# If I cook it on the reactor, is it fusion cuisine?



## Umbran (Oct 16, 2014)

Scientific American today has an article about how Lockheed had announced they've made a breakthrough that makes fusion energy possible in the near future.I'd very much like to believe in this, as it could save us from so many problems.  And it isn't like Lockheed is a two-bit operation.  But until they actually demonstrate it....

http://www.scientificamerican.com/article/lockheed-claims-breakthrough-on-fusion-energy/


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## Morrus (Oct 16, 2014)

Interesting.  The fact that it's a major corporation like L-M does make a difference.  There have been so many claims about this over the decades.


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## Mishihari Lord (Oct 16, 2014)

Cool, but until they tell what type of fuel their fusion reactor will need it's hard to tell how useful it will be.


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## tuxgeo (Oct 16, 2014)

Mishihari Lord said:


> Cool, but until they tell what type of fuel their fusion reactor will need it's hard to tell how useful it will be.




The classical fuels are deuterium and tritium.


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## tuxgeo (Oct 16, 2014)

. . . the double-posting bug is back. . . .


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## Mishihari Lord (Oct 16, 2014)

tuxgeo said:


> The classical fuels are deuterium and tritium.




Of course, but even if it isn't something exotic, if I remember my physics right it's a whole lot easier to harvest a quantity of deuterium than it is of tritium.


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## Dannyalcatraz (Oct 16, 2014)

This could revolutionize the food truck business!


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## Hand of Evil (Oct 16, 2014)

never mind the same story

Looks like we will know in a few years...Space, here we come!


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## Umbran (Oct 16, 2014)

Mishihari Lord said:


> Of course, but even if it isn't something exotic, if I remember my physics right it's a whole lot easier to harvest a quantity of deuterium than it is of tritium.




It is - generally speaking, we don't harvest tritium.  The stuff only has a half life of about 12 years, so we must work with recently created tritium.  

It is created naturally in very small amounts by cosmic ray interaction with the upper atmosphere (it eventually falls as rain, and gets to the ocean), but he concentrations are very low.

Most tritium in use today is created by bombarding Lithium with neutrons in a fission reactor, or as a byproduct from reactors that use heavy water as coolant (deuterium bombarded with neutrons can become tritium).


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## GMMichael (Oct 16, 2014)

Reality check:

- LM wouldn't straight-up lie about such a discovery, but they WOULD leverage it to gain investor (stock market) interest.

- I highly doubt that fusion would "save" us from problems, because the problems are in human decisions, not capabilities.  We already have the technology for a green earth and to end world hunger.  We're just not using it until it's profitable.


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## Janx (Oct 16, 2014)

Umbran said:


> It is created naturally in very small amounts by cosmic ray interaction with the upper atmosphere (it eventually falls as rain, and gets to the ocean), but he concentrations are very low.




Just brain storming here, but would it work if we took a bucket of water up to the ISS and left it outside the airlock for a few days, to turn it into tritium?

Obviously, when I say bucket, I mean NASA designed vessel for bombarding H20 with cosmic rays in space...


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## Umbran (Oct 16, 2014)

Janx said:


> Just brain storming here, but would it work if we took a bucket of water up to the ISS and left it outside the airlock for a few days, to turn it into tritium?
> 
> Obviously, when I say bucket, I mean NASA designed vessel for bombarding H20 with cosmic rays in space...




In theory, somewhat.  We get tritium on the ground because the atmosphere is *big*, and has a wide area to catch cosmic rays.  A small bucket isn't a large target, and won't catch many cosmic rays.  Plus, water is heavy, so taking it to orbit and back isn't cheap.  I'd have to work out the density of cosmic rays at ISS height to be sure, but I don't think that's a win.

You could put the bucket in the beam of a particle accelerator, and get much the same result, without all the mucking about in orbit.  Of course, running a particle accelerator costs money/energy, so this may not be a win.

Having the tritium be a *byproduct* of something else profitable (say, running a fission power reactor) is probably a better bet - you're getting the tritium almost for free, then.


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## Mustrum_Ridcully (Oct 16, 2014)

DMMike said:


> Reality check:
> 
> - LM wouldn't straight-up lie about such a discovery, but they WOULD leverage it to gain investor (stock market) interest.
> 
> - I highly doubt that fusion would "save" us from problems, because the problems are in human decisions, not capabilities.  We already have the technology for a green earth and to end world hunger.  We're just not using it until it's profitable.




