Re: 'Glow' discharge
From: Tesla List <tesla-at-pupman-dot-com>
To: tesla-at-pupman-dot-com <tesla-at-pupman-dot-com>
Date: Wednesday, February 16, 2000 7:53 PM
Subject: 'Glow' discharge
>Original Poster: "Sarah Thompson" <sarah-at-telergy-dot-com>
>I'm new to the list. I've not yet built a TC, so I'll refrain from asking
>lame questions until such time as I'm half way through it and can't get it
Be better to ask lame questions regarding what hardware is needed to
implement your design requirements
>The reason I want to make a TC is for the purpose of creating ionised gas
>for experiments in MHD.
I like that idea ;-)
Especialy if the power generated is fed back (bootstrapped) into the
mechanism, as in turbojet engines.
>One experiment I want to do is related to MHD power generation. I'd like to
>be able to ionise the air moving along a non-conductive pipe, whilst also
>causing a hefty current to flow across it (through the gas). The electrodes
>need to be longitudinal with respect to the pipe, and maybe 1 - 2" apart
>parallel. If the theory works, it should be possible to blow gas through
>pipe and extract power from a coil wound around the pipe.
Usualy a magnetic field (from magnets, >10Kgauss) is used and voltage is
generated at the electrodes; you probably know this though. I don't quite
get your plan.
Low resistivity, or highly conductive plasma for low loss, like you will
want, will take high currents. At atmospheric pressures the discharge will
kink into filamentary arcs. So you will have to operate in short <100uS
pulses or continous RF.
>The other experiment is a little weirder. What I'd like to be able to do is
>create an even 'glow' discharge around a spherical or dome shaped
>such that the air around the conductor gets ionised, but streamers or
>are avoided. Is this even possible with a TC?
Yes, just need very thin wires or sharp points. You can do that with a car
coil. The breakdown voltage gradient in air is inversely proportional to the
radius of curvature of the conductors.