Re: Mica (and turning)

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-uswest-dot-net>" <jimlux-at-earthlink-dot-net>


> 
> If said mica is in a cylindrical shape, I'm guessing it's probably
> reconstituted mica, like wood chips that make up particle board, with some
> unknown binder added to it to keep it together.  The electrical properties
> of this binder would need to be considered.
> 
> A "k" value refers to the dielectric constant - the factor that a
> capacitor's capacitance value using this material for a dielectric would be,
> over an identical cap using a vacuum for dielectric.  This k factor implies
> nothing about what dielectric losses would occur, and in a capacitor, the
> dielectric loss factor is what determines how suitable, loss-wise, a
> material is for use as a capacitor dielectric.  But in the context of a
> secondary form, it's not clear that there's a significant an e-field where
> dielectric loss in the form would occur.  The magnetic field is probably the
> dominant thing that the form sees, and I'm not sure what physical property
> is a predictor for losses in a magnetic field.

hysteresis in the material is a predictor for losses in magnetic field


> 
> Lastly, no one has ever shown that the use of exotic materials in secondary
> forms is *measurably* any better than common PVC pipe, at least in spark gap
> based coils.
> 
> Gary Lau
> Waltham, MA USA