ABSTRACT
Plasma is an ionised gas. However, not every cloud of ionised gas is plasma. The main special feature of the plasma state can be explained by the following hypothetical experiment (Fig. I.1.1).
It is assumed that a photon with the energy ω falls on the single stationary atom with ionisation energy I and ionises the atom (Fig. I.1a). As a result, an electron with the energy
ε ω1 ( )e I= h − (I.1.1)
separates from the resultant almost stationary ion. We now consider two identical atoms, situated at a certain distance a from each other and irradiated consecutively with a small delay one atom after the other (Fig. I.1b). From the first atom, the electron is emitted as previously with the energy ε1
ε ε δε2 1 1( ) ( ) )e e= − ( (I.1.2) because this atom must overcome attraction to the first ion.
