Quasi-neutrality
The property of a plasma where positive ion charge density and negative electron charge density are nearly equal across spatial scales larger than the Debye length.
Governing formula
n_e ≈ ∑ Z_i n_i (For scale lengths L ≫ λ_D)
SI unit
Dimensionless Balance Condition
In depth
Because electrostatic forces are immense, any localized charge imbalance generates intense electric fields that rapidly pull mobile electrons to restore charge balance. Macroscopically, net charge density is zero.
Examples in the real world
Bulk neutral plasma behavior inside fluorescent lighting tubes, industrial processing chambers, and space plasmas.