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Author Topic: Homopolar Generator, a new one?  (Read 2386 times)
Group: Experimentalist
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Hi All,

I would have liked to experiment a lot more on this homopolar generator, to do things cleaner and better measured, but I'm too bad at mechanics. I hope it's a new model, and not known for a century as the last "good idea" I had!  :-[  :)

Two years ago, but 3 or 4 years after my first experiments where I saw this effect, I discussed the subject on a physics usenet forum (in French here), but nothing conclusive came out.
After at least 6 years, I think it's time to entrust this to better experimenters and analysts than me. The experiment is very easily reproducible and the voltage can be measured beyond any doubt (several hundreds mV).

I summarized my experiment  in the pdf here (I prefer to leave it there rather than post it to be able to rework it and have the updated version at this link).
I invalidated the hypothesis of a "Faraday disk" type of operation, and included an operating hypothesis of which I am not sure, a force on electrons with spin oriented, in a magnetic field gradient.


It's all in the pdf but for those who want an overview first, here's the principle:

Along a ferromagnetic conductive axle rotating in front of an axially magnetized coaxial cylindrical magnet, a potential difference is measured between 2 sliding contacts, one close to the magnet and the other further away. The direction of the PD depends on the direction of rotation and the polarity of the magnet. The order of magnitude of the PD is about half that obtained by a Faraday disc the size of the magnet, driven by the same motor.

Here is the diagram:


Here is my experiment where you can see the poverty of my mechanical skills:


Thank you for your feedback


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How does it behave when the spinning rod is replaced with a Copper, Aluminum or Brass rod ?
   
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How does it behave when the spinning rod is replaced with a Copper, Aluminum or Brass rod ?

I just tested with Al, it's mentioned in the pdf. No significant current could be measured (< 100µV). I think there should be a current, but too weak because the magnetic field lines are not "attracted" by the rod. So not only the magnetic field is much weaker, but the field gradient is even weaker.


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You can create a homopolar motor or generator using a cylinder instead of a disc.  If magnetic flux lines pass through the cylinder wall (i.e. have a radial component) then rotation of the cylinder will induce a potential along the cylinder.  Your ferromagnetic rod will have radial flux lines along the surface as the flux from the magnets leaks out sideways.  Then your results are simply explained by the v X B induction.  Just a thought.
Smudge
P.S.  If you have the ability to measure DC microvolts you wouldn't like to try the experiment without the rotation would you?  If you measure anything then it could be that magical dragging of spin polarized electrons through a magnetic field gradient.
   
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You can create a homopolar motor or generator using a cylinder instead of a disc.  If magnetic flux lines pass through the cylinder wall (i.e. have a radial component) then rotation of the cylinder will induce a potential along the cylinder.  Your ferromagnetic rod will have radial flux lines along the surface as the flux from the magnets leaks out sideways.  Then your results are simply explained by the v X B induction.  Just a thought.
Smudge

I don't think so in our case, because how would you explain that "if the sliding contact near the magnet is not on the periphery of the axis, but on the end of the axis, no difference in the order of magnitude of the voltage is observed"?


Quote
P.S.  If you have the ability to measure DC microvolts you wouldn't like to try the experiment without the rotation would you?  If you measure anything then it could be that magical dragging of spin polarized electrons through a magnetic field gradient.

I have a HP 3468A that can measure µV. The problem here is that the sliding contacts are noisy, as well as the motor that is powered by the mains and vibrates. Under 1 mV, the voltage is not stable so that my measurement with an aluminium axle was not significant.

Without rotation as you suggest, the test is feasible. I'll try tomorrow. But if the electrons are dragged through the gradient, they must also escape the gradient to be able to loop the circuit and form a current, otherwise the forces will balance them at some point, and therefore no current and no voltage will be observed. How do you think we could get around the difficulty?


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Thanks for sharing your find F6FLT :)    I'll have to try replicating over here when I get a chance.

I wonder if the effect is more related to the surface velocity or to the RPM?  If it is Lorentz-like induction, then a larger diameter cylinder should have a higher gradient due to the higher surface velocity..


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Thanks for sharing your find F6FLT :)    I'll have to try replicating over here when I get a chance.

I wonder if the effect is more related to the surface velocity or to the RPM?  If it is Lorentz-like induction, then a larger diameter cylinder should have a higher gradient due to the higher surface velocity..

