Quasi-neutrality

 Quasi-neutrality: A bulk plasma is considered to be neutral as a whole if we are observing it from distances greater than Debye lengths, however, if a process is investigated at the characteristic lengths less than the radius of Debye sphere, the plasma does not appear to be neutral. In other words, plasma is neutral as it comprises an equal number of positive and negative ions but not so neutral such that the interesting electromagnetic forces may vanish.

Debye Length, which is defined as the shielding length of a charged particle in plasma, is directly proportional to the square-root of the thermal energy of the electrons and inversely proportional to the  number density of electrons in plasma.