Project FOOF - Declassified!

If polywell fusion is developed, in what ways will the world change for better or worse? Discuss.

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zapkitty
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Project FOOF - Declassified!

Postby zapkitty » Mon Apr 12, 2010 4:23 pm

"Fusion On Orbit Fastest" - Project FOOF :)

If polywell and pB11 pan out I've been considering the best methods to implement a polywell-powered spacecraft as quickly and as economically as is feasible. I believe that research enabling the quick application of such systems in space is important to overall fusion research and development.

And while I, like many others, want to get in my spaceship parked in my back yard and fly straight to Mars without any stops along the way... it would seem to be a good idea to build some less ambitious intermediate types of spacecraft first :)

Here I'll postulate that one way to Fusion On Orbit Fastest is to use current launch vehicles to loft a prototype fusion power supply for a small commercial space station.

As of spring 2010 the phrase "small commercial space station" is practically synonymous with a Bigelow Aerospace inflatable "Sundancer" module and it seems that one or more of these 8.7 meter by 6.3 meter pods would be a good match for hosting a prototype space-based polywell with net power in the 100 megawatt range... a spaceborne WBD. Call it a WBD-S.

A standard Sundancer has 180 cubic meters of pressurized volume and includes basic life support. It can have a Russian-style docking adapter on one end and one of the new American LIDS adapters on the other end. It can support its own solar power arrays and can be fitted with airlock nodes and a variety of propulsion modules.

Thus the module should be able to hold the technicians and their monitoring gear in pressurized comfort. I'd think that two such modules or a 14 meter long "BA-330" should hold all the crew and facilities that would be needed for an extended testing regime.

A crew return vehicle, most likely a Spacex Dragon capsule, would remain docked at the station while the testing of the prototype was underway.

The WBD-S reactor module would be mounted behind a shadow shield and, if needed, at a distance from the station on an inflatable truss The dimensions of the shield and truss being based on what seems prudent for testing.

The most difficult part of the station will be the module holding the reactor. If even a breakeven polywell setup has a minimum diameter of 7-8 meters then there will be no launch vehicle capable of lofting an assembled reactor into LEO... much less the research and testing module such a reactor would need to be nested in.

And understand this: assembly in microgravity is hard. Assembly in microgravity in vacuum is damned hard. Assembly in microgravity in vacuum in a spacesuit is a royal pain in the ass. After the harsh lessons learned from the construction of the ISS anyone who plans on even more intricate assembly work on orbit needs to be aware that such a project is simply not going to happen.

(At least not until after they finish developing skinsuits)

But Bigelow has offered to make custom modules to order and so I hope it would be possible to wrap the parts of the WBD-S in such a custom module and then to assemble the station on orbit and inflate the module. Then the wBD-S would be assembled inside the module and the module depressurized as needed for testing.

Given the probable testing regime pumps to scavenge some air back during each depress would probably pay for their own development in replacement air mass lifted to LEO.

That's a basic outline. I'd like to flesh it in as more data on polywell infrastructure needs becomes available and I've further notions on selling the power the WBD-S generates while operating to various experiments also hosted on board the station....

zapkitty
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Postby zapkitty » Tue Apr 20, 2010 6:09 am

Tempting... A possible way to speed deployment... but is it cutting things too close? Needs a sanity check here...

While PW doesn't scale small very well it is a fact that current spacecraft power regimes deal in kilowatts, not megawatts. Even pulse generation of a few MW a couple of times per day would be a fountain of limitless power from the point of view of ISS or Bigelow operations... at least as they are currently planned... and should serve well enough for researching and validating PW operations in space.

So if the interior diameter of a Bigelow Sundancer module should be about 5.4 meters and the cylindrical section should be about 4.8 meters before curving up to the module axis...

... and the latticework core of the module as been disassembled and removed...

... and as Bigelow module walls are in many ways tougher than ISS module walls...

... and as the need for cooling and startup power etc will require connections to, and a good deal of auxiliary equipment located in, adjacent nodes anyway...

... a PW and collection gear would technically fit in a Sundancer, albeit crowding the module walls.

