imap_processing.idex.idex_l2a.fit_impact#

imap_processing.idex.idex_l2a.fit_impact(time: ndarray, time_of_impact: float, constant_offset: float, amplitude: float, rise_time: float, discharge_time: float) → ndarray[tuple[int, ...], dtype[_ScalarType_co]]#

Fit function for the Ion Grid and two target signals.

Parameters:

  • time (np.ndarray) – Time values for the signal (us).

  • time_of_impact (float) – Time of dust impact (us).

  • constant_offset (float) – Initial baseline noise.

  • amplitude (float) – Signal height (pC).

  • rise_time (float) – How fast the signal rises (s).

  • discharge_time (float) – How fast the signal decays (s).

Returns:

Function values calculated at the input time points.

Return type:

np.ndarray

Notes

Impact charge fit function [1]: Y(t) = C₀ + H(t - t₀)[C₂(1 - e^(-(t-t₀)/τ₁))e^(-(t-t₀)/τ₂) - C₁]

References

[1]

Horányi, M., et al. (2014), The Lunar Dust Experiment (LDEX) Onboard the Lunar Atmosphere and Dust Environment Explorer (LADEE) mission, Space Sci. Rev., 185(1–4), 93–113, doi:10.1007/s11214-014-0118-7.