Hi Reiyuki,

For me, it doesn't depend on the diameter, as the sliding contacts can be made at the center of the ends instead of the cylinder surface.
With the configuration shown in your picture, and for the same magnet size, the gradient in the cylinder will be surely less than with a thin axis (but should work).

With a much stronger neodimium magnet, I had less voltage because the diameter was half that of the ferrite magnet. The gradient is here the most important thing.



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Without rotation as you suggest, the test is feasible. I'll try tomorrow. But if the electrons are dragged through the gradient, they must also escape the gradient to be able to loop the circuit and form a current, otherwise the forces will balance them at some point, and therefore no current and no voltage will be observed. How do you think we could get around the difficulty?
If the external circuit is not ferromagnetic, say copper (which it likely is) then there is no spin polarization there and the gradient has no effect on that external circuit.  In going from Fe to Cu the spin polarization decays over a very small distance like micro-meters.  However that means there are two dissimilar metal contact points and although the (thermocouple) Seebeck effects cancel there is such a thing as the magnetic Seebeck effect where the Seebeck voltage is affected by a magnetic field.  Maybe that magnetic Seebeck effect exactly cancels the voltage gained through the Fe.
Smudge
   
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If the external circuit is not ferromagnetic, say copper (which it likely is) then there is no spin polarization there and the gradient has no effect on that external circuit.

I've tried.  I let the HP 3468A heat for a long time to stabilize it. I fixed an enamelled copper wire near one end of the ferromagnetic rod and sent it back along the rod to the other end, where I connected the voltmeter which displays 10 µV +/-1, without a magnet. It is difficult to say where this gap comes from, it depends on the contacts, but it was stable.
 
When I approach the magnet, the voltage fluctuates by several tens of µA (induction), then it stabilizes at the same value as without the magnet. Reverse polarity of the magnet does not change anything.
 
Update 2019-02-26
Contrary to my first idea, the force on a magnetic dipole should be proportional to B, not H, even for an electron inside a ferromagnetic material. So I looked for another explanation for the null result.
When an electron moves through the ferromagnetic material due to the field gradient and reaches the copper wire through which it can escape, there is another field gradient in the opposite direction, due to the fact that copper does not concentrate the magnetic field unlike a ferromagnetic material. Thus, the field outside is much less intense than the field inside, reversing the direction of the gradient. The electron gets stuck somewhere in between.

The idea of replacing copper wire with ferromagnetic wire would not change anything. The gradient along one half-circuit will always be the opposite of the gradient of the other half-circuit. The electrons will move in both half-circuits to the area of the highest gradient until the Coulomb force balances them.

We are therefore obliged to rotate the axis to obtain the imbalance causing the current.




« Last Edit: 2019-02-26, 10:46:22 by F6FLT »


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I am continuing this thread as the origin of my homopolar generator is not clear.
What is the principle of a homopolar generator like the Faraday disc?

The traditional explanation is that the electrons in the disc moving in the field of the magnet, are subject to the Lorentz force, perpendicular, and therefore move between the centre of the axis and the periphery of the disc, where the sliding contacts are.

Now if we place ourselves in the reference frame of the disc, we see the external circuit connected to the sliding contacts rotating, and the Lorentz force is seen exerting itself on the electrons of the circuit external to the disc. The effect would thus be reciprocal.
But beware, when we take a small circular magnet and a large disc, the sliding contacts are outside the magnetic field and yet we still have the effect without being able to adopt the explanation of the Lorentz force seen from the reference frame of the disc, so the explanation would not be reciprocal.

A less traditional but nevertheless academic explanation is that the electric circuit cuts the magnetic flux, see diagram.
On the loop ABCDO, we look at the cut flux at time t and t+dt. The segment DO has rotated by an angle dθ = ω.dt, which adds a new segment DD' to the loop. The magnetic flux through the loop ABCDD'O is Φ.B(t+dt) = B.r².dθ/2 = r².B.ω.dt/2 and integrating, EMF = -dΦ/dt = -r².B.ω/2, where r is the radius of the disc.

From this we can formulate very simply the general principle of operation of a homopolar generator: we need a magnetic flux through an electric circuit in two parts, one of which is movable relative to the other.
The flux being conservative, whether it is one or the other part that we take as reference, each one sees the other one cutting the same flux, which generates the electromotive force.

The next step : to re-analyse my generator using this principle.



