I haven't messed with this for a while, so I just stuck a couple of aluminum strips cut from a pie plate into a drinking glass full of saturated borax solution. The aluminum strips were hooked in series with a 65 watt light bulb plugged into 120 volts AC.
The light bulb turned on at full brightness, but dimmed to no light at all within two minutes. The aluminum strips gave off their characteristic blue glow, which at this voltage requires almost total darkness to see. Tiny sparks are seen at random on the surface of the aluminum strips, especially where they enter the borax solution and at their edges. If you move your eyes back and forth rapidly, you can see that typical 60Hz flicker, meaning that that the glow doesn't continue between cycles. It would be interesting to find out just how fast the glow turns on. I had formed the idea, after seeing the hollow columnar structure Bill provided a link to, that a plasma must be forming within the aluminum oxide cells. This doesn't seem to be the case. I looked at one of the strips with a diffraction grating and was surprised to see a continuous spectrum, not line spectra indicating ionization. Further, the glow really isn't blue, it's white. It's just that it's so dim that we tend to see it as blue or blue-green. A full continuous spectrum from red to violet is visible, although it doesn't seem to be as bright on the red end. I was particularly surprised not to see some evidence of the sodium double D lines, which usually overwhelm the spectra of other elements, since borax is sodium tetraborate. The sodium line was only occasionally visible in some, but not all of the random sparks. I also occasionally saw what I took to be a hydrogen red line in the sparks. I'm fresh out of fluorescent dyes, so I just opened up a yellow fluorescent Hi-liter pen and soaked it in the borax solution. This worked well in showing that there is apparently some UV being emitted. I have a UV spectromenter good to 190nm, but it's made for very high power and no reading could be had at all. Since the voltage gradient across the aluminum oxide semi- conductor layer must be tremendous, I'm wondering if this isn't just high temperature incandescence. The total heat would be low, but the local temperature might be very high. I plan to do these same tests at higher voltage and with DC. Any thoughts on this, Horace? M. _______________________________________________ Join Excite! - http://www.excite.com The most personalized portal on the Web!
