TallDave wrote: Yes, I think I ended up liking your calc better.
Thank you.
TallDave wrote:WB-8 needs to show some beam-beam power scaling and loss scaling at least vaguely resembling Bussard's claims. Then hopefully WB-8.1 will show we can burn p-B11. And then, maybe we try to build a world-changing reactor.
I think the gradualist mindset is a result of the slow progress of all those big toks that never quite ignited. High-beta devices may jump right from 64W total power to 100MW net power.
In one of his last postings on this forum, Dr. N. warned against trusting scaling laws "confirmed" by units at this small scale.
Seems to me that if they provide a "100mW design" and design in margin etc. they may "surprise surprise" hit 100MW but if scaling doesn't work and they only break even... Crafty planning I think, what?
After all, if the target is 100MW and he is off DOWNWARD but 9 orders, "turn out the lights, this party's over". If he is 9 orders OVER his 100mW target, "oh happy day"!
Well, sure, I don't disagree with any of that. But Murphy lives by cost = r^3 just like the rest of us, and after several decades of fusion research people are excited to get a few minutes of Q>1 for billions of dollars. As Rick said on Cosmic Blog, these (Polywell) machines just aren't that expensive.
I guess I'm just impatient.
n*kBolt*Te = B**2/(2*mu0) and B^.25 loss scaling? Or not so much? Hopefully we'll know soon...
Wasnt it stated by Tom Ligon a while ago that the WB effect doesnt need to really exist for the machine to work, you just have to make it bigger, not 100 times bigger, maybe 10 times bigger?
TallDave wrote:As Rick said on Cosmic Blog, these (Polywell) machines just aren't that expensive.
Depends by what/whose calculation; price per actual experimental neutron is won by tokamaks, hands down. Price per actual experiment, hands down to Polywell. Price per Q>1 device, all we've got is two divide-by-zeros there.
Price per research paper? Depends what's important to you - to gravy-train researchers it's the peer-reviewed research papers. Again, tokamak, hands down.
Robthebob wrote:Wasnt it stated by Tom Ligon a while ago that the WB effect doesnt need to really exist for the machine to work, you just have to make it bigger, not 100 times bigger, maybe 10 times bigger?
yes, that blitheringly unjustified stuff was spat out at some stage - the idea being that if it doesn't work as an IEC device then it'd simply 'fall-back' to work as a thermal confinement device. No reasons at all for such a claim, except the hopeful pipe-dreams of fusion-wannabies.
We all know the machine wont do a tok's job, I doubt anyone believes it can. It has always been about how to keep the system from thermalizing.
What I said is just that the WB effect simply enhenced the scaling law by a whole lot, but before WB, it's supposed to still increase like r^3 or something like that.
Get your strawman outta here.
Note: I didnt type darn.
Last edited by Robthebob on Sun Feb 14, 2010 6:31 pm, edited 1 time in total.
Robthebob wrote:We all know the machine wont do a tok's job, I doubt anyone believes it can. It has always been about how to keep the system from thermalizing.
OK, if you're talking about something else then that's fine, but this WB-as-thermalised-system was touted as a fall back.
If you're speculating that it'll work without a 'WB', then all I would say is that a "WB" is just a matter of degree - you will always have cusps, the question is merely at what point are they so small that you then call it a "WB". Sounds like a length-of-a-piece-of-string question, then.
Depends by what/whose calculation; price per actual experimental neutron is won by tokamaks, hands down.
Bad accounting. You're confounding a nonlinear relationship with a linear comparison; as with a lot of things, there are large economies of scale. Polywells may produce far more neutrons per dollar with the same funding.
Obviously if WB-9 produces 100MW for $100M that blows up the current comparison, and you probably have something that can generate power at a profit which turns the question on its head.
Come to think of it, if WB-8 produces 64 watts for $8M, where is that on the exponential scale? How many watts can you get from an $8M tok?
On the WB: It's necessary. Rick is on the record saying we can kiss our behinds goodbye without it.
n*kBolt*Te = B**2/(2*mu0) and B^.25 loss scaling? Or not so much? Hopefully we'll know soon...
Simon, re:
"I think 1 mW - 10 W - 100 MW is about as extreme a I'd like to go.
The trouble with a progression like that is that the devices are so mechanically different that you can't build much off your previous devices. You go from a device where cooling is not a consideration to one where cooling is everything."
This is all R&D until a 100 MW device is built and Murphy is beat down like a dog. With that in mind, shouldn't a 10 W machine (continuous operation assumed) give you scaling information needed for a 100 MW machine? Assuming it matches present theory, isn't a 100 MW machine within known engineering methods of construction (cooling, shielding, SC design, mechanical support, vacuum pumps, high voltage supplies, etc) and is actually off the shelf for most components?
Are you suggesting that going from 10 W to 100 MW is not the right step size (from an R&D view) and should have an intermediate step?
Cheers
Counting the days to commercial fusion. It is not that long now.
TallDave wrote:Bad accounting. You're confounding a nonlinear relationship with a linear comparison; as with a lot of things, there are large economies of scale. Polywells may produce far more neutrons per dollar with the same funding.
Well, if you agree it is so then I have proved my point - it depends on the person doing the rationale for the meaning of *expensive* and Rick's comment isn't worth the energy to excite my pixels.
The recent UK govt research input into all UK fusion is running at about GBP14M per year. I think an estimate for JET total to date would be reasonably at about GBP200M. For that GBP200M JET has produced a total of ~3E20 neutrons. That's about 1E12 neutrons per US dollar.
So if you ran a 1million neut/sec fusor continuously for 10 days and that fusor cost one dollar to build and run, then you'd be beating JET on neutron emissions per price.
3.1 Magnetic Grid (MG) Insulated, Wiffleball (WB) Polyhedral Device (WB8)
3.1.1 The Contractor shall construct and test a small-scale MG Insulated, Wiffleball Polyhedral Device, WB8. WB8 shall be built based on results of WB7 (built under contract N68936-03-C-0031) and shall utilize design and
performance knowledge gained from test of prior WB machines.
3.1.2 The design shall use circular coils around each main face cusp axis. The device shall use emitter electron gun arrays and an ion beam drive. The machine will be operated in magnetic fields with pulsed currents. WB8 shall be operated at a magnetic field strength of approximately 0.8 Tesla, which represents an increase of 8 times the magnetic field strength of previous WB machines. Improvements over previous WB machines in WB confinement, ion energy and fusion reactivity are expected as a result of these changes to WB machine design.
Ya know... one thing the contract DOESN'T specify is polyhedron shape. This one MAY actually be an icosadodec. They certainly have the money for it!
