Shock Tube Stodies on the Association Recombination of NO⁺ and Electronics

A new shock tube method is developed, in which the gases are ionized by the shock wave and subsequently quenched by a strong rarefaction wave. As the quenching sped 10⁶K/s has ho reached, the ionization is in non-equilibrium during the process. A piezo-electric tiansducer and a langmuir probe are used to monitor the changing state parameters, and the variation of the ion density.
The composition of the experimental gases are 4.7% air mixed in argon. At the reflection shock region, the equilibrium temperature T₅=4150K, pressure P₅=0.4 MPa and ion density NO⁺=2.7×10¹²cm^-3 are determined by shock speed consistent with the dired meastirements.The kinetic equation for the recombination reaction of \mathrmNO^++\mathrme \undersetk_r^+\stackrelk_r^+\rightleftarrows \mathrmN+\mathrmO in the quenching proals has been derived as k_\mathrmr^+\left\mathrmNO^+\right=\left(\frac\mathrmd \ln \left(\rho / \rho_5\right)\mathrmd t-\frac\mathrmd \ln \left(\left\mathrmNO^+\right /\left\mathrmNO^+\right_5\right)\mathrmd t\right) /\left(1+K^+ /\left\mathrmNO^+\right\right) where K⁺=k_f⁺/k_r⁺ is the equilibrium constant, N and O is the local number density of atom N and atom O respectively. As the N~10¹⁷cm^-3in this case, in the evaluation of the variation of N and O we let reaction 1017cm-3 in this one, in the evaluation of the variation of N and O we let auction 2 \mathrm~N+\mathrmAr \rightleftharpoons \mathrmN_2+\mathrmAr is in the frozen,2 \mathrmO+\mathrmAr \rightleftharpoons \mathrmO_2+\mathrmAr is in equilibrium and N+O→NO₊ is in finite rate. Using the calculated value of the local N, O and the measured ρ/ρ₅, NO⁺/NO⁺₅, the value of k_\mathrmr^+=5.5 \times 10^17 T^-0.52 \mathrm~cm^3 \mathrm~mol^-1 \mathrm~s^-1 at 3100K＜T＜3700K is deteremined. The comparison of this result with the existal data shows that the dependence of k_r⁺ on T is consistent with Hanson’s estimate, and the quantity of the k_r⁺ is consistent with Lin’s data, and three times smaller than Dunn’s measurement.