Unusual plasma heating phenomenon

I'm not sure how to categorize this, but it is not directly related to LENR, although it might be possible related to some claims using plasma discharge apparatuses. So in the off-topic section this goes for now.

In the past couple days I came across an unusual (i.e. not often encountered) heating phenomenon while experimenting with atmospheric glow plasma discharges. There is probably nothing out of the ordinary occurring here, but it shows how an apparently low power could heat up small amounts of material to surprisingly high temperatures. Here is one of the several videos I made of the process.

Description: a small section of nickel-wound guitar steel wire was previously melted into a ball with an approximately 750V plasma discharge. This video shows a reheat attempt. A 15.4 kOhm resistor in series with the anode acted as a ballast. The screwdriver acted the anode (+), the bottom steel plate acted as the cathode (−).

As the NiFe ball (of about 1 mm diameter) attached itself to the cathode, it started glowing brightly in the process (emitting numerous sparks in the first attempt). Temperature got high enough to cause the steel surface beneath the ball to blacken. The screwdriver/anode did not receive any substantial melting damage.

It appears that the heated material at the cathode heats up to its melting point, but no more than that. Nickel melts at 1453 °C; mild steel depends on the composition but should be above 1300 °C. The beginning of the video also shows that if the ball is at the anode no significant heating will occur.

* * *

A similar heating process can be observed with similar amounts of mild steel or copper, but not elemental aluminium (e.g. foil), at least directly/easily. The NiFe material shines brighter than copper, but not as much as aluminium when conditions are right (I think that comes from aluminum oxide, which becomes conductive at a high enough temperature).

From a few measurements I attempted, it is plausible that the impedance of the plasma region is in the order of 8 kOhm, which means that the total circuit resistance is about 23.4 kOhm. The voltage drop at the ballast resistor while a discharge is occurring is about 475−550V depending on conditions. One could work out roughly 23W total circuit power, with 15W dissipated at the ballast resistor and 8W at the heated material/plasma region.

I think what could be happening here is that while 8 watts is not a very large power, it might be concentrated on a very thin region which can heat the material up to its melting point. However this occurs only when the heated material is at the cathode and does not dissipate heat efficiently. This sounds kind of obvious, but a less obvious factor is that such heated material will start producing thermionic emission possibly in a positive feedback loop with temperature.

I'm not entirely certain of the processes involved though, so I look forward to reading others' suggestions.

Zephir_AWT

That was my initial expectation as well, since usually the anode is the electrode reported to heat up more (e.g. as in spark plugs). But I'm apparently seeing the opposite effect here.

Polarity reversals are possible mistakes though, so I just tested it.

With the black terminal of the multimeter on the unused ground output of the DC boost converter (from Amazon, link) like this:

Black: ground; red: steel plate ==> −465V (negative voltage)

Black: ground; red: screwdriver/nail ==> 283.2V (positive voltage)

Normally both terminals would have about the open circuit output voltage, but the green capacitor on the positive side (marked "V+") currently connected to the screwdriver got accidentally damaged by overheating from being too close to the ballast resistor after I tested this effect too long. I later added extra wire so that the capacitor on that side won't be too much affected anymore.

I replaced the faulty V+ capacitor with a slightly smaller but suitable one I already had at disposal. Open circuit voltage is > 800V across output terminals.

The screwdriver is still connected to V+ output and the plate to V− output. Here's a very ugly photo showing this (and the very ugly temporary connections). The 15 KOhm resistor is acting as a ballast to avoid brief sparks discharges. To the right a closeup of the inputs/output from a vendor photo of the device.

I put a stranded copper wire filament on the plate (–). The filament could be quickly be melted into a small ball and made glow brightly with the plasma discharge, although not as brightly as the nickel-wound steel section I previously used. I think the brightness depends on the melting point of the material.

Quote from Zephir_AWT

I don't understand, how boost converter rated to 390V generates spark at distance few millimeters..
I'm also missing rectifying HV diode in module picture. There should be voltage doubler or something similar in circuit.

It produces +/− (plus and minus) 390V relative to GND.

V+ = +390V; V- = −390. Total = 780V (nominally)

Slightly higher voltages seem possible in practice at the maximum voltage setting than stated by the manufacturer, so this is how >800V are obtained.

As this is a DC boost converter, it should work by chopping at a high frequency input DC current into the pulse transformer (the large yellow square component), producing AC. I believe the resulting AC is finally rectified with a simple voltage doubling circuit, produces both a positive and negative voltage. However I haven't performed any detailed circuit analysis, nor I claim any expertise on this regard.

https://en.wikipedia.org/wiki/Voltage_doubler#Delon_circuit

Quote from Zephir_AWT

Technically the ball can be also heated by impacts of positively charged ions from air..

