Study of the Pressure and Temperature Dependence of Electron-Ion Recombination in Neon

Abstract

Conventional microwave and mass-spectrometric techniques have been used to study the loss rate of electrons and ions in the afterglow following microwave discharges in neon. Under the conditions of the experiment, the afterglow decay rate is controlled by the recombination of electrons with the only observed ion species, Ne 2 + , yielding a recombination coefficient which has a value of o;(Ne2 + )= (1.8=t0.2)X10~7 cm 3 /sec at 295°K and a temperature dependence of T^" -0 -45^0 -04 over the range covered, 295-503°K. At any given temperature, the measured recombination rates show no systematic dependence on the neon gas pressure over the range used, 8-30 Torr, indicating that the observed recombination process is a two-body reaction. Temporal mass analysis shows similar decay rates for the Ne 2 + ions and for the electrons over the major portion of the afterglow.

The electron temperature dependence of the recombination coefficient in neon

“…The present results show very good agreement with the results of previous studies (Hess 1965, Frommhold et a1 1968, Kasner 1968, and indicate the possibility of using a TMOm microwave cavity for measuring the electron temperature dependence of electron loss processes by means of a relatively simple method.…”

Fluctuations and correlations of the formative and statistical time delay in neon

“…Also, the minimum values of the breakdown time delay t dmin are presented in figure 2, as an estimation of the formative time delay [21]. According to [22,23], the molecular neon ions Ne + 2 are dominant during the glow in our conditions. Their number density decay in the afterglow (the region Ia in figure 2) can be described by the equation dn…”

“…Here, n i0 represents the initial number density of molecular neon ions, β is the electron-ion recombination coefficient (1.8 × 10 −7 cm 3 s −1 [22,23]) and ν = D/ 2 + k cn [N 2 ] is the first order decay frequency. It includes the diffusion decay frequency (D a = 23.6 cm 2 s −1 is the ambipolar diffusion coefficient of Ne + 2 ions [24] and = 1.08 cm is the characteristic diffusion length of the tube) and conversion of molecular neon ions to nitrogen ions produced in Ne + 2 collisions with nitrogen impurities Ne + 2 + N 2 → N + 2 + 2Ne (the rate coefficient k cn = 9.1×10 −10 cm 3 s −1 [13,25]).…”

Electron Temperature Dependence of Recombination ofNe2+Ions with Electrons

“…(Ne^) = (1. 75±0.2)x 10" 7 cmVsec at T^ = 300°Kto a value (4.0±0.6)xl0" 8 at T e = 4600°K. This behavior may be compared with the results of Frommhold, Biondi, and Mehr 9 (FBM) who used a nonresonant waveguide heating mode (which permitted more accurate determinations of the electron temperature) but did not employ mass analysis.…”