First ionization coefficients in hydrogen, neon, and argon

Values of the first ionization coefficient η in hydrogen have been determined in the range 40 < E/p 0 < 500 V cm -1 mm -1 of mercury at 0° C to ±2% (where E is field strength and p 0 the gas pressure at 0° C). Evaporated metal film electrode tubes have been developed so that rigorous outgassing procedures could be adopted, and an analysis has been used whereby the values of η can be correctly calculated from the current-voltage data. Preliminary results have also been obtained for neon and argon (commercial spectroscopically pure) using the same techniques.