[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:

[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 😉

[emmetb]

I’m currently in the process of installing such a device on my rooftop. 😉

Initially i’m interested in leading the wires through a container of water, isolating one of the electrodes in an insulated ceramic tube, like these scientists from the Max Planck institute did:
Long-living plasmoids from an atmospheric water discharge
(excerpt attached with this post, original link: http://iopscience.iop.org/0963-0252/17/2/024014)
I was struck when i saw this. Not by lightning. Rather i was struck by the striking resemblance between this experimental setup and the DPF (cf. Figure 1. in the paper).

Attached files

balls_excerpt3.pdf (480 B) 

[emmetb]

Talking about lightning. Could a simple lightning rod suffice to replicate LPPX experiments on the cheap? Of course you could only expect to get a couple of shots per device per year so you would need several devices prepped at anyone time. But the costs would be offset by the fact that you could do away with switches and capacitor banks. 🙂

[emmetb]

Would you mind CC-ing me?

[emmetb]

Just installed COMSOL 3.4 is that recent enough for what you’re trying to do here? Note i have no experience with comsol (or any other FEM package for that matter) so i’m afraid i won’t be of much use myself, but i would be curious to watch over the shoulder of somebody more experienced.

[emmetb]

rashidas wrote: Here is a link to an article on Traveling Wave Nuclear Reactors. Could this give Focus Fusion a run for its money?

http://www.technologyreview.com/energy/22114/

A breeder like this will not be cheap to build and maintain. It is sodium cooled, because of the high temperatures involved. Yet this traveling wave concept is kind-of creative. Funny how it burns down like an extremely long lasting candle: 1 cm per year (conceptually at least, in reality i believe the burn region remains static). If the technical difficulties are overcome it may make a very real contribution to solving our energy problems in the short to medium term, especially because it has the potential to burn down depleted uranium.

For a while at least, we probably need to use everything at our disposal to simultaneously kick our carbon habit and deal with humanity’s rising energy needs. But once aneutronic fusion is realized to its full potential, we can phase out this messy, dangerous fission technology once and for all 😉

[emmetb]

dennisp wrote: Umm…wow. What he almost doesn’t bother to mention is that he may know how to cure all infectious diseases.

Thanks! Totally missed that part. That is so cool 🙂 See: i told you he made sense “on some level” 😉

[emmetb]

So if Occam’s razor can be reformulated for use by physicists as:

When faced with a choice between two competing theories describing the same physical phenomenon we should always prefer the simpler, more concise one.

Then there should also exist a reformulation/specialization of this adagium for use by engineers:

When faced with a choice between two competing devices for obtaining the same physical goal we should always prefer the simpler, more efficient one.

I’m still working on a further specialization for use by plasma physicists pursueing fusion energy… 😉

[emmetb]

Breakable wrote: http://www.ted.com/talks/david_deutsch_a_new_way_to_explain_explanation.html

Thanks for posting that. Deutsch has a very interesting take on things. Initially i was convinced by his talk.

But now i believe there’s a problem with his position though. The problem is that it is easy to vary 😉 His position is weak because of the words “easy” and “hard”. These are completely subjective notions. The central issue is whether you want a binary notion of truth or a continuous one. Deutsch says empiricists were wrong and then goes on to tell us why he is (more) right. But that’s not completely fair because he’s actually setting out to do something quite different from what empiricism had in mind. Empirical science only purports to be a method to ultimately falsify theories (theories can never be proven, only falsified). These claims still stand, even today. What Deutsch is trying to do here, and not very successfuly in my opinion, is to compare two theories without falsifying either. This is simply a different thing. It implies a continuous notion of truth, i.e.: my theory is more true than yours. As such it is outside the scope of empiricism which deals in absolutes, i.e.: something is possible until it is falsified.

