Townsend Ionization Coefficients and Uniform Field Breakdown in Hydrogen and Nitrogen at High Pressures

Runaway breakdown in the Jovian atmospheres

“…A more useful comparison is how the runaway breakdown threshold compares with the conventional breakdown field for the Jovian atmospheres. The conventional breakdown field for hydrogen, the principle component, is often reported to be about half the value for air, or 1500 kV/m [ Yair et al , 1995; DeBitetto and Fisher , 1956; Cobine , 1941]. However, this threshold involves the Townsend discharge mechanism in which electrons are liberated from a cathode.…”

High Pressure Gas Filled RF Cavity Beam Test at the Fermilab MuCool Test Area

“…When an electron gains enough energy to ionize the gas, a cascade of electrons can be produced, called a Townsend Avalanche [30]. The current in the gas is given by:…”

Handbook for Gas Filled RF Cavity Aficionados'

“…One would guess that it would pull in field lines within a radius comparable to its height. Thus, the average field at the end of the rod would be increased by the ratio of the two areas or by (h / r) 2 and an emitter with a ratio of 10:1 can give a field increase of 100. One can actually investigate this a little farther.…”

“…Of course, we have a well defined shape and microscopic changes in the shape will change the local field for distances comparable to the roughness of the point. In any case, 0.5 (h / r) 2 gives an indication of what the emitter needs to look like for a given field enhancement. An interesting question is how fast does the field fall off and approach the uniform applied field.…”

“…Consider a small section of the conductor dV with density Rho and Heat Capacity C(T) carrying a current density j(t). The joule heating minus the cooling can be equated to the increase in temperature dW = j(t) 2 …”