[jamesr]

I’d imagine it would be pretty easy to design an experiment (although not necessarily to get good results!) where you build a few dozen detectors made up of a He3 or BF3 neutron counter and an antenna to pick up the EM pulse together with a GPS location/timer accurate to a few ns and data logger. Then space them in a grid a mile or so apart in a thunderstorm prone area. Leave them logging every strike for a season, then come back and process the results.

You can triangulate the position of the lightning strikes fairly simply, then although the neutron detections may only be barely above the noise level, over a few thousand strikes you may be able to build up reasonable statistics, using the delay from the EM pulse, giving not only the position (co-location with strike?), energy distribution, and maybe infer the height (ie do they come from the low level arc, or the jets/sprites higher in the atmosphere)

[jamesr]

asymmetric_implosion wrote: James: FF will only burn a tiny amount of fuel per shot. My guess is it will be on the same order as an optimized NIF. NIF may not be perfect and it will not be a viable fusion reactor but physics breakeven is likely. Engineering gain is another story…

Obviously if you include all the fuel in the DPF chamber only a tiny fraction is burnt, but of that confined in the plasmoid(s) then maybe upto 70% could be fused.

For NIF I think they’re hoping for ~40% (of the DT gas and ice shell – not including ablative layer), but if they don’t get a burn wave then I guess it’ll be more like 2%

[jamesr]

asymmetric_implosion wrote:
Bad news though, NIF will hit breakeven first. It is dubbed too big to fail by NNSA and others in DOE.

NIF will fail – the only way they’re going to get ignition is by a clever PR redefinition of what ignition is.

They may be able to get the hot-spot at the centre of the pellet to ignite, but some new models show that if you take account of electron degeneracy properly, the alpha particles do not have sufficient stopping power to heat the compressed pellet and create a burn wave propagating outwards.

So I expect if NIF do come out with any news of having reached ignition, take it with a pinch of salt and look out for the burn-up fraction. Getting a pinpoint in the centre to ‘ignite’ is pointless unless it results in fusing of a reasonable fraction of the pellet.

[jamesr]

I wish all the rhetoric could be less nationalistic. Energy is a global issue, grassroots & regional campaigns on specific issues have there place. However I think to really get the message across of the scale of the problem, any campaign needs to be global and inclusive in its nature. Individual nation states do not have the power or will to implement the kind of changes needed.

I know FFS and FEL are based in the USA, but why not frame any response to this kind of report from a national body to encourage collaboration with other nations, EU & UN bodies, multinational companies etc.

Also with regard to military spending, although the US military, via the DOE has spent a large amount of money on NIF and the associate computer modeling research into inertial fusion energy. A lot of the key data is classified, hampering civilian research as they do not have to required information.
There are lots of researchers around the world that would like to work on inertial fusion but can’t because of proliferation paranoia, limiting access to codes and data.
I’m sure there are classified codes out there which would be a great start in modeling a DPF plasmoid, but anything that can cope with high density plasmas that include radiation feedback terms (ie opacity) tend to be classified.
If you want people to sign a pledge it should include any research paid for by taxpayers money (from any country) should be freely available to the entire world.

The astronomy community is a good model – for most projects now, the group who put up the money for an experiment/satellite etc get first dibs on the data, then after a set period eg. 6months, or after first journal publication it is open to everyone.

[jamesr]

It seems the wiki already has some spam users: https://focusfusion.org/wiki_en/index.php?title=Special:RecentChanges

Maybe the registration needs to be tightened up. Is there any way to actually link the wiki userid to the main site user database??

[jamesr]

Brian H wrote:
The bottom line seems to be that there were periods when Earth was getting zapped with multi-megaamp currents from solar or other source(s).

We still are… Coronal Mass Ejections still make fantastic auroral light shows… it is just that there is too much light pollution for most people to be able to see the detail.

I think we should adopt the squatting man as our mascot

[jamesr]

Basically use (…) for inline expressions or
$$
A + B = C
$$
for centered separate equations

I’ve updated the help page accordingly: https://focusfusion.org/wiki_en/index.php/Help:Contents

[jamesr]

Yay – it works!! 🙂

[jamesr]

That looks ideal zapkitty! If I understand it correctly it could work over the whole site including the forums.

[jamesr]

How about wikia.com?

I just created a quick test page http://fusionplasma.wikia.com/wiki/Category:Maths_Test and it seems to work OK.

[jamesr]

vansig wrote:

I thought that the Sun uses the CNO cycle?
— http://en.wikipedia.org/wiki/CNO_cycle

No, our sun is too small for the CNO cycle to be a significant contribution. As it says in the wiki, a star needs to be at around 1.3 times as massive as the sun for its core to be hot enough to support this cycle.

The size/temperature dependence is shown here: http://csep10.phys.utk.edu/astr162/lect/energy/cno-pp.html

[jamesr]

Oh Well, thanks for trying.

I’ll try and jot some ideas down over the weekend and start putting up some content. I don’t just want to repeat what is already out there on other wikis like http://fusionwiki.ciemat.es and Wikipedia. But there will inevitably be some repetition. Particularly for short glossary type entries defining terms.

I think where we can stand out from the other wikis is, in part, being more accessible to a general audience, but also covering the big picture.

[jamesr]

DerekShannon wrote: A *tougher* (shatter-proof!) insulator material than alumina, but still with as good or better dielectric strength and heat-resistance, pretty pretty please? Oh, and it has to come in the shape of a hat, with no delivery lead time, and people pay to have it taken off their hands ;-D

I’m not sure about their physical properties (and I’m sure any good one won’t come cheap) but how about some of the insulators mentioned in:
http://www.apelc.com/pdfs/6.pdf

After all, you cannot assume an insulator that has good properties at DC or low frequencies will react in the way you want with the fast rise time in a DPF. So looking at what they use in the Radar & microwave world may be of use.

[jamesr]

delt0r wrote: I didn’t read it all in detail since he misses a pretty serious detail with D+D fusion. That is he claims D+D fusion gives 4He, which it does not. A 10sec wiki search would have told him that.

Yes, he’s a little misleading on that – although it is what happens eventually, as in the Sun. On Earth we have to deal with the intermediate products
The initial reactions (with a 50/50 split) are of course:
D + D -> He-3 + n
D + D -> T + p

but then you get all the other combinations
D + T -> He-4 +n
D + He-3 -> He-4 +p
He-3 +He-3 -> He-4 + 2p
He-3 + T -> He-4 + p + n
He-3 + T -> He-4 + D
n + p -> D

Which all end in He-4. Given D+T much larger cross section than DD, in a DD reactor most of the tritium gets burnt up instantly rather than causing a legacy problem. Although there is still enough that precautions need to be taken. Another important aspect is that the neutrons from the DD primary reaction are only 2.45MeV not 14.1MeV so need slightly less stopping power in the shielding/blanket.

On the whole I found the article well written, and the subsequent posts I wouldn’t term biased – I’d say they had a pretty healthy scepticism.

[jamesr]

Maybe the tide is turning. There seems to be a growing opposition to the publishers at the moment:
http://arstechnica.com/science/news/2012/01/researchers-boycott-publisher-will-they-embrace-instant-publishing.ars
http://gowers.wordpress.com/2012/01/21/elsevier-my-part-in-its-downfall/

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