Now it is not to say that it is not interesting to try and order theories in terms of “goodness of explanation”. But if you want to do this you need to follow the scientific method and come up with something that is formal and expressible in the language of mathematics. Some would claim that this has actually been done. Conceptually it was already proposed by the 14th-century franciscan friar Father William of Ockham (http://en.wikipedia.org/wiki/Occam’s_razor). And you might say that, mathematically, it was worked out in the work of russian mathematician Andrey Kolmogorov (http://en.wikipedia.org/wiki/Kolmogorov_complexity)

The impact of Kolmogorov’s ideas of algorithmic complexity on the scientific endeavour can be summarized as follows (and i’m quoting one of my own professors here):

Science is, essentially, a form of data compression.

This is to be taken quite literally: if you want to know whether some sequence of numbers is generated by a physical process (with some degree of predictability in it) you can approach this problem as though you were writing a data compression algorithm. The trick is then to find a good model for the underlying physical process. As soon as you manage this you can probably get a very good compression on your dataset (by encoding the dataset using a description of your model, the initial start conditions and some small number of corrective bits to account for the noise). When you succeed in doing this (and you model also compresses new datasets generated by the same process), it means you have found a “good” explanation for your data, but this time in a truly quantitative sense (give me another model and we just compare, on the same dataset, how well each model manages to compress it). In sum, this makes the Kolmogorov/Occam theory a more scientific explanation of what science does than the Deutsch theory 😉

[emmetb]

nemmart wrote:
Clearly the same problems would exist for NIF. I wish someone had asked Mr. Moses
if these engineering challenges had been solved and shown to work? and if not, how can
he be so confident about timeframes and costs, etc.

Exactly! All these risks/chances should be taken into account and then multiplied by the respective costs/benefits. That’s how rational decisions are made! Of course DPF fusion also has many unknowns and it is still open whether it is feasible. Yet the costs of running the experiments are much lower and the potential benefits both in terms of basic science (LPP is planning to go into physical domains that have so far not been investigated) and economy of scale are much greater.

[emmetb]

NIF is primarily about stockpile stewardship, not energy. That’s not to say there can’t be useful overflow between the two. But, frankly, i find it worrying that a big-shot (no pun intended) guy like Ed Moses feels inclined to paint such a rosy picture to the audience. He should be fair about the risks and uncertainty of the investment he is asking the American people to make, once again. Especially considering the fact that the costs would, once again, dwarf the costs of a more diversified approach to fusion research.

[emmetb]

It should be relatively easy to handle such a substance in a standard industrial setup like a running FF reactor

Notwithstanding the fact that decaborane handling may pose a very real challenge for our courageous LPP scientists in this moment 🙂

[emmetb]

Tulse wrote: I’d be careful about touting lack of toxins — decaborane is poisonous. It should be relatively easy to handle such a substance in a standard industrial setup like a running FF reactor, but that doesn’t mean there aren’t toxicity concerns.

As you say these are concerns, not problems, in contrast for photovoltaics:

During normal operation, photovoltaic (PV) power systems do not emit substances that may
threaten human health or the environment. In fact, through the savings in conventional
electricity production they can lead to significant emission reductions. There are, however,
several indirect environmental impacts related to PV power systems that require further
consideration. The production of present generation PV power systems is relatively energy
intensive, involves the use of large quantities of bulk materials and (smaller) quantities of
substances that are scarce and/or toxic. During operation, damaged modules or a fire may lead
to the release of hazardous substances. Finally, at the end of their useful life time PV power
systems have to be decommissioned, and resulting waste flows have to be managed.
Environmental Aspects of PV Power Systems, IEA PVPS Task 1 Workshop, 1997

There are far reaching ideas around to overcome all of these problems by switching to sophisticated, self-replicating, nanotechnological systems otherwise known as plants 😉

[emmetb]

Rezwan wrote:

So what about this then:
“How Green is it? Hands down the greenest form of energy for high power-density applications: no CO2, no nuclear waste, very small environmental footprint in terms of construction materials needed per MW, no storage and distribution problems, no problem with toxins as found in fotovoltaics, not in competition with land for agriculture and forrests.”

Thanks for the suggestion!

I’m trying to shorten the first page to add more things on it (like news feeds in better position). So I’ve left your quote off the front. However, the link “How green is it” goes to a page, and I’ve inserted the quote above as the second paragraph.
supergreen!

[Author]

Posts