Does D+He3 hide the real plasmoid density?

[MTd2]

According to the new report:

http://lawrencevilleplasmaphysics.com/index.php?option=com_lyftenbloggie&view=entry&year=2011&month=02&day=05&id=24:january-progress-high-efficiency-high-rez-plasmoid-and-the-path-to-higher-fusion-yield&Itemid=90

It was observed 2 signals of of 5.5MeV and 21MeV ions. The second one was unexpected while the 1st one 5x bigger than the expected signal.

According to wikipedia, the fusion yields are:

D + He-3 → He-4 ( 3.6 MeV ) + p+ ( 14.7 MeV )

http://en.wikipedia.org/wiki/Nuclear_fusion#Criteria_and_candidates_for_terrestrial_reactions

Close values to 5.5MeV and 21MeV. The values above are almost both 30% smaller. That would be inside the error, would they?

What I think is happening it is that there is a first batch of neutrons, corresponding to what is called preshock. It produces He3. It happens that the cross section of He3 + Deuterium is big so, there is a lot of aneutronic fusion

The cross section of D+He3 is 10 times bigger at 150KeV- 200KeV!
http://upload.wikimedia.org/wikipedia/commons/d/d0/Fusion_rxnrate.svg
that means 10x more chance likely to react! It ends up inhibiting D+D reactions . That means that even if a small quantity of He3 is present, it will represent most of the reactions. The result will be a much smaller neutronic yield, given that D+He3 is aneutronic.

The He3 temperature as a result from D+D is 800KeV. It has the same mass of tritrium. Somewhere else, it is stated that the current to trap tritium is 1.2MA,
( https://focusfusion.org/index.php/site/article/re_analysis_of_texas_data/ ) given that Helium has more charge and is a bit slower, it will be trapped at lower currents, perhaps at 700KA. So, it canibilizes D+D above 700KeV

Note that the fact that in this way the density of the plasmoid is just apparent. If tritium is even more reactive than D+He-3, so it will take advantage at 1.2MA, showing a closer to real density charge in the plasmoid, if the system is analyzed by the perspective of emitted neutrons.

So, in reality, FoFu is already at 1J or above, considering the aneutronic energy.

[MTd2]

Even though the number of He3 is small than D, it is likely that the probability of fusion with Deuterium is hugely enhanced by 2 factors:

1. It is 1/3 slower than deuterium at thermal equilibrium because it is heavier.
2. It loses energy 4x faster than deuterium by Bremsstrahlung radiation.

Being slower means that it will collide much more frequently with D than Deuteriums collide between themselves. Any random 2 deuteriums will most of the time have a much smaller relative radial speed difference than between a D and He3. Losing energy by bremsstrahlung very fast means that it will lose speed faster and this just will increase its probability to collided with a D.

So, He3 has much much more collisions than any Deuterium. Plus, its cross section at 150-200KeV is almost 10x higher than D+D.

[MTd2]

A more stable situation is He3 closet to the axis and Deuterium closer to the border. But what happens it is that colder He3 will be in contact with hotter D. The D+ He3 below 100K is too low, so He3 will just cool without fusion, but if any of them fuses, it will just emit and alpha + proton at very high energies.

So, what will happen is that the He3 layer and D will cool each other and tend to expand adiabatically , given that the plasmoid is mostly opaque to xrays. This will tend to reduce the cross section for D+D. The good side of this it is that the shear between layers of different layers and the plasmoid will last longer and given the conteracting negative pressure to the compression.

[MTd2]

Now, if this works, it is great news for when 1.2MA is reached. Tritium will be trapped and given that it has the same high mass of He3, but low charge, it will sit in the outer layer. The good news it is that D+T have the greatest cross section at 80Kev – 200KeV, which makes its location on the colder zone a great advantage to increase fusion rates. It is actually the highest at least among the lightest nucleus.

[DerekShannon]

Very interesting, I’m sure Eric will chime in when he has a minute.

