[nemmart]

zapkitty wrote:

Oh come on Zap, why would you assume that the only way to increase the fusion output beyond 66 KJ is by changing to D-T fuel?

Would you believe it was your statement of the need to increase the fusion gain by a factor of 6? 🙂

nemmart wrote: There are more parameters that can be tweaked than just the fuel…

But they all amount to increased heat in the core… unless you’re postulating some currently unknown mechanism that will lead to a far more efficient fusion process than is currently envisioned?

While there is some flexibility there, some leeway towards a core that is a bit hotter or a bit cooler, there is just not near enough margin to septuple the output without melting the core.

Well, if the scaling law is roughly the current to the 5th power, then a raising the fusion output by an additional factor of 6 might not be that big of a deal. It might be far easier to raise the fusion output by a factor of 6 than to hit the conversion efficiency targets of 80-90%.

And in terms of heat, if you raise the fusion output, just slow down the shot rate so you don’t overheat the core.

[nemmart]

zapkitty wrote:

The thermal output of an FF unit operating at 200 Hz has been estimated at ~7 MW thermal… doable, but pushing things a bit.

Initiating each shot requires 100 KJ from the capacitors. If the conversion efficiency is low (say 40%) then you won’t get enough energy from each shot to recharge the capacitors for the next shot. And the shots/sec is irrelevant.

The question is core temperature and so the results will be the same whether you increase the shot rate or the energy per shot.

The final set of beryllium electrodes will be quite a bit smaller than the old copper and current tungsten designs. Less mass and closer to the plasmoid. Increase the temperature too much [em]and the anode is going to be slag.[/em]

nemmart wrote: A plan B designed around a lower conversion efficiency would require far more energy from the fusion reactions, something like 400 KJ per shot instead of the planned 66 KJ.

That would, of course, mean switching from an aneutronic to a neutronic process. Switching from pB11 fuel to D-T fuel… from hydrogen-boron to deuterium-tritium .

And that just means that the anode will not only be slag but the entire FF core will be highly radioactive for centuries to come. Not very good for the FF project.

The temptation of D-T… the low-hanging but extremely radioactive fruit of the fusion fuel tree.

Interesting aside: EMC2’s Polywell project recently seems to be trying to use the prospect of D-T fuel to lure in investors… which seems odd since D-T’s intense high-energy neutron flux would quench the HTSC coils a Polywell power generator would need to function.

Oh come on Zap, why would you assume that the only way to increase the fusion output beyond 66 KJ is by changing to D-T fuel? There are more parameters that can be tweaked than just the fuel. Why not go to a higher power like 3 MA, perhaps by increasing the capacitor voltage, or going to 15 capacitors instead of 12? See, I don’t know the various parameters that can be tweaked and what the real physical limitations are. But there must be someone on the forums who does know the parameters and could formulate a realistic plan B.

[nemmart]

zapkitty wrote:

I would advocate that someone on the LPP team or who knows what parameters can be tweaked should be looked to see if there is an alternative configuration that produces more fusion power per shot.

This seems to be a fairly common misconception… the power output of an FF unit is primarily determined by its pulse rate. Any increase in individual shot power can be approximated by increasing the pulse rate.

And the maximum pulse rate is governed by anode cooling. The thermal output of an FF unit operating at 200 Hz has been estimated at ~7 MW thermal… doable, but pushing things a bit.

Mhmm, well, I probably should have written “more fusion energy per shot” rather than “fusion power”.

Initiating each shot requires 100 KJ from the capacitors. If the conversion efficiency is low (say 40%) then you won’t get enough energy from each shot to recharge the capacitors for the next shot. And the shots/sec is irrelevant. A plan B designed around a lower conversion efficiency would require far more energy from the fusion reactions, something like 400 KJ per shot instead of the planned 66 KJ.

[nemmart]

If the onion and ion beam capture hit the 80-90% targets then everything will be just peachy.

But I’ve been following this project for a while and there are more twists and turns than a
mountain road. Switch problems that had to be overcome, arcing issues, plasma impurities,
and several redesigns of the cathode and anode…

It’s not too difficult to imagine a scenario where the fusion works, but the engineering to hit
the 80-90% conversion efficiencies fails. This could be for a lot of different reasons, maybe
the ions comes out at different velocities and must be sorted and some energy is lost. Or
maybe the ions come out in a spread out cone and not directly down the axis of the machine.
Who knows. And I’m sure there are even more issues for the onion.

