Plasma Beta
The fundamental measure of a magnetic field's effect on a plasma is the
magnetization parameter, . The fundamental measure of the
inverse effect is called , and is defined as the ratio
of the thermal energy density, , to the magnetic energy
density,
. It is conventional to identify the plasma
energy density with the pressure,

(1.34) 
as in an ideal gas, and to define a separate for each plasma
species. Thus,

(1.35) 
The total is written

(1.36) 