And so it is a question of capabilities - we must have the capability to do it at profit.


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## Umbran (Oct 16, 2014)

DMMike said:


> - I highly doubt that fusion would "save" us from problems, because the problems are in human decisions, not capabilities.  We already have the technology for a green earth and to end world hunger.  We're just not using it until it's profitable.




Not true - some of them are already profitable, but we still aren't using them.  And if we did use them, they'd become even more profitable, but still we don't use them.  Discussing why that is goes to politics, I'm afraid.

It isn't the fusion itself which saves us, it is the total package Lockheed is suggesting, which would be profitable enough to be a no-brainer, and get past many of our current political issues.  

Lockheed is talking about a 100 megawatt power plant on a truck.

A quick web search tells me that an average, an American home utility customer uses about 11,000 kilowatt hours of electricity each year, so a sustained power use of about 1.3 kilowatts, on broad average.  If my quick math is correct, then just one of Lockheed's reactors puts out enough power for _tens of thousands_ of homes.  It could power, for example, the entire residential customer base of the town I live in!

Fuel costs would be the stickler here.  We don't currently produce tritium on industrial scales....


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## Dannyalcatraz (Oct 16, 2014)

Come on down to Terawatt Tom's Tritium Emporium!  We got solutions to ALL your fusion fuel confusions!  And we're blowing up the competition with our new low, low, LOW pricing!


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## Umbran (Oct 17, 2014)

As a note - when I said one of these could power my town - that was in a theoretical sense.  It would require running the thing at or near full output, which is not normally something you want to do with a power generating plant.  With one and a half, you'd be running with more suitable margins.  Or maybe one, with a nice offshore wind turbine farm as a supplement...

That brought me to another point.  Several folks in other places have asked why a company as big as Lockheed would need partners to help develop this.  Lockheed knows power generation, after all - they build nuclear power plants for navy vessels.  I suspect the first concept for the fusion reactor was similarly for large navel vessels.  So, why does Lockheed need partners?

The answer is in my point above.  Assume Lockheed has cracked the basic fusion issue, and they can fit in in a 7'x10'(x10') space*.  Think, for just a moment - how do you get all that electric power *out* of that tiny space?  With a normal power plant, you have much more space, you don't have to crowd the outgoing cables together.  For this, all that power has to come out of a very small surface area.  The currents would be enormous.  If you use classic copper wire, the heat would similarly be enormous.  If you get it out on superconducting cables... well, you need superconducting cables.  Either way, with the enormous current would come enormous magnetic fields as well, which would put physical stresses on the thing...

So, there are some engineering and materials challenges implied by that power output and size that nobody, Lockheed or otherwise, has ever tried to meet.  



*The power plants on modern nuclear vessels are more like 30' to 40' per side.


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## Mishihari Lord (Oct 17, 2014)

Umbran said:


> Fuel costs would be the stickler here.  We don't currently produce tritium on industrial scales....




So the next trick is how do we produce or harvest tritium using less energy than we get out of the fusion plant.  Or modify the process to use fuel that's more readily available.  One idea that immediately comes to mind is to run water through a fission plant and purify out the tritium produced.


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## Umbran (Oct 17, 2014)

Mishihari Lord said:


> So the next trick is how do we produce or harvest tritium using less energy than we get out of the fusion plant.  Or modify the process to use fuel that's more readily available.  One idea that immediately comes to mind is to run water through a fission plant and purify out the tritium produced.




As I mentioned above - tritium is a known byproduct in heavy-water cooled fission reactors.  It isn't enough to "run water through" - you need to start with deuterium or the yield will be too low to be economical.


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## Scott DeWar (Oct 17, 2014)

I saw something about a thorium powered car on you tube. Is that a possibility?

http://blogs.cars.com/kickingtires/2011/08/a-car-that-could-go-1000000-miles-without-refueling.html


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## Umbran (Oct 19, 2014)

Scott DeWar said:


> I saw something about a thorium powered car on you tube. Is that a possibility?
> 
> http://blogs.cars.com/kickingtires/2011/08/a-car-that-could-go-1000000-miles-without-refueling.html




Um, no.  That article, and a bunch of others I read in searching around on this topic, are pseudoscientific gobbledigook.  Complete nonsense.  The various articles about the thorium-powered car are not self-consistent, but if I try to piece them together, I get the following:

They take some Thorium, heat it up to "energize" it, make it put out laser light, and use that laser light to heat water, and run a steam turbine.  And, while the Thorium is radioactive, they say there is no actual nuclear reaction going on here.