But would the researchers be able to work with the equipment? Would the alpha collectors be too densely packed to allow the people to get at the rest of the gear?

If not, then what about a similar setup with a BA-330? The 330 is the followon to the Sundancer at the same diameter and about twice the length and is intended to be the main module for Bigelow stations after the Sundancer is deployed. Although it comes after the Sundancer it should still be faster and cheaper than a custom larger module for the PW... and will have room to allow gear to be shifted laterally within the module.

So... does either a Sundancer or a BA-330 seem workable from an accessibility point of view?

Other problems or caveats?

Nik
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Skylon by modules, or Heavy Lift.

Postby Nik » Tue Apr 20, 2010 10:28 am

Uh, as I see it, you must arrange to assemble eg Skylon-shipped Polywell modules in shirt-sleeve environment, vent, bake then retreat to safe distance and light up.

Alternative is a one-shot ride on super-heavy lift rocket that the Big_Ob wants NASA to build...

Pure coincidence, of course, of course...

zapkitty
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Re: Skylon by modules, or Heavy Lift.

Postby zapkitty » Tue Apr 20, 2010 1:37 pm

Nik wrote:Uh, as I see it, you must arrange to assemble eg Skylon-shipped Polywell modules in shirt-sleeve environment, vent, bake then retreat to safe distance and light up.


Skylon would work wonders for shipping PW parts... when it's flying ;)

But I was aiming at using existing LVs so as to get a test unit lofted as a research project as soon as was feasible after net power has been reached. Net power should be within months, hopefully, and Skylon is still years away from test flights.

As for assembly under atmospheric pressure: that pretty much leaves a Bigelow module as the only currently viable place on orbit where you could assemble a net power PW. Thus my wondering if one could install a PW directly into an existing Bigelow module rather than having to order up a larger-diameter custom module just for testing and validation.

As for having a PW next door while on orbit... well, space stations produce net water and it makes an acceptable shielding material, especially for shadow shields. And the 40cm thick layered synthetics of the Bigelow module walls contain lots of hydrocarbons etc and are respectable shields in and of themselves. It's one of their selling points.

Add a node or two or an inflatable truss/spacer (based on BA's currently flying Genesis modules perhaps) for distance shielding and the station inhabitants should be fine.

Or an additional Sundancer in the module chain being used to house testing and support gear and for bulk storage would be good for both distance and mass shielding as well.

The question is would it be possible to design the PW itself so that it could operate and be worked on... in a Sundancer? Or a BA-330?

Betruger
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Postby Betruger » Tue Apr 20, 2010 3:45 pm

I've never looked for actual documentation, but IIRC the Bigelow modules have a load bearing structure down their middle.

zapkitty
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Postby zapkitty » Tue Apr 20, 2010 4:56 pm

Betruger wrote:I've never looked for actual documentation, but IIRC the Bigelow modules have a load bearing structure down their middle.


There is a lattice work truss down the middle, but Bigelows are supposed to retain their structure sans the truss once inflated so I said "... and the latticework core of the module as been disassembled and removed..."

Oops...

... "inflated"...

... and the modules must be rigid indeed with 14 psi holding them steady across all those square inchesi... but once the module is depressurized for PW operation we will have a problem.

The module walls would not deflate as an earthly balloon would but they won't be providing much support either.

(Thanks! ... this is why its good to have sanity checks :) )

Hmmm... once on orbit could a truss replacement structure be integrated utilizing the collector supports and magrid nubs along with the original truss?

If that is possible then the truss could remain, running from hatch to hatch down the axis of the module and holding, and becoming part of, the PW assembly somewhere along its length.

Betruger
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Postby Betruger » Tue Apr 20, 2010 5:46 pm

Part of the PW assembly is what I was thinking, shoulda been clearer. Sorry.

Also, lots of Bigelow details can be found by searching patents. The biggest publicly mentioned design might be there too. Over three thousand cubic meters IIRC.

