Mobility of Ions in Hydrogen

Abstract

The drift velocity of positive ions in hydrogen was measured over a range of $\frac{E}{p_0}$ (ratio of electric field strength to pressure) from 0.6-110 V per cm per mm Hg by means of a double-shutter velocity spectrometer. From these data the mobility (ratio of drift velocity to electric field) at a standard gas density of 2.69×${10}^{19}$ molecules per ${\mathrm{cm}}^3$ could be calculated. At low electric-field strengths the observed mobility was 10.2 cm per sec per V per cm at room temperature. At an $\frac{E}{p_0}$ of 10 the mobility began to rise, passing through a maximum of 14.3 at an $\frac{E}{p_0}$ of 60. The mobility at small electric field strengths was also measured as a function of temperature from 77-470°K. Its value remained nearly constant at about 10 from 77°K to room temperature and then rose abruptly to 11.5 at 375°K. These results are compared with other recent measurements and it is suggested that ${\mathrm{H}}_5^{+}$ cluster formation may be responsible for the unusual behavior of the mobility of the hydrogen ion.