So, I ask, where does the energy come from?

Can you make a laser out of thorium?  Probably.  You can make a laser out of just about any material.  But lasers are based on a quantized electrodynamic process.  You put some energy in (often in the form of just normal, non-coherent light, but you can use other ways), and excite the electrons in the material.  When the electrons drop down to their original places, they emit very specific frequencies of light, and when one atom does it, there's a cascade so they all do - and you get out a bunch of very specific, coherent light.  But this is just turning some energy put in into a different form of energy out - it is merely conversion.  If you make a laser out of thorium, you still have to plug that laser into the wall, or a battery, or something.  So, what's powering your thorium laser?  

Can you make a nuclear reactor that runs on thorium fuel?  Yes.  And there are some reasons why you might want to do that.  But it isn't all that much different from one that runs on uranium - it is still a big old nuclear reactor.  You can't (and don't want to) put one under the hood of your car.  Even if you made it small enough, the reactor would put out some pretty hard radiation that would not be stopped by a few thin layers of aluminum foil.  I am pretty sure nobody wants a car that gives them radiation poisoning or cancer.

You can probably also make a "nuclear battery" out of thorium, but those don't have sufficient power output to run something like a car - you typically use such to run the electronics on spacecraft for long journeys.

All that stuff about how thorium is dense, and so 8 grams of it can power your car for a century?  That's flimflam designed to sound all sciencey.  Thorium isn't particularly dense - gold and uranium are more dense, for example.  Moreover, grams are a measure of mass. Density is a measure of mass per volume.  8 grams of thorium will be 8 grams, no matter the density!  If it is super dense, it'll take up small space, if it is not dense, it'll take up more space.  But it will still be 8 grams!

So, all in all, that Thorium powered car is stuff and nonsense.  Pay it no mind.


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## Scott DeWar (Oct 19, 2014)

Well, that's not any fun, radiation poisoning or cancer? blech! 

Ok, so at best, Thorium is good as a long life low power battery and would require shielding that would make it 'not feasible'. Do I have the basics?

It looked like one of the descriptions of thorium powered cars required a laser to melt the thorium for it to be fissionable which had me wondering of the power used to power generated ration to see if it would produce enough to move the car with the heavy shielding need  for a reaction core. Do I have the basics of needed power core necessities?


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## Umbran (Oct 19, 2014)

Scott DeWar said:


> Ok, so at best, Thorium is good as a long life low power battery and would require shielding that would make it 'not feasible'. Do I have the basics?




It is more that the power output of such devices* is not large enough to be used in something like a domestic vehicle.  The Mars rover Curiosity has one that puts out about 125 Watts of power - enough for a couple of light bulbs, not enough to get you to work at 60 mph.



> It looked like one of the descriptions of thorium powered cars required a laser to melt the thorium for it to be fissionable which had me wondering of the power used to power generated ration to see if it would produce enough to move the car with the heavy shielding need  for a reaction core. Do I have the basics of needed power core necessities?




The descriptions are, as my father would have said, horsehockey.  They are gobbledigook put together to sound convincing, but do not match up with anything in reality.  You don't need a laser to melt the thorium.  Thorium and its oxides melt at Very high temperatures (like, thousands of degrees Fahrenheit).  You aren't going to melt that in a car engine.  You aren't going to use a fission reactor in a car - melting or not, that produces hard radiation that takes shielding on the order of yards of concrete.  Heck, the descriptions also say that there is no nuclear reaction going on!


*It isn't technically a battery.  The radioactive decay produces heat - the heat is used to create electricity through thermocouples.  They are just sometimes called "nuclear batteries".


