swept_probe_analysis

plasmapy.diagnostics.langmuir.swept_probe_analysis(probe_characteristic, probe_area, gas, bimaxwellian=False, visualize=False, plot_electron_fit=False, plot_EEDF=False)

Attempt to perform a basic swept probe analysis based on the provided characteristic and probe data. Suitable for single cylindrical probes in low-pressure DC plasmas, since OML is applied.

Parameters:
  • probe_characteristic (Characteristic) – The swept probe characteristic that is to be analyzed.
  • probe_area (Quantity) – The area of the probe exposed to plasma in units convertible to m^2.
  • gas (Quantity) – The (mean) mass of the background gas in atomic mass units.
  • visualize (bool, optional) – Can be used to plot the characteristic and the obtained parameters. Default is False.
  • plot_electron_fit (bool, optional) – If True, the fit of the electron current in the exponential section is shown. Default is False.
  • plot_EEDF (bool, optional) – If True, the EEDF is computed and shown. Default is False.
Returns:

  • Results are returned as Dictionary
  • ”T_e” (astropy.units.Quantity) – Best estimate of the electron temperature in units of eV. Contains two values if bimaxwellian is True.
  • ”n_e” (astropy.units.Quantity) – Estimate of the electron density in units of m^-3. See the Notes on plasma densities.
  • ”n_i” (astropy.units.Quantity) – Estimate of the ion density in units of m^-3. See the Notes on plasma densities.
  • ”n_i_OML” (astropy.units.Quantity) – OML-theory estimate of the ion density in units of m^-3. See the Notes on plasma densities.
  • ”V_F” (astropy.units.Quantity) – Estimate of the floating potential in units of V.
  • ”V_P” (astropy.units.Quantity) – Estimate of the plasma potential in units of V.
  • ”I_es” (astropy.units.Quantity) – Estimate of the electron saturation current in units of Am^-2.
  • ”I_is” (astropy.units.Quantity) – Estimate of the ion saturation current in units of Am^-2.
  • ”hot_fraction” (float) – Estimate of the total hot (energetic) electron fraction.

Notes

This function combines the separate probe analysis functions into a single analysis. Results are returned as a Dictionary. On plasma densities: in an ideal quasi-neutral plasma all densities should be equal. However, in practice this will not be the case. The electron density is the poorest estimate due to the hard to obtain knee in the electron current. The density provided by OML theory is likely the best estimate as it is not dependent on the obtained electron temperature, given that the conditions for OML theory hold.