Aneutronic fusion

[chrismb]

You are confusing alpha emitters with alphas. Not exactly the same thing. You are aware that a He4 is not an Am210, no?

I've no idea what you are saying. Are you saying that a polywell reaction core *isn't* [intended to be] an "alpha emitter"? What then induces a nuclear reaction is the energy the alpha carries away with it - and it matters not whether it comes from an alpha emitting isotope or a nuclear fusion core if it has the same energy. I've not said a fast alpha particle *is* radioactive, it is the *product* of something radioactive - though it has the same effect; ionisation and nuclear mutation.

(Polonium-210 actually glows, in sufficient quanitity, apparently. It puts out 100's of watts per gramme of substance!)

[MSimon]

You are confusing alpha emitters with alphas. Not exactly the same thing. You are aware that a He4 is not an Am210, no?

I've no idea what you are saying. Are you saying that a polywell reaction core *isn't* [intended to be] an "alpha emitter"? What then induces a nuclear reaction is the energy the alpha carries away with it - and it matters not whether it comes from an alpha emitting isotope or a nuclear fusion core if it has the same energy. I've not said a fast alpha particle *is* radioactive, it is the *product* of something radioactive - though it has the same effect; ionisation and nuclear mutation.

(Polonium-210 actually glows, in sufficient quanitity, apparently. It puts out 100's of watts per gramme of substance!)

OK. Properly excited C12 is an alpha emitter. However, alphas themselves are not radiation emitters. I don't need a permit for a bottle of helium. They can be radiation if they are going fast enough. And as you well know they are easily stopped. Even at very high energies.

BTW to go back to an earlier question: there was a thread on a particle decelerator design that could handle any range of input energies. Efficiency depending on the number of collectors. Did you ask that? Some one did somewhere and I forgot to answer.

[TallDave]

Oh btw, I brought up the <1% just because that's the informal cutoff for what's considered aneutronic.

http://en.wikipedia.org/wiki/Aneutronic_fusion

Sorry if that appeared to be an estimate rather than a top of the possible range.

[KitemanSA]

I forget where, but someone had a scheme for handling a diverse set of alpha energies.

If they really come out the cusps in a beam, it should be fairly simple. Run them thru a magnetic field and split them into seperate beams and charge the several collecting plates accordingly.

[D Tibbets]

Several modifiers to the secondary radiation concerns of high speed alpha particles from P-B11 reactions.

Hopefully <1% means alot less than 1%.

Materials for the first wall can hopefully be selected to reduce the secondary radiation (at least neutrons) produced.

A modest correction, but IF it can be done, an efficent direct conversion of the alphas would result in a needed fusion rate ~1/3 that of a thermal cycle fusion/fission reactor. In CB's comparison, a 5% neutron output for a fission nuclear plant would be equivalent to 15% when electrical conversion efficiencies ar taken into account.

If a high Q is possible with whatever reaction the waste alphas, neutrons, etc will be proportionatly less. An extream example: If Q= 2 then 1 GW of gross fusion power is needed to provide 500MW net power. If Q= 100 then only ~ 505 Mw of gross power is needed. Of course this presumably would be easier to achieve with D-D over P-B11.

For fixed sites the shielding will be considerable irregardless. For mobile, especially space, applications any weight you can shave off the shielding is disproportionatly benificial.

I have to agree with CB that concentrating our efforts on D-D Polywell developement/ speculation is more reasonable for 1st generation efforts, but it is more fun to persue the holy grail.


Dan Tibbets

[MSimon]

I forget where, but someone had a scheme for handling a diverse set of alpha energies.

If they really come out the cusps in a beam, it should be fairly simple. Run them thru a magnetic field and split them into seperate beams and charge the several collecting plates accordingly.

That is one possibility. Another was an electrostatic collector that collected alphas of varying energies. I'm going to look it up and park the pdf somewhere useful for easy access.

[MSimon]

http://www.askmar.com/Fusion_files/Venetian%20Blind.pdf

A direct energy converter.

[ohiovr]

alpha particles are radiation. Just not as much of a nuisance as neutron radiation. If you need a pure, no neutron reaction, 3He+3He is the way to go.

[MSimon]

alpha particles are radiation. Just not as much of a nuisance as neutron radiation. If you need a pure, no neutron reaction, 3He+3He is the way to go.

If I have a HeNe laser tube I have to get a radiation license? Because there are a heck of a lot of alpha particles in one of those operating tubes.

[ohiovr]

Your HeNe laser has helium ions traveling at over 11,000 Kilometers per second?

[MSimon]

Your HeNe laser has helium ions traveling at over 11,000 Kilometers per second?

Ah. So just having alphas around is not radiation? But I thought you said.....

[KitemanSA]

Your HeNe laser has helium ions traveling at over 11,000 Kilometers per second?

Ah. So just having alphas around is not radiation? But I thought you said.....

I think he is trying to distinguish (pretty much like wikipedia does) between an alpha particle (3+MeV of energy) and a more run of the mill ionized Helium atom (low keV?). What makes the He ion into an alpha partical (i.e. "radiation") is that it radiates quickly carrying energy away. At least that is how I see it.

[MSimon]

Your HeNe laser has helium ions traveling at over 11,000 Kilometers per second?

Ah. So just having alphas around is not radiation? But I thought you said.....

I think he is trying to distinguish (pretty much like wikipedia does) between an alpha particle (3+MeV of energy) and a more run of the mill ionized Helium atom (low keV?). What makes the He ion into an alpha partical (i.e. "radiation") is that it radiates quickly carrying energy away. At least that is how I see it.

I'm more inclined to call it radiation (at what ever KeV level) if it is emitted as part of a nuclear process. OTOH a minimum KeV level might be good.

[KitemanSA]

I'm more inclined to call it radiation (at what ever KeV level) if it is emitted as part of a nuclear process. OTOH a minimum KeV level might be good.

Until the artifice of particle accelerators came along, I would have agreed with the "nuclear process" definition. Now, I think it needs a mini-eV value. Wikipedia does not state a min value, but does indicate a common range (3-7 MeV) for nuclear processes. So maybe about 1 MeV?

[KitemanSA]

http://www.askmar.com/Fusion_files/Venetian%20Blind.pdf
A direct energy converter.

Thanks for the reference, I finally found time to read it is some detail. I do note that the authors actually imply a benefit to a degree of pre-seperation. So maybe what needs to be done is what I said,

If they really come out the cusps in a beam, it should be fairly simple. Run them thru a magnetic field and split them into seperate beams and charge the several collecting plates accordingly.

then use the venetian blinds at the end of each beam to maximize the efficiency wrt the spread within each beam.