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## Scott DeWar (Oct 19, 2014)

Umbran said:


> It is more that the power output of such devices* is not large enough to be used in something like a domestic vehicle.  The Mars rover Curiosity has one that puts out about 125 Watts of power - enough for a couple of light bulbs, not enough to get you to work at 60 mph.
> *It isn't technically a battery.  The radioactive decay produces heat - the heat is used to create electricity through thermocouples.  They are just sometimes called "nuclear batteries"




believe or not, I actually knew that



Umbran said:


> The descriptions are, as my father would have said,
> *horsehockey*​.
> They are gobbledygook put together to sound convincing, but do not match up with anything in reality.  You don't need a laser to melt the thorium.  Thorium and its oxides melt at Very high temperatures (like, thousands of degrees Fahrenheit).  You aren't going to melt that in a car engine.  You aren't going to use a fission reactor in a car - melting or not, that produces hard radiation that takes shielding on the order of yards of concrete.  Heck, the descriptions also say that there is no nuclear reaction going on!




Horsepucky is what my grandpa would have said, step dad would use a more colorful metaphor that is not suitable for grandma's eyes.

Yeah, I figured it was pseudo science. It is just good to get clarifications. Out of curiosity, is there any research on improving the thermocouples to be more efficient and produce more power out of the heat radiating out? I realize there is nothing you can do for the shielding. its hard radiation and its gonna need thick leaded concrete.


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## Umbran (Oct 19, 2014)

Scott DeWar said:


> believe or not, I actually knew that




You might, but there may be other readers who didn't, so I included it as a nod to increasing science knowledge in the Universe



> Out of curiosity, is there any research on improving the thermocouples to be more efficient and produce more power out of the heat radiating out?




I'm sure there is, but in the end, you are limited by the power output of the slow decay fo radioactive materials - a chunk of a given material will only put out so much heat per unit time, and that's it.  Even if you were 100% efficient at gathering that energy, it isn't going to run a car.


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## Scott DeWar (Oct 19, 2014)

got it.


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## Jhaelen (Oct 20, 2014)

I'm a bit confused. So what's the actual breakthrough, here? The size of the reactor?

I mean, there's this ITER project in South France where they already started building a fusion power plant, isn't there?


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## Umbran (Oct 20, 2014)

Jhaelen said:


> I'm a bit confused. So what's the actual breakthrough, here? The size of the reactor?




Lockheed has not been terribly open about exactly what their technical breakthrough has been - which makes sense, as they probably want to patent the heck out of it.  But the size and timescale difference implies they've found some really interesting idea they need help exploring.



> I mean, there's this ITER project in South France where they already started building a fusion power plant, isn't there?




ITER is an experiment with one type of fusion reactor.  It began construction in 2007.  Currently, they expect construction to be finished in 2019.  They don't expect to actually get power out of the thing until 2027 - 20 years after breaking ground.  The first commercial power plant is expected to be a follow-on from ITER, not ITER itself, with the implied design and construction times for that added on.

Meanwhile, Lockheed says it thinks it can make a fusion reactor in a decade, soup to nuts, production ready.  Now, from most folks, this claim would be scoffed at.  But Lockheed already does fission power plants for naval vessels - they are not new to this game.  They are not small, and are known to be technically competent.


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## Jan van Leyden (Oct 20, 2014)

Did they announce anything about the containment problem? Or is the Fleischmann&Pons, aquarium-scale cold fusion back? This kind of "announcement" won't get me buying Lokheed shares; there's got do be a lot more evidence for that.


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## Umbran (Oct 21, 2014)

Jan van Leyden said:


> Did they announce anything about the containment problem? Or is the Fleischmann&Pons, aquarium-scale cold fusion back?




There's nothing saying it is cold fusion.  Just that it can fit into a small space.  I haven't seen anything about the process.

But, again, let us be clear - this is Lockheed.  They already provide nuclear plants for submarines and other naval vessels.  They've been working on advanced energy projects for years, and have more than a small amount of proven technical skill.

And their announcement was a request for partners - they admit they can't do it alone, and are looking for help from various sources, including the academic community.  It then follows that scientists outside Lockheed are going to get eyes on the thing.  It isn't like they can play the cold fusion shuffle under this setup.


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## Scott DeWar (Oct 21, 2014)

Just thinking out loud here, if "small" means submarine and aircraft carrier power supplies, then that descriptor might be subjective as compared to a 100 acre sized compound. Not so much as being small as in 10 x 10 x 10 sized room. Unless they plan on making it a basement install kind of thing.


