Discussion Overview
The discussion revolves around the speed at which an air-core electromagnet can be magnetized and demagnetized using DC pulsing, specifically focusing on the potential to achieve very high frequencies (10-100 GHz) without hysteresis or retentivity effects. Participants explore the implications of using air-core versus ferromagnetic cores and the challenges associated with high-frequency operation.
Discussion Character
- Exploratory
- Technical explanation
- Debate/contested
- Mathematical reasoning
Main Points Raised
- Peter questions the feasibility of achieving instantaneous magnetization and demagnetization of an air-core electromagnet at high frequencies, specifically in the 10-100 GHz range.
- Some participants clarify that hysteresis and retentivity are properties of ferromagnetic materials, suggesting that air-core designs would avoid these issues.
- Jim mentions that eddy currents in ferromagnetic materials limit frequency response, referencing powdered ferrite cores as a solution for high-frequency applications.
- Peter seeks to understand if a small copper air-core electromagnet would retain any magnetic field after being pulsed at 10 GHz, or if the magnetic field would precisely follow the DC pulses.
- Another participant notes that at 10 GHz, the wavelength of electromagnetic radiation is only 30 mm, implying that the physical dimensions of the circuit must be considered.
- Peter expresses a desire for a clean DC square-wave pulsing without delay between current and magnetic field, emphasizing the importance of achieving precise control over the magnetic field.
- There is a discussion about the operation of air-core inductors in microwave ovens, with questions about whether they are fed with DC or AC, leading to further exploration of their functionality at high frequencies.
Areas of Agreement / Disagreement
Participants generally agree that hysteresis and retentivity are not concerns for air-core electromagnets, but there is no consensus on the specific capabilities and limitations of operating at such high frequencies. Multiple competing views remain regarding the practical implementation and theoretical limits of the proposed setup.
Contextual Notes
Participants acknowledge that the discussion involves complex considerations at high frequencies, including the effects of circuit dimensions and the nature of the signal being used. There are unresolved questions about the precise behavior of the magnetic field in response to high-frequency pulsing.