expensive Macor-ring I got from the workshops back in march. Yeah, well, I blew it up today.
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...
1 week ago