plasmapy.diagnostics.langmuir.get_EEDF(probe_characteristic, visualize: bool = False)[source]

Implement the Druyvesteyn method of obtaining the normalized Electron Energy Distribution Function (EEDF).

  • probe_characteristic (Characteristic) – The swept probe characteristic that is to be analyzed.

  • visualize (bool, optional) – If True a plot of the extracted electron current is shown. Default is False.


  • energy (astropy.units.Quantity, ndarray) – Array of potentials in V.

  • probability (float, ndarray) – Array of floats corresponding to the potentials representing the EEDF in normalized probabilities.


The Druyvesteyn method requires the second derivative of the probe I-V characteristic, which inherently amplifies noise and measurement errors. Therefore it is advisable to smooth the I-V prior to the use of this function.

The Druyvesteyn analysis results in the following equation [druyvesteyn-1930]:

\[N_e \left( \epsilon \right) = \frac{2}{A_pe^2} \sqrt{\frac{2 m \epsilon}{e}} \frac{\textrm{d}^2 I}{\textrm{d} V^2}\]



Druyvesteyn, M.J. Z. Physik (1930) 64: 781