OBTAINING ATTACHMENT CROSS SECTIONS OF C₄F₇N BY ANALYSIS OF ELECTRON SWARM PARAMETERS

Some new fluorinated gases such as C₄F₇N and C₅F₁₀O are potential SF₆ alternative gases but the fundamental properties including cross sections data are still very limitted. The electron attachment process is extremely important in the kenetic of electronegative gases. We introduced a method for obtaining attachment cross sections by analysis of electron swarm parameters. For this purpose, the investigated gas was added in small proportion to different carrier gases and the effective ionization rate constants were measured, with the pulsed Townsend experiment. Based on some reasonable assumptions, we can obtain attachment cross sections by solving an integral equation. We used the finite difference approximation method to convert the integral equation into a system of linear equations.Then the regularization method was used to obtain a stable solution. We described the principle of this method in detail and applied it to the C₄F₇N. The present estimations gave us some useful information. For energies below 0.01 eV, the solution for attachment cross sections of C₄F₇N tends to converge to zero. There are three peaks in 0.01~0.1eV, 0.1~1eV and 1~3eV respectively, which is in agreement with the reference results. Finally,we discussed the usefulness of the method for the cross sections derivation from swarm data as well as its limitations.