Handheld Fusion Reactors

Point out news stories, on the net or in mainstream media, related to polywell fusion.

Moderators: tonybarry, MSimon

chrismb
Posts: 3161
Joined: Sat Dec 13, 2008 6:00 pm

Post by chrismb »

D Tibbets wrote:You might need conversion efficiency of the fusion energy AND waste heat/radiation energy at 99.999999935% 8) . Lots of luck!
Not really. I don't want to disappoint, but if you were, say, trying to generate only heat then, OK, you could get a Q of 1.0000....001. But if it were heat you were trying to generate with your electrical energy then better to stick it into a reverse cycle air con unit that'd give you a Q of 2 to 3.

alexjrgreen
Posts: 815
Joined: Thu Nov 13, 2008 4:03 pm
Location: UK

Post by alexjrgreen »

Art Carlson wrote:Even if you can make a 0.5 MeV ion beam, and even if you can make it with 100% energy efficiency, when it slams into a solid target it will unavoidably lose more energy by heating the electrons in the solid than it will produce by fusion. This is true for D-T and it is 1000 times more true for p-B11.
Is this still true for meta-materials?

Might provide someone with a PhD...
Ars artis est celare artem.

Art Carlson
Posts: 794
Joined: Tue Jun 24, 2008 7:56 am
Location: Munich, Germany

Post by Art Carlson »

alexjrgreen wrote:
Art Carlson wrote:Even if you can make a 0.5 MeV ion beam, and even if you can make it with 100% energy efficiency, when it slams into a solid target it will unavoidably lose more energy by heating the electrons in the solid than it will produce by fusion. This is true for D-T and it is 1000 times more true for p-B11.
Is this still true for meta-materials?

Might provide someone with a PhD...
The electrons in solids have interactions measured in eV. I don't know exactly, but I think even the innermost electrons of uranium cannot be bound with more than 100 keV. If protons come tearing into a boron compound with a good fraction of an MeV, they just don't care what the electrons were doing before they got there.

Says I.

When I start thinking about it, I ask myself a passle of interesting question like, Why is the energy important and not the relative velocity? and, Is the total energy of the proton decisive or just the energy it imparts to a typical electron as it passes? I stand by my prejudices, but if you want a real explanation you should ask somebody else, maybe a solid-state physicist.

rcain
Posts: 992
Joined: Mon Apr 14, 2008 2:43 pm
Contact:

Post by rcain »

is there any way to produce/maintain a quasineutral plasma inside (a charged/magnetized) ablation well?

fusionfordummies
Posts: 2
Joined: Thu Mar 31, 2011 7:07 pm

Ionization energy

Post by fusionfordummies »

Art,

Don't inertial and magnetic fusion face the same ionization energy problems? In ICF, the targets are solid DT at 17K that are imploded but must also ionize the material in addition to compressing and heating it. In Magnetic confinement, the electrons are stripped off from the high heat temperatures of the plasma. In both cases, to make a working reactor the ionization energy must be recovered to some high fraction, no?

I don't see why this would be any different for a proton beam shot at a boron source?

FFD

Tom Ligon
Posts: 1871
Joined: Wed Aug 22, 2007 1:23 am
Location: Northern Virginia
Contact:

Post by Tom Ligon »

My own version of this technology, which I admit up-front is a totally science-fictional gizmo for a novel, is a pico-accelerator array with electron cascade energy capture. This was all dreamed up before I met Dr. Bussard.

Works thusly ... a ceramic material is devised which is a solid matrix of very specific molecular design. In it are a huge number of structures that are essentially empty toruses (this inspired by a truely nutty friend who proposed this actually happens in ATP molecules in-vivo). These are excited by external application of microwaves, causing single protons to circulate in these tori ... basically tiny cyclotrons.

The target atom in my device was sodium, and the product magnesium ... in principle there is some mass loss and thus energy produced. These sodium atoms were fed one at a time into the target area of the cyclotrons, which gated the proton into them by some shift in the electronic state of the molecule. This meant a specific proton targeted a specific sodium nucleus, held in just the right spot. Which sounds cool, but I'm sure Art or Chris will point out just how small a nucleus is compared to a molecule, and the aim still ain't good enough. Some additional magic tech is needed.

This has a wiff of cold fusion tech ... the coulomb repulsion can only kick in when the particles are close because electrons in the surrounding material mask them. The structure was also presumed to be a superconducting material involving scandium and rare earths, and I dreamed that up before the actual discovery was made! Part of the rationale for the superconducting twist was a limitation of the range of electromagnetic forces in superconductors possibly aiding fusion.

Energy from the reaction was to be turned into electricity via a capture scheme for displaced electrons modeled on photosynthesis.

chrismb
Posts: 3161
Joined: Sat Dec 13, 2008 6:00 pm

Re: Ionization energy

Post by chrismb »

fusionfordummies wrote:Art,

Don't inertial and magnetic fusion face the same ionization energy problems? In ICF, the targets are solid DT at 17K that are imploded but must also ionize the material in addition to compressing and heating it. In Magnetic confinement, the electrons are stripped off from the high heat temperatures of the plasma. In both cases, to make a working reactor the ionization energy must be recovered to some high fraction, no?

I don't see why this would be any different for a proton beam shot at a boron source?

FFD
You are misunderstanding the differences. Magnetic and inertial confinement (ICF) are thermal fusion processes. So this is about making a really hot gas, the contents of which fuse. In this way, there are no kinetic collision losses* as such, because any heat given up to a struck particle by the striking particle remains within the hot gas.

In a beam-target system, this is described as 'locally hot, generally cold'. All but the fast particle is cold, so once the particle hits this cold stuff, it will cool down. In condensed, cold matter, this process is totally dominated by the electrons sucking out the kinetic energy of the fast particle. Once this happens, all those joules are 'lost', whereas in a thermal plasma, those kinetic energy joules stay within the plasma ('energy confinement') to go on to cause fusion. There is no energy confinement to speak of in the beam-target systems you are talking about.

*(there is much electro-magnetic collision losses within plasma, which emit x-rays and cool down rapidly by loss of that energy. In this way, energy is, indeed, transferred preferentially to the electrons, but the thermal energy itself still remains within the electron plasma, whereas the beam-target process, the electrons rapidly dissipate the thermal energy to the cold material and thence to the environment)

fusionfordummies
Posts: 2
Joined: Thu Mar 31, 2011 7:07 pm

locally hot, generally cold

Post by fusionfordummies »

Hi chrismb,

That's why I said the "ionization energy must be recovered". So if you shot a boron target with protons, some fraction would heat the target and some fraction would cause fusions reactions proportional to the reaction cross sections. The two questions are:
1. What is the fraction (I don't know the sigmas) and is there a temperature or configuration where this can be maximized to a significant number? The fraction doesn't have to be a 100%, in fact it can be probably 0.1% and it'd still be possible to get net energy out.
2. What is the best way to recover "all those joules"? Heating water or some type of thermoelectric effect?

Maybe point#1 has been researched to death already but I haven't seen the work.

I think restricting research on this subject because of Point #2 is not a good argument. We don't know how to do that for ICF or magnetic confinement yet either.

Regards,
FFD

Post Reply