[zapkitty]

vansig wrote: However, I read this spring that the plasmoid size is turning out to be smaller than expected — at least in deuterium. if that turns out to be true for boron also, then it would tend to reduce the yield per shot.

I thought the trend mentioned was toward smaller, yet hotter plasmoids?

[zapkitty]

nemmart 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?

Dunno about that group but the basic principle is known: micron-gap thermovoltaic tunneling.

In fact one company was incubated at MIT and took those initials for its name: mtpv corporation.
http://www.mtpvcorp.com

… as I said the principle is known… making it into salable products remains to be seen but it would be tremendously useful if they succeed…

[zapkitty]

… so… going by jamesr’s figures then, onion or no onion, a 50
kW generator capable of running for a half-hour should be able to bring even one of the newly-popular (if somewhat bowdlerized) thermal DPF systems up to speed?…

… that’s not a bootstrap problem.

[zapkitty]

Brian H wrote: Well, initially the idea was to get 25MW out of a FoFu by running it at much higher Hertz. I think 330Hz –> 5MW was decided pro tem to be the best balance of useful power and feasible cooling given current tech. But there will always be the same ratio of heat waste to electricity generated, more or less, so running slower would just mean using more generators to get the desired output, with the same total heat waste. What would be gained?

Well, remember, that for the container DPF the target was already 2MWe to simplify cooling and to fit a known market for portable 2MWe generators.

My current idea of having the option to be able to skip the “bootstrapping in the wilderness” step entirely by having the unit capable of just barely idlng while in transport from wherever power is last available before the worksite… is a different implementation of the same concept…

Sp while you two discuss different rollout strategems for the tech as a whole… 🙂

… would it seem safe to assume at this point that the bootstrap will probably not be an big issue?

[zapkitty]

Brian H wrote: … But since the FoFuz are so cheap, maybe it would be better to install in pairs, so one could carry the load (or enough of it) whenever the other was being serviced. Or link 2+ community sites for the purpose. Or …

Let’s think inside the box for a moment… how about configuring the container so that the DPF can run at just over breakeven without having to deploy the tower?

(Assuming that the tower block is even required in the end… might not be…)

You’d only start it up just before the DPF is deployed to the worksite but being either towed on a semi or hanging under a fusion-powered cargo copter it should be okay if only venting maybe a 100 kW of heat or less…

[zapkitty]

Brian H wrote: It occurs to me that starting up an FF generator in a remote location or carried on/powering a vehicle (distant from either other (operating) generators or the grid) will take some arranging. The capacitors have to be charged up to initiate the self-sustaining sequence, and that would have to be from either the grid, a small auxilliary generator, or batteries, I suppose. The capacitors couldn’t be counted on to hold charge for any useful period of time after a shutdown, either.

Is this likely to be much of a concern or problem?

For my idea of a DPF in a shipping container I’d decided on a small gas turbine generator, designed for neither quiet operation nor optimized for fuel efficiency… and it doesn’t have to charge the caps all at once.

500 kW at 800 amps are common ratings for a gear set sufficiently small (>1.6m3) to be folded into the container’s cooling system area, and the exhaust would be ducted up through the tower… but I wasn’t going to actually go there until I had sanity-checked some ideas I have for the basic cooling mechanisms in the tower.

But wherever the generator winds up just run it until the caps are charged and let the DPF rip…

An auxiliary idea I’d had, but not required, is to have the DPF container with the ability to draw power from its transport the same as a reefer container would. Enough to keep the caps partially charged up, but short of the point on their discharge curve where the caps start leaking excessively… even if the caps are nowhere near a full charge this would save charge-up time when the order to start the DPF is given.

Offworld operations would seem to require either solar panels or fuel cells.

[zapkitty]

Henning wrote: In vacuum? 15m^2 for 5MW? Really? Sorry, I just didn’t know.

Not exactly.

When you are relying strictly on radiation for heat rejection and can’t use convection, as is the case in space, then the efficiency of the radiator varies as the fourth power of the radiator temperature.

from my worksheet:

kWe 5062.98
kWt 5062.98
stefan’s 5.67E-008
emissivity 0.85
temp (c) 1000
radiator area (m2) 40
double-faced (m2) 20
sqrt 4.47 meters per side.

…………. now let’s cool things down a bit ……….

kWe 5004.6
kWt 5004.6
stefan’s 5.67E-008
emissivity 0.85
temp (c) 450
radiator area (m2) 380
double-faced (m2) 190
sqrt 13.78 meters per side.

Henning wrote: So with atmosphere you’ll wouldn’t need a water-driven colling tower. That’s great! Or am I missing something?

Still working on the parameters for the DPF portable container but no, the point of an open-system water cooling tower at a power station is to get rid of massive quantities of heat for as little energy expenditure as possible… and when you can evaporate water and discard it that’s easy.

