In this paper we present some computational aspects of investigations of the early stages of development of the gas breakdown discharges via applying a fully kinetic model for particles and binary processes in a self-consistent electric field. Coupled set of Newton and Poisson equations is solved by so called Particle in Cell (PIC) model. Microscopic plasma parameters, i.e., ion and electron velocity distributions and corresponding fluid quantities are obtained as functions of position, time and pressure for a fixed computational domain geometry and dimension, i.e., for fixed system length in one-dimensional plane discharge. The paper is a first step towards implementing one by one additional particle-particle, particle-field and particle-boundary processes, and additional surface and volume sources and sinks of particles and energy during the gas discharge breakdowns in various gases.
COBISS.SI-ID: 11983899
The Gas Discharge Tubes (GDT's) represent one class of a wider group of high-power switches and surge protecting devices such as electronic, electro-mechanic, gas surge arresters etc. realisations. Such element serve as reliable electrical resistors with infinite resistivity, physically installed between the ground and certain critical points in the electrical supply networks of civil-engineering objects, so as to act as ideal electrical short-cuts in the occasions of external over-voltages, capable to bear extremely high currents with, on one hand, very prompt response to unwanted values of over-voltage and, on the other hand, having as short as necessary relaxation time back to ideal resistor state. In this paper we are interested in the particular question of the effects of external magnetic field to the time-developments of the discharge that might be related to possible optimisation of GDT’s, aiming for over-voltage protection against the atmospheric lightning. Method of investigation is numerical simulation based on kinetic modelling of the electