Re: How can I create a stream of plasma at ambient pressure, that glows?

What you are describing is a small scale version of the Northern Lights.  
It is possible to create plasma glowing plasma streams, but it is not 
always possible to control where they will go.  You have a couple of 
options:

Welding Arc: nice and bright, you can control where it goes, but you will 
be limited to short arc lengths (no more than an inch or so) and your 
"target" must be part of the electrical circuit.  Also, you require some 
sort of "welding gas" such as argon or CO2.

Tesla Coil Discharge: nice, bright, big, but not very controllable.  (It 
won't behave like a light sabre.)  Try "http://www.zap.to/TeslaWeb" for 
more information or search the web on "tesla coil".

It's possible to generate a stream of plasma; this is how plasma torches 
operate.  There is an arc discharge within the "plasma torch" and the 
plasma is forced out in a stream, but it doesn't glow and it doesn't go 
very far (again, probably on the order of a couple of inches).

I'm not sure if any of these are suitable as the ignitor for your ramjet.

Good Luck,

Chris Seaman
Alcoa Technical Center