A presumably closed system such as a disaster response power plant or a desalinization plant requires a bit more fiddling but even for the DPF container my Transformer(tm)-like cooling tower is a closed loop water system akin to nothing so much as a big car radiator… a car radiator cubic meters in volume and using several tons of a standard water-antifreeze mix 🙂

[zapkitty]

Aeronaut wrote: Ladies and gentlemen, our most apparent detractors, like most posts in these threads, seem to assume that we mere mortals can do nothing to change reality.

Uh… translation? What is an “apparent detractor”?

Advising of a set of very real pitfalls and possible countermeasures to same is hardly being a “detractor” and such labeling serves no useful purpose in discussing a set of facts that are very much in evidence.

As for the rest of your comment… you seem to think that the middle managent will be calling the shots for the uber-wealthy…

… when the results so far have been those in power announcing yet another “grand bargain” with the uber-wealthy via their proxies in the corporations… a bargain that always winds up with the oligarchs walking away everything they wanted with a cherry on top and everyone else getting screwed, blued and tatooed.

The question you should be thinking on is this one:

“How can you deal with them when they believe they can have everything without your help and have no problem with being as dishonest and as ruthless as it takes to get exactly what they want?”

[zapkitty]

Brian H wrote:
As I keep re-iterating, I can’t see how they could cause trouble for anyone but themselves. The initiation of FF power production (or even setting up a generator mfg. plant to make and sell them) would leave any region/jurisdiction/market that opted to refrain from getting on board out in the cold. No customer base will put up with 10X+ higher costs just because a quasi-monopoly wants to exclude the competition or sell only a higher-margin product. Businesses and their jobs and production will ‘vote with their feet’, if all else fails.

Plus — investing in FoFus and quickly increasing the market (consumption) has a much better ROI than standing pat. I’m sure their accountants will make that quite clear to them.

Perhaps you miss the point… they will try as surely as the sun rises. This immense change will mean an opportunity for equally immense profit-taking on the part of our lords and masters.

They are very used to bending governments and laws to their will and getting their way no matter what it costs their serfs… I mean their “customers”…

They will try and they, de facto, wield vast power.

But it will be funny to watch the “deregulation” tide suddenly turn, at least as far as this particular subject is concerned, and those fierce advocates for liberty will start carefully explaining how aneutronic fusion must be strictly regulated under experienced corporate oversight.

And the House and the Senate will, again, carefully follow their instructions from the oligarchs…

[zapkitty]

vansig wrote: Any use for flexible ceramics? eg: to enable higher operating temperatures

https://www.flexibleceramics.net/Developed_Products.html

(… pleasant daydream about a replacement power system for current spacecraft equipped with the ridiculously small radiator that comes from running it at 1000 degrees C… add some clever multilayered insulation engineering using vacuum and the rest of the spacecraft can stay cool as a cucumber…)

[zapkitty]

Aeronaut wrote: I’d hazard a guess that the average person has no idea how plentiful, cheap, clean energy is going to help improve his or her world. It requires too much imagination without a benefit such as paying 1/20th of their current electric bill. And in the winter, something like 1/20 of their heating bill. Those make effective carrots worthy of some extra thought.

… so what you’re saying is that we need is a grassroots combination of an Atoms For Peace program (this time with a reality-based set of projections) and a Five Year Plan for the Effects of Fusion on the Global Economy (this time based on an economic model that bears some relation to reality)… I’ll get right on that… 😉

[zapkitty]

MTd2 wrote: Also, no mention of milestone 4 and 5, and things seems to get confusing, because generally either projects follow linearly or in parallel. It seems these 2 steps were also ignored and preparations for milestone 6 and 7 is just everything that is being done right now.

I thought that this was sort of an intermission period with Lerner-hakase in Greece and that various related tasks were being performed in the meantime as schedules and funding allowed?

[zapkitty]

And the problem with that is that the massive and unrelenting corporate funding of climate change denialism has created a class of people who have honest and serious doubts about the concept of human influence on the global climate and are extremely vocal about it… while remaining blissfully unaware that they have created a self-perpetuating and self-repairing belief system that exists to further oligarchic talking points…

[zapkitty]

Tulse wrote:

You know what I’m talking about though, right?

Focus fusion jet packs? 🙂

… errr… even a flying car would be a bit too small for the currently proposed DPF specs… a flying mobile home, perhaps?

[zapkitty]

Given that the competing units are gas turbines with very hot exhausts I see no problem with upping the tower exhaust temperature to about 150 degrees C or higher… still short of igniting stray leaves blowing by :)… and enabling us to drop the extra power required for cooling by quite a bit.

Thoughts?

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