losses

[ydoaPs]

So, say we have a system set up taking advantage of the casimir effect but instead of two plates, there are dozens or even hundreds. If the plates were fixed on the ends, would the casimir effect result in compression of the plates? If so, could these plates be piezoelectric and thus be used for generating electricity?

 

I can't seem to find the losses here, but I also don't know much about the physics involved. I know that the plates would attract or repel in the absence of an external field, but does it still work in the presence of a field(such as the one created by the current produced by the piezoelectric plates)? Would the plates reach some sort of equilibrium where the compression is such that the distance between the plates means the casimir effect no longer works?

[swansont]

IIRC one of the ways of looking at the effect is that quantum fluctuations in the charge induces a mirror charge in the plates and these attract. Putting a dielectric between the plates would tend to kill the effect.

[ydoaPs]

IIRC one of the ways of looking at the effect is that quantum fluctuations in the charge induces a mirror charge in the plates and these attract. Putting a dielectric between the plates would tend to kill the effect.

So, what if the plates were neutral conductors and the bases to which they are attached are piezoelectric?

[swansont]

So, what if the plates were neutral conductors and the bases to which they are attached are piezoelectric?

 

I think you'll find that assembling the structure costs more in energy than you could get out it.

[imatfaal]

I actually did the maths for a thread in a different place (this was to answer a question of the force for 5 micrometre separation and plate size 100m*50m)

 

 

F = -1/240(A.hbar.c.π^2.s^-4)

 

F = force

A = Area

c = speed of light

hbar = reduced plancks constant

π = pi

s = seperation

 

in same order as above eq

F = -1/240 (100*50).(1*10^-34).(3*10^8).(3.14)^2.(5*10^-6)^-4

 

F = -1/240 (5*10^3).(1*10^-34).(3*10^8).(10^2).(6.25*10^22)

 

F = -1/240 (15/6)*10^(3-34+8+2+22)

 

F = -1/240 (2.5*10^1)

 

F = -.01

 

(to explain long-winded route - all done by hand cos I am a masochist)

 

let's check units via dimensional analysis

 

F = -1/240(A.hbar.c.π^2.s^-4)

= m^2 . js . ms-1. m-4

= jm-1

 

Joules per metre is the Newton. So in effect your football field apparatus which would cost multiple millions - (and remember it's gotta be in a hard vacuum) will generate a force of around one hundredth of a newton.

With separation being to the minus fourth power that's the variable any technological project must concentrate on lowering. I don't understand the physics well enough to be sure on one point - could you layer the plates? ie would you be able to get a large overall contraction through a multiple layer wafer where the gap between A and B experiences the effect, as does the gap between B and C... etc

Edited April 6, 2011 by imatfaal

[ydoaPs]

With separation being to the minus fourth power that's the variable any technological project must concentrate on lowering. I don't understand the physics well enough to be sure on one point - could you layer the plates? ie would you be able to get a large overall contraction through a multiple layer wafer where the gap between A and B experiences the effect, as does the gap between B and C... etc

I was thinking concentric cylinders. I think you're right about the distance thing. With my idea, the limiting factor would probably be the piezoelectric material; does it need a minimum thickness to generate a voltage? Given my extreme lack of knowledge in this area, I have no clue.

[ydoaPs]

Anyone know any equations for power output of a piezoelectric material given a stress and a thickness? I'm thinking by the time the material is thick enough to even have the piezoelectric effect, the separation is too great to have the casimir effect happen, but I want to calculate to confirm.

[swansont]

Just ran across this. I offer it without endorsement or critique; it's on arXiv

http://arxiv.org/abs/1104.3813

[ydoaPs]

April 18th, eh? They stole my idea!!! Now I'll never get my Nobel prize! I guess I need a thicker tin foil hat.

 

Hold on, WHAT? Page 28 says the estimated power is 1MW/cm³? That's WAY more than I thought. The only reason I thought it was a crazy idea was that I thought it violated conservation of energy. If you have a big enough ZPM, you can power a time traveling Delorean!

 

Just ran across this. I offer it without endorsement or critique; it's on arXiv

http://arxiv.org/abs/1104.3813

So, I'm still having trouble grasping the energy balance.

[ydoaPs]

Anyone find problems with the paper yet?

[ydoaPs]

I think you'll find that assembling the structure costs more in energy than you could get out it.

Assuming that it works, I think the biggest limitation would be structural integrity. The paper linked in this thread mentions that it generates power through vibrations on the order of THz. It seems to me that such a rapid vibration would quickly cause and accumulate microfractures until the piezoelectric material no longer induces a voltage. If I knew more about engineering, I could theoretically calculate how long this device would produce its ~1MW/cm³.

 

I think you might be right on the energy balance here, as the power itself is coming from the piezoelectrics rather than space. The power depletion will use the energy used to make the piezoelectrics piezoelectric and to assemble the structure itself.