Ionization rate at higher electron densities in DC fields measured in an electrodeless discharge

In a toroidal discharge tube, a constant electrie ring field is induced for a time much longer than the electron collision time. The inducing magnetic field, however, is prevented from penetrating the discharge tube. The torus contains a weakly preionized gas. When the electric field is applied, the electron density essentially grows exponentially with time. If losses can be neglected, the exponential coefficient is identical with the ionization rate. The growtry rates of the electron density are determined by microwave interferometry for electron densities of $10^{11}$ - $10^{12}$cm$^{-3}$. Ionlzatlon rates have been measured as function of $\frac{E}{p}$ in hydrogen and nitrogen.