Core material for high power high frequency coil/solenoid

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Discussion Overview

The discussion revolves around the search for suitable core materials for high power, high frequency coils or solenoids, particularly focusing on achieving high magnetic field strengths (up to 1T) at frequencies ranging from tens of kHz to hundreds of MHz. Participants explore the limitations of typical ferrite cores and the challenges associated with using air as a core material.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants note that typical ferrite cores are effective up to about 1 MHz, but question whether materials exist that can function effectively at higher frequencies.
  • There is concern regarding core loss in ferrite materials, which may limit their effectiveness at high frequencies.
  • One participant emphasizes the need for a high strength B field at high frequency and questions the feasibility of achieving this with air cores, suggesting that a core material could reduce the required current.
  • Another participant raises the issue of saturation limits in materials, indicating that finding a suitable core that does not saturate at high field strengths is challenging.
  • Some participants discuss the possibility of using multiple smaller coils in parallel to achieve the desired field strength and explore the idea of using capacitors in conjunction with the coils.
  • There is a suggestion that pulse operation might allow for easier current management compared to continuous operation, although the saturation limits would remain unchanged.
  • Concerns are raised about the practicality of supplying kiloamp currents and the associated cooling requirements for air core coils.
  • Participants express uncertainty about the average B field strength in powerful SMPS ferrite cores and suggest looking up datasheets for specific materials.
  • One participant mentions Ferroxcube materials that may work at higher frequencies but notes that most ferrites saturate at lower magnetic flux densities.

Areas of Agreement / Disagreement

Participants generally agree on the limitations of ferrite cores and the challenges of achieving high field strengths with air cores. However, there are multiple competing views regarding the feasibility of different core materials and configurations, and the discussion remains unresolved regarding the best approach to meet the specified requirements.

Contextual Notes

Limitations include the dependence on specific material properties, saturation limits, and the need for further exploration of current calculations and coil configurations. The discussion does not resolve the complexities involved in achieving the desired magnetic field strengths at high frequencies.

  • #61
I'm not sure I understood your remark, well the field lines are going to loop back anyway whether there is a disc or isn't one I was just thinking that maybe I can put them to good use, although on a second thought if they experience another disc in their path that would in total lessen the strength of the field and I'm not sure whether the effect of cancelling circumferential currents would outweigh the extra mechanical complexity and other factors, probably not.
If I make a slotted disc I would have to use some low permeability (the same as air) composite material disc on which to attach the multiple thin and slotted copper fragments that join at the center for more structural integrity, this way I could sandwich the thin copper plate between the non-conductive discs to make one larger rotating structure.
 
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  • #62
You need to specify exactly what you are trying to do. Many things are provably impossible. The design of magnetic machines is well defined. You need to shorten the magnetic field lines and you need to minimise the air gaps. You cannot get away with breaking the laws of physics by negotiating with the devil, or by getting a more expensive lawyer. Are you dreaming or engineering?
 
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