Possible hybrid between inertial confinement/dpf fusion?

[emmetb]

The new movieclips of the pinching plasmoid just posted on the website are extremely cool! The ICCD footage of the actual kinking filament forming the plasmoid makes it really visual what is going on inside the machine. I also like the Ben Franklin theme. Warning people not to try this at home is probably a good idea. Having said that, of course i started constructing my own kite right-away 😉

On a more serious note. Seeing the images in sequence makes me wonder whether the same pinch effect could be achieved in an alternative way. Perhaps even in such a way as to circumvent some of the scaling problems of the DPF due to electrode erosion and cooling issues.

In particular, i wonder whether it would be possible to condense decaborane into microscopic coil-like structures, and shoot these “pellet-coils” with high kinetic energy into a much larger open induction coil, subjecting the pellet-coil to a huge magnetic flux change in the process. I guess this could be seen as the reversed principle of a:
http://en.wikipedia.org/wiki/Explosively_pumped_flux_compression_generator
Of course no explosives are being used but the high kinetic energy of the microscopic pellet-coil entering into the magnetic field of the much larger outer induction coil would have the same net effect. This way it might be possible to induce enough current in the pellet-coil to whip it into a plasma and instantly pinch it. Or am i just raving here??

[Milemaster]

Surely shooting a tiny Decaborane pellets into the plasmoid will avoid some premature heating problems producing inertial confinement. Y always thought of having a resonant focusing of the x-rays bouncing from a cylindrical shaped chamber to the plasmoid zone as a way both to transfer wasted energy into the reaction an condensing the gas to increase density in the proper region. Other ideas like the magnetic confinement could be developed.

[emmetb]

Milemaster wrote: Surely shooting a tiny Decaborane pellets into the plasmoid will avoid some premature heating problems producing inertial confinement. Y always thought of having a resonant focusing of the x-rays bouncing from a cylindrical shaped chamber to the plasmoid zone as a way both to transfer wasted energy into the reaction an condensing the gas to increase density in the proper region. Other ideas like the magnetic confinement could be developed.

I see this is your first post, so welcome to the forum! 🙂

I didn’t explain properly in the previous post. Let me give it another go. When listening to people who are skeptical about the DPF approach to fusion, most often i heard the argument that a DPF cannot produce useful amounts of power before the problems with heating and erosion of the electrodes will stop us from scaling up the reaction far enough to reach break even.

Now whether or not this is true remains to be seen of course. LPPX is testing this. Even if it turns out that DPF fusion does not scale well enough to make it practical, going to these high magnetic fields and heavy ions like LPPX is doing with their FoFu machine is for sure interesting. Especially it might demonstrate the quantum magnetic field effect kicking in. That would be really great because it would show that it is possible to reduce Brehmsstrahlung, preventing premature cooling of the plasmoid, in principle enabling aneutronic, Pb11 fusion, the holy grail of fusion.

So that’s all very interesting but while we wait for the real scientists to work their magic, we layman like to speculate in order to entertain ourselves (it’s not like we have anything else to do 😉 )

The post was not about the phase that comes after the formation of the plasmoid where the actual fusion occurs, it was about the phase leading up to the formation of the plasmoid where we are discharging the capacitor bank across the electrodes to get the reaction started. In particular i was thinking about potential ways to get rid of the problems with heating and erosion of the electrodes. I guess a pre-requisite to do that would be to produce a similarly large current in a small volume without discharging across metal electrodes.

An explosively pumped flux compression generator can produce such large currents by compressing a circular conductor inside a containing magnetic field. But of course it’s not very practical to set of a high explosive for each pulse. Or is it? In another tentative fusion proposal, which is inertial confinement fusion, people are actually contemplating doing pretty much that: setting of a tiny hydrogen bomb for each pulse.

So why not put the three things together: fusion by collapsing plasmoids, flux compression to generate the starting pinch, and inertial confinement to achieve the flux compression. That’s why i started rambling about these coil-pellets: a tiny ring of boron, embedded in a pellet of ablation material.

