Hey Nick. You write: >2. I tried Keith's suggestion of looking at different >dilutions of NaCl - going from saturated to way down >to less than .01M. Hmmm...sorry. Could not get the >sheath or plasma to start. Just electrolysis.
You don't have enough voltage to start it. I was working in the range of 100 to 400 volts with my old pulsed setup, I'm sort of surprised that you can see this at 50V even given the ideal nature of your cathode. I have a 80 volt 3 amp Kepco supply on the bench right now; my setup is a 50ml beaker with an anode of stainless steel mesh covering the inside of the beaker, and a cathode of a wire of the aforementioned mesh. My solution is good old NaCl. You write: >3. Going down below about 1M KOH:H2O still seems to >squelch the effect. Going up to saturated soln. >enhances it. With a weak solution of NaCl, at about 70 volts I begin to see the effect. When I switch to a strong solution, I see a much more robust effect. I can lower the voltage to about 60V and still see the effect. NaCl is just out of your power supply voltage range; given that the currents in your microcathode experiment are so much more reasonable I'm sure you can find something with more voltage and confirm my experimental results. I'm guessing that a 100V supply would be more than ample to light up all the electrolytes you mention. So I can confirm that the effect is more pronounced with higher concentration AND that it works with NaCl. I should go back to my old notes and see if I just remembered that bit about concentration wrong or if there was something about the other aspects of my setup that made it behave differently. As I said initially, there's a lot going on here, and my old setup was quite a bit more sophisticated than what we're messing with right now ( I think I spent 15 minutes to get the results above ). The geometry of the cathode, particularly the ratio of inactive area ( electrolysis ) to active ( plasma ) is very different, perhaps this is swamping out the inverse relationship I was seeing to conductivity to what we're seeing now. Before I throw away this now brown mess away, is there anything else you'd like me to try? K.
