Re: Strange shock (fwd)

["John Williams" <jwilliams-at-edm-dot-net> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

Hi,
	I made a post about this a few days ago but apparently
it got lost with the current list server problems.
	I also made a post about this well over a year ago about
this effect.

	Here is the one I sent recently:

Hello,

	Somewhere back in the archives is a post I made about this effect.
	It isn't friction or the usual mechanisms we think of when talking
about the accumulation of static charges.
	Before there were semiconductor rectifiers there were devices
used to produce dc from ac that depended on ions as the charge carriers
in a partially evacuated envelope.  In the envelope was a noble gas and a
quantity of mercury.  The gas was chosen to ionize oppositely from the mercury
vapor.  The trick being that, because of the greatly differing mass of the ions
conduction was favored in one direction over the other.  It was crude and
didn't produce the sort of rectification we expect to day, but it worked after
a fashion.
	Well, air is composed of a mix of gases of differing masses that
ionize differently.  The difference doesn't have to be all that great for a
favored conduction direction to be created.  It wouldn't take much for a few
hundred thousand volt field to develop a surface charge on the insulation
of the coil windings of a few hundred volts of static.
	I've had this happen consistently in a closed garage on a not
particularly
dry night, so you can rule out wind, friction and humidity.  The coil was only
about four inches wide and about twenty one inches tall, and when shut off
and touched after running the accumulated surface charge would "bite" you
every time.
	There may be a reason that the effect was more noticable with this
small coil.  It was designed to be a table top magnifier, so it didn't sit
in the
center of a primary coil.  There wasn't anything anywhere near it that would
act to bleed off the accumulating charge.  Even the transmission line was
a copper pipe a half inch in diameter terminated with one inch brass spheres.
No sharp edges.  Nothing around to provide a quick leakage path.

	John

_____________________________________________________

	That's my "two cents" anyway...

>Original poster: "Jim Lux" <jimlux-at-jpl.nasa.gov>
>
>A quick test could be to take a piece of single sided copper clad board,
>ground the copper side and put it on a stand a few feet from the TC (out of
>range of the sparks) with the insulating side towards the coil.  Then,
>attach a few threads or similar insulating things (thin mylar ribbon would
>also work?) to the copper clad.  Run the coil. If charge builds up, the
>threads will be repelled away from the surface and stand out or up (as the
>case may be).
>
>----------
>> From: Tesla list <tesla-at-pupman-dot-com>
>> To: tesla-at-pupman-dot-com
>> Subject: Re: Strange shock (fwd)
>> Date: Saturday, July 15, 2000 3:30 PM
>>
>> Original poster: "Antonio Carlos M. de Queiroz" <acmq-at-compuland-dot-com.br>
>>
>> Tesla list wrote:
>>
>> > Original poster: "Ed Phillips" <evp-at-pacbell-dot-net>
>>
>> >         Based on my observation here, the charge is stored in the
>varnish
>> over
>> > the windings.  Typical example is when I run my hands over the surface
>> > of a small coil with heavy shellac layer on it.  I get multiple
>"shocks"
>> > as my hands move to various places on the outside of the coil.  Similar
>> > to the effect I get when I use the VDG to store charge on a piece of
>> > sheet plastic.  Can't imagine any other possible storage mechanism.
>>
>> Without any doubt. The grounded secondary coil attracts charges created
>> by streamers/sparks to the surface of the varnish covering the coil,
>> where they stay until slowly drained by leakage resistances, or by
>> someone touching the coil. A good shock can be probably obtained if
>> someone touches the secondary wire (or the top terminal) and the surface
>> of the secondary simultaneously (obviously after turning the coil off!).
>> Try to use a VDG to charge a piece of sheet plastic while holding your
>> hand at the back of the sheet (making a ground connection similar to
>> what the secondary coil does), and then touch the face of the plastic
>> that was charged by the VDG. For a greater effect, try the same with a
>> metalized (at one side, that you touch) plastic sheet.
>>
>> Antonio Carlos M. de Queiroz
>>
>>
>>