Caption: Types of plasma located on a log-log plot of electron density versus temperature. The image may NOT be completely reliable or yours truly is somehow reading it wrongly (see item 1 below). Dots showing exactly where the types are located would be a good idea. But whatever its deficiencies, the log-log plot does show the vast range of plasmas in electron density and temperature.
Features:
The free electrons in a metal (an ordinary metal NOT an astro metal) plus the ions fixed on their crystal lattice may be considered plasma.
This explains why the temperature axis is also given in the energy units electron-volts (eV).
E = kT = [8.6173324(78)*10**(-5) eV/K]*T ≅ [10**(-4) eV/K]*T ,where k is Boltzmann's constant and eV is electron-volt which is a convenient microscopic energy unit.
Note
1 eV = [1.602176565(35)*10**(-19) coulombs]*[1 Volt] .