Plasma electrolysis at lower voltages

Quote from Rob Woudenberg

can

The video shown above shows mainly glow discharge rather than sparks, so indeed in such setup spark initiated cavitation is not likely.

The downwards directed 'sprites' show a peculiar effect. Seems that the big floating gas bubbles are formed in the sprites area below the tungsten tip. This could be recombined H atoms to H₂. The violet glow is clearly hydrogen plasma.

How the reaction looks depends on voltage and electrolyte concentration; in all cases anyway there is not just an ordinary glow plasma as seen in low-pressure gas discharge environments, but numerous discharge events that show as random bright spots on the surface which I think is why sometimes the reaction is called "micro-arcing" or "sparking".

Here is how it looked in 10M KOH solution (which turned dark purple from potassium–iron ions from the steel anode at high pH) at 50V using the same 1mm-thick tungsten rod (5x slow motion).

At higher power levels/electrolyte concentrations the 'sprites' seemed to be generated all round the cathode, not just ejected from below, although I don't have a good video showing this (it can be somewhat observed in the above slow-mo animation as the reaction lights up).

I am still not sure whether cavitation has a direct effect on the possible LENR on the surface of the cathode in this case; it seems like it would be of secondary importance. One has to realize that the electric field generated under operating conditions due to charge concentration is strong enough to cause the breakdown of the gaseous layer surrounding the electrode at atmospheric pressure (or greater), which should put it in the MV/m range or above. I would expect this to be a primary factor for any observed anomaly.

Quote from Curbina

They are definitely the hydrodynamic expression of a coherent matter wave. These are very poorly understood, but much more complex than simply “bubbles”.

I don't know whether they are coherent matter waves, but they definitely do not look like simple bubbles.

Bing Translation:

Quote from Cherepanov2020

‎Dear , ‎‎can‎‎ ! There are no "electric charges" in nature! There are no "electric fields" in nature! If you do not independently study the mistakes of Maxwell, who, thanks to his inattention and "school mistake", which he made in his treatise "Electricity and Magnetism", then you will never understand the physics of these processes ... There are no "charges" on either the proton or the electron... By their rotation, they form their own magnetic field... and own magnetic poles...‎

Even if all electric charges were actually tiny magnetic fields, my point is that the conditions arising between the active electrode and the surrounding electrolyte are more extreme than they might seem on a first look, and that the reaction cannot be explained just by the applied electrode voltage (only 50V in the case of the previously posted movie).

Increasing the electrolyte concentration up to saturation using a strong electrolyte seemed to lower the voltage from which a visible plasma could be observed; possibly effects due to metal deposition contribute too. This appears to occur also with alkali electrolytes at very high pH; I definitely saw it occurring with copper on tungsten after the solution turned deep blue (photo below).

Acid electrolytes also work well for similar reasons and I think that H2SO4 (sulfuric acid) solution at battery acid concentration (37%) could improve things even further, but I never dared to try, since the reaction causes the electrolyte to nebulize, and after a short period of testing all surfaces in the surrounding environment become covered with electrolyte droplets... the main reason why I haven't performed more related testing lately also with safer electrolytes (it needs better equipment or a better reaction cell).

Alan Smith

If they are due to material ejected from the cathode, they must not be from the base cathode itself or the wear rate would be too high.

They also formed with acidic electrolyte (10% HCl) but only when dendritic deposition was not occurring on the cathode and the reaction was acoustically noisier. This might be strictly a function of reaction intensity causing cavitation in the surrounding electrolyte.

Here is a video with 10% HCl electrolyte where such sprites can be seen under several conditions (clearer in full screen):

Quote from can

At higher power levels/electrolyte concentrations the 'sprites' seemed to be generated all round the cathode, not just ejected from below, although I don't have a good video showing this (it can be somewhat observed in the above slow-mo animation as the reaction lights up).

It turns out I actually had a better video of this from past tests. I posted a brief gif earlier on, but not the video.

Here I used a somewhat diluted potassium carbonate-sodium bicarbonate solution and the applied voltage was 62V.

The solution was diluted because at higher concentrations and voltages the electrolyte would accumulate in solid form on the cathode, stop the plasma and start getting dissociated, producing sparks and explosions as a result, which I also mentioned and showed earlier in the thread. For the most part this tells that the local electrolyte concentration may greatly increase during operation—per se not an anomaly, although this is not normally even visually observed.

