How this calculator works
Debye screening describes how mobile charges weaken a small electrostatic disturbance. Plasma mode includes the electron contribution with fixed ions. Electrolyte mode uses molar ionic strength, half the sum of ion concentration times squared valence, and a uniform solvent permittivity. It assumes dilute, weakly coupled conditions and small potentials; concentrated solutions and strongly coupled plasmas need more complete models.
Formula
Plasma: lambda_D = sqrt(epsilon0 kBT/(ne e²)). Electrolyte: lambda_D = sqrt(epsilonr epsilon0 kBT/(2 NA e² I)), where I is in mol/m³. In eV mode, kBT = thermal_eV × e.
Worked example
At 10000 K and electron density 1e18 m^-3, electron Debye length is about 6.9009 micrometres. Raising temperature to 40000 K doubles it to 13.8018 micrometres.
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Frequently asked questions
Does one eV mean one kelvin?
No. One eV is a thermal energy kBT, equivalent to about 11604.5 K.
Is ionic strength the salt concentration?
Only for some salts. Compute I = one half of the sum of c_i z_i² using consistent molar concentration units.
Are ion contributions included in plasma mode?
No. It is the electron screening length with stationary ions, rather than the combined multicomponent plasma length.