Arc polarity for fusing wire?

Current images of fusor efforts, components, etc. Try to continuously update from your name, a current photo using edit function. Title post with your name once only. Change image and text as needed. See first posting for details.
User avatar
Rich Feldman
Posts: 895
Joined: Mon Dec 21, 2009 11:59 pm
Real name: Rich Feldman
Location: Santa Clara County, CA, USA

Re: Arc polarity for fusing wire?

Post by Rich Feldman » Sun Mar 11, 2018 6:05 am

Here's a picture of the shielding-gas cup I made for wire balling. The general setup is about the same as the unshielded apparatus that I showed earlier in this thread.
Argon is flowing at a few cm per second -- any more than that, it carries away heat & it takes a lot more current to melt the wire end. I was surprised to see a cathode glow coating the last couple mm of upper electrode, at atmospheric pressure. I think there's a bit of it on the tip of the screw in today's picture.
The photo shoot brought evidence that argon ionizes more easily than air. Variac was just high enough to start the arc (electrical measurements will follow sooner or later). Soon after an unplanned stoppage of the gas flow, the arc got skinny and orangey and then went out. It came back by itself when gas flow was restored. Macro photos to follow sooner or later.
Here, on the same station, is a fancy projector lamp I picked up at the flea market this morning. No diode, and variac at 100%. I think it's what they call a xenon short-arc lamp. Don't know which terminal is the cathode, or whether they are normally energized with AC. I guess normal current is on the order of 1 ampere.
Richard Feldman

Post Reply