Miniaturizing Focus Fusion

[Timo]

Brian H wrote:
For trucks, consider that the total weight of the FF generator, including shielding, is expected to be about 2 tons. I don’t think you get it under the hood; it would have to be a special configuration.

What I actually did mean is there a physical limitation to how small we can get. This first generator FF generator is probably quite a lot too big for for example cars, but can it get that small even in purely theoretical level? Lets say 250kW FF reactor?

Brian H wrote:
As to going orbital, there are some old Air Force studies of DPF as an SSTO power source, using MHD drive. I believe the conclusion was that there was power to spare. If so, theoretically FF is the basis of a sci-fi one-ship-does-all vehicle! If I can find the links, I’ll post them.

Multi-hued Dragon drive? 🙂 Seriously MHD usually means magneto hydrodynamic drive IE. boat motor, I think you mean MPD = Magnetoplasmadynamic drive.

[Timo]

Brian H wrote:
As to going orbital, there are some old Air Force studies of DPF as an SSTO power source, using MHD drive. I believe the conclusion was that there was power to spare. If so, theoretically FF is the basis of a sci-fi one-ship-does-all vehicle! If I can find the links, I’ll post them.

Found one PDF which has couple of interesting references that might help your search: “http://namcub.accela-labs.com/stories/pdf/Advancements in Dense Plasma Focus (DPF) for space propulsion.pdf”

I don’t have time to search further just now, but this definitely is interesting.

[Aeronaut]

Welcome to FFS, Timo. Excellent backgrounder link. Not much hope held out for SSTO without big, expensive rockets, but then the Rocket Equation said to expect that, lol.

[Brian H]

Timo wrote:

For trucks, consider that the total weight of the FF generator, including shielding, is expected to be about 2 tons. I don’t think you get it under the hood; it would have to be a special configuration.

What I actually did mean is there a physical limitation to how small we can get. This first generator FF generator is probably quite a lot too big for for example cars, but can it get that small even in purely theoretical level? Lets say 250kW FF reactor?

Brian H wrote:
As to going orbital, there are some old Air Force studies of DPF as an SSTO power source, using MHD drive. I believe the conclusion was that there was power to spare. If so, theoretically FF is the basis of a sci-fi one-ship-does-all vehicle! If I can find the links, I’ll post them.

Multi-hued Dragon drive? 🙂 Seriously MHD usually means magneto hydrodynamic drive IE. boat motor, I think you mean MPD = Magnetoplasmadynamic drive.
Size: AFAIK, the sizes of DPF devices are constrained by the minimum physics requirements of generating a plasmoid. I’m not sure if it can be made that low-powered.

MHD — well, you’d better let the USAF know it’s misusing the term! :cheese: I found the paper:
http://oai.dtic.mil/oai/oai?verb=getRecord&metadataPrefix=html&identifier=ADA446973
and it says, in part:

The objective of this study was to perform a parametric evaluation of the performance and interface characteristics of a dense plasma focus (DPF) fusion system in support of a USAF advanced military aerospace vehicle concept study (Froning, Czysz, 2006). This vehicle is an aerospace plane that combines clean “aneutronic” dense plasma
focus (DPF) fusion power and propulsion technology, with advanced “waverider”-like airframe configurations
utilizing MHD airbreathing propulsion and power technology within a reusable single-stage-to-orbit vehicle. Early
versions of such an aerospace vehicle, available by 2025, would rapidly reach Earth orbit to deploy, sustain, and
reconstitute space forces with flight operations and take-off weights that are comparable to those of current heavy
Air Force jets. It would rapidly accomplish global reconnaissance or weapon delivery to ground, air, or space threats
by sub-orbital flight around the Earth; and, there would be no requirements for jet tanker fleet logistics support.
Such an aerospace vehicle would have: advanced sensors; communications; and structures; beam weapons; stealth
features; and other unique features, characteristics, and capabilities that might be available by the 2025 time period
to revolutionize propulsion and power capabilities in the more near-term.

