CollisionDB: DataSet D108069

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

Process	EEX: Excitation
Data type	cross section \| uploaded on 2023-02-08
Comment	Fit function and data were taken from Janev et al. p22. Errors: E<30eV -> 40%, 30eV<E<80eV -> 20%, E>80eV -> 10%.

Method	semi-empirical
Columns	E /eV sigma /cm²
Threshold	1.889 eV
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

\[\sigma_{ex}^{n=1 \rightarrow 3,4,5} = \frac{5.984 \times 10^{-16}}{I X} \Bigg[ \frac{E - I}{E}\Bigg]^{A_6} \Bigg[ \sum_{j=1}^4 \frac{A_j}{X^{j-1}} + A_5\ln X \Bigg], X = \frac{E}{I}\]

Python

def h_eex_janev_15(E, A1, A2, A3, A4, A5, A6, I):
    """
    This function calculates electron impact excitation cross sections (in cm2) of 
    H n=1 to n=3, 4, 5 and n=2 to n=3
    param E: requested electron-impact energy in eV
    type E: float, np.ndarray
    param Ai: fit coefficient 
    type Ai: float
    param I: threshold energy in eV
    type I: float
    """
sigma =  5.984e-16/E*((E-I)/E)**A6*(A1/(E/I)**0+A2/(E/I)**1+A3/(E/I)**2 +
                                         A4/(E/I)**3+A5*np.log(E/I))
return sigma

Fit Precision

2.4 %

Fit Coefficients

A1	5.237e+00
A2	1.192e+02
A3	-5.954e+02
A4	8.167e+02
A5	3.891e+01
A6	1.320e+00
I	1.889e+00

x-range

1.889 –