E vs H field strength levels to ionize different gases?

[ELS122]

Is there a chart or a book listing the different levels of E and H fields required to ionize different gases?

[LaserSteve]

your looking for Paschen Curves, and once you find Paschen's Law for gas X, you can work backwards from there.   Ionization Voltage in Ev is another method that can be worked backwards from the listed value to what you seek.  This is very serious math, so start with Paschen's Curves.    I  long ago stopped doing the math and just put the tubes on the fill station after a first approximation, so I will not be much help.

Tying in H is whole different can of worms, as inductive coupling to a gas is vastly situationally dependent, and generally requires a High Q resonant circuit with inductive coupling or nothing happens.

Steve

[TimFox]

Note that the Paschen curve for a given gas graphs the voltage between the electrodes for a glow-discharge tube as a function of the product of pressure x distance.
The voltage increases quickly to the left (low pressure), shows a broad minimum for intermediate values of the product, and then increases again to the right (high pressure).
The Wikipedia article on Paschen curves is a good start.