Such a high thrust/high Isp system with a high power generation capability would allow military versatility in sub-
orbital space, as early as 2025, and beyond as early as 2050, with a vehicle that embodies advanced
communications-guidance-navigation-control and airframe materials, and augments aerospace vehicle propulsion
and power with field propulsion and power for flight acceleration and ΔV increases of as much as 400 percent for
enhanced capabilities within near-earth and cis-lunar space (Froning, Czysz, 2006). This would be in addition to
enabling even more advanced forms of weapons and defensive capabilities, such as pulsed-train plasmoid weapons,
ultrahigh-power lasers, and gravity devices (Davis, 2004).

The page link above is to the abstract, and it contains a link to the original full report: http://handle.dtic.mil/100.2/ADA446973

Be warned: this downloads a small PDF file without an extension. You’ll have to edit the filename to add “.pdf” to get your software to read it.

[Timo]

Brian H wrote:

What I actually did mean is there a physical limitation to how small we can get. This first generator FF generator is probably quite a lot too big for for example cars, but can it get that small even in purely theoretical level? Lets say 250kW FF reactor?

Multi-hued Dragon drive? 🙂 Seriously MHD usually means magneto hydrodynamic drive IE. boat motor, I think you mean MPD = Magnetoplasmadynamic drive.

Size: AFAIK, the sizes of DPF devices are constrained by the minimum physics requirements of generating a plasmoid. I’m not sure if it can be made that low-powered.

IOW it depends of how small equipment is capable or producing pinch that is powerful enough to produce practical amount of energy. I don’t think plasmoid itself is constraining factor. That is if I have understood the physics right (which is not at all sure thing).

Brian H wrote:
MHD — well, you’d better let the USAF know it’s misusing the term!

I found out that MHD is used for magneto hydrodynamic systems in systems that include fluid dynamics after posting. “hydro” refers to fluids in general.

Brian H wrote: I found the paper:
http://oai.dtic.mil/oai/oai?verb=getRecord&metadataPrefix=html&identifier=ADA446973

The page link above is to the abstract, and it contains a link to the original full report: http://handle.dtic.mil/100.2/ADA446973

Be warned: this downloads a small PDF file without an extension. You’ll have to edit the filename to add “.pdf” to get your software to read it.

Works fine with FF 3.6.12, no need to add “.pdf”. This is what I got: http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA446973&Location=U2&doc=GetTRDoc.pdf

[Aeronaut]

The Focus Fusion test reactor is roughly the dimensions of a 36 cup coffee pot, so it can go into lawn mowers if you can get the shielding, capacitors, vacuum pumps, and other support systems small enough and light enough.

[Timo]

Aeronaut wrote: The Focus Fusion test reactor is roughly the dimensions of a 36 cup coffee pot, so it can go into lawn mowers if you can get the shielding, capacitors, vacuum pumps, and other support systems small enough and light enough.

That sounds nice. 5MW car engine 🙂 Even if it were just very heavy duty trucks, it would still be great improvement over current ICE fossils. Definite ship powerplant material.

I think the shielding is the major problem to miniaturize, others are more or less just engineering challenges.

If I understood physics right you need something that has high hydrogen concentration to capture neutron radiation which basically means water, that that is something that weights a lot. Tried to find some measurements about capacitors but didn’t find any. 25-50kV doesn’t sound much, but IIRC those capacitors are quite big. That might be another not so minor challenge.

[Aeronaut]

Timo wrote:

The Focus Fusion test reactor is roughly the dimensions of a 36 cup coffee pot, so it can go into lawn mowers if you can get the shielding, capacitors, vacuum pumps, and other support systems small enough and light enough.

That sounds nice. 5MW car engine 🙂 Even if it were just very heavy duty trucks, it would still be great improvement over current ICE fossils. Definite ship powerplant material.

I think the shielding is the major problem to miniaturize, others are more or less just engineering challenges.

If I understood physics right you need something that has high hydrogen concentration to capture neutron radiation which basically means water, that that is something that weights a lot. Tried to find some measurements about capacitors but didn’t find any. 25-50kV doesn’t sound much, but IIRC those capacitors are quite big. That might be another not so minor challenge.

I’m currently resigned to a 1 meter water jacket and the same caps, maybe even switches, that LPP’s using for my sketches.

[Timo]

Aeronaut wrote:

I’m currently resigned to a 1 meter water jacket and the same caps, maybe even switches, that LPP’s using for my sketches.

One meter radius ball would weight roughly 4.2 tons, and that doesn’t leave much space for actual equipment. Not quite car material. Does it have to be that big? Is there a better material?

[zapkitty]

And thus the notional DPF “box” can be described as 3m x 2m x 2m… if you work within those constraints for the time being you’ll be less likely to be taken by surprise…

… and why a fusion-powered passenger car? If aneutronic fusion is proven then Chevron will have no choice but to relax its death grip on large NimH battery applications… or they won’t have any options left at all except the auction block.

[Timo]

zapkitty wrote: And thus the notional DPF “box” can be described as 3m x 2m x 2m… if you work within those constraints for the time being you’ll be less likely to be taken by surprise…

… and why a fusion-powered passenger car? If aneutronic fusion is proven then Chevron will have no choice but to relax its death grip on large NimH battery applications… or they won’t have any options left at all except the auction block.

Just hypothetical mind game. How small can we get.

Maybe passenger cars are out of the question for some time, maybe forever, but just one of those 5MW 3x2x2m boxes would power bigger boats and ships just nicely. Other thing I could imagine is a big cruiser-like blimp (airship, dirigible) with nearly infinite range. Would you like to go air-cruising in luxury blimp? I would. Cross-Atlantic flight that takes several days, but with comfort of the luxury ship. Maybe heavy-duty very large range helicopters? 3x2x2 is small enough to fit in locomotives several times over, so trains definitely get that benefit. No more expensive electric overhead wires. This can revolutionize much more than just household electricity needs.

I can’t imagine the savings of the fuel costs for bigger cruisers and cargo ships.

Passenger cars would obviously be battery electric vehicles powered by distributed “grid” of fusion reactors for a long long time unless/until we can get the actual reactor small enough to fit into car.

[zapkitty]

Timo wrote:

Just hypothetical mind game. How small can we get.

Just don’t omit cooling… some applications favor simpler cooling methods than others.

Waterborne transport is easiest. Aircraft can jettison their waste heat into the airstream and can even get some of that energy back with careful design. Locomotives should be easier than road vehicles…

… spacecraft operate in an environment where radiating heat is the key. Different parameters than planet-based transport systems..

[Aeronaut]

We can get much smaller and lighter in some applications where shielding may not be absolutely required- such as a very remote/ underground power plant, perhaps. Just be extremely careful to be sure all possible concerned parties are in complete agreement over the precise meaning of the vague concept of ‘safety’ before you try marketing the possibility, lol.

[Brian H]

Timo wrote:

I’m currently resigned to a 1 meter water jacket and the same caps, maybe even switches, that LPP’s using for my sketches.

One meter radius ball would weight roughly 4.2 tons, and that doesn’t leave much space for actual equipment. Not quite car material. Does it have to be that big? Is there a better material?
It’s a 80-100 cm. shell, not a ball. The calcs are somewhere on the site; try https://focusfusion.org/index.php/forums/viewthread/91/#346 (from 2006).

[Timo]

Brian H wrote:

I’m currently resigned to a 1 meter water jacket and the same caps, maybe even switches, that LPP’s using for my sketches.

One meter radius ball would weight roughly 4.2 tons, and that doesn’t leave much space for actual equipment. Not quite car material. Does it have to be that big? Is there a better material?
It’s a 80-100 cm. shell, not a ball. The calcs are somewhere on the site; try https://focusfusion.org/index.php/forums/viewthread/91/#346 (from 2006).

I guessed that it is not a ball, but ball is a shape with smallest possible volume to surface area and as such also weight. So I minimized it right there, and still got 4.2 tons of weight. Any other shape and it weights even more. Water is heavy stuff.

(which reminds me a case when I explained someone the power of tsunami by giving him mental image of one cube of water coming at 50kph to the wall of a house and telling that is basically same as small car hitting the same place at same speed, and that is just tiny one meter high wave. His face was worth looking when he realized what that means).

[Author]

Posts