My guess is that CCP is the name of an industrial process that makes use of Townsend discharge. However, I was unable to find any article or paper confirming this.
A Townsend discharge operates by applying a DC voltage across a gap between a cathode and anode. Electrons are emitted by the cathode and collide with air molecules in the gap. Once ionized, the positive ions move toward the cathode while the new secondary electrons move toward the anode. This is repeated multiple times resulting in a shower of electrons resulting in an avalanche breakdown.
A capacitively coupled plasma (CCP) relies on a radio frequency (RF) power supply connected to two parallel, conducting plates. Once an ionization occurs in the gas between the plates, the electrons are accelerated by the AC electric field of the RF power supply but the much heavier ions experience much smaller accelerations due to their masses being at least 1836 times more than the electrons. The accelerated electrons can then initiate an avalanche breakdown if the oscillating electric fields are large enough.
If one isolates one of the plates using a capacitor, the electrons will accumulate on this plate resulting in a DC electric field being established in addition to the AC field from the RF power supply. The negative plate does not discharge immediately because of the capacitor attached used to isolate it. Recall the ions were not significantly accelerated by the AC field in the first design but here, with the DC field present, they can be accelerated toward the isolated plate.
Can someone clarify exactly what the relationship between these two processes is?
It seems they are related but the Townsend discharge relies almost entirely on a DC power supply while the CCP often uses an RF power supply (at least this is the main difference between Townsend's original version and modern CCP set ups).