To me, this seems like a significant risk to the project.

So why not have a plan B in place? I would advocate that someone on the LPP team or who
knows what parameters can be tweaked should be looked to see if there is an alternative
configuration that produces more fusion power per shot. We know that a heat engine can
achieve 40% efficiency and as per the earlier post:

> fusion energy output is 4x the input (input energy + 4x for fusion energy=5x input * .4 = 2x
> input, as is the current goal).

I realize that using a heat engine will increase the cost of the energy produced by a FoFu significantly.
But it should still be significantly cheaper than a natural gas plant. It would provide base load power
and would still be a very compelling option.

[nemmart]

That doesn’t really answer my question. If we assume a 40% conversion efficiency for both X-Rays and alpha particles, is it
still possible to engineer a DPF power source? i.e., fusion energy output equal to 4x input energy?

[nemmart]

Mike Weber Goodenow wrote: Extremely interesting. $25 to $30 million for a generator, within 5 years of a successful test, which may be 3 months away? That’s fascinating.

Er, I’d say 3 months away is a wee bit on the optimistic side.

[nemmart]

Breakable wrote: http://fora.tv/2010/06/16/Ed_Moses_Clean_Fusion_Power_This_Decade

This was a nice talk. Thanks for posting it.

There are a couple of question that I wish had been asked…

I had seen a talk on the web a few years about about ITER — here’s the link: http://vmsstreamer1.fnal.gov/VMS_Site_03/Lectures/Colloquium/050428Smith/index.htm

In the talk, Chris Smith discusses the very difficult engineering challenges:
1) Designing the lithium blankets and the processing to replace the tritium burned
2) The heavy neutron bombardment weakens the containment structure

He said the engineering challenges would take years to solve and test and would require
a dedicated IFMIF facility.

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.

[nemmart]

QuantumDot wrote: there is a design for a thermo photo voltaic device that in theory could achieve 85 percent efficiency, from what i have read it hasn’t come close to actually achieving that but there is hope that it will.

This sounds like Power Chips (www.powerchips.gi). Not sure if it’s snake oil or if it’s real. Anyone know the scoop on these guys?

[nemmart]

Lerner wrote: Brian, your model of free consumers optimizing their own choices does not fit the real world. The energy companies cannot possibly make up the tens of trillions of dollars they will lose if the price of oil falls to anywhere near its cost. The principle owners of the energy companies are the major global financial intuitions—BP’s main owner is JPMorgan-Chase, for example. They will be bankrupt if oil and gas falls to its cost of production. The few thousand individuals who sit on the boards of directors of the giant companies in every industry in the world (who are also generally directors of financial institutions or energy companies) are themselves most heavily invested in energy and in finance, which are the most profitable industries. They will not make decisions based on the competitive advantage of a given industry, but on maximizing their own personal wealth, which means protecting oil and gas, even if that means higher costs for everything else.
As others have pointed out, the best way to counter these few immensely wealthy individuals—a method which has worked in the past—is building (over years) mass movements that can counter their political power. Focus Fusion folk need to be part of doing that, building our own efforts and reaching out to potential allies who want cheap, clean energy and everything that brings with it. The first step is educating people about what can be done, and what needs to be done–and inoculating people against future dirty tricks—like lumping aneutronic fusion together with fission so it can be labeled as too dangerous to use or falsely claiming that it will contribute to nuclear proliferation, etc.

I wouldn’t worry too much about the potential longer term politics. That stuff will play out — if FF works, it will be adopted somewhere and it will spread over time. The thing that I would worry about the most is making sure that the results are clear and reproducible. Although there will be an incredible temptation, do not hold back on any “secret sauce” in the interest of holding on to the profits. Just patent some important bits, license it out for small sums per unit (5% royalty maybe?) and hope for the best. Set this technology free. The world really needs it.

What really would kill this dead is if the results aren’t reproducible. It’s critical that alternative fusion approaches do not suffer another Pons and Fleischmann fiasco.

[nemmart]

Just thought I’d chime in — haven’t seen any more data from the shots in a long time. Anything interesting coming?

[nemmart]

Okay — let’s dream for a minute. Suppose FF works… (all posts should start with that).

