What does the EPC ( Photon & Electron Emissions) method measure in physical terms?
The EPC method is based on the stimulation of photon and electron emissions from the surface of the object whilst transmitting short electrical pulses. In other words, when the object is placed in an electromagnetic field, it is primarily electrons, and to a certain degree photons, which are ‘extracted’ from the surface of the object. This process is called ‘photo-electron emissions’ and it has been quite well studied with physical electronic methods. The emitted particles accelerate in the electromagnetic field, generating electronic avalanches on the surface of the dielectric (glass). This process is called ‘sliding gas discharge’. The discharge causes glow due to the excitement of molecules in the surrounding gas, and this glow is what is being measured by the EPC method. Therefore, voltage pulses stimulate optoelectronic emission whilst intensifying this emission in the gas discharge, owing to the electric field created.