Re: tesla coil is an air core. why?

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

Original poster: "davep by way of Terry Fritz <twftesla-at-qwest-dot-net>" <davep-at-quik-dot-com>

 
> why does the tesla coil use an air cored design?
	Short answer:

	Because that's what works best, so far.

 	Tesla started with cored coils.  With the materials

	available, he found that air core (no core) worked
	best.  I'd guess new materials (except maybe
	ferrite) have not changed this.


> I thought of a few reasons, but wasn't sure if i was right.

> core materials can have hysteresis losses, eddy current losses,

> problems with saturation, and poor high frequency response.
> therefore air cores are better?

	yes yes yes and yes.
	(unless i lost count....)
	ALSO a metal core tends to be tricky to manage
	around Really High Voltages.


> I'm guessing that if you used a core the coil would loose

> considerable efficiency or fail to oscillate (since the

> core would increase the  inductance.)

	It could be readjusted.


> but what if you used a diamagnetic material as a core.

	I can't think why?
	'core' has two reasons:
	physically support the windings:
		HDPE, cardboard, etc do nicely.
	Concentrate the magnetic fields, reducing stray
	fields and device size.
		Since size is of less importance than
		avoiding losses (which are lowish anyway)
	
	and avoiding sparks to core are critical,
		no core (in the magnetic sense) is used.

	There was some discussion of a ferrite core
	secondary.  Could someone summarize?
-
	best
	dwp

...the net of a million lies...
	Vernor Vinge
There are Many Web Sites which Say Many Things.
	-me