I imagine the reaction would then go as follows. Just like for normal inertial fusion you would shoot the pellet into the reaction vessel. Then the lasers would hit the mantle of ablation material creating an inward shockwave that compresses the pellet. Unlike normal inertial confinement fusion the vessel would additionally be surrounded by a solenoid to generate the required magnetic flux, and unlike normal inertial confinement fusion the shockwave need not be *so* powerful as to fuse the material inside, it need only be strong enough to sufficiently compress the conducting ring inside the pellet. (As a fortunate side effect the conductivity of the boron will improve with the increase of pressure and temperature.) The compression should cause a sudden magnetic flux change inducing a large current. Then we should get a pinch, kink, plasmoid, fusion, ion-beam etc. etc. It’s all pure speculation really… but it would sure increase awesomeness if it were possible 😉

[Patientman]

emmetb wrote:

So that’s all very interesting but while we wait for the real scientists to work their magic, we layman like to speculate in order to entertain ourselves (it’s not like we have anything else to do 😉 )
It’s all pure speculation really… but it would sure increase awesomeness if it were possible 😉

I really like your speculation. Although some people do go off the path a bit. I hate to ask this next question and totally expose my ignorance on certain subjects. I perceive the need for certain electro-magnetic materials for passing the generation of energy, but (here it comes) could you use LARGE open ended fiber optical transmission lines to pass the energy into the chamber? I’m done, sorry.

[Aeronaut]

Why not use the cap bank as a semi-automatic rail gun and skip the explosives altogether?

[emmetb]

Patientman wrote:

So that’s all very interesting but while we wait for the real scientists to work their magic, we layman like to speculate in order to entertain ourselves (it’s not like we have anything else to do 😉 )
It’s all pure speculation really… but it would sure increase awesomeness if it were possible 😉

I really like your speculation. Although some people do go off the path a bit. I hate to ask this next question and totally expose my ignorance on certain subjects. I perceive the need for certain electro-magnetic materials for passing the generation of energy, but (here it comes) could you use LARGE open ended fiber optical transmission lines to pass the energy into the chamber? I’m done, sorry.

:shut: oh, peer cruelty… well i meant no disrespect, even though this flux-compression idea may be far fetched and naive.

My last undoubtedly futile attempt to save a shred of dignity. I just found this report about laser driven magnetic flux compression for magneto-inertial fusion.
http://www.lle.rochester.edu/media/publications/lle_review/documents/v110/110_01Laser.pdf
It’s relatively recent so the stuff is actually actively researched in the context of magneto-inertial fusion. Of course that doesn’t mean it could also be used differently to pinch the plasma into a plasmoid, but still…

Anyway with this kind of response i guess it’s better to move this thread to noise. :down:

[MTd2]

The problem I see it is that the duration of the plasmoid, at most 50 ns, is much smaller the usual variability of the time from firing to pinch, which is at around 200ns. So, it is hard to have a target.

[Ferret]

On the same note of hybridizing the ICF and DPF, there exists the possibility of replacing ICF lasers with DPF – like particle guns. So instead of huge inefficient lasers there would be a couple of dense plasma devices that may not achieve nuclear fusion themselves but fire jets of particles at a solid fuel target, burning its outer layer and inducing inertial confinement and fusion in the target. Several such devices placed around the target would fire synchronously. The idea came from http://en.wikipedia.org/wiki/Railgun#Trigger_for_Inertial_Confinement_Fusion

The main advantage: possibly much smaller and more efficient DP devices compared to lasers. And simpler and cheaper too.

Main disadvantages:
– synchronous firing: how well could it be achieved?
– target acquisition: they have to fire straight, not around corners.
– particle beams are not neutral, but positively charged. Electron beams fire the opposite way. So electrons may have to be added to the particle beam in order to make it neutral (or maybe this is not necessary).
– in some conditions, firing plasma at targets generates an electric field that effectively shields the target from the plasma. Would the same happen here? Neat stuff, anyway. And quite new too: http://phys.org/news/2012-07-deflector-shields-lunar-surface.html

Post your opinions on this. And hey, if you run out of activities or you simply get some funds / benefits from this, you could consider “feeding” some of the ICF projects with DP devices of this sort. I know some X-ray generators have been developed from DP machines.

[Author]

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