Debye_length
- plasmapy.formulary.lengths.Debye_length(T_e: Quantity, n_e: Quantity) Quantity [source]
Calculate the exponential scale length for charge screening in an electron plasma with stationary ions.
The Debye length is given by
\[λ_D = \sqrt{\frac{ε_0 k_B T_e}{n_e q_e^2}},\]where \(n_e\) is the electron number density, \(T_e\) is the electron temperature, \(k_B\) is the Boltzmann constant, \(q_e\) is the elementary charge, and \(ε_0\) is the vacuum permittivity.
Aliases:
lambdaD_
- Parameters:
- Returns:
lambda_D – The Debye length in meters.
- Return type:
- Raises:
UnitConversionError – If either argument is in incorrect units.
ValueError – If either argument contains invalid values.
- Warns:
UnitsWarning
– If units are not provided, SI units are assumed.
Notes
Plasmas will generally be quasineutral on length scales significantly longer than the Debye length.
The electrical potential will drop by a factor of \(∼\frac{1}{e}\) every Debye length away from the vicinity of a charged particle.
See also
Examples
>>> import astropy.units as u >>> Debye_length(5e6 * u.K, 5e15 * u.m**-3) <Quantity 0.002182... m>