From: TheSubdued@yahoo.com (Joshua Dickerson)
Newsgroups: alt.lasers,sci.physics.plasma
Subject: Re: Corona preionization
Organization: http://groups.google.com
References: <f3b87972.0312132258.b470eed@posting.google.com> <6VYCb.1573$mC1.1456@newsread1.news.atl.earthlink.net>


I have done some initial experiments trying to get barrier discharge.
For some reason, I only get barrier discharge when the capacitor is
charging. Once the capacitor reaches equilibrium, the barrier
discharge ceases. What I mean by the capacitor is the metal
plate/dielectric/air/dielectric/metal plate from my barrier discharge
setup:

__________________ Metal sheet
|||||||||||||||||| Dielectric (polyethylene .006 ")
Air (where Corona/barrier discharge occurs)
|||||||||||||||||| dielectric (polyethylene .006 ")
------------------ Metal sheet

During discharge (via an external over-volt spark gap connected to the
metal sheets) of this capacitor, very little corona is formed.
Initialy, I was detecting the corona via flourescent paper I made
using a neon colored highlighter. The corona produces a little UV as
a side effect, so why not? :)

I'm still experimenting, but still quite confused. Why only
during charging? I'm only using 7 kV. Maybe pulsed corona discharge
(which seems continuous due to persistance of vision) only forms at a
higher voltage. but the fact that i'm getting large, plainly visable
(ie: without the stained paper) amounts of corona in the air (albiet
briefly) from 7 kV is significant.

Best Regards,
- Josh.


"rprovins10" <rprovins10@earthlink.net> wrote in message news:<6VYCb.1573$mC1.1456@newsread1.news.atl.earthlink.net>...
> My guess is its like the trigger wire for a xenon photo strobe, only running
> constantly instead of a single pulse
> might even want to try running RF through the "trigger wire"
> Rob Provins
>
> "Joshua Dickerson" <TheSubdued@yahoo.com> wrote in message
> news:f3b87972.0312132258.b470eed@posting.google.com...
> > I have successfully designed, built and operated my own T.E.A
> > air/nitrogen laser. It's 30 cm long, runs on 6 kV, main capacitors
> > are 4.7 nF. Works decent enough and has a bright, multi-mode beam
> > (something like TEM84), but there are a few hot spots in the
> > discharge. Just today, I saw this interesting concept at
> > http://www.karakas.8m.com and I was immediately envious. Karakas was
> > able to get a uniform discharge using corona preionization.
> > Unfortunately, he doesn't provide enough detail for me to implement it
> > myself. What's worse, there is very little information that I can
> > find off the net. Does anyone understand how he has everything
> > connected? The only way i can make sense of his design is that corona
> > is formed at the moment of discharge and he is getting barrier
> > discharge off a single capacitor plate/dielectric next to the anode.
> > Can anyone help? Thanks!
> >
> >
> > Best Regards,
> >
> > - Josh.


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