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## Umbran (Oct 21, 2014)

Scott DeWar said:


> Just thinking out loud here, if "small" means submarine and aircraft carrier power supplies, then that descriptor might be subjective as compared to a 100 acre sized compound. Not so much as being small as in 10 x 10 x 10 sized room. Unless they plan on making it a basement install kind of thing.




As I noted upthread - the naval power plants Lockheed currently makes are characteristically about 30' to 40' on a side.

This power plant is supposed to fit on a large truck - 7'x10' are the characteristic measures they've suggested.  So, a third to a quarter of the size in each dimension - one ninth to one-sixteenth the total volume of what's on a naval vessel.

I wouldn't expect it to be a "basement install" in a home - there's no home that needs 100 megawatts of power.  But, havign it fit on a truck to ship it out to towns that have lost power to storm or other disaster seems to be one idea for using the thing.


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## Dannyalcatraz (Oct 21, 2014)

It would also make things like smaller nuclear subs possible.  That has both military and scientific possibilities.


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## Scott DeWar (Oct 21, 2014)

Umbran said:


> As I noted upthread - the naval power plants . . . . .
> I wouldn't expect it to be a "basement install" in a home - there's no home that needs 100 megawatts of power.  But, havign it fit on a truck to ship it out to towns that have lost power to storm or other disaster seems to be one idea for using the thing.



 a little quick math, that would supply enough power at 100 amps/240 volts each and would be about 500 homes


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## Umbran (Oct 21, 2014)

Scott DeWar said:


> a little quick math, that would supply enough power at 100 amps/240 volts each and would be about 500 homes




Well, how many people it supplies depends on how you do the calculation.  

Note that, aside from a couple of major appliances, most of the house is running at 120 volts.  If the house is using 100 amps (it probably isn't, mind you, but say it is), that's 12,000 watts (12 kilowatts).  That's like 8300 homes on the generator.

If instead we say the house is running 240 volts, 100 amps (again, isn't - no home is running a full power capacity, and that voltage is only for a few of the major power-hog appliances), the thing will cover half as many - over 4000 homes.

In terms of total energy consumption - a typical home uses about 11,000 kwh of energy a year.  That means that the average use is only 1.3 kilowatts, a tenth of the possible maximum.  Considered this way, it can cover tens of thousands of homes.


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## Scott DeWar (Oct 21, 2014)

Well, typically a home will use about an average of 67% of the panel's rated power, so for a 200 amp home, 167 amps at 240 volts; 100 at 150 amps.


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## WayneLigon (Oct 21, 2014)

Umbran said:


> I wouldn't expect it to be a "basement install" in a home - there's no home that needs 100 megawatts of power.  But, havign it fit on a truck to ship it out to towns that have lost power to storm or other disaster seems to be one idea for using the thing.




Cargo copters could also drop one in. 
Also would be useful for remote facilities, underwater labs, etc. 
Developing countries could certainly find one useful.
Also, it could be the final trigger in the electric car revolution - even a small station like this could provide power to small roadside fueling kiosks for an entire state or more. Or it could power a roadway grid that cars could pull from.


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## Scott DeWar (Oct 21, 2014)

How much would one of these things weigh? Could a cargo copter do that.


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## Umbran (Oct 22, 2014)

Scott DeWar said:


> How much would one of these things weigh? Could a cargo copter do that.




They stated you could fit one on the back of a large truck.  While not explicitly stated, the implication is that it would be transportable thereby.  

There are cargo copters that can lift loaded large trucks, so I would think the answer is yes.


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## Scott DeWar (Oct 22, 2014)

ah. 'k


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## Scott DeWar (Oct 29, 2014)

I have been thinking. Last night actually. if this reactor gets  moves to a weather disaster sight, and a reactor requires cooling, specifically LOTS and LOTS of water, that would limit its ability to be used, right?


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## Umbran (Oct 30, 2014)

If it needs lots and lots of water, yes, that would be an issue.  We don't know what its cooling needs are, though.


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## Dannyalcatraz (Oct 30, 2014)

1,000 Nubians with ostrich feather fans, perhaps?


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## Umbran (Oct 30, 2014)

Well, no.  I was more wondering if they'd have something new and exotic in mind.

