What are sparks from electricity made of?  - Page 1
Forum section: electronics / general

author: Beamin
author_rank: Super Contributor
timestamp: December 18, 2019, 01:56:22 pm
content: I was watching frame by frame video of different types of sparks and realized electrical sparks last far too long to just be hot plasma or gas. When you see sparks come off things what are you seeing? Is it little balls of metal or is it more like miniature ball lightning? Also these sparks seem to radiate out rather then jump across like a classic electrical arc. What makes their color black body radiation or electron spectral lines? Do they leave small amounts of dust behind? If so they look big to our eyes but how big and hot are they?

author: David Hess
author_rank: Super Contributor
timestamp: December 18, 2019, 03:05:11 pm
content: They are hot vaporized material. They may travel in curved paths because of strong magnetic fields which is very apparent when using a spot welder.

author: tszaboo
author_rank: Super Contributor
timestamp: December 18, 2019, 04:50:41 pm
content: There are different type of sparks in electronics, depending on conditions.They are different at high current, higher voltage (meaning like 20V), when making contact, or when opening a contact.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 18, 2019, 06:40:40 pm
content: The discharge itself is ionized gas, with some metal at the contact points vaporized into it. Sparks in hard vacuum are triggered by field emission (at much higher field strengths) and stray gas, and are mostly composed of metal sputtered out from the surface. Further heating of the metal causes it to vaporize, melt and fragment further, enhancing the discharge and often producing sparks.Duration of discharge makes some difference. A very brief spark (often a static discharge) runs out of current before much material is able to vaporize, and the spark moves very little in that time. So you get a wirey looking spark, and the color is mostly blue or purple, corresponding to ionization of oxygen and nitrogen.Repetitive pulsed discharges (a lot of Tesla coils) may be visibly composed of this kind of discharge, either with branching appearance (the prior spark provides a still-slightly-ionized channel that is reignited on the next spark, and more sparks branch out from it) or streaking (as the same path is taken on each pulse, but convection moves the path through the air). Often you can see the choppy streaking, other times it just looks smeared over.Sustained discharges (arcs) glow with heat as surrounding air is heated and ionized, and as more electrode material is eroded and ionized, hence coloring the arc. Sodium yellow being a huge component, because sodium ions are so bright even when present in trace amounts. (Actually sodium is pretty much everywhere, not even in trace amounts, but more like ppb to ppm. Salt is in your sweat and finger oils, if nothing else.)Tim

author: German_EE
author_rank: Super Contributor
timestamp: December 18, 2019, 07:47:39 pm
content: The material the contacts are made of plus a little bit of nitrogen and an even smaller amount of oxygen.

author: TerraHertz
author_rank: Super Contributor
timestamp: December 18, 2019, 10:59:23 pm
content: Quote from: Beamin on December 18, 2019, 01:56:22 pm"Sparks" encompasses a vast range of phenomenon, many types of materials, gasses, energy and pressures. Please be more specific. You mention watching a slowed down video, so how about posting a link if you want a detailed explanation of some particular effect.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: December 18, 2019, 11:08:13 pm
content: The different effects can be quite sensitive to exact conditions. One arc I generated in my way under regulated youth generated a spectacular spray of material that left very fine ash (?) threads in the air that could be grabbed by one end and pulled around. I was never able to duplicate that effect in many many trials. Details of the setup will be closely held to protect the lives and property of others.

author: ajb
author_rank: Super Contributor
timestamp: December 18, 2019, 11:24:25 pm
content: "sparks coming off of things" as opposed to arcs are generally bits of material that are incandescently hot and/or burning. This could be a result of an electrical arc, whether intentional (welding) or otherwise (kapow!), or a mechanical process like grinding, or impact, or chemical explosion (fireworks), or other things. The cause of the color depends on if they are simply very hot (black body emission, or as close as a real material gets) or burning (chemical reactions as in fireworks), or both. Note that things that start off as simply very hot tend to quickly transition to burning in an oxygenated atmosphere. For example welding is generally done under some sort of shield, either flux or inert gas, but when a bit of molten metal flies off out of that controlled environment it quickly starts oxidizing. Whether you'd get enough oxidation on something like a bit of molten copper flying though the air to get a visibly colored spark versus just the black body emission, I'm not sure.

author: eti
author_rank: Super Contributor
timestamp: December 18, 2019, 11:47:28 pm
content: They're formed from sheer excitement

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 19, 2019, 01:31:02 am
content: Quote from: CatalinaWOW on December 18, 2019, 11:08:13 pmGalvanized screw, zinc burns with a blue/green flame leaving a cloud of white smoke (don't breathe it!)Tim

author: CatalinaWOW
author_rank: Super Contributor
timestamp: December 19, 2019, 04:31:14 am
content: Quote from: T3sl4co1l on December 19, 2019, 01:31:02 amWasn't that. One electrode was tungsten salvaged from a light bulb. Other electrode was either copper or aluminum, I don't remember but was in sheet form. Lots of stored energy at high voltage, even for vacuum tube days. Was trying to electro-explosively form the sheets into a mold. A case of not nearly enough knowledge. Not even enough to learn much at that point. And by the time I had enough knowledge I knew how far from the right path I was on and had also lost the desire for that particular project.

author: HighVoltage
author_rank: Super Contributor
timestamp: December 19, 2019, 08:48:43 am
content: This is a very complicated subject and depending on so many factors of how the spark was generated.If it is a high voltage spark, there are usually 3 phases:- breakdown discharge (nano second range)- arc discharge (micro second range)- glow discharge (milli second range)Depending on material for electrodes and surrounding gases, it can vary a lot of what the sparks are made out of.I have created 10 mm long sparks (in air) with about 2000 A discharge current in the nano second range only and it looks very hot, bright and is loud but there is almost no erosion on the electrodes.