When you work with plasma, you tend to forget the humongous amount of energy you can pump into a very small area when something goes wrong. While this is more or less what my thesis is all about, I nevertheless did not check if the reactor was really pumped down before I adjusted the matching. This includes driving the electrode with about 1500 Volts for a moment.
If you for some reason only switched on the roughing pump, the reactor will be at an pressure of about 7 mbar - perfect for a hollow cathode to ignite in a cornder. Subsequently, all 300 Watts of power will be concentrated in an area of about half a square centimeter. Which will then get hot enough to melt metal and crack ceramic - a thousand Euros worth of it in this instance.
Oh well, the price of progress...
The great thing about reading your blog is that I am so often out of my depth. This is one of those times. I have no idea what I'm looking at... but it looks like a horrible burn. Maybe put some aloe on it?
ReplyDeleteThis is more my failing then yours - intimately familiar (insert physicist - lab equipment joke here) as I am with the setup, I did not even notice that nobody will be able to figure out what the photo is meant to represent - you can't even figure out the scale!
ReplyDeleteThe ceramic ring is about 5 mm wide, and seperates the electrode where the power is delivered (the flat thing) from the ground-screen (the thing with the window) which helps keep the plasma where it is supposed to be.
Which doesn't help you, either. Maybe I'll write some posts about my experiments someday.
I'd try the aloe-idea, but I'm afraid it would contaminate my plasma chamber. But maybe you are on to something, who knows what aloe-plasma can do?