Electrical Corona Discharge
Classical electrical corona discharge (dielectric barrier discharge) is obtained using a generator and electrode(s) connected to a high-voltage source, a counter electrode at potential zero and a dielectric used as a barrier. That is, a high-frequency, high-voltage discharge (step-up transformer) creating a potential difference between two points requiring earth ground 35+kV and 20-25kHz. Custom electrode configurations allow for treating many different surface geometries – flat, contoured, recessed, isolated, etc. One application example is a corona discharge treating system for electrical connectors in which a combination of pin and ball electrodes concomitantly treats 3D small diameter holes and flat exterior surfaces, US Patent US5051586 (1991)2. Ozone is produced in the plasma region as a result of the electrical discharge. Corona discharge has been found to be reasonably effective at cleaning the invisible hydrocarbon materials present after, e.g., solvent or detergent washing.
Myth: Atmospheric plasma is a low-cost replacement technology for corona discharge.
Fact: Corona discharge often is more effective for treating larger surface areas and at greater surface depth. In fact, many atmospheric plasma systems are more expensive.
Frequently Asked Questions
What is electrical corona discharge treatment?
Classical electrical corona discharge -- dielectric barrier discharge -- uses a generator and electrodes on a high-voltage source, a counter electrode at zero potential, and a dielectric acting as a barrier. It is a high-frequency, high-voltage discharge creating a potential difference between two points, typically requiring an earth ground at 35+ kV and 20 to 25 kHz.
Can corona discharge treat three-dimensional parts, or only flat film?
Custom electrode configurations allow many different surface geometries to be treated -- flat, contoured, recessed and isolated. One documented application is a corona treating system for electrical connectors where a combination of pin and ball electrodes treats small-diameter 3D holes and flat exterior surfaces at the same time, covered by US Patent US5051586 (1991).
Is atmospheric plasma a cheaper replacement for corona discharge?
Not generally. Corona discharge is often more effective over larger surface areas and at greater treatment depth, and many atmospheric plasma systems are in fact more expensive rather than less. The choice should be made on treatment requirement and geometry, not on an assumption about relative cost.
How effective is corona discharge at cleaning?
It has been found reasonably effective at removing the invisible hydrocarbon residues that remain after solvent or detergent washing, so it is often used as the step that follows cleaning rather than as a replacement for it.
Is ozone produced by corona discharge?
Yes. Ozone is produced in the plasma region as a result of the electrical discharge and has to be managed in the installation.
