The fundamental principle for neutralisation of static charges is the same whatever the technique used. Where a material has a positive surface charge electrons must be delivered to the surface to bring the charge back into balance. Where the surface charge is negative the excess electrons must be removed from the surface to neutralise the charge.
The delivery or removal of electrons can be done by one of the three following methods, either
1) Movement of electrons through the material itself
2) Movement of electrons through another material in contact with the surface
3) Movement of electrons through ionisation of the surrounding air
The delivery or removal of electrons can be done by one of the three following methods, either
1) Movement of electrons through the material itself
2) Movement of electrons through another material in contact with the surface
3) Movement of electrons through ionisation of the surrounding air
There is in actual fact a fourth method, sparking, which occurs when the surface voltage is sufficiently high to cause the air to become conductive. However the occurrence of sparking is normally due to the lack of application of other methods!
Humidity
As previously noted moisture on (or within) a material will tend to leach away static charges down to earth. For example paper generally has a relatively high moisture content and does not maintain particularly high levels of static. However if the paper is particularly dry static can become a severe problem.
Passive Ionisation
The close proximity of a conductor to a charged object will tend to discharge it. For example Meech Model 974 Carbon Fibre Brushes will reduce static charges in materials passed in close proximity to the brush.
Radioactive Ionisation
Radioactive sources such as polonium cause ionisation of the surrounding air which will neutralise surface static charges. Meech do not supply Radioactive Eliminators. A drawback of radioactive eliminators is the fact that they are only available on annual leases. The radioactive source loses its effectiveness over time and requires replacement on an annual basis.
Active Electrical Ionisation
By using high voltage AC or DC, ionised air can be produced which can then be used to neutralise surface charges. The use of AC or DC systems is application dependent.
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