The typical way nuclear power is used is to heat water - you take the fast moving fission products, dump them into a large mass that stops them, and they deposit their kinetic energy as heat.  It is really just a heat engine with fission as a heat source.  And the efficiency of a heat engine rises as the difference in temperature between the hot and cold sides rises - so, you typically need lots of cold coolant to get them to work well.

But, what if what they're talking about isn't a heat engine?   What if they have a way to extract the kinetic energy of the fusion products in a different way?  Then, you might not need nearly so much coolant...

If, for example, they have a way to collimate the fusion products - basically, make a particle beam -  they're charged particles, and you could extract the kinetic energy through magnetic fields, directly into electricity!


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## Scott DeWar (Oct 30, 2014)

Dannyalcatraz said:


> 1,000 Nubians with ostrich feather fans, perhaps?






Umbran said:


> Well, no.  I was more wondering if they'd have something new and exotic in mind.



Though not new, that would be *exotic*.


Umbran said:


> The typical way nuclear power is used is to heat water - you take the fast moving fission products, dump them into a large mass that stops them, and they deposit their kinetic energy as heat.  It is really just a heat engine with fission as a heat source.  And the efficiency of a heat engine rises as the difference in temperature between the hot and cold sides rises - so, you typically need lots of cold coolant to get them to work well.



righ, exactly what I had in mind.


Umbran said:


> But, what if what they're talking about isn't a heat engine?   What if they have a way to extract the kinetic energy of the fusion products in a different way?  Then, you might not need nearly so much coolant...
> 
> If, for example, they have a way to collimate the fusion products - basically, make a particle beam -  they're charged particles, and you could extract the kinetic energy through magnetic fields, directly into electricity!




Or some form of heat transducer that is vast more improved and compact then water.

Out of curiosity, can a particle beam exert physical force?


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## Umbran (Oct 30, 2014)

Scott DeWar said:


> Or some form of heat transducer that is vast more improved and compact then water.




Eventually, you have to dump heat into the broader environment.  That means dumping it into air, water, or dirt.  Dirt (used for household heat pumps, for example) requires a permanent installation, and doesn't have convection or mixing to help you spread the heat out - not useful for a mobile, high-power station.  That means, ultimately, you need to dump into water or air.



> Out of curiosity, can a particle beam exert physical force?




Yes.  They are particles.  They have momentum.  Technically, a stream of bullets is a "particle beam" - there are just *lots* of particles. 

Ever hear of a "solar sail"?  Just a really big, reflective sail catching the momentum of particles of light and turnign them into motion of an object.

Now, with modern technology, getting a beam of ionized single atoms/particles so energetic and numerous that it'd be felt as a force by, say, a guy standing in front of it... that's not something I expect to see here...


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## Scott DeWar (Oct 30, 2014)

Solar sail, of course. same thing. <duh!> I wasn't thinking of a particle beam as a weapon, but rather some sort of motin inducing generation source, such as a water mill or steam turbine moves a shaft to gear box to generator.


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## Umbran (Oct 30, 2014)

Scott DeWar said:


> Solar sail, of course. same thing. <duh!> I wasn't thinking of a particle beam as a weapon, but rather some sort of motin inducing generation source, such as a water mill or steam turbine moves a shaft to gear box to generator.




Oh, using the beam *directly*?  Goodness, no, you wouldn't want to do that.  This would be a beam of high energy Helium ions.  It'd be not dissimilar to pointing a continuous lightning bolt or arc welder at your water wheel.  I don't think we've yet built a substance that would withstand that kind of punishment.


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## Scott DeWar (Oct 30, 2014)

I was picturing something like an electron beam, like what is found in a CRT, focused slightly and pointed at a negatively charged surface of a chemical nature(?) and like charges repelling.


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## Umbran (Oct 30, 2014)

There is a limit to how much static charge you can put on a physical item - eventually, the charge is built up to the point where electrons will arc to nearby surfaces.

In essence, you're talking about a beam of plasma - in other fusion schemes, they use powerful magnetic fields to contain the plasma in which fusion is taking place, because no physical material can withstand the temperatures.  I think the same holds here - the stuff has "heart of a star" kind of energies.


