polywell reactor for booster rocket applications?

Discuss how polywell fusion works; share theoretical questions and answers.

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Skipjack
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Post by Skipjack »

if you want me to say it differently: I might be wrong, but I do not think that a reactor on a nuclear sub makes a cost effective means of electricity generation for the general public (a cost effective commercial reactor).

93143
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Post by 93143 »

Skipjack wrote:if you want me to say it differently: I might be wrong, but I do not think that a reactor on a nuclear sub makes a cost effective means of electricity generation for the general public (a cost effective commercial reactor).
This kind of ties into your previous post. They're actually the same technology (LWR) if I'm not mistaken. (At least in the US. Here in Canada we use heavy water reactors, which have certain advantages, such as the ability to burn natural uranium. But they're still pressurized water reactors.) There are better designs available, but all the public thinks about is Chernobyl and Three Mile Island, so nothing gets done.

Also, it's not that much more difficult to build a large fission reactor than to build a small one. They scale easily. Polywell doesn't scale easily to the required power levels for space launch.

On the other hand, considering how difficult and expensive spaceflight is now, maybe I overstated the case... but I still think that if you can't make a normal-sized Polywell into a profitable conventional powerplant, an SSTO based on a huge one is going to be an exercise in throwing away money. Deep space might be another matter, because the required power levels are lower...

KitemanSA
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Post by KitemanSA »

Skipjack wrote:Uhm, nuclear electricity is also not price competitive with coal... at least not yet.
If you made the coal plants pay all equivalent costs that the Nukes have to pay, the nukes would be WAY more than price competative. But the smokers don't pay much to poison our air and water. Ah well.

Heck, if the smokers had to meet the radiation emission limits that nukes do, they'd be closed one and all (or nearly so).

93143
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Post by 93143 »

KitemanSA wrote:Heck, if the smokers had to meet the radiation emission limits that nukes do, they'd be closed one and all (or nearly so).
Hehe... good point. I worked on a project once assessing mitigation options (ie: scrubbing) for mercury emissions from coal plants; it's distressing how much junk there is in coal smoke...

I do actually believe that if polywell works at all, it should be possible to build a reasonably competitive power plant. I also think it should be useful as a space launch technology. But if one of those were to prove unworkable, I suspect it wouldn't be the power plant, just based on the thermal loads and plasma regimes involved.

I'm still hoping Dr. Woodward and his hangers-on are on to something. Imagine a Polywell-powered engine that gets on the order of 1 newton per watt - you could afford to fly in loops for artificial gravity... or have a stealth space battleship with a LHe-cooled outer hull and a big chunk of ice in the core as a heat sink...
djolds1 wrote:LACE engines like SABRE max at approx 700 seconds Isp.
Technically, SABRE isn't a LACE because it doesn't liquefy the air. Just a niggle. And regarding Skylon, somebody seriously needs to pony up the $1e10 to get that thing built - Ares I costs more than that by itself...

...unless they mean British billions? That's, um, $1e13?

Skipjack
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Post by Skipjack »

Heck, if the smokers had to meet the radiation emission limits that nukes do, they'd be closed one and all (or nearly so).
Oh I agree. That was not my point though. I was simply tieing on to some things that others here claimed, like that BFRs or any fusion reactor for that matter would probably never be commercially viable as a powersource (to expensive).
Now I am saying that in space applications the stakes are different ones, than they are with commercial power generation.
I dont understand why that is so hard to understand.
E.g. a polywell reactor used for an SSTO would only have to have a lifetime of say 100, maybe 200 missions. That would equal a "burn time" of what? 2000 minutes maybe? That is nothing for a commercial reactor, but for an RLV that is huge!

On the Sabre and Skylon:
I have been following this for a while. Unfortunately it is forever and a day away, even if they magically got funding. I dont think the guys behind it will see it come to life.
Also people like Gary Hudson are quite skeptical of the concept.
Now I do admit that I dont know enough about all this to know who is right. I just hope that some miracle happens (Polywell, Skylon, inprobability drive ;) ) that will make Space truly affordable within my lifetime. People are having great dreams of moonbases and interplanetary missions and we can barely make it into orbit. It is a shame!

Nik
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Semi-OT...

Post by Nik »

Hi, here's a link with some info on nuclear powered aircraft designs.

There's enough info in thumbnails to tease, but google may find more on a specific design without buying an UpShip data CD...
http://www.up-ship.com/drawndoc/drawndocair.htm

And Reaction Engine's home page...

http://www.reactionengines.co.uk/

FWIW, placing and bonding the zillion capilliary tubes for their proof-of-concept heat exchanger was a feat in itself. When I asked about aeolian harping in wind tunnel, I was told several tones were heard during spool-down...

IIRC, funding for the simplified 'antipodean' air-breathing engine will be on a commercial basis. IMHO, that should pay for developing the orbiter's combined cycle...

My thought is that something with a 'look & feel' like Concorde#2 may be widely acceptable for trans-atmospheric use, but flying a 'nuclear' polywell may raise hackles for a long time...

What was that saw about never underestimating public ignorance ??

It may take a 747-P or A-300-P to ease concerns, and then only as a cargo carrier. Um, what's the odds DHL jumps aboard ??

