Untried Homopolar Generator Experiments

(c)1996 William J. Beaty

Diagram: Pipecaps and mercury test [Pipecaps and mercury GIF ]
some HPG Device diagrams:
In 1992-94 I messed around with homopolar generators, ("HPGs" or "N-machines",) tried a simple test, and drew some GIFs of possible devices. Check out the above links for these diagrams.

The general idea was that an HPG might lack back-torque if the rotor and stator circuits are radially symmetrical. If all wires were replaced with cups and tubes, would the mechanical energy per output wattage be reduced? If this were true, conservation of energy would be violated. The generator would create large currents and heat output, yet it would require little driving energy. If a pair of these was hooked together in motor/generator configuration, they might self-accelerate anomalously and spin without extrnal energy input. Impossible by standard physics, of course. Yet a radially-symmetric HPG does not change flux linkage when rotating, and so it might not be expected to produce output currents. Yet it does. Tewari and Depalma in fringe-science publications claim to have observed anomalous behavior when investigating these devices. If there is a way to extract the energy of the quantum vacuum sea, perhaps here is a device which accomplishes the feat.

The pipecaps/mercury experiment was my crude attempt to detect changes in electromagnetic braking in a shorted, symmetrical HPG. I hoped to compare the braking forces with and without the permanent magnet present. Unfortunately my setup didn't show low friction without the magnet, since the oxide crust on the mercury contributed a large friction compared to the EM braking effects. The crust/scum on the mercury gave such high friction that I couldn't see any obvious difference between the magnet version and the no-magnet version. To detect forces, I only relied on twisting up the thread and making crude time measurements of the unwinding. Later I realized that the crust could be eliminated. This experiment needs to be repeated.

Hint for anyone who wants to try the experiment: silver-plate the copper so that the mercury will wet it, and put light oil on the mercury to seal it from oxygen and prevent the formation of an oxide scum layer. This will vastly lower the friction and make the differences between the magnet version and the no-magnet version measurable. Big hint: build a large, heavy version of one of these shorted-out generators, spin it with a motor, stick it in a calorimiter, and see if unexplained excess heat is evolved. (See if the shorted homopolar generator makes more heat energy than is input by the wires to the driving motor.)

In thinking long and hard about HPGs, I have come up with some observations and questions. Are you confused about spinning magnets versus spinning disks? Here's more to think about. Perhaps it will help to clarify things.

The diagram below depicts a simplified Homopolar Generator (HPG). Rather than using a separate external circuit and a spinning disk, I've combined them into a two-disk arrangement. One half of the device in fig 1a is the "disk," of a classic HPG, while the other half acts as the "external circuit." Carbon brushes connect the halves with sliding contact. Liquid metal brushes would be better.

[GIF of two-halves cylinder w/central post, carbon brush on lips and post tips, rotating between magnet poles, counterrotating]

The two halves are placed together in fig 1b. When a magnetic field is applied (vertical field in fig 1b) and the two halves are spun together as a unit, the relative motion of the metal and the magnetic field should cause a radial voltage to appear, which causes the rim of the metal assembly to aquire a positive charge, and the axis of the assembly to receive an equal negative charge. No current appears, instead the device acts like a charged capacitor as long as the rotation continues. Also, if the metal assembly is held still and the magnets are spun instead, the same radial voltage should appear and the same separation of charges should exist on the object, again with a voltage only. There is a momentary separation of charge, but no constant current.

Fig 1c shows my idea of how HPGs are able to create electric currents. If the upper and lower halves of the device are spun in opposite directions, the polarity of the radial voltage and the radial separation of charges should be opposite in each disk. Since the two halves are in sliding contact, the positive and negative regions are in electrical contact and a very large electric current should appear. This current is zero if the two halves are spun together. It is large if one half spins and the other is kept still. It is twice as large if both halves are spun in opposite directions. However, any relative rotation of the magnet, or the magnetic field, should result in equal voltages radially across both halves, and therefore should create no relative voltage between the halves, so rotating magnets should create no current. In other words, the magnetic field might spin with the magnet or it might not, but this cannot be detected by the HPG disks. The HPG doesn't care if the magnet spins. Instead, it only cares about differing rotation of the two metal parts.

If you hold one half of the metal parts still and spin the other half, you create a "classic" HPG having a spinning disk and a nonspinning "external circuit." Simply add a current meter in series with the shaft of the non-spinning half depicted above. You can even carve away most of the shell of the non-spinning half and form it into "wires". You'll end up with the "classic" HPG circuit in full.

This then shows why the rotating copper parts might apply back-action forces against the external circuit, but need not apply any forces against the permanent magnet. It explains the seeming non-reversibility of current-generating action in Faraday's homopolar experiment. It appears that there is a paradox, and that the rotation of Faraday's disk generates current, while rotation of his bar magnet does not. In reality, the only important motion is the *relative* movement between Faraday's disk and his external circuit, and the rotation of the magnet is unimportant. Of course the presence of the magnetic field is necessary to accomplish the effect and create current, but its rotation relative to the average rotation of the disk-plus-circuit assembly only creates a net radial charge separation without creating constant current.

Once we realize that the external circuit is the "stator" of the device, the homopolar generator is not as weird as it first seems.

Note that these are all untested thought-experiments. There is a small chance that the HPG does not work as I describe above, and that there is a true anomaly here. If the mechanical energy input to a homopolar generator is not in perfect 1:1 proportion to its heat output, then there are mysteries here to be investigated.