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## Scott DeWar (Oct 30, 2014)

understood. So, back to the solar sail, then. How would it be able to work with the above limitation?


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## Umbran (Oct 30, 2014)

Scott DeWar said:


> understood. So, back to the solar sail, then. How would it be able to work with the above limitation?




Well, a solar sail takes photons from a very large area, and bounces them off it's reflective surface.  In bouncing off, the photons exert a force on the sail.

The sail is *huge*.  The NASA Sunjammer, which was cancelled just earlier this month, would have had a sail area of about 13,000 square feet.  It would have produced thrust about equivalent to the weight of a packet of sugar.

The more you concentrate the incoming light/particles, the smaller the sail could be.  But, then, the sail has to be tough.  We aren't talking about light, now - the fusion produces helium ions and neutrons with high energy.  We can't do much with the neutrons - the're not charged, so we don't have a handle on them, and cannot easily collimate them. That leaves us with the helium nucleii.   - we are talking about charged particles moving close to the speed of light.  Individually, not a big deal.  But, in numbers and energy enough to turn a 100 MW generator?  We don't have the materials to take that hit in a small space.

But.. to take the concept.... On a smaller scale - fire the beam down a long tunnel.  The tunnel is in hard vacuum, so you aren't worried about air getting in the way.  The tunnel is long enough that  the beam has spread out and isn't too harsh.  Put your particle-turbine blades down at the end of the tunnel.  You still have to deal with the fact that the things are charged - that'll cause damage long term, so maybe you have to charge the blades with electrons, which is annoying.

That's why I'm thinking something more like a reverse tokamak.


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## Scott DeWar (Oct 30, 2014)

I see your points. It is actually quite clear!


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## Scott DeWar (Oct 30, 2014)

So, back to square one. Are you suggesting this beam of negatively charged Helium ions, super hot and traveling at, say, .9 C (provided it is in a hard vacuum) moving through a magnetic field will generate an electrical charge?


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## Umbran (Oct 31, 2014)

Scott DeWar said:


> So, back to square one. Are you suggesting this beam of negatively charged Helium ions, super hot and traveling at, say, .9 C (provided it is in a hard vacuum) moving through a magnetic field will generate an electrical charge?




It will not generate an electrical charge.  It can induce current.

The beam is of positively charged particles.  That is *itself* a current - charge is going from point A to point B.  You know what we call a thing that takes a high-voltage current in one place, and turns it into a low-voltage current in another place?  A transformer.  Charges moving in one wire create a magnetic field.  We use that field to move charges in another wire, a process we call "inducing current".  The energy from one wire moves into the other wire, by way of magnetic fields.

The only difference is that one of the currents is actually a stream of free charged particles.  Not a *small* difference, but... well, I'll be interested in seeing if I am right.


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## Scott DeWar (Oct 31, 2014)

So the stream of charged particles can act as the primary of a transformer? I thought that it had to be a changing electrical field, 'alternating current'. it seems that the stream is a Direct current.

addm: I remember that inductive coils resist changing current, giving DC a more steady current, or resisting a changing current causing a field of magnetic flux that is then induced as a current in a secondary coil, Right?


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## Umbran (Oct 31, 2014)

Scott DeWar said:


> So the stream of charged particles can act as the primary of a transformer? I thought that it had to be a changing electrical field, 'alternating current'. it seems that the stream is a Direct current.




Well, we are now digging into engineering details. The basic fact is that we have energetic particles with a handle (their charge).  There's several ways we can be clever and get at their energy.

For example - it is only a steady, direct current if the fusion source is constant.  If, instead, we pulse that source* (say, as some useful multiple of 60 cycles per second), then we have the basis for an alternating current.  





*Some forms of fusion are done with a fuel pellet you shoot with big frikkin' lasers until the pellet is hot enough to undergo fusion.  If you pulse those lasers, you may be all set!


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## Scott DeWar (Oct 31, 2014)

Umbran said:


> For example - it is only a steady, direct current if the fusion source is constant.  If, instead, we pulse that source* (say, as some useful multiple of 60 cycles per second), then we have the basis for an alternating current.



I was like 
 DUH! of course. pulse dc works just fine with a transformer! That is interesting about the laser heating of a fuel pellet. Never even heard of that. Of course you ca pulse a laser, so that is a piece of cake to do. clever.


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