I'm not expert in this matter, but could it be possible, that once material melts, the energy of ions is absorbed elastically?

It would explain, why the heating in this way cannot exceed the melting point of material too much.

I don't have clear ideas of why this happens, to be honest. However it only occurs if there is a small amount of material that is allowed to heat and reach high temperatures.

If I strike directly the cathode flat steel plate, nothing particularly noteworthy occurs. From this, my deduction was that it is related with a positive-feedback, temperature-related effect. I have to point out that I have no way of directly measuring temperature, I'm only determining this by subjective observation.

Quote from Zephir_AWT

But the melting point of nickel (1,455 °C) isn't so high with compare to copper (1,085 °C) - the difference in brightness is striking.

Could you make photo of the glowing nickel ball through welding glass (dark filter)?

I don't have a welding glass filter but I can try reducing the exposure time of the camera. I had to use an aluminium anode this time because apparently the screwdriver got magnetized and kept attracting the Ni-Fe ball in a few first tests.

I cut a new small section of nickel-wound guitar string.

It quickly melted after a short test.

1/2000s exposure 50 ISO in the first few seconds after a second test. The blob forms a ball, probably due to the applied electric field—although this only is my hypothesis.

1/4000s 50 ISO unfortunately wasn't enough to tame the bright light.

After several seconds it starts melting into a blob again—it seems it's getting cooler too.

After this I stopped the test, also to not overheat the ballast resistor which I'm using beyond its rated power.

I have also to point out that the amount of Nickel wire wound around in the guitar string section seems very limited.

LeBob

That also occurs with pure copper, mild steel (mostly iron with some C) or pure nickel, so I don't think that layering between different metals might necessarily be occurring. It's important however that the material is conductive. It's indeed possible that either the electric field or the magnetic field from the conduced current (in the order of 35 mA) might be shaping the metals into balls, but I do not have clear answers on this regard. If layering is occurring it's likely that at the very least an outer oxide thin shell is forming due to oxygen, on the other hand.

I also get the impression that the heating is stronger when the material arranges itself into a ball; it could be a geometry-induced effect in that a mathematically ideal sphere will have an infinitely small point of contact with the underlying electrode and so it will heat up faster. Just a speculation, however.

It's difficult to take a good close-up photo of the cooled samples with my cameraphone, but here are some samples. The larger one was composed of copper filaments, although it now has a lustrous gray appearance. The iron/steel material from the guitar in string, in isolation, tends to rust very easily.

Somehow these balls reminded me of Gennadiy Tarassenko's geophysical ideas, although I do not know much about the details.

I got a request of taking a photo of the cathode emission point with a light filter, but that didn't go well either. I could only decrease the shutter time but all photos ended up being blurry due to unusual light conditions. Here the screwdriver is the cathode (negative electrode). A glow plasma (presumably) is emitted from a small bright point onto one of these spheres, here not very efficiently heated due to it being the anode.

* * *

EDIT: by the way, the process can also be potentially dangerous (besides shock hazards) depending on testing conditions. This is a video from yesterday:

I was heating a small copper ball on top of a piece of Al/Al2O3 (alumina formed from high-temperature oxidation). The screwdriver was the anode (+), the bottom plate the cathode (−) and voltage across output terminals from the DC boost converter was about 750V. As in previous tests as recently posted, a 15 kOhm ballast resistor was put in series with the circuit to limit the current and avoid a spark discharge and constrain the plasma reaction into the glow discharge region (jury still out on whether I'm producing arcs or actually a glow discharge).

When copper oxide and aluminium heat up together at a high enough temperature, there's a risk of producing a thermite reaction, which is what I think occurred here. CuO-Al thermite is a very fast burning reaction: https://en.wikipedia.org/wiki/Thermite#Copper_thermite

Note that from incandescence alone, before the thermite reaction occurred, the aluminium piece heated significantly above the melting point of Al metal. I think the portion heating up this much was composed of mainly Al2O3 (alumina, aluminium oxide).

LeBob

I did not think of that, but it could be the case. The material is at least partially molten, and a current is passing through it, so the magnetic field generated could be reinforcing its spherical shape.

LeBob

A related effect at play, helping spherical shape formation, should be the molten layers spinning along the axis of the current direction due to the magnetic field generated. I don't think huge shearing forces would be generated inside the material, but the heat might be redistributed efficiently and help the sphere reach homogeneously high temperatures. Since the sphere might be only barely touching one electrode, heat could be accumulated fast and not be easily dissipated to the outside environment (as mentioned previously).

