On 07/06/2017 01:00 PM, Jeff Liebermann wrote:
On Thu, 6 Jul 2017 09:51:44 -0400, Phil Hobbs
wrote:

No, it's a coupled plasma/surface effect. It's really cool. It
peaks down around a few tenths of a millitorr, but it's still
appreciable at higher pressures.

According to Wikipedia:
https://en.wikipedia.org/wiki/Incandescent_light_bulb the gas
pressure in a common light bulb is about 70 kPa or 525 torr. That's
quite a bit higher than a few tenths of a millitorr.


The light bulb thing was discovered by somebody turning on an
incandescent lamp and wiping out his reception.

I don't quite believe it. In the early daze of light bulb research,
it was wrongly assumed that a better vacuum produced a better light
bulb. So, early light bulbs had a fairly high vacuum, which might
explain the RF interference,

How exactly, if not Barkhausen? Hot wires don't produce a lot of RF IME.

except that radio hadn't really become
common at the time. Eventually, someone figure out that it was the
water in the glass that was killing the filaments. Once the water
was baked out of the glass, subsequent light bulbs had a much lower
vacuum.

If you read my original post, I pointed out that it was only the old
fashioned evacuated bulbs that showed the effect, not the modern argon ones.

I don't know if the pressure in the transient suppressor is low
enough for Barkhausen--if not, it's probably the neon bulb
oscillation as others have said.

I don't think that the ceramic gas discharge tubes have a vacuum.
More like they are under pressure in order to lower the conduction
current. However, I'm guessing and don't have time to look it up
right now.

You don't want to reduce the conduction current in a gas suppressor
tube, though, do you? My guess is that they'd be a torr or two, to get
lower breakover voltage, which is on the high side for Barkhausen, for sure.

Cheers

Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net