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Before continuing the analysis, see here the simulations that Hunternico has just done: https://www.overunityresearch.com/index.php?topic=4385.msg102372#msg102372

Note that the key points of the generator are :
- a ferromagnetic axle, the higher the permeability the better
- the larger the magnet diameter, a large ferrite magnet is better than a smaller neodymium magnet.

The field lines of the magnet should follow the axis and loop back to the magnet as far as possible.

Hunternico's simulations :


With mu-metal







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This is what started my interest in OU almost a decade ago  :).

Imo the best model to analyze the homopolar with is Weber's electrodynamics. Using that you can see very quickly where the origin of the voltage is due to the nature of relative motion. The model basically states that if there is no relative motion then there is no force aka E field.

So according to Weber's EM you get the following conclusions.

Disk   Magnet   Voltage source
spinning   spinning   stationary circuit
spinning   static   spinning disc
static   spinning   spinning disc
static   spinning   both disc and circuit(but they cancel each other)


Especially the last case is very unintuitive in classic electrodynamics, but this is due to the fact that Weber EM also predicts a longitudinal force. This can only be detected with very sensitive equipment but technically a rotating magnet generates an electric field around itself.
   
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This can only be detected with very sensitive equipment but technically a rotating magnet generates an electric field around itself.

What experiments have verified this?


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tExB=qr
According to Gyroscopic Force Theory (GFT) electrodynamics, you can replace the magnetic field with gravity if you force the disc to precess.  This is very difficult to do mechanically, so this has not been verified.

   
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Theories without experimental confirmation, no matter who they come from, are not science until proven otherwise. Please discuss them elsewhere.


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Theories without experimental confirmation, no matter who they come from, are not science until proven otherwise. Please discuss them elsewhere.

The title of this thread is "Homopolar Generator, a new one?" and I have just described a "new" homopolar generator.

Scientist, as you desire to be, do not discard new theories or new devices merely based on the fact that they are not "proven".
   
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The title of this thread is "Homopolar Generator, a new one?" and I have just described a "new" homopolar generator.

You described nothing.
This thread is dedicated to the new homopolar generator I proposed and described in the first post, not to all homopolar generators. No need to make us believe that you would not have understood it, it would be a pure lie.

Quote
Scientist, as you desire to be, do not discard new theories or new devices merely based on the fact that they are not "proven".

Your answer needs clarification. A reflection on my person is inappropriate. Moreover, I have no such desire.
1) I am only trying to use the scientific method because it is the only method that works.
2) I am doing research in accordance with the purpose of this forum. Unlike you, I don't spend my time peddling the improbable theories of others, and moreover without providing any personal analysis.

For the question of "not proven" theories, see my signature. If, unlike those scientists you mention, you want to bring up dubious theories without being able or believing yourself obliged to provide any rational reasoning linking them to the proposed device, this is not the right thread.
Magical thinking is not the method here.


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What experiments have verified this?

There's very little literature on this but here is one:

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/JZ070i019p04951

A spherical rotating magnet can cause plasma around it to rotate. This is because the E field due to rotation would point radially in/out and this attraction of charge will cause movement in turn "triggering" the Lorentz force which causes these charges to rotate around the sphere.
   
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There's very little literature on this but here is one:

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/JZ070i019p04951

A spherical rotating magnet can cause plasma around it to rotate. This is because the E field due to rotation would point radially in/out and this attraction of charge will cause movement in turn "triggering" the Lorentz force which causes these charges to rotate around the sphere.

When a text seems to say the opposite of everything others say, it is either that we are dealing with an incompetent author or that we have not understood. I think it's the latter.

This text does not say that a rotating magnetised sphere creates an electric field capable of driving electrons, it even says the opposite:
"The same sphere, rotating in vacuo however, generates a quadrupole electric field in the surrounding space [], and this will not cause individual ions and electrons to rotate with the angular speed of the sphere."

The question is only that of a sphere rotating in a plasma, which is made up of agitated charged particles. Any displacement of charges crossing the magnetic field lines will tend to deflect them at 90°, this is the E = -1/c * (ꞷ x r) x B field they are talking about (as seen from the charges), so the final stable position for the ions to stay aligned with the field lines is to rotate with it.

A plasma is not a neutral conductor with static charges.


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When a text seems to say the opposite of everything others say, it is either that we are dealing with an incompetent author or that we have not understood. I think it's the latter.

This text does not say that a rotating magnetised sphere creates an electric field capable of driving electrons, it even says the opposite:
"The same sphere, rotating in vacuo however, generates a quadrupole electric field in the surrounding space [], and this will not cause individual ions and electrons to rotate with the angular speed of the sphere."