Think about ports:
– there are limited places for ports – requires a coast and deep water
– shipping is damn slow
– the busy ports often have long unload queues
– a lot of freight just passing through the port — only because there is not a direct route from source to destination.

Imagine a different world:
– all major freight transport goes by air — because it’s fast and the fuel is free
– airports to handle freight get built everywhere
– trucks are only used to get the goods from the local airport to the final destination
– use a point to point air traffic control system, handled locally by each plane instead of the centrally managed mess
– imagine instead of all these truckers having a truck they were all pilots, owning their own freighter and controlling their own route

So what would this enable?
– much shorter supply chains (that’s a huge huge win right there)
– it completely changes food distribution, you’d actually get fresh produce that was out of season 😉
– you could probably reduce the amount of highway maintenance and rail maintenance dramatically, you just wouldn’t need it
– it’s really decentalized, a bit like PCs replacing mainframes.

I love it!

[nemmart]

Breakable wrote: It seems the output is ~6.4 mj per shot.
https://focusfusion.org/index.php/site/article/how_will_we_get_there_from_here/
So its not MW or MWH but joules(not power but work), because it is per shot not per second.
If we have 1000 shots per second the the power would be ~6.4 gw
if 1 shot per hour then only 1.7 kilowatts.
It probably boils down into thermal and radiation flux management. EE part probably is hard only at mult-hertz.
I think the first prototypes as well as first generation units will be low frequency to reduce complexity of radiation and thermal management.
As the escaping radiation flux is probably a function of frequency, at this low frequency the shielding requirements probably can be considerably reduced
to fit a FF unit into a backyard, a truck, maybe with improved shielding materials even into a car.
Probably after a few generations of reactors are developed we will see it climb into MW or GW range and made smaller to fit onto a plane.

The units are wrong – it’s 6.4 kj not mj. See the “how_will_we_get_there_from_here” doc. Also, I think in Eric’s google tech talk, he mentioned 330 hz.

[nemmart]

jamesr wrote:

Is it silly me or is the 0.282 kN = 0.282 MW?
Edit:
Boeng output is probably per second
Where FF is per hour, in that case we need ~203 modules with electrical output
or 102 with full output in case efficiency is similar.

1W = 1Nm/s so 0.282MN/s is equivalent to 0.282MW

another way of looking at it is: Power = (force *distance) / time = force *speed

So if we take the maximum speed (rather than the cruising speed) then this should be where the maximum force the engines can produce is just maintaining the speed and not accelerating it.

We have max speed (from the same wiki link above) = mach 0.92 @35000ft = 988km/h = 274m/s
Force = 4*262kN = 1048kN

Therefore Power of 747 at full thrust = 1048000*274 = 287152000W ~300MW

or 60 5MW FF generators!

Something is fishy though. According to http://www.howstuffworks.com/question192.htm, a 747 burns 36,000 gal over a 10 hr flight, or about a gallon a second.
A gallon of Jet A has ~121 MJ. 121 MJ delivered in 1 second is 121 MW. Therefore, averaged over a 10 hour flight, you need 120 MW, or 24 FF’s. The difference
might be explained as a peak vs. average output.

[nemmart]

psupine wrote: I’m still trying to understand some of the subtleties too (I bet we all are!), so please excuse me if this question is so bad that it isn’t even wrong …

Doesn’t conservation of momentum require a significant e-beam to balance the ion-beam from which we hope to extract significant energy? So if optimality has the e-beam energy reduced as much as possible, I’d have thought that the ion-beam is similarly down to nothing or else the plasmoid shoots sideways (or rather in FuFu, up).

I’m sure someone can set me straight. I hope to get there eventually.
Thanks

Lerner wrote: It is very difficult for the electrons to balance the momentum of the ions which are thousands of times heavier. Two things can absorb the momentum of the ion beam–the motion of the plasmoid, or the magnetic field that the plasmoid is tied to. It is probably mostly the latter, since otherwise the plasmoid would smash into the anode before the pulse ended.

I think this is a really interesting question. I don’t understand why one should expect the alpha particles to all go in the right direction, down the axis of the anode. When the excited C12 fissions, I would expect the alpha particles to go shooting out in random directions, with piles of energy. More energy than is in the plasma. Is there a good reason to believe the plasma can capture this energy as opposed to the alpha particle punching through it?

When you run a DPF with deutrium what what percentage of the fusion energy gets captured by the plasma? Does the amount of neutron radiation change with direction?

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