Alan Smith

That could possibly have happened with sodium bicarbonate, but I don't recall for how long exactly I had been testing the same solution at high temperatures in that video. At that point it might have mostly decomposed to the more stable carbonate, since as explained above, for those tests I diluted the solution to avoid solid accumulation at the cathode.

Below is a video (which I haven't posted before, it seems) made with the previously used more concentrated sodium bicarbonate/potassium carbonate solution mixture which caused solid accumulation on the cathode. Temperatures were high and outgassing was probably occurring, but no sprites as in the other videos with plasma electrolysis, though some weird-looking emission occurred from the cathode (maybe due to metallic sodium or potassium formation).

At 0:28 I turned power down and the intense bubbling stopped.

EDIT: gif of some of the emissions from the electrolyte-covered cathode:

Stevenson

They do really look like tracks for a cloud chamber or electric discharges, which left me wondering for a while. I think however they are likely to be caused by tiny droplets of Na/K metal or Na/K hydride formed from the electrolyte accumulated at the cathode (while electrolysis was still occurring) and reacting with water.

Using thinner cathode wires, the electrolyte formations could be easily removed and put into a container. Crushing them with a pair of pliers in the atmosphere would cause them to sometimes fizz and smoke. The interior also looked dark with some metallic-looking areas. I mentioned that at the time of those tests in an earlier comment.

Other tests also suggested the formation of alkali elements in metallic form under similar conditions. This one below (I posted a similar one before but not quite the same) was with just K2CO3 solution close to saturation, which didn't seem to accumulate on the cathode in the way sodium (bi)carbonate did, but produced interesting light shows and explosions.

The reaction of alkali metal with water has been suggested a while back to cause a Coulomb explosion, that is, electrons are stripped from the material which becomes positively charged and its atoms also start repelling from each other. I think such positively charged material would be affected by local and external magnetic fields, although I haven't tried applying one manually.

To make it clear, the above animations are from tests made several months ago; at the moment I'm not geared to repeat them.

A further question might be how all of this is related with plasma electrolysis. The relation is that electrolyte accumulated on the electrode under the same conditions that caused plasma electrolysis, if the electrolyte concentration was too high. This might be clearer in this (previously posted) video:

I made a quick round of tests to see if I could repeat the same effect. I initially tried just sodium bicarbonate but I couldn't manage to make it work properly due to too low electrolyte conductivity preventing a plasma and electrolyte accumulation from starting. After I added some potassium carbonate and KOH solution leftover, it worked about as it previously did several months ago.

The anode was a steel sheet and it colored the solution brown in the initial attempts with sodium bicarbonate only. This did not seem to affect the desired outcome significantly, other that the electrolyte accumulating on the cathode was brown and that I had to put the cathode close to the glass wall since the solution was rather cloudy.

I made a collection video showing many such events for those interested. I tried applying a magnet but I couldn't discern much difference, although I had the impression it reduced the rate of events. I need a better magnet, however.

I used a 0.3 mm tungsten cathode and up to 62V DC by using two power supplies in series, one adjustable and another with fixed voltage.

EDIT and a gif (4x slow-mo; normal version also attached):

Quote from Paradigmnoia

To me, they look a bit like the mini Coulomb explosions that occur when putting Rb into water.

There is some similarity, although so far I haven't been able to find videos showing underwater explosions of tiny amounts of it (or of potassium metal).

This could also be similar but again it's mostly above the water surface.

Paradigmnoia

I was aware of this slow-motion video from the supplementary information from a paper published on Nature on the subject by the group who first proposed the idea, but it's not exactly similar to the underwater squiggly traces I have been seeing.

Occasionally I have tried to invert polarity, and it always works worse or not at all for the same applied DC voltage, producing less intense plasma, weaker EMI, lower local heat and so on. With AC it might be roughly equivalent of operating it with smoothly pulsed DC, in that it will work properly only for half of the AC cycle.

The electrode still needs to be of small area compared to the counter-electrode, or no plasma will be generated. So, typically since one electrode will be much larger than the other, the plasma (weak or strong) will be observed only on the small one regardless of polarity.

With the opposite polarity (anode) the 0.3 mm tungsten wire will get eroded very quickly due to oxidation and quick removal of the formed oxide layer.