Numerical analysis of the lasing behavior of a DF–CO₂chemical laser

Abstract

The variational methods of Kohn and HulthCn are employed to calculate the scattering lengths for elastic collisions between positrons and hydrogen and helium atoms. Allowance is made for the dipole polarizability of the target atom by using a trial function which includes a term corresponding to the first-order perturbation of the atom due to the electric field of the positron.The effect of allowing for the dipole polarizability of the atom is to change the sign of the scattering lengths for both hydrogen and helium in agreement with the variational calculations of Spruch and Rosenberg for hydrogen. I n the case of hydrogen the total elastic cross section at zero impact energy is increased when allowance is made for polarization, but in the case of helium it is decreased from 0*72na," to 0.10.irao2. The experimental cross section derived by Teutsch and Hughes for 18 ev positrons in helium is still smaller, being only 0.023 & 0 . 0 0 6~~~~.