Which brings me back to those nuclear aircraft designs...
:)

KitemanSA
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Post by KitemanSA »

Skipjack wrote: Oh I agree. That was not my point though. I was simply tieing on to some things that others here claimed, like that BFRs or any fusion reactor for that matter would probably never be commercially viable as a powersource (too expensive).
IF the BFR works anything like is claimed it should, I can't help but think that it will be VERY competitive. JMHO

djolds1
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Post by djolds1 »

93143 wrote:I'm still hoping Dr. Woodward and his hangers-on are on to something. Imagine a Polywell-powered engine that gets on the order of 1 newton per watt - you could afford to fly in loops for artificial gravity... or have a stealth space battleship with a LHe-cooled outer hull and a big chunk of ice in the core as a heat sink...
Woodward? Don't hold your breath on that one.
93143 wrote:
djolds1 wrote:LACE engines like SABRE max at approx 700 seconds Isp.
Technically, SABRE isn't a LACE because it doesn't liquefy the air. Just a niggle. And regarding Skylon, somebody seriously needs to pony up the $1e10 to get that thing built - Ares I costs more than that by itself...

...unless they mean British billions? That's, um, $1e13?
~1.5E10 USD.
Vae Victis

93143
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Post by 93143 »

djolds1 wrote:Woodward? Don't hold your breath on that one.
I'm not. If it works as well as they claim it will, the Ph.D. thesis I'm working on will be obsolete. And I won't care...
93143 wrote:...unless they mean British billions? That's, um, $1e13?
~1.5E10 USD.
Not American billions of British pounds. British billions (yes, I know they're obsolete) of American dollars...

djolds1
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Post by djolds1 »

93143 wrote:
djolds1 wrote:Woodward? Don't hold your breath on that one.
I'm not. If it works as well as they claim it will, the Ph.D. thesis I'm working on will be obsolete. And I won't care...
IMO LQG has better odds for a GUT, but that's an informed layman talking.
93143 wrote:
93143 wrote:...unless they mean British billions? That's, um, $1e13?
~1.5E10 USD.
Not American billions of British pounds. British billions (yes, I know they're obsolete) of American dollars...
Long scale vs the US/Metric short scale.

Long scale "1 billion" = 1E12
Vae Victis

93143
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Post by 93143 »

djolds1 wrote:IMO LQG has better odds for a GUT, but that's an informed layman talking.
I haven't read all of the papers yet, but I was under the impression they were just making use of somebody's formulation of Mach's principle in terms of General Relativity. They aren't aiming for a GUT. Now mind you I wouldn't shed tears if the LHC failed to find the Higgs boson - you can't go 3.5 parsecs in 11 days with an MLT...

The latest data from Woodward's lab supposedly has a 10 dB signal-to-noise ratio. So unless he's lying (people do now and then) or he's missed something in his test setup or data analysis (not impossible by any means), the basic effect might actually be real. But it's still at the 3 neutrons level right now, and much more of a long shot due to the nonstandard approach to physics...
Long scale vs the US/Metric short scale.

Long scale "1 billion" = 1E12
Exactly. Ten of those is a lot of money. Somehow I don't think they mean that...

icarus
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Post by icarus »

Nik: ... interesting thinking, it recalls some feasibility work I did on gas-core nuclear rocket. Biggest problem with them is keeping the fissile material in the core and not exiting with the propellant ... vortex flows are thought to be a way these might work.

http://en.wikipedia.org/wiki/Gas_core_reactor_rocket

There was also some question about the inherent stability of the pressure waves of a gaseous fissioning system ..... but upside is between 5-15kg of UF4 will get you into orbit and interplanetarily, three months to Mars. Apparently they fired one up for more than a minute at Los Alamos in the early 70's and nothing more has been officially heard about them (IIR Bussard may have been peripherally involved in this project also).... 3 months to Mars also means some pretty stunning figures for first strike ICBM's too, if you know what I mean.

Now get this, how about using the Polywell electron core concept to hold an ionised fissioning plasma in the core location and running the propellant around that?? ... solves fuel loss problem of gas core nuclear and gives another control knob for balancing reaction rates.

Sounds like a interplanetary engine concept with awesome ISP and mostly known physics, although ionised fissioning gases might be a little fun to work with until the bugs are ironed out.

Skipjack
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Post by Skipjack »

Someone had the idea to make the gas core reactor "light bulb" style.
The basic idea was that a gas core reactor emitts most of its heat via light and that one could in theory build a transparent bulb from fused silica arround it. That would allow most of the spectrum to go through. So you would keep the fissile material in and let the heat out.
I dont quite know how well that would work in praxis, but that was the idea.
Polywell- if it works as advertized- would probably work better than a gas core reactor. The problem is that we dont know yet how well it will work.

Nik
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Test-ban treaties...

Post by Nik »

"... nothing more has been officially heard about them"

IIRC, NERVA and related projects fell victim to various test-ban treaties.

One spin-off from those nuclear aircraft studies was a direct-cycle nuclear ram-jet proposal. Come armageddon, a dozen of these would go critical, launch on boosters, then trail fall-out Westward from Alaska. After dropping thermonukes on (n-1) targets, they'd kamikase...

Upside is that Polywell, Tokomak and laser-pulse fusion are not considered 'weaponisable'.

OTR, I'd guesstimate any third-gen Polywell would be a fair fit to a 'RockTug' with a laser sized for comet slicing & dicing...

Skipjack
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Post by Skipjack »

I never heard of a treaty that disallowed NERVA based rockets. Orion (nuclear pulse propulsion) yes, but not NERVA.

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