>> Does cold-cathode production require bombarding ? I was going to get started >> in neon art about 10 years ago, but the dangers of bombarding outweighed the >> rewards in my opinion. >> One little mistake, and you die. None of the few remaining neon shops in my >> area would accept bombarding jobs, so I never got started. >
> Anyone want to try and explain bombarding to me??? What, why, where, when, > how etc. Thanks, Ira. While cold cathode production doesn't necessarily require bombarding, it is the usual approach. It's done for two reasons. One is to clean out impurities in the tube so you can get a clean fill gas (the heat of the process breaks down and/or evaporates contaminants, so the vacuum pump can remove them), the other is to "activate" the electrodes by converting the carbonates into oxides by breaking them down with heat. You can also clean your tubes by baking them in an oven while pumping, and activate your electrodes with induction heating with an external apparatus such as the Fluxeon. The usual procedure is to hook the tube to the vacuum manifold, and attach a large, high voltage, high current transformer with a variable supply to the electrodes. Pump the tube down to a low vacuum, then turn on the bombarder transformer. The whole tube lights up as whatever gases in it are ionized, and rapidly starts getting hot. It's cool to watch, as the color changes and striations appear in the discharge as the pressure changes. The person running it modulates the bombarder current as needed to get the tube clean. Normally, some method of monitoring the tube temperature is used to determine when it's up to temperature. Then the tube is pumped down more, and the bombarder transformer is switched on again and adjusted to about ten times the normal tube current. The lower pressure concentrates the heat in the electrodes, which warm up to glow red hot, at which temperature they become activated. The classes I took, the students were allowed to watch bombarding from a safe distance if they wished (I always did), but weren't allowed to operate the bombarder themselves. After a bunch of classes, where I demonstrated that I could work safely and take direction, and convincing the teacher that I understood the bombarding process and its dangers, I was eventually allowed to bombard my own tubes with supervision. I made and bombarded many of my own tubes, and I'm quite proud of them. That shop had since acquired an oven so they can clean tubes without bombarding them, and they may well have gotten an induction heater to activate electrodes as well. If I were going to set up my own shop, I'd go that route, as bombarder transformers are big, heavy, power hungry, expensive, hard to obtain, and DANGEROUS. That said, I've loved gas discharges and high voltage ever since I was little, and I still enjoy watching tubes get bombarded. - John -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send an email to [email protected]. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/A2D748FF-C49A-44C0-8301-97362427313C%40mac.com. For more options, visit https://groups.google.com/d/optout.
