Experimental Determination of Electron Concentrations and Effective Frequencies of Electron Collisions with Neutral Particles in Air, N2, O2, Co, Argon, and CO2 Behind Shock Waves

摘要

Measurement of radio-wave absorption simultaneously at two frequencies of 37,500 MHz and 18,750 MHz behind a reflected wave in a shock tube indicated that equilibrium ionization is achieved in air and in nitrogen during times of 70-17- Mu sec at 2800-4800 degrees K and at pressures of 0.3-6.20 atm. Comparison of absorption curves with Topler scan of the process of shock wave reflection from the end of a tube made it possible to explain the significant increase of conductivity after it reached an equilibrium value as a result of the additional heating of the gas by the shock wave being reflected from the interface. The measured values of effective cross-sections of electron collisions with neutral particles in air, nitrogen and CO are quite close to the data found in other papers. However, the cross-section tends toward a sharper increase in nitrogen at temperatures higher than 4000K. Cross-section values in molecular oxygen and in CO2 were significantly less in the present investigations than those found by others. (Author)