On 2021-12-02 22:00, Jones Beene wrote:
Do you by any chance have a radiation monitor capable of seeing a
signal from your cell when unpowered ?
It would be significant if there was an increase in counts which
tracked the onset of a visible plasma (assuming the plasma itself is
below the threshold for detection)
I used to have a cheap Geiger counter, but since my background radiation
level is too high with daily variations attributable due to radon gas,
I've never been able to get useful measurements out of it, so eventually
I gave it away. A more sensitive detector similar to one described by
Holmlid in a few publications (the "muon detector") would likely work,
but it would require a budget of at least 1000-1500$ (with used parts
from Ebay or similar) which I cannot justify spending.
I tried a webcam/CCD/CMOS detector and while it seems to work for cosmic
muons, on the long term (unpowered cell) it appears to work like a very
insensitive Geiger counter (giving only a few hundred "events" per day),
also tracking daily local radon variations. Furthermore, when the plasma
reaction is ongoing, the camera may be affected by heat (increasing
background/thermal noise) and electromagnetic emissions from the cell
(causing random camera malfunctions) if it's too close, so overall I
haven't had much luck with it.
I have more successfully measured RF emissions with a 30$ USB-SDR
receiver. Measuring signal amplitude in real-time gives a good idea of
how intense the reaction is and how it changes with experimental
conditions. Curiously, RF emissions increase to a moderately high level
just before a visible plasma starts appearing (apparently reflecting
current instabilities), then drop to a low level as it appears, and
finally progressively increase as voltage is further increased, up to
intense levels. Supposedly, it is possible to optimize the reaction with
this real-time information. No way of detecting a signal with the cell
powered off without some sort of heavy shielding though, due to
background RF emissions.
Judging by RF emissions, the same plasma reaction appears to emit
significantly stronger emissions (keeping other variables about the
same) when an acidic electrolyte like 10% HCl is used instead of KOH.
Higher concentration HCl or sulfuric acid solution could probably give
interesting results in this regard but I never dared trying: the fumes
need to be vented away safely and droplet formation is an issue (after a
period of operation, most surfaces surrounding the cell become covered
by tiny electrolyte droplets, which can be a serious hazard at high
electrolyte concentration).
With an acidic electrolyte (10% HCl, that I tried) if you drop a thin
cathode wire very slowly into the liquid it is also possible to observe
a weak plasma from the nano-sized dendrites formed by electroplating
from as low as 15V or less (slightly higher values preferred), but no
strong RF emissions occur compared to the "true" plasma electrolysis
reaction at higher voltages.
I hope this helps,
Cheers, BA
