These plasmas are generated in closed chambers in a vacuum (10-3 to 10-9 bar). The decreased particle count per volume in comparison to atmospheric pressure leads to a greater free travel length and to a comparatively lower number of impact processes. Therefore the plasma has a lower tendency to relax and can spread more widely in the space. Strong pumps are necessary for evacuating the chamber. Low pressure plasma does not have inline capability.
High pressure plasma
High pressure plasmas are generated in special gas discharge lamps, for example. They have no importance in the treatment of surfaces.
Corona process, corona treatment
Corona treatment is a physical process involving high voltage and is mainly used for treatment of films. The disadvantage of corona pretreatment is its relatively low activation potential and the sometimes inhomogeneous results on the surface treated. In individual cases, there may also be unintended treatment of the reverse side of the film. Moreover, the surface tension obtained does not remain stable very long, and the treated components can only be stored for a limited time.
Atmospheric pressure plasma, atmospheric plasma – today’s form of plasma treatment
Atmospheric plasma is generated under normal pressure. This means that low pressure chambers are not required. With the patented Openair® jet technology , it is now possible for the first time to integrate very effective and – what is more – protective plasma (because it’s potential-free) directly into manufacturing processes under normal pressure conditions. Treatment with atmospheric pressure plasma is thus especially cost-effective and is widely available as an alternative to low pressure plasma and corona processes. The big advantage of atmospheric plasma is its inline capability. As a rule, it can be integrated into existing production systems with no problems.