The corona discharge is the unimpeded discharge of the free electrons from an electrical conductor. This process is only possible under a high electrical field strength, and increase with the increased voltage. The air stream increases the corona discharge on the electrode, because the electrones are fushed away.
The free electrons seeks the shortest route to the next grounded part. They contact the powder particles and remain adhered to them. The ionised powder particles are attracted all grounded objects like the free electrons. The free electrons that don’t hit powder particles and the ionized air are called space charge and have an influence on the coating quality.
As soon as the ionized powder particles meet the grounded workpiece, a counter-charge is created on the workpiece. Both charges mutually attract one another. Because the powder is not electrically conductive, the charge cannot discharge and the attractive force remain, ensuring the first adhesion. The discharging current, consisting of free electrons, air ions, and the influence current of the counter-charge, flows from the grounded workpiece.
The charged powder is pushed towards the grounded workpiece by only the electric force equal to the charge of the particle.
