Homopolar generator: disk vs. helix

In summary, the Homopolar generator uses a rotating helical plate to generate a magnetic field. The field is generated by the voids in the plate that are packed with a paramagnetic material.
  • #1
Goldscuttle
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Hi,

I'd like to build a homopolar generator. Since generating magnetic fields of uniform density of any useful size is very tricky to do with off the shelf permanent magnets (I've tried!) I had the idea to use DC solenoids instead. But with a rotating helical plate in place of the cylindrical solenoid core. (basically replace the iron core with a screw with wide, thick threads) In either case, the voids will be packed with a paramagnetic material in order to encourage the fields to flow between the planar surfaces. The core will be made or allowed to spin while the coil remains stationary.

Below are two diagrams that I hope clarify what I'm describing. The one on the left is the more conventional plate rotating while cutting through magnetic fields, there are just more of them. The helical one on the right I haven't ever seen but it occurred to me as a possible simplification. I have several related questions about this theoretical contraption before I plunk down a few bucks on a prototype.

Could a shaft made of stacked rings (such as copper washers threaded onto a metal spindle) be expected to perform identically to a bona fide helix where the surface between ends is continuous?
ie. For the stacked rings would the currents add like battery cells in series or would they cancel out?
And, since the helical core has no center spindle except maybe for mechanical support, would the voltage difference simply be measured from any inner edge to the outer edge of the same elevation? OR is the voltage gradient the same as the stacked ring config? (center to edge)

TIA for any improvements/pitfalls that you can point out.
Finite_Length_Solenoid_field_radius_1_length_1.png
 
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  • #2
One problem is that the voltage gradient in your design lies along the radius of the disk. It is the same for the top and the bottom of the disk so it does not increase up the stack, but cancels. You must use external brushes on the disk circumference, or change the configuration of the disks and magnetic fields. See:
https://en.wikipedia.org/wiki/Homopolar_generator#Drum-type_generator
 

FAQ: Homopolar generator: disk vs. helix

What is a homopolar generator?

A homopolar generator is a type of electrical generator that uses a magnetic field and relative motion between a conductor and a magnetic field to produce electricity.

What is the difference between a disk and helix homopolar generator?

The main difference between a disk and helix homopolar generator is the shape of the conductor. A disk generator uses a flat disk-shaped conductor, while a helix generator uses a coiled conductor in a helical shape.

Which type of homopolar generator is more efficient?

It is difficult to determine which type of homopolar generator is more efficient as it depends on various factors such as the size and materials used. Generally, a helix generator may be more efficient due to its larger surface area and longer conductor length.

Can a homopolar generator produce high voltages?

Yes, a homopolar generator can produce high voltages. However, the voltage is limited by the speed of rotation and the strength of the magnetic field.

What are the applications of homopolar generators?

Homopolar generators are commonly used in high-power applications such as particle accelerators, electric motors, and electromagnetic launch systems. They can also be used in some portable devices and experimental projects.

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