There is a chance that the device of fig. 1c will not create back-action against whatever mechanical forces are causing it to turn. In this case a motor could be used to spin one disk, and the current in them would create heat, but the current would not create electromagnetic back action, and so the motor would do no work in driving the disks, resulting in heat energy "from nowhere." Or as with the Searle device claims, the generated current in the disks might even create a motor action which would spin the disks, which would create higher current but no back-action force, which would in turn spin the disks even faster, and which would create continuous acceleration, an explosive runaway flywheel reaction, and again create "energy from nowhere." If you short out a radially constructed HPG and spin it fast enough, will it start spinning faster and faster, until it shatters from the radial forces? There are rumors that such things happen. I haven't heard that anyone has tried this recently and verified that nothing mysterious occurs.

I'll leave you with this though. In the diagram below, I have attempted to sketch the electrostatic field created by a spinning disk magnet. It seems as though there is an imbalanced charge along the rim of the magnet. However, since charge is conserved, a region of opposite charge must appear elsewhere. The equal and opposite charge is not on the magnet at all, it is hanging in space along the axis of rotation! (At least my crude drawing strongly suggests this. Am I mistaken?)

[GIF of spinning disk magnet, virtual charge along axis of rotation!?]

Is this real? Isn't it like those strange circular e-fields which exist in the empty space around a toroidial AC inductor? But this is the DC version. And I cannot see how the e-field could have these closed loops, since the field lines seem to end in empty space at the axis of rotation. If there were a cloud of charged particles surrounding this spinning magnet, would the rotating field cause them to collect at the axis? Surely simple electromagnetic physics doesn't have such a gaping flaw. However, I've heard that in Gen. Rel., EM does not apply correctly when the objects in question are rotating. Is this true? I don't know how to think about this, and if I've made an error in visualizing it, I cannot see my error. [perhaps the concept of 'lines of flux' doesn't apply to the e-field generated by a changing magnetic field?]


   Faraday Paradox (WP)

   PDF papers at U. Texas Center for Electromechanics

   N-machines in nuclear submarines: the hunt for compact power

   Earth's core simulated with rotating liquid metal

   IEI (Ireland) finds new Faraday Disk effect
   http://www.iei.ie/papers/faraday/faraday71.html, also some discussion

   THE HOMOPOLAR HANDBOOK: A definitive guide to faraday disk and
   N-machine technologies,  by Thomas Valone, 1994.  Published by 
   Integrity Research Institute, 1377 K St. NW, Suite 204, 
   Washington DC 20005  See bookstore

   Don Lancaster's "Tech Musings", tinaja.com site:
   - muse117.pdf, Shattering HPG Myths
   - muse121.pdf, Understanding Faraday's Disk

   Homopolar motor torque equation

   W. Johnson Gyro Force Theory: Faraday disk (.pdf)

   Delpalma's site http://depalma.pair.com/

   Eric K's free energy EM skepticism

   Dr. I. Moroz current homopolar generator research

   Spinning Magnetic Fields, Jovan Djuric
   Journal of Applied Physics v48 #9 Sep 1977 p 3981

   Comments on Spinning Magnetic Fields, A. Viviani
   Journal of Applied Physics v46 #2 Feb 1975 p 679   

   From CyberWorkshop:
      Homopolar Generator Principle (jap lang)
      HPGs I(jap lang)
      HPGs II  (jap lang)
      HPGs III  (jap lang)

   Graneau's EM forces, bibliography

   Fenyman Lectures on Physics, Vol II, Sect 3.10

      R. J. Stephenson, Experiments with a Unipolar Generator and 
      Motor, AJP 5, 108-110 (1937).

      Dale R. Corson, Electromagnetic Induction in Moving Systems, 
      AJP 24, 126-130, ( 1956).

      David L. Webster, Relativity in Moving Circuits and Magnets, 
      AJP 29, 262-268 (1961). 

      Thomas D. Strickler, Variation of the Homopolar Motor, AJP 29, 
      635 (1961).  A. K. Das Gupta, Unipolar Machines, Association of 
      the Magnetic Field with the Field-Producing Magnet, AJP 31,
      428-430 (1963).

      David L. Webster, Schiff's Charges and Currents in Rotating 
      Matter, AJP 31, 590-597 (1963).

      Thomas Strickler, Motional emf's and the Homopolar Motor, 
      AJP 32, 69, (1964).

      Little Stinkers: Electromagnetic Induction, TPT 4, 1966.  
      R. Becker, "Electromagnetic Fields and Interactions, Blaisdell 
      Pub. Co.,      378-383, (1964).

      P. Lorrain and D. Corson, Electromagnetic Fields and Waves, 
      W. H. Freeman, 338-343, 657-664, (1970).

      Robert D. Eagleton and Martin N. Kaplan, The radial magnetic 
      field homopolar motor, AJP 56 #9, 858-859 (1988).

      Daniel F. Dempsey, The rotational analog for Faraday's magnetic
      induction law: Experiments, AJP 59, 1008-1011 (1991).

      J. Guala Valverde and P. Mazzoni, The principle of relativity 
      as applied to motional electromagnetic induction, AJP 63 #3, 
      228-229 (1995).

      Gerald N. Pellegrini and Arthur R. Swift, Maxwell's equations 
      in a rotating medium: Is there a problem?, AJP 63 #8, 
      694-705 (1995).

      Richard E. Berg and Carroll O. Alley, Unipolar Generator: A
      Demonstration of Special Relativity - Department of Physics 
      and Astronomy, Univ. of MD- College Park.

      Aurthur I. Miller, Frontiers of physics, 1900-1911 Selected 
      Essays: Unipolar Induction: A Case Study of the Interaction 
      Between Science and Technology, 153-180, Birkhauser at Boston

      Panofsky and Phillips, Classical Electricity an Magnetism, 
      pages  240, 342-345.

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