I tried with a small piece of aluminium foil again in the same process; I couldn't get it to melt, only to shine quite brightly in what seemed more like a combustion reaction. The material in the end pulverizes and white poorly conductive residues remain (probably Al₂O₃). The screwdriver was the anode (+), the steel plate the cathode (−); voltage across the DC boost converter's output terminals about 830V; 15 kOhm ballast resistor in series with the anode.

With aluminium foil alone there has to be only just a little amount of material, or nothing special will happen. It seems as if it conducts heat away too quickly, but if this was the case copper would then be even worse on this regard. Strange.

LeBob

That could be a reason, but perhaps it is not the entire story. It's possible it might simply react too quickly with oxygen in the air and form a thick surface layer of Al2O3 under the quick temperature rise, which would quench the electrical conductivity-dependent reaction.

It might be interesting to test at some point with titanium, as it forms not very easily reducible oxides like aluminium, but still is a transition metal. It's not an exceptionally good electrical conductor, however. Tungsten could also possibly outshine all samples tested so far: if the reaction stops at the melting point of the element as previously speculated, it should reach about 3400 °C, although combustion/oxidation might be a negative factor. It's a good electrical conductor too. http://hyperphysics.phy-astr.g…base/Tables/rstiv.html#c1

Magnetism might have a role with iron and nickel, but it shouldn't with most other transition metals (unless you have a different definition in mind).

As in past occasions, hopefully these blog-style comments here that might not even be on-topic with the forum's main subject are not too much of a nuisance.

* * *

After some testing with small amounts of oxidized nickel metal from a coin, which did not behave as well as expected, a few key characteristics for the ideal material came to mind:

• It should be a good electricity conductor
• It should be as unreactive as possible (i.e. not oxidize, at least in the atmosphere)
• It should preferably have a high melting point

There are not many options looking at the periodic table. The ideal metal would likely be a noble metal. Also see the reactivity series (also here). Thus, in probably increasing order of suitability:

Cu < Ag < Pd < Pt < Au < Os < Ir

Of these, the one with the best value would probably be Ag, the absolute best possibly Ir.

* * *

So, thinking that an unoxidized clean material would work better I made a test with an oxidized nickel fragment but with also the addition of small amounts of graphite brushed on the underlying steel cathode surface, which should have helped with the known carbothermic reaction by reducing surface oxides. I believe with this I managed to achieve more easily a bright luminous sphere.

I managed to obtain a couple clear 1/4000s 50ISO photos of the bright nickel sphere (formed from an originally elongated flat nickel piece). Even though this is the least light-sensitive setting I could set, it still looked white on the photos. I was looking at the bright sphere through the camera screen in order to not get temporarily blinded.

Quote from LeBob

Keep posting, its all related somehow! If you can, approach a hydrino/H2* or a pico-chemical reaction amateur replication. The other thread about it gives a little hope. I wish I had a lab and trusted proffesional lab volunteers/comrads. These experiments aren't that expensive in comparison to alternatives. Some may want the affexts to be nuclear or vacuum based so bad they will see these blog style posts about electro chemistry and metallurgy as off topic. I see the relavent connections though and greatly appreciate it. Have a restful weekend!

Perhaps a connection to LENR experiments would be more obvious if somehow this persistent intense heating effect at the cathode as shown above could be integrated in a small sealed cell containing hydrogen. Putting aside any unusual/anomalous hydrogen interaction that could ensue, the reducing environment would make the heating easier to observe, and a low pressure would help increasing temperatures, in addition of allowing a larger electrode gap to be used. I can't help but feel that I might be reinventing the wheel/[incandescent lamp], though.

In the example above the glowing sphere must have had a temperature > 1500 °C, by the way.

Quote from Zephir_AWT

The character of discharge indicates high frequency AC rather than DC output, after then it would have no meaning to distinguish between cathode and anode.

The output should be pulsed DC. A buyer on Amazon took an oscilloscope reading. It looks like a reverse sawtooth wave. Under load the pulses should decay quicker, but still be overall considered as DC rather than AC.

https://www.amazon.com/Qianson…-Capacitor/dp/B01IVMU2XI/

Quote from LeBob

How about a high Ag or Cu stainless Fe alloy? Mixing metals into an alloy may be more cost effective and with similar effects as pure Ag.

I could try tomorrow melting Cu filaments or CuNi alloy pieces together with mild Fe in the same sphere-forming process. However it's possible that the lower melting point will make for a poorly performing material in terms of perceived brightness/temperature, or that the property of CuNi of rapidly forming a passivating oxide layer at high temperatures will not make it work at all.

At the moment I do not have stainless steel sources that I can easily use, unfortunately.