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PostPosted: Sun Jun 27, 2010 8:37 am 
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http://iopscience.iop.org/0953-2048/23/7/073001

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The discovery of superconductivity at relatively higher temperatures in a non-cuprate system, LnFeAsO1 [?] xFx (Ln = lanthanides) has created tremendous activity among the reseachers in this field. This review is an overview on the present status and the future scope for iron pnictides. The various structural categories of iron based superconductors, the structural aspects, different preparation techniques of the material and the necessity for its optimization are discussed. The highlighting features of iron pnictide, i.e. the very high upper critical field, moderate magneto-transport and thermal properties, are also included. The article gives a summary of the prevailing arguments of researchers to relate the material to cuprates and also the comparative features of classical and MgB2 superconductors.


Let me add that critical field could run as high as 300 T at 0K for some of the materials. That means that a 15 T field with a 2 m coil is doable. i.e. it ups the power density by a factor of 5. Not too shabby. Of course if we go to 1m the power doubles. And now you have upped the power density by a total factor of 80 (did I do that calc right?).

Any way my gut feeling is that power producing machines will use coils with a 1 m bore (maybe less). What does that mean? A power producer in volume will come in at under $2 million or so for the reactor vessel and coils. This is starting to get interesting. Power supplies at $2.5 mil or less. Vacuum pumping at $1 million or less. Instruments and controls at under $1 million. So the energy producer should be about $6.5 mil. Power collection another equal amount. So you are talking $13 mil for 100 MW - in production. At $1/w capital cost d no fuel cost electricity would cost about $.05/KWh at a capital cost of $.13/W you are talking electricity at under $.01/KWh. Certainly under $.02/KWh. That means early retirement for most existing power plants.

The only fly in the ointment is that all we have is lab samples. This stuff is probably 5 years away from production and 10 years from reasonable cost.

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PostPosted: Sun Jun 27, 2010 4:19 pm 
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This would be useful not only for fusion power, but also for Heim drive (if it is real).


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PostPosted: Sun Jun 27, 2010 5:47 pm 
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Very cool. I take it you read the paper and this is where the 300 T max field figure came from?

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Last edited by GIThruster on Sun Jun 27, 2010 6:56 pm, edited 1 time in total.

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PostPosted: Sun Jun 27, 2010 6:07 pm 
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GIThruster wrote:
Very cool. I take it you read the paper an this is where the 300 T max field figure came from?


It is a conservative extrapolation from one of the Hc graphs. It may be more like 1,000 T @ 0K.

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PostPosted: Mon Jun 28, 2010 6:11 am 
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kurt9 wrote:
This would be useful not only for fusion power, but also for Heim drive (if it is real).


Heim theory (and hence Heim drive) could already be tested in principle, the problem is that still too few scientists consider it as worth testing.


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PostPosted: Mon Jun 28, 2010 3:09 pm 
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Giorgio wrote:
kurt9 wrote:
This would be useful not only for fusion power, but also for Heim drive (if it is real).


Heim theory (and hence Heim drive) could already be tested in principle, the problem is that still too few scientists consider it as worth testing.


That's why it won't get tested until it gets really cheap to do so. Or unless one of us gets rich in a start-up business and finances the testing themselves.


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PostPosted: Mon Jun 28, 2010 4:18 pm 
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Yes well, with more than 40 years of searching for and not finding gravitons, you could make the argument that Heim's theory has already been tested and utterly failed.

Absence of evidence is never evidence of absence, so we can't say we KNOW there are no gravitons, but honestly, it sure doesn't look like there are.

We know Einstein's field theory works in describing gravity and that particle theory does not. People only posit things like gravitons because people like particles. They make us think we understand, whereas nebulous "fields" most often do not.

That doesn't mean that gravity is ever going to be best described with any sort of particle theory.

IMHO, there is almost no chance Heim was correct.

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PostPosted: Mon Jun 28, 2010 6:45 pm 
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The Hc2 tables that I see are on pages 11 and 12.

A recent very high critical field of 122 Tesla (by WHH extrapoliation) for the La based system.

From figure 10
NdFeAsO.7F.3 and Sm compound and another Nd compound seem to track to very high Hc2(Tesla)

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PostPosted: Mon Jun 28, 2010 7:37 pm 
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nextbigfuture wrote:
The Hc2 tables that I see are on pages 11 and 12.

A recent very high critical field of 122 Tesla (by WHH extrapoliation) for the La based system.

From figure 10
NdFeAsO.7F.3 and Sm compound and another Nd compound seem to track to very high Hc2(Tesla)


Yes. Extrapolate from NdFeAsO.7F.3 (green curve - figure 10) - 20T delta for a 1K change at about 45K. Extrapolated to 0K = 900 T. As I said 300 T at 0K is conservative. My estimate of 1,000 T @ 0 K was strictly eyeball (not bad huh?)

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PostPosted: Mon Jun 28, 2010 10:02 pm 
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GIThruster wrote:
Yes well, with more than 40 years of searching for and not finding gravitons, you could make the argument that Heim's theory has already been tested and utterly failed.

Absence of evidence is never evidence of absence, so we can't say we KNOW there are no gravitons, but honestly, it sure doesn't look like there are.

We know Einstein's field theory works in describing gravity and that particle theory does not. People only posit things like gravitons because people like particles. They make us think we understand, whereas nebulous "fields" most often do not.

That doesn't mean that gravity is ever going to be best described with any sort of particle theory.

IMHO, there is almost no chance Heim was correct.


The only way to know for sure is to do the damned experiment that D&H have been yakking about for the past 4 years.


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PostPosted: Mon Jun 28, 2010 10:15 pm 
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Just takes money. I'm sure there are plenty of labs that would be happy to give it a go, from George Hathaway's up in the Great White North, to EarthTech in Austin, to some of the national labs. . .

What, you wouldn't rather study algal flows in Antarctica or why children fall off tricycles?


(No joke, US Army once paid to find out why kids fall off tricycles. Just FYI, it's because they sometimes run into things. Was a couple million dollar study back in the 50's. :-P)

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PostPosted: Tue Jun 29, 2010 7:52 am 
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GIThruster wrote:
IMHO, there is almost no chance Heim was correct.


I tend to agree with this point, yet some of the mathematical results that have been derived by his hypothesis are quite interesting for their consequences and his ingenious way of calculating particle masses has been the only innovation I saw in this field in the last 20 years.

Hopefully some of those scientists who got bored of placing obstacles in front of kids to make them fall will divert part of their budget to see if they can make photons to fall as gravito-photons instead :P


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PostPosted: Tue Jun 29, 2010 5:20 pm 
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Hmm. A quick look here http://hypertextbook.com/facts/2000/AnnaWoo.shtml says the record is 850T for a destructively pulsed magnet. With the kind of forces you're putting on the metal, what's the strongest continuous practical field you can manage? More like 50T?


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PostPosted: Wed Jun 30, 2010 5:55 am 
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Colonel_Korg wrote:
I don't think that Polywell would gain much from magnetic field strengths that would affect the positive ions as much as the electrons.

I'm not sure about that but, wouldn't very strong magnetic fields inhibit the process of getting the ions to collide in the center of the polywell where they are drawn to by the negative charges of the electrons?


Magnetic fields and moving electrons are all about angle. At some angles (electrons traveling along field lines) there is no beam deflection.

Now there is more to it than that (gyroradius for example) but the above covers the very basics.

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