[MTd2]

You can arrange 1 mol of He in a cube of 28cm of size. 0.1 trillionth of that means a cube about 2400 smaller or of 10micrometers. That’s for an ideal gas, that is, 1atm and 300K. At constant pressure it swallow to 1cm^3 at 100KeV. There is compression of course, but considering that ideal gas fails at 2atm in general, because it starts to show incompressibility factors, we see that He3 can be quite a factor in scattering Deuterium.

[MTd2]

I was thinking of what would be a good visual description of this situation. The picture I have in mind is the Plasmak, but without the contain layer:

http://www.prometheus2.net/ICC_2002_POSTER.pdf

In this case, there are 2 superimposed torus: an he3 torus and a deuterium torus. The he3 will be nested inside the deuterium, but given that the bremsstrahlung of He 3 is 4 times more intense than deuteriums, it will have a relatively shorter tail than deuterium and will tend have a large cross section around the center because it will be more concentrated.

[MTd2]

This is a sequence of events that more or less describe what I am thinking.

http://img689.imageshack.us/i/plasmoid1.jpg/
http://img683.imageshack.us/i/plasmoid2.jpg/

In the Lee’s model, the pinch is formed by the equilibrium of the compressing radial plasma and the self reflected supersonic waves at the z axis. The mantle of the plasmak is formed by the pinch itself of the Lee Model. The filaments cut through the pinch, though and rich the center of the plasma. The instability is created in the middle compact plasma and it sucks the matter content of the pinch, forming the plasmoid.

The plasmoid lasts even after after the pinch is. According to Lee’s model, the pinch lasts about 20ns, whereas the emission of Ions lasts 40ns.
There is strong neutron emission in the begining, while D+D is being burned, and in the end, after He3 is depleted.

Note that this looks like a little bit the the main sequence star from its burth until supernova.

Pinch looks like the initial nebula. D+D correspond to a star in the main sequence. D+He correspond to the Giant branch, where as I explained above there is a tendency of He to cool and expand the system, and in this case, avoid the plasmoid contraction. And the final emission represents the supernova stage, where the He cannot hold anymore the EM(instead of gravity), which ends in the explosion of the plasmoid/star.

[Lerner]

The problem with this is the order of magnitude of the numbers. The beams we are looking at have 10^14-10^15 ions. The number of He3 produced is 10^10-10^11 and a much smaller number of those then undergo fusion.

[MTd2]

But only a small part of those ion beams take part in the reaction. At 100KeV, 10^11 ions occupy about ~1 cm^3 at 1atm. Compressed to lead density, isotermicaly, they would occupy around 100cubic micometers. So, those other ions must be extremely cold and outside the plasmoid or in the periphery. It seems then that proportionally, He 3 disrupts the core of the reaction.

[benf]

Thanks MTd2 for highlighting the thespaceshow, which I would have otherwise missed. Your persistence clued me into it and I’m glad I tuned in…very informative show! I’m not a physicist, so bear with me with these questions; Are you proposing to not use hydrogen and pB11 in the future, despite it’s advantages? Are the reactions that you’re describing so advantageous that you think Focus Fusion should just stick with using Deuterium and “go for the gold” by tweaking how it interacts with He3? From what I gathered listening to you on the show, you think it would be equally aneutronic?

[MTd2]

Hi benf,

Actually, I am trying to see that the nature of the plamoid is a little bit different of what is proposed by Eric, and that the results pB11 plasmoid probably won’t correlate with the D+D. For example, I propose that the nature of the plasmoid is of “subtype” plasmak.

Plasmak is a kind of toroid onion in which the outer layer compresses progressively the inner layers. So, most of the fusion happens in the center. He3 is produced by the fusion of deutrerium. So, in my view, the caputred He3 by the plasmoid magnetic field would emit bremsstrahlung too fast and literally sink to the bottom of the onion. Thus, its presence would disrupt the D+D reaction, given that D+He requires higher temperatures to react. Plus, the He3 would cool faster due its bremsstrahlung emission being 4 times bigger than the Deuterium. That would cool the inner layers and bring down fast the toroid core temperature and thus diminishing further the reaction rates.

So, using neutrons as a gauge for the pB11 plasmoid is not a straightforward case, because pB11 would have a very pure core, which is not the case of D+D.

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