SECONDARY EFFECTS IN IONIZATION AND DECAY PROCESSES

Secondary ionization processes by which secondary electrons are produced are the one which sustain a discharge after it is established due to ionization by collision and photo ionization.

• Electron emission due to positive ion impact

• Electron emission due to photons

BREAKDOWN IN NON-UNIFORM FIELDS AND CORONA DISCHARGES

• The partial breakdown of a gas, known as corona discharge, is one which manifests itself in everyday life and is the direct cause of lightning.

• This phenomenon has been transformed into an area of rapid exploitation, with commercial applications including the environmental control of exhaust gases, the treatment of polymers and semiconductor manufacturing.

• However, coronas can be highly undesirable in industrial systems that employ electromagnetic waves for the processing of materials, in medical applications, and in communications.

• In such systems, the occurrence of corona discharges can lead to arcing, which in turn, may lead to fires or even explosion.

• There is therefore a need to increase our fundamental understanding of corona in order both to identify and study the factors that cause problems, and to facilitate optimization of processes, where coronas are desirable.

• Use of numerical modelling, both to understand the physics behind corona and allow the design of optimized systems