CollisionDB: DataSet D108007

\[\mathrm{He}^{2+} + \mathrm{H} \; n=3 \rightarrow \mathrm{He}^{+} + \mathrm{H}^{+}\]

Process	HCX: Charge Transfer
Data type	cross section \| uploaded on 2023-02-08
Comment	Fit function taken from p120. Error: E< 1/(n^2) keV/u -> 60%, 1/(n^2) keV/u<E< 25/(n^2) keV/u -> 40%, 25/(n^2) keV/u<E< 200/(n^2) keV/u -> 30%, E>200/(n^2) keV/u -> 20%

Method	semi-empirical
Frame	Target
Columns	E /eV u^-1 sigma /cm²
Ref	B37: R. K. Janev, J. J. Smith, "Cross sections for collision processes of hydrogen atoms with electrons, protons, and multiply charged ions", IAEA- Atomic and Plasma–Material Interaction Data for Fusion, Vienna 4 (1993). [https://www.iaea.org/publications/1839/atomic-and-plasma-material-interaction-data-for-fusion]
Data	Download (data from fit)

Fitted Data

Fit Function
Details

\[\sigma_{CX}^{n>2}(E) = A_5^4 \frac{7.04 \times 10^{-16} A_1 \bigg[1 - e^{-\frac{4}{3A_1}\big(1 + \tilde E^{A_2} + A_3 \tilde E^{3.5} + A_4 \tilde E^{5.4}\big) } \bigg]}{1 + \tilde E^{A_2} + A_3 \tilde E^{3.5} + A_4 \tilde E^{5.4}}, \tilde E = EA_5^2\]

Python

def h_hcx_javen_he_scaled(E, A1, A2, A3, A4, A5):
    """
    This function calculates He+2 impact charge exchange cross sections (in cm2) of 
    H n > 2
    param E: requested impact energy in keV/u
    type E: float, np.ndarray
    param Ai: fit coefficient 
    type Ai: float
    """
    E = E/A[4]**2

    sigma = 7.04e-16*A5**4*A1*(1-np.exp(-4/(3*A1)* 
                   1+E**A2+A3*E**3.5+A4*E**5.4)))/(1+E**A2+A3*E**3.5+A4*E**5.4)
    return sigma

Fit Precision

2.4 %

Fit Coefficients

A1	2.003e+02
A2	1.459e+00
A3	2.038e-04
A4	2.000e-09
A5	3.000e+00

x-range

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