langmuir 0.2.0

Functions for work on Langmuir probe theory

Functions for work on Langmuir probe theory

Installation

Install from PyPI using pip (preferred method):

pip install langmuir

Or download the GitHub repository https://github.com/sigvaldm/langmuir.git and run:

python setup.py install

Usage

The tables for attracted-species current for finite-radius probes in an isothermal Maxwellian plasma given by Laframboise is implemented. E.g. to get the normalized current for a spherical probe of 1 Debye length and a normalized potential of 25:

>>> from langmuir import *
>>> R = 1
>>> eV_kT = 25

>>> f = lafr_attr_current('Sphere')
>>> I = f(R, eV_kT)
>>> print("{:.3f}".format(I))
21.895

The function linearly interpolates between values given in Laframboise’s tables. The argument kind can be used to change to quadratic interpolation. To get the current in Ampére’s you must find the normalizing current:

>>> n=1e11
>>> T=1e3

>>> I0 = lafr_norm_current('Sphere', R, n, T)
>>> I = I0*f(R, eV_kT)
>>> print("{:.1f}mA".format(I*1e3))
-216.5mA

Likewise for cylindrical probes. The current is then in Ampère’s per meter so you must multiply by the probe length:

>>> l = 25e-3
>>> f = lafr_attr_current('Cylinder')
>>> I0 = lafr_norm_current('Cylinder', R, n, T)
>>> I = I0*l*f(R, eV_kT)
>>> print("{:.1f}uA".format(I*1e6))
-711.0uA