Using the equation (3.68), calculate plasma conductivity at electron number density ne= 1016cm3, and electron-neutral collision frequency 1010sec1, which is typical for thermal plasmas. Compare this plasma conductivity with conductivity of cupper at normal conditions. Assuming ven(v)=ven= const, and integrating (3-66) by parts, gives the well-known formula for electron conductivity: =mvennee2 This formula can be presented in a convenient numerical form: =2.82104ven(s1)ne(cm3),Ohm1cm1 Plasma conductivity (3-67) is determined by electron density ne (the contribution of ions will be discussed next) and the frequency of electron-neutral collisions, ven. The electron density can be found using the Saha equation (3-14) for quasi-equilibrium thermal discharges and from the balance of charged particles in non-equilibrium non-thermal discharges. The frequency of electron-neutral collisions, ven, is proportional to pressure and can be found numerically for some specific gases from Table 3-1. Relations (3-67) and (3-68) determine the power transferred from the electric field to plasma electrons. This power, calculated per unit volume, is referred to as Joule heating: P=E2=mvennee2E2 Also relations (3-67), (3-68), and (4.3.9) determine electron mobility e, which is the coefficient of proportionality between the electron drift velocity vd and electric field: vd=eE,e=enee=mvene