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Anodic Glow Discharge III

Boric Acid

     Anodizing in boric acid makes a thin nonporous oxide film. Cell impedances are very high even when using the acid in a concentrated solution. It was easy to reach 100's of volts at a few milliamps over a short period of time. The discharge glow color was greenish yellow, and it became visible at a higher voltage than the other electrolytes tested.

At high overpotentials a crowding effect took place which concentrated current at the spot in the center of the anode, as you can see in the above picture. The whitish/yellow spot directly beneathe the cathode followed along when I moved the cathode across the surface of the anode. More about this spot on the next page.

Oxalic Acid

     In order to work the higher current regimes required of electrolytes such as oxalic acid I began using water filled beverage cans as they provided better heat sinking. I also began cooling the cans to experiment with colder anode and electrolyte temperatures during conditioning. One of the results of those experiments was an oxide layer that generated a pale blue glow under anodic glow discharge.

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