lightning, Xrays

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

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

I see from the news
http://www.napa.ufl.edu/2003news/lightxray.htm

that there has been experimental measurement of Xray emission from 
lightning strokes.

It's historically been the case that you needed both HV and High Vacuum to 
get Xrays.  Therefore, there's no radiation hazard from, e.g., a tesla coil.
Here's a case (not likely to be duplicated by the casual amateur) where you 
get Xrays with HV, but no vacuum.
I was aware that you can get Xrays from very fast rise time sparks (>1E9 
A/microsecond, as I recall), but this is something new...

It's also in Science, vol 299, page 694-697 "Energetic Radiation Produced 
by Rocket-Triggered Lightning", J.R.Dwyer, et.al.