Measurements of the drift velocity of electrons in mixtures of nitrogen and carbon dioxide from 100 to 1000 Td

The arrival-time spectra (ATS) of electrons in mixtures of nitrogen and carbon dioxide have been measured for reduced electric fields from 100 to 1000 Td at room temperature by using a double-shutter drift tube. The drift velocity of the electrons in and mixtures was evaluated from a previously reported ATS method. In mixtures of and , we found that is larger than the value predicted by a linear combination of the drift velocities of the pure gases based on the mole fraction (partial pressure) of in the mixture, k, in the range of low . We refer to this as the `mixing effect'. In contrast, a linear combination of the drift velocities of the pure gases based on k was found to accurately predict the drift velocities in mixtures in the higher region . In addition to the experimental evaluation, calculations of in these gas mixtures were carried out by a Boltzmann equation analysis, and the results were compared with those from the ATS measurements. The ratio of the longitudinal diffusion coefficient to the electron mobility was also estimated. The value of , called the characteristic energy, also shows a small mixing effect with increasing k in the range of low and increases monotonically in the range of , while the value decreases linearly as k increases in the higher range.