The question is only that of a sphere rotating in a plasma, which is made up of agitated charged particles. Any displacement of charges crossing the magnetic field lines will tend to deflect them at 90°, this is the E = -1/c * (ꞷ x r) x B field they are talking about (as seen from the charges), so the final stable position for the ions to stay aligned with the field lines is to rotate with it.

A plasma is not a neutral conductor with static charges.

I agree with most of what you say. To me it's very surprising that even more than 100 years of the original faraday experiment. We have no experiments exploring this in far greater detail. Since we're dealing with mV range values setting up such sensitive experiment was probably not feasible back then but now we can detect nano volts but it needs to be shielded good enough so external fields which can be in kV range don't skew the results. But this should all be trivially possible and proving that a rotating magnet produces a static electric field is quite a significant "discovery" even though some models of EM already predict this.
   

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I agree with most of what you say. To me it's very surprising that even more than 100 years of the original faraday experiment. We have no experiments exploring this in far greater detail. Since we're dealing with mV range values setting up such sensitive experiment was probably not feasible back then but now we can detect nano volts but it needs to be shielded good enough so external fields which can be in kV range don't skew the results. But this should all be trivially possible and proving that a rotating magnet produces a static electric field is quite a significant "discovery" even though some models of EM already predict this.

One thing I have never been able to find someone attempt was running a Faraday generator in a vacuum using plasma as the 'brush' between the perimeter and outer conductor.


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To me it's very surprising that even more than 100 years of the original faraday experiment. We have no experiments exploring this in far greater detail. Since we're dealing with mV range values setting up such sensitive experiment was probably not feasible back then but now we can detect nano volts...

For me it is not surprising that this is no longer done. On the one hand it has already been done since everyone was surprised by the absence of any difference in effect with the rotating or fixed magnet in Faraday's experiment, on the other hand following this kind of observation, the laws of electromagnetism were elaborated and synthesized in Maxwell's equations. As no counter-examples or anomalies have been found that would call electromagnetism into question, there is no reason to set up this kind of experiment. In science you take what you find, you don't try to see what you want to see, unless you have good reasons for it. Inconsistency between an effect and the theory is one, but not the need for free energy or extraordinary effects.



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Here's a very good thesis I came across a while ago:

http://www.df.lth.se/~snorkelf/LongitudinalMSc.pdf

What people don't know is that Maxwell stress tensors (which you can equate to "classical" non-relativistic EM) readily predict longitudinal forces. This is why I mentioned that Weber's EM is equivalent to it, it does not predict "new" science. in fact even Weber himself proved that his force model is fully conservative so there's no hope for OU unless you deal with permanent magnets which behave differently from moving charges. it just does so with less compute heavy FEMM models making 3d simulations solvable in near real time. This is also how I visualize these forces best and how the rotating magnet generating an electric field around it in space again this is not even OU or anything as any movement of this external charge will try to torque the magnet to a standstill. Energy conservation at its finest.
   
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Here's a very good thesis I came across a while ago:

http://www.df.lth.se/~snorkelf/LongitudinalMSc.pdf

What people don't know is that Maxwell stress tensors (which you can equate to "classical" non-relativistic EM) readily predict longitudinal forces. This is why I mentioned that Weber's EM is equivalent to it, it does not predict "new" science. in fact even Weber himself proved that his force model is fully conservative so there's no hope for OU unless you deal with permanent magnets which behave differently from moving charges. it just does so with less compute heavy FEMM models making 3d simulations solvable in near real time. This is also how I visualize these forces best and how the rotating magnet generating an electric field around it in space again this is not even OU or anything as any movement of this external charge will try to torque the magnet to a standstill. Energy conservation at its finest.

This subject is very controversial, there is no convincing evidence of a longitudinal force. If you look here "Ampère longitudinal forces revisited" you will see that other explanations are provided for the experiments cited in the thesis, and this work seems to me to be at least as strong, if not stronger, than the other.
Note also that F=q.E is a longitudinal force on the electrons confined in a conductor, a force that no one denies, and if it cancels out well on one turn, there is no reason why it should be homogeneous along the whole circuit. By trying to explain everything by magnetism, we forget the basics.

As for "the rotating magnet generating an electric field around it in space", this is also an experimentally unproven assertion in the case where the mechanical rotation axis corresponds to the magnetic axis (otherwise, obviously, it is the variable electric field of induction).



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