RE: 130kW Coil Update [helium gap]

From: 	Greg Leyh[SMTP:lod-at-pacbell-dot-net]
Sent: 	Wednesday, December 10, 1997 3:40 PM
To: 	Tesla List
Subject: 	Re: 130kW Coil Update

Edward V. Phillips wrote:

> "The 30HP, 500VDC Westinghouse motor seems to have no problem with
> this, however.  Cursed aero drag = v^3!"
> Greg:
>         Have you considered running it in helium?  Would cut the
> windage significantly and help with cooling.  Don't know what
> the effect would be on gap breakdown.

Alas, the gap is of the open frame type, far from airtight.
As I understand it, helium actually has a lower heat capacity,
since monatomic elements only have 5 degrees of freedom, 
where diatomic ones have 7, allowing them to carry more heat
energy per deg C.  That's why He compressors run so hot.

At STP, I believe that helium gas has a much lower breakdown 
voltage than dry N2.  But is this good or bad?