Talk-Polywell.org

Poor little fuel pellets are being exposed to dangerous UV laser pulses at NIF!

I would be more impressed if I heard some fusion results from the tests, but who am I to complain? I'd like to here what EMC2 is producing, too. But they so say the laser pulses are a megajoule. Does that sound a bit weak for a fusion shot on a pellet around 6 mm in diameter?

http://www.rdmag.com/News/2010/10/Gener ... nt-At-NIF/

On the topic of the NIF, could someone explain something to me - it's my understanding (which might be wrong, not sure), that each pellet will burn for like a few millionths of a second, or milliseconds - very short duration, anyhow.

How would this concept be used to generate continuous energy? I guess they'd have to setup a facility where they basically 'machine gun' the pellets, igniting several hundred or thousand per second in sequence, and use something like ultra-capacitors (or, perhaps flywheels, or some combination thereof) to 'bank' the power between bursts, so that power draw from the plant can be 'smoothed' out, to mask the 'spikey' nature of the power generation?

Since they will get their power as heat, the cooling/shielding material will heat up to some operating temperature with repeated shots. I think they were expecting a charge/drop/fire cycle of several dozen per minute.

WizWom wrote:Since they will get their power as heat, the cooling/shielding material will heat up to some operating temperature with repeated shots. I think they were expecting a charge/drop/fire cycle of several dozen per minute.

I suspect that the charging time for the 192 NIF lasers if going to be considerably more than a few seconds. And of course the energy needed to create any single fusion event will almost certainly greatly exceed the energy produced.

This shot was damped with ordinary hydrogen, since they didn't want any actual fusion. Chickens!

And NIF will never be the basis for actual energy production. The laser-charging, pellet-cycling, explosive plasma-management problems are several bridges too far.

WizWom wrote:Since they will get their power as heat, the cooling/shielding material will heat up to some operating temperature with repeated shots. I think they were expecting a charge/drop/fire cycle of several dozen per minute.

The original design specification was requesting a cool down time between each shot of 5 hours or less, or minimum of 700 shots year.
https://www.llnl.gov/news/newsreleases/ ... 06-01.html

If it didn't change should still be the figure of reference.

Consider than only around 15% of the total energy is actually transferred to the chamber, the rest needs to be dealt with in the form of heath and x-rays.

WizWom wrote:Since they will get their power as heat, the cooling/shielding material will heat up to some operating temperature with repeated shots. I think they were expecting a charge/drop/fire cycle of several dozen per minute.

I was under the impression that they would need to fire several dozen times per second to have any chance for any useful power outputs.

From 5 hrs to second time scales. The charging and cooling requirements would be a lot more than the currently huge structure already built. Even if theoretically possible, the cost per kWh may put even Tokamaks to shame.
The wild card may be shortend duration lasers that deliver more net energy / nanosecond to the target, such as what is being built in Italy. These may have advantages (or not) in terms of engineering and cost.

Dan Tibbets

Like ITER, it's a very complex, impressive and exciting science project with little practical value even if it does what it's supposed to.

I agree with Dan and Talldave. Seems like a nice (and quite expensive) science experiment. I just can not see how will ever lead to an economic fusion based energy source.

Skipjack wrote:I agree with Dan and Talldave. Seems like a nice (and quite expensive) science experiment. I just can not see how will ever lead to an economic fusion based energy source.

If it could be seen how it would lead to a working energy source, then experiments would be unnecessary.

Work done at the NIF with respect to Fusion as a power source will be handed off to others, like the University of Rochester in New York State, and the folks musing the Hiper project in England.

I still like the NIF for fusion research despite the sticker shock, and the non melodious song and dance performed for Congressional funding.

Helius wrote:

Skipjack wrote:I agree with Dan and Talldave. Seems like a nice (and quite expensive) science experiment. I just can not see how will ever lead to an economic fusion based energy source.

If it could be seen how it would lead to a working energy source, then experiments would be unnecessary.
...

What a remarkable statement! Since it is clear how Polywell and FF, e.g., would lead to working energy sources, are experiments on them unnecessary?

Brian H wrote:

Helius wrote:

Skipjack wrote:I agree with Dan and Talldave. Seems like a nice (and quite expensive) science experiment. I just can not see how will ever lead to an economic fusion based energy source.

If it could be seen how it would lead to a working energy source, then experiments would be unnecessary.
...

What a remarkable statement! Since it is clear how Polywell and FF, e.g., would lead to working energy sources, are experiments on them unnecessary?

Correct, If your premise were only true.

Last week I watched "Wall Street Money Never Sleeps," one of the highlights of the movie was a NIF type fusion project that the main character and his fiancee want to sink $100 million into. Fortunately for the young couple, they have a very responsible parent, Gordon Gecko(the Micheal Douglas character), who takes away all their money to invest, no doubt, in more lucrative ventures.

In the end however, he does invest the $100 million in NIF, only after making a Billion with it, and only because he's convinced fusion will be the next speculative bubble! Sounds like NIF already has a few people bamboozled.

You can know how something might work (physics) but have a very difficlult, expensive, or seemingly impossible engineering challenge. Such applies to Tokamaks and NIF.
If I had to guess which ICF approach might be most viable as a power plant, I would favor Zandia Lab's Z- pinch. Mostly because I believe they use a spherical target that the could droped into the chamber and zaped when it reaches the center. The laser requires a hollow cylinder that has to be precisely oriented in three dimensions. Doing this many times per second in a very harsh environment with some durable mechanical positioning apparatus would be a daunting task in itself.

Breakthroughs in extremely powerful short burst lasers and development of some magnetic (or electrostatic) system that positions and holds the target might relax the challenges some.

PS: Current research uses gold horboliums (sp?) to hold the target. From the size of the target, I'm guessing that it might weigh ~0.1 gram or more. Burning one perhaps 10 times per second would consume ~ 3600 g per hr, or ~ 120 ounces, 3,000 ounces per day, 900,000 ounces per yr. per plant. Some recovery might be possible, though it might be as expensive as lithium generation in the Tokamak. If other nearly as dense materials (like lead) could be used the problem would be less. Then there is the tritium problem , so lithium blankets and all of the problems with that would also need to be addressed. Even for a fusion fission hybird this would be a very expensive neutron source. Even a feeble (below breakeven) FRC or DPF or Polywell , or General Fusion approach would probably be much more compact and very much more cheaper in this application.

Dan Tibbets

horboliums => Hohlraum?