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.

[TimFox]

Back to the original question:
For atoms (and molecules) the relevant parameter is the ionization energy, which is the energy required to extract the first electron from a neutral atom, leaving a positive ion behind.
Chemists quote this in kJ/mol, and physicists in eV.  See a list:  https://en.wikipedia.org/wiki/Ionization_energies_of_the_elements_(data_page)
One mnemonic from my student days is that the ionization energy of the hydrogen atom is 13.6 eV, just like the specific gravity of liquid mercury (13.6 g/cm³).
The ionization energy of the H₂ molecule, the normal form of gaseous hydrogen, is higher, about 15.4 eV.
It is possible to ionize atoms or molecules with a high electrostatic field, known as "field ionization" (q.v.).
In my university days, we did this by applying up to 10 kV to a sharp tungsten point, achieving a (huge) field value on the order of 100 V/nm = 10¹¹ V/m near the tungsten surface in a hydrogen atmosphere (roughly 10^-4 Torr), where we increased the current by cooling the needle and its surroundings to 78 K (liquid nitrogen) to enhance the gas supply to the narrow region around the needle.
See  https://physics.stackexchange.com/questions/384241/could-a-strong-enough-electric-field-tear-a-hydrogen-atom-apart
Field ionization is used to make a small-diameter source of ions for microscopes and microprobes, and as a source of ions for mass spectroscopy.