Earlier I made other tests by deliberately adding more impurities to the electrolyte, reusing the previous one which had already significant amounts of iron dissolved in it.
- < 10 mg Al in the form of thin strips from a 20 micron foil
- 130 mg Cu "powder" (cut from a stranded Cu wire)
- Added a few more drops of HCl
- Refilled with tap water (added just before the new test and during it)
I haven't performed objective measurements, but it seemed more lively than before, in that discharges were seemingly more likely to occur. I also have the impression that water evaporated faster.
Before I go through all the videos I made, I wanted to share this. Spraying water (tap water here) directly on the electrodes would cause often current to increase significantly, sometimes evolving in a full short-circuit (or "welding reaction" as I called it in the past).
Interestingly but not unexpectedly the electromagnetic noise recorded with the AM radio stopped exactly when the continuous plasma started. The thick portion with high low-frequency content in the spectrogram below starts (0:40:65) when similarly an irregular low pitched noise starts in the video, and terminates (at about 0:40:15) when the "welding reaction" occurs. EDIT: the EMI recorded was also the highest throughout the testing session during this part.
Regarding GM readings, the second set of red dashed lines below denote when the last testing session started-stopped. It doesn't seem like there was any increase, but right in the end there was a small CPS spike, which might or might have not been coincidental since that was about when I made the video above. The window was open during the test. EDIT: added the past 3.5 days of data. It seems as if today the tests made readings become slightly lower and irregular than in the past days. Hard to tell whether this is a genuine effect, though.
Unfortunately electrode erosion and in particular anode erosion has been severe just during this test. For some reason the top portion of the anode became black - possibly due to chlorine from the electrolyte (but I don't think that much got evolved; no significant smell and no discomfort felt).
A longer, likely more boring video showing how it typically behaved after injecting tap water on the electrodes. At 1:55 and 2:05 larger "explosions" occur. The loud low-pitched noise was probably due to vibrations transferred from the coil.
A brief earlier sequence where numerous small, presumably hotter (bluish) explosions/discharges occurred in quick succession, eventually evolving in a full welding-type short-circuit.