Plasma ball radio-frequency energy

[Taulant Sholla]

I read Wikipedia's description of how a plasma ball works. Question: What kind of energy is the "radio-frequency energy from the transformer"? Is in the form of electric field energy, magnetic field energy, or both? Thank you!

(from Wikipedia)...
Although many variations exist, a plasma lamp is usually a clear glass sphere filled with a mixture of various gases (most commonly neon, sometimes with other noble gases such as argon, xenon and krypton) at nearly atmospheric pressure. A crackle tube is a related device filled with phosphor-coated beads. Plasma lamps are driven by high-frequency (approximately 35 kHz) alternating current at 2–5 kV.[1] The drive circuit is essentially a specialized power inverter, in which current from a lower-voltage DC supply powers a high-frequency electronic oscillator circuit whose output is stepped up by a high-frequency, high-voltage transformer. The radio-frequency energy from the transformer is transmitted into the gas within the globe through an electrode at its center. A much smaller hollow glass orb can also serve as an electrode when it is filled with metal wool or a conducting fluid that is in communication with the transformer output. In this case, the radio-frequency energy is admitted into the larger space by capacitive coupling right through the glass. Plasma filaments extend from the inner electrode to the outer glass insulator, giving the appearance of moving tendrils of colored light within the volume of the globe (see corona discharge and electric glow discharge).

 

[Ibix]

Is in the form of electric field energy, magnetic field energy, or both?

You can't have a changing electric field without generating a magnetic field and vice versa. So definitely both. In fact, given that how an electromagnetic field is divided into an electric and a magnetic field is observer-dependent, it's best to just call it the energy of the electromagnetic field and be done, I think.

 

[Taulant Sholla]

Thank you!

Do you think this RF energy directly ionizes the gas atoms, or does it cause them to "heat up" through their oscillations to the point where they ionize?

 

[Ibix]

I must confess I'm not an expert on plasma. I can suggest reading about "breakdown voltage". My understanding is that the electric field is strong enough to pull an electron off an atom of gas, with enough energy that it'll knock another electron loose. The result is a chain reaction that generates a fairly straight filament of plasma.

I may not have a completely reliable understanding.