...
I can't recall the website I'd used to find Bigelow patents, but I'll look for it again in a bit. This is where I first read about the >3000cu.m module:
http://www.space.com/businesstechnology ... 00414.html

BenTC
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Postby BenTC » Tue Apr 20, 2010 9:43 pm

zapkitty wrote: ... and the modules must be rigid indeed with 14 psi holding them steady across all those square inchesi... but once the module is depressurized for PW operation we will have a problem.


Have an extra layer at the wall to continue to be pressurised once the air is evactuated from the main structures, so it holds up like a bouncy castle.
Last edited by BenTC on Wed Apr 21, 2010 12:29 pm, edited 1 time in total.
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KitemanSA
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Re: Project FOOF - Declassified!

Postby KitemanSA » Wed Apr 21, 2010 12:16 am

zapkitty wrote: Here I'll postulate that one way to Fusion On Orbit Fastest is to use current launch vehicles to loft a prototype fusion power supply for a small commercial space station.
Use it as the power sourse for a hypersonic skyhook. The limiting factor on a HS is the ability to re-boost after capturing and raising a payload. Most plans incorporate an electro-dynamic tether (effectively an electric motor) to re-boost but that takes quite a bit of power. Published papers show a re-boost time of about 14 day which REALLY limits the functionality. 50 times the power allws 50 time the mass boosted per unit time. I think a Polywell would do GREAT for this purpose.

Betruger
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Postby Betruger » Thu Apr 22, 2010 1:46 pm

This is the website I'd found some details from.
http://www.freepatentsonline.com/
You might get just enough details for a reasonable enough estimate of the specifications of those unannounced jumbo modules.

MSimon
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Postby MSimon » Wed May 12, 2010 6:24 am

While PW doesn't scale small very well


Actually with SC magnets it does scale small very well.

i.e. a 2 m dia SC magnet at 10T could produce 20T at 1 m dia.

Since power scales as B^4 while volume scales as R^3 power rises linearly with reduced dimensions. There are limits to this - i.e. enough volume for the magnets and their cooling, but that is the trend.
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KitemanSA
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Postby KitemanSA » Wed May 12, 2010 2:47 pm

MSimon wrote:
While PW doesn't scale small very well
Actually with SC magnets it does scale small very well.
i.e. a 2 m dia SC magnet at 10T could produce 20T at 1 m dia.
I believe this requires the magnet's cross-section (i.e., the minor diameter of the torus) to remain the same size. In such a case, the thing isn't actually scaled.
What also doesn't scale is the ability to ionize puffed neutral gas fuels.
There does seem to be a required minimum size, but what it is remains to be determined.

zapkitty
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Postby zapkitty » Sat Jul 10, 2010 10:39 pm

Bumping this...

Given the concept of deploying polywell fusion ASAP for R&D as an eventual spaceborne power supply the question would seem to be...

... how low can you go?

A polywell that could generate net power at 100 kW or less would be much easier and much faster to deploy than one that has a minimum output of 100 MW and the heat output that goes with that power level.

And it would be even better if the polywell with the 100 kW power level could be dialed up into the multi-megawatt range as appropriate cooling systems are developed and brought online :)

... but can a polywell go that low?

WizWom
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Postby WizWom » Sun Jul 11, 2010 3:30 am

Even in LEO, the vacuum is much lower than you can get on Earth.
Your polywell in space for space only work does not need a vacuum chamber. All you need is the core, and your energy grid. And a simple reflector system on one hemisphere will allow it to produce thrust - and, incidentally, serves as primary shielding.

Owing to this, you need only be at the diameter of the core - 1 to 1.5 meters, and then you can use an extending shield/thrust plate.

Its likely you could fit an interplanetary craft with a polywell power source into a space shuttle easily. The Ares V should also have no trouble. Make it structurally capable of lunar landing, and a couple tons of equipment allows fueling from lunar ice.

And then you can go anywhere you please, as power and rocket mass are both effectively unlimited.
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GIThruster
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Postby GIThruster » Sun Jul 11, 2010 4:56 am

Kitty, I love the idea here in this thread, but don't you think that before we see real investment on orbit, we need to see a new transport system that is safe, quick, convenient and economical? Once we have that, what goes to orbit seems almost trivial by comparison.
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