Cold and hot at the same time?
Plasma is widely used in practice thanks to its unique properties. Plasma temperature is one of its key
properties. Temperatures of man-made plasmas used in a large variety of applications can range from
tens to millions of degrees Celsius.
Interestingly, plasma can exhibit multiple temperatures at once.
This is due to plasma being a multicomponent system, consisting of electrons and heavier particles
such as ions or neutral atoms. When plasma is generated by electric discharge, electrons receive
energy from the electric field. This energy is then transferred to heavier particles by collisions with
electrons.
Since only a fraction of kinetic energy is given out by an electron upon each collision, it
takes time before temperatures of electrons and other components in plasma equilibrate. It is
therefore not uncommon for plasma to be characterized by electron temperature, commonly ranging
from 10,000 to 200,000 degrees Celsius, whereas the overall plasma temperature could be much
lower.
For example, while the overall gas temperature in a plasma globe lamp is slightly above the
room temperature, the electrons can be as hot as 20,000 degrees Celsius. This is because only a small
fraction of the total gas in the lamp is ionized whereas the rate of heat dissipation through the surface
of the lamp is high enough for keeping the gas cool. Here we arrive at another important plasma
property, the degree of plasma ionization, which is defined as a proportion of neutral particles that
are ionized. Completely ionized plasmas can be found in space and thermonuclear plasma systems.
Partially ionized plasmas are much more common and are widely used in practical applications
ranging from etching micrometer deep trenches in silicon crystals for fabrication of integrated circuits
to cut tens of centimeters thick slabs of steel.
Useful links:
Plasma cutting machine
https://www.amazon.com/Plasma-Cutter-Machine/s?k=Plasma+Cutter+Machine
https://www.langmuirsystems.com/crossfire
https://www.weldersupply.com/C/6/PlasmaCuttingMachines
https://www.stylecnc.com/plasma-cutter/
https://www.millerwelds.com/equipment/plasma-cutters
https://www.homedepot.com/b/Tools-Welding-Soldering-Welding-Machines-Plasma-Cutters/N-5yc1vZ1z18gva
https://thebestcnc.com/cnc-plasma-cutter-guide/
