The conductivity ratio, p , together with the electron radiation temperatures, T,, were measured in a n NO afterglow, using a microwave wave-guide diagnostic method and noise sampling technique respectively. T h e normalized values of p are plotted versus To in the electron radiation t e m p e r a t~~r e interval 1 200-12 000 I<' for pressures ranging from 0.25 to 4.0 Torr. A s s~~m i n g the electrons to be Maxwellia~lized, the total collisiol~ frequency can be expressed as v, = iV . 1.50 X 10-8z~(eV)~/2 within the limits of accuracy of the experiment; however, the relation v, = iV . 1.55 X 10-8z~(eV)o'4 yields a closer fit to the meall of the experimental data. The electron thermalization is found to be nearly independent of pressure, indicating that metastable i~lteractions may occur; some of these have been included in the discussion.
The time dependence of the electron density, Ne(t), and radiation temperature, Te(t), has been measured in d-c. discharge afterglows of NO and NO–Ne mixtures. Microwave wave-guide transmission and noise-sampling techniques were used. In pure NO the experimental results were compared with those computed for a recombination–attachment controlled plasma using Gunton and Shaw's values, and good agreement was found. In the NO–Ne mixtures p(Ne) was about 20 Torr, and p(NO) was varied from 0.5 × 10−3 to 0.10 Torr. It was found that 1/Ne(t) was linear over extensive ranges of Ne(t) indicating two-body electron–ion recombination. The results yield [Formula: see text] and the three-body attachment coefficient K = 2.2 × 10−31 cm6sec−1 for Te = Tgas = 300 °K. Te(t) decayed nonexponentially varying with p(NO) indicating that Penning ionization takes place together with other collision processes which are briefly discussed.
Using published cross sections for rotational excitation and de-excitation caused by dipole and quadruple interactions in carbon monoxide, the average electron energy loss rate, [Formula: see text], is computed as a function of excess electron temperature, Te − T, for the case of a maxwellian velocity distribution for various gas temperatures, T. It is found that the dipole and quadrupole contributions to the loss rate are in the ratio 3:1 with the composite electron energy relaxation time given by pτ = 338 ns Torr for Tgas = 300 °K. The initial values of [Formula: see text] caused by dipole interaction decrease more rapidly with temperature than T−1/2, which was the temperature variation found in the case of quadrupole interaction. Experimentally, microwave cross-modulation results pertaining to the isothermal afterglow of a d-c. discharge in CO yielded the value pτ = 113 ± 11 ns Torr for T = 300 °K. The apparent discrepancy between theory and experiment is discussed.
The electron time decay in an afterglow following a short pulsed d.c. discharge in CO has been investigated using microwave diagnostic techniques. The gas was heated to an average temperature of 775 OK. Two-body electron-ion recombination and ambipolar diffusion were found to be the only important electron removal mechanisms present in the pressure interval 0.2 < p < 2 Torr with the rate constants a, = 3.9 x cm3 s-I and D,po = 372 cmZ s-I Torr respectively. If we postulate a T-Y dependence for a,, comparison with room temperature results yields y = 0.57. The diffusion coefficient appears to increase strongly with temperature based upon an estimated zero field mobility for CO+in CO at 273 "K found in the literature.
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