Talk-Polywell.org

Amateur 'fusioneers'.
http://www.individual.com/story.php?story=103637618
OBS.
Linked from the ITER site.
http://www.iter.org/default.aspx

I remember Kulcinsky referred to polywell as a dark horse over a year ago, that he didn't have the answers about it yet but expected to get them soon.
In the article he's quoted as saying 25 to 30 years till commercial reactor. That could be interpeted to mean he's skeptical of WB8, but more than likely I'm reading too deeply between the lines.

choff wrote:I remember Kulcinsky referred to polywell as a dark horse over a year ago, that he didn't have the answers about it yet but expected to get them soon.
In the article he's quoted as saying 25 to 30 years till commercial reactor. That could be interpeted to mean he's skeptical of WB8, but more than likely I'm reading too deeply between the lines.

Ther is some confusion in the article, probably from the writer. Selfsustainig the reaction (ignition) only applies to thermonuclear processes like Tokamac of laser confinement. I have generally considered that breakeven fusion has been already been achieved in hydrogen bombs. Though reading the Wikipedia article makes me wonder. The purpose of the tritium, etc. is to provide neutrons to convert a shell of uranium 238 into plutonium and thus greatly increase the fission yield. I don't know wether the fusion adds net power or actually consumes a small amount of the otherwise aviable power before the boosted fision kicks in. The relatively small blast yield of the 'neutron bomb' that has the fusion componant but not the secondary blanket of uranium 238 would support the idea that the fusion energy yield in the hydrogen bomb is not at breakeven (or at least not significantly above it). Otherwise, why use the fusion to produce neutrons to drive a seconday fission process. The term hydrogen or fusion bomb is missleading as they are actually boosted fision bombs. Perhaps this was intentinal in an effort to confuse the compitition.

In that case the NIF may indeed be the first to reach fusion breakeven (or at least thermonuclear ignition), though JET came close. And of course, if Bussard had suceeded in convincing backers to persue the 'WB100' aggressively it might have been in close competition with NIF to be first to net power.




Dan Tibbets

Early bombs were called fission-fusion-fission bombs, because they worked that way. The U-238 wasn't transmuted, it was directly fissioned by the different kind of neutron put out by the fusion reaction--I can't remember how exactly all that worked.

modern "clean" weapons place a greater focus on the fusion stage, and leave out the second fission stage. While the first weapons got close to 70% of their yield from the U-238 tamper fission, modern weapons are designed to get sometimes more than that from the fusion stage.

The NIF is no where near break even.

Also IIRC it is not yet operational.

kunkmiester wrote:Early bombs were called fission-fusion-fission bombs, because they worked that way. The U-238 wasn't transmuted, it was directly fissioned by the different kind of neutron put out by the fusion reaction--I can't remember how exactly all that worked.

modern "clean" weapons place a greater focus on the fusion stage, and leave out the second fission stage. While the first weapons got close to 70% of their yield from the U-238 tamper fission, modern weapons are designed to get sometimes more than that from the fusion stage.

In that case, then yes, breakeven fusion reactions have already been achieved on Earth, though in a violent way.

MSimon wrote:The NIF is no where near break even.

Also IIRC it is not yet operational.

I wondered if I was wrong to consider ignition equivalent to breakeven as opposed to merely a prerequisite for breakeven in a thermonuclear fusion reactor.

I know NIF stands for National Ignition Facility.
What does IIRC stand for?

Dan Tibbets

IIRC - common (not common enough?) internet slang - If I Recall Correctly

Google is pretty good these days for "strange" acronyms and abbreviations.

MSimon wrote:IIRC - common (not common enough?) internet slang - If I Recall Correctly

Google is pretty good these days for "strange" acronyms and abbreviations.

Yep, the acronyms for IIRC is the first listed item from a Google search. I like the fourth possibility.

http://www.acronymfinder.com/IIRC.html

Dan Tibbets

Ahhhhh.....Isnt NIF to test Pu for bombs . . .. . . .

I'm sure they'll have some plasma data that will be of interest when done, but really now, it has very little to do with what we are interested in here at talk polywell.

kunkmiester wrote:Early bombs were called fission-fusion-fission bombs, because they worked that way. The U-238 wasn't transmuted, it was directly fissioned by the different kind of neutron put out by the fusion reaction--I can't remember how exactly all that worked.

modern "clean" weapons place a greater focus on the fusion stage, and leave out the second fission stage. While the first weapons got close to 70% of their yield from the U-238 tamper fission, modern weapons are designed to get sometimes more than that from the fusion stage.

Fusion generates fast neutrons and the cross section of U238 is higher than U239. That's the purpose of "fast breeder" reactors - you use fast neutrons to burn the U238 and convert it to PU which also has high cross section. With all the U238 lying around it made sense. Now that U238 punches holes in armor, there is reason to get the fusion stage working to release more gammas rather than neutrons. Overall bang for the buck = don't waste anything.

The next stage is shaped nuclear charges. I'd love to know how they intend to make that happen.

kunkmiester wrote:modern "clean" weapons place a greater focus on the fusion stage, and leave out the second fission stage. While the first weapons got close to 70% of their yield from the U-238 tamper fission, modern weapons are designed to get sometimes more than that from the fusion stage.

And 4th generation weapons purge the fission primary entirely.

drmike wrote:The next stage is shaped nuclear charges. I'd love to know how they intend to make that happen.

Project Orion developed that waaaay back in the day, called it Casaba-Howitzer.

Now that U238 punches holes in armor, there is reason to get the fusion stage working to release more gammas rather than neutrons.

It's a whole heck of a lot cleaner too. Fun thing, the first lithium deuteride bomb had a much greater yeild then they thought, because the lithium reaction produced fast neutrons too, fissioning more uranium.

And 4th generation weapons purge the fission primary entirely.

How the blue blazes do you expect to do that? If conventional explosives were enough to create enough fusion to create an explosion, it'd be mind boggling. Or are "fourth gen" weapons still in progress?

That would actually make the salt cavern idea practical. Drop a bomb down, melt the salt, harvest the heat, repeat. One of the more unconventional ideas.

kunkmiester wrote:

And 4th generation weapons purge the fission primary entirely.

How the blue blazes do you expect to do that? If conventional explosives were enough to create enough fusion to create an explosion, it'd be mind boggling. Or are "fourth gen" weapons still in progress?

Chemical explosives are of course insufficient; that was determined back in the '50s. Here is an open source review of some possibilities.

kunkmiester wrote:That would actually make the salt cavern idea practical. Drop a bomb down, melt the salt, harvest the heat, repeat. One of the more unconventional ideas.

PACER? Waste of material. A Wang Gun has potential tho.