Static discharges corona discharge

Static eliminating devices that ionize the atmosphere around the device are available. Static eliminators are divided into two main groups silent (corona) discharge eliminators, such as inductive eliminators, or high voltage eliminators which initiate an impact ionization of the air by applying strong electrostatic fields, and radioactive eliminators that provide a multitude of ions from independent ion sources (9). 

An AC corona discharge in the throat leads to a cloud of charged droplets whose large momentum allows very long travel distances. Multiple devices for eliminating static discharges in powder silos have been tested [41] but the tests did not address typical flow rates for large capacity, dense phase pneumatic transfer operations. 

Langdon19 reported measurements of electrostatic properties of film a 5 kY d.c. voltage was applied and it was found that when film was treated by corona discharge the rate of decay of the applied static charge was increased considerably as treatment was increased, so was the rate of decay. 

The use of static SIMS for the characterization of surfaces of polypropylene (PP), PTFE and a PMDA-ODA type poly-imide is described. Interfaces between evaporated copper or chromium films onto PTFE and polyimide were also analyzed. Some of the polymer substrates were modified by ion beams, corona discharge in air or plasma treatments in air, At and H2. It is demonstrated that SIMS is highly complementary to XPS for the analysis of such modified surfaces, in that effects such as crosslinking, unsaturation and formation of low-molecular weight material at surfaces can be detected. 

With the help of complementary surface analysis techniques such as XPS, Static SIMS and AES, we have been able to show how a short (23 msfilms leads to a slight oxidation of the surface as well as to the formation of N2 containing species. These modifications are necessary for the improvement of the adhesion observed with a scotch-tape test. However, the presence of oxygen is not the only factor responsible for a good adhesion, since the AES profiles of die deposited aluminium, show the same oxidized interface in the case of the non treated metallized polymeric film. The films are pretreated in a corona discharge configuration (hollow electrode-grounded cylinder) and the aluminium is deposited onto the film in situ. 

A corona discharge is induced upon application of an electric potential of several kV across the electrodes. Ionized molecules from the air are forced by the electric field to move to the surface of the sample. The deposited ions induce image charges on the earthed electrode. Thereby, a static electric field of about... 

---