Debye sphere

In plasmas and electrolytes, the Debye length (also called Debye radius), named after the Dutch physicist and physical chemist Peter Debye, is a measure of a charge carrier's net electrostatic effect in solution and how far its electrostatic effect persists. A Debye sphere is a volume whose radius is the Debye length. With each Debye length, charges are increasingly electrically screened. Every Debye‐length ${\displaystyle \lambda _{D}}$, the electric potential will decrease in magnitude by 1/e. Debye length is an important parameter in plasma physics, electrolytes, and colloids (DLVO theory). The corresponding Debye screening wave vector ${\displaystyle k_{D}=1/\lambda _{D}}$ for particles of density ${\displaystyle n}$, charge ${\displaystyle q}$ at a temperature ${\displaystyle T}$ is given by ${\displaystyle :k_{D}^{2}=4\pi nq^{2}/k_{B}T}$ in Gaussian units. Expressions in MKS units will be given below. The analogous quantities at very low temperatures (${\displaystyle T\to 0}$) are known as the Thomas-Fermi length and the Thomas-Fermi wave vector. They are of interest in describing the behaviour of electrons in metals at room temperature.

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