Townsend´s First Ionization Coefficients and Sparking Potentials in Crossed Electric and Magnetic Fields

Townsend´s first ionization coefficients have been measured in corssed electric and magnetic fields for values of B/p ranging from 0.013 TESLA. TORR-1 to 0.064 TESLA.TORR-1 and for 103 x 102¿ E/p¿ 331 x 102 V.M-1. TORR-1 in oxygen and for 122 x 102¿ E/p¿488 x 102 V.M-1.TORR-1 for dry air. The values of effective collision frequencies determined from the equivalent pressure (pe) concept generally increase with E/p at constant B/p and decrease with increasing B/p at constant E/p. Effective collision frequencies determined from measured sparking potentials at high values of E/p increase with decreasing E/pe. The drift velocity and mean energy of electrons in oxygen in crossed electric and magnetic fields have been derived.