At what voltages does arcing occur?
That's a totally vague/meaningless question.
It depends on the dielectric and the distance between the charged points.
Electricity will arc at any voltage.
The key search term for answering that is "Paschen Curve":
In dry air at room temperature and one atmosphere of pressure, it's about 10kV per centimeter of separation, but like people said, it will depend on many factors.
If arcs are encased in a glass container generated when gas is being ionized, could the arc pass through the container if the voltage is large enough? If so, what could I do to prevent that from happening?
Once again you have asked a question that is so vague as to be meaningless.
I can easily envision situations in which it does and in which it does not. BE SPECIFIC.
I think, the most general answer is, yes it can. So if you don't know what you are doing, don't do it.
Here's what I'm doing:
I'm trying to calculate the maximum volume of Helium gas that can be ionized into plasma if I apply a power of 1 watt, where the voltage is 1000 volt and the current is 0,1mA.
DATA 1: The ionization energy for Helium is 2372,3KJ/mol
DATA 2: Molar mass = 4,002602 g/mole
DATA 3: Density = 0,1786 g/L
I multiply the inverse ionization energy (in mole) with the ionization energy (in Joule/mole)
(1/2372,3*10^3)mole * 2372,3*10^3 J/mole = 1 Joule
1 Watt = 1 Joule per second
I multiply the inverse of the ionization energy (in mole) with the molar mass of Helium.
(1/2372,3*10^3 mole) * 4,002602 g/mole = 1,687224213*10^-6 gram
I multiply the mass (in grams) with the density to find the volume:
(1,687224213*10^-6) g / 0,1786 g/L = 9,446944082*10^-6 L = 9,446944082 mm^3
I take the third/cubic root of the volume to find the lengths of the gas container in [x,y,z]
3sqrt(9,446944082) = 2,11mm
So in order to ionize 1,68 micrograms of Helium in a 2,11x2,11x2,11 mm tank, you'll need to supply a current of 0,1mA through 1000 volt.
Is this correct?
For example, USB plasma globes uses neon, xenon and krypton which have lower ionization energies, thus the volume is allowed to be larger. One USB plasma globe was the size of my hand and ran on 5 Volt and 300mA (or 1,5 Watt).
Now concerning this thread: I want to increase the pressure to reduce the ionization energy and increase the voltage to increase the plasma flux density. The problem is, I don't know the maximum voltage that I could apply to my system without arcs passing beyond the glass container.
The size of this container is going to be nominal 20mm in diameter, cylindrical.
Regardless of the voltage output I'm going to limit the power output to about 1,5 Watt.
Separate names with a comma.