INVESTIGATION TO DETERMINE COLLISION FREQUENCIES OF TYPICAL RE-ENTRY WAKE CONTAMINANTS.

Abstract : Electron cyclotron resonance techniques were used to determine the electron-sodium collision frequency in thermally generated sodium plasmas over the temperature range from 1140K to 1390K which corresponds to a mean thermal energy range of 0.098 to 0.120 eV. Over this energy range the effective electron-sodium collision frequency was found to be constant at a value of 5.15 x 10 to the 10th power/torr/sec. Thermochemical calculations of the various species present in the vapor phase for oxygen and nitrogen compounds of sodium indicate that at energies near 0.1 eV vapors of these materials would be completely dissociated. Therefore, the main contribution to the collision frequency from these materials would be due to the presence of free sodium. Measurements of the electron collision frequency in two component systems which are composed of sodium plus oxygen or soidum plus nitrogen with high overpressures of these gases, so that the predominant collisional broadening is not due to sodium but due to the presence of the second component in the system, are in substantial agreement with the results reported by Engelhardt and Phelps for nitrogen and the results reported by Shkarofsky for oxygen. (Author)