pyrfu.mms.scpot2ne module#

pyrfu.mms.scpot2ne.scpot2ne(sc_pot, n_e, t_e, i_aspoc: DataArray | None = None)[source]#

Compute number density from spacecraft potential. Function uses number density and electron temperature to compute electron thermal current. A best fit of the photoelectron current to the thermal current is used to determine the photoelectron currents and temperatures. These are then used to construct a new number density from the spacecraft potential.

Parameters:

  • sc_pot (xarray.DataArray) – Time series of the spacecraft potential.

  • n_e (xarray.DataArray) – Time series of the electron number density.

  • t_e (xarray.DataArray) – Time series of the electron temperature. Function accepts scalar temperature or tensor (scalar temperature is used in either case).

  • i_aspoc (xarray.DataArray, Optional) – Time series of the ASPOC current in \(\\mu\) A.

Returns:

  • n_esc (xarray.DataArray) – Time series of the number density estimated from SCpot, at the same resolution as sc_pot.

  • i_ph0 (float) – Value of the photoelectron currents ( \(\\mu\) A) of the first population.

  • t_ph0 (float) – Value of the temperature (eV) of the first population.

  • i_ph1 (float) – Value of the photoelectron currents ( \(\\mu\) A) of the second population.

  • t_ph1 (float) – Value of the temperature (eV) of the second population.

Notes

Usual assumptions are made for thermal and photoelectron current, vis., planar geometry for photoelectrons and spherical geometry for thermal electrons. Currently the calculation neglects the ion thermal current, secondary electrons, and other sources of current. ASPOC on does not work very well.