Transition from the Three-Body to the Dissociative Electron-Ion Recombination in an Argon Plasma

Abstract

An experimental study is presented which is concerned with the transition from the three-body to the dissociative electron-ion recombination in an argon plasma. The measurements are performed, by using the propagation technique of the 8 mm wave, in decaying plasmas produced behind reflected shock waves in a T -type tube. It is filled with argon at initial pressures from 5 to 18 Torr. The electron densities and temperatures are respectively in the ranges from 10 13 to 10 10 cm -3 and from 10 3 to 3×10 2 °K. The recombination coefficients determined from the measured density decays are explained by the three-body recombination process for the electron densities above 10 12 cm -3 . The coefficients, on the other hand, are interpreted by the dissociative process for the electron densities below 10 11 cm -3 with the electron temperatures close to 3×10 2 °K. The transition between these two processes is discussed.