Defining fire as a plasma is a challenging subject that experts in physics and chemistry have to deal with, therefore, the most popular expressions for it is “almost plasma” or “partial plasma.” Something common that we all agree on is that the fire heats and burns… but what if it were possible to create a cold fire/cold plasma? Under the right conditions, cold fire freezes what it touches, and The Action Lab channel on YouTube has just shared two videos with excellent demonstrations.
Fire: Accelerated oxidation of material under the combustion process. The flame is the part of the fire that emits visible light, and the process is exothermic, so it also emits energy as heat. A generic and handbook description without a doubt. But if we try to explore its relationship with plasma, then the science gets complicated. For some, when gas reaches the minimum temperature that allows it to be seen, it is known as a plasma. For others, everything depends on the level of ionization, and in the case of fire, it would not be so high.
So partial plasma? Semi plasma? If that sounds too confusing, let’s look for the common pints. Fire and plasma are hot, and the idea that they can turn into something “cold” is contradictory… unless we alter their conditions a bit. That’s what they made at The Action Lab channel, Cold Fire!
It all starts with an electrode, which reaches tens of thousands of volts. The potential is so high that the gas around the electrode is ionized. The key to converting that fire/plasma into cold is to displace the thermal energy while keeping the electrons free. This requires a gas that is easily ionized and that has a higher thermal conductivity. It is called, helio.
By adjusting the gas flow, its circulation becomes fast enough to ensure that the ions do not accumulate thermal energy, but not the free electrons. So, why do those electrons not those burn us? The answer is that they do not have the necessary mass. That transforms the cold fire into an excellent sterilizer, destroying viruses and superficial bacteria without burning material.
However, the experiment from the first video is at room temperature. So how do we create cold fire that freezes what you touch, the solution is to drastically reduce the temperature of the gas. This situation opens a whole range of possibilities, but The Action Lab channel followed the dry ice routine, placed on a copper coil. This causes the helium temperature to drop to -78 degrees Celsius. The most complicated thing is filming the freezing (it looks better with lots of light, although that “covers” the plasma), but the shortcut was to wet the objects before placing them near the electrode.
