Fit Function: na_hel

Fit Function \[\sigma_{p}^{hel, Na}(E) = A_1 \cdot 10^{-16}\Bigg[ \frac{e^{-\frac{A_2}{E}}\ln\big(1 + A_3E\big)}{E} + A_4\frac{e^{-A_5E}}{\big(A_7E\big)^{A_6}}\Bigg]\]
Comments Python code requires NumPy imported as `np`.

Python

Arguments
namedescriptionunitstype(s)
E impact energy keV u-1 float, np.ndarray
A1 fit coefficient cm2 keV u-1 float
A2 fit coefficient keV u-1 float
A3 fit coefficient keV-1 u float
A4 fit coefficient keV-1 u float
A5 fit coefficient keV-1 u float
A6 fit coefficient float
A7 fit coefficient keV-1 u float
Return values
namedescriptionunitstype(s)
sigma cross section cm2 float, np.ndarray
Code 
def na_hel(E, A1, A2, A3, A4, A5, A6, A7):
    """
    This function calculates proton impact electron loss (ion + CX) cross sections (in cm2) of 
    Na 3s to 5s.
    param E: requested electron-impact energy in keV/u
    type E: float, np.ndarray
    param Ai: fit coefficient 
    type Ai: float
    """
    sigma =  A1*1e-16*((np.exp(-A2/E) * np.log(1 + A3*E))/E + A4*np.exp(-A5*E)/(A7*E)**A6)
    return sigma