billionaire, I would be tempted to plunk down the bucks just to see if it could work.

There's been a lot of discussion on this over at nasaspaceflight.com too, but nothing really substantial yet. I am skeptical of the claims of high thrust with hundreds of thousands of seconds of specific impulse--this implies power levels of hundreds or even thousands of GigaWatts. Cooling structures at these power levels is not a trivial engineering feat: also neutron bombardment of superconducting magnets necessitates creative radiation shielding. Frying your magnets with intense neutron radiation is a surefire way of destroying their superconductivity--which will have bad consequences too.

Still, it's interesting. If p-b11 fusion ever get's off the ground, we will have a lot of fuel for it everywhere in the solar system. And that's a good thing!

-- Edited by GoogleNaut at 03:05, 2007-04-15

Andrew · Senior Member

He also came up with the famous Bussard interstellar nuclear ram jet, which was proven to be unworkable, from an energy-balance point of view.

Actually, I recall that the concept of a magnetic sail has evolved from it, and it "could" work, but it would be very difficult to do (anti-matter has been suggested).

If p-b11 fusion ever get's off the ground, we will have a lot of fuel for it everywhere in the solar system.

I'd be satisfied if we could get that damn He-3 working. It would give a reason for both fusion and space technology to develop.

EDIT:
That's pretty much all the information I could get about Polywell.
http://www.strout.net/info/science/polywell/index.html

-- Edited by Andrew at 19:50, 2007-04-15

Andrew · Senior Member

For anyone interested, there is a forum regarding Polywell fusion: http://www.talk-polywell.org/bb/index.php

He also came up with the famous Bussard interstellar nuclear ram jet, which was proven to be unworkable, from an energy-balance point of view.

Actually, I recall that only the idea of using the thing to go relativistic and relying on it alone to get fuel and propellent was proven to be unworkable. The idea of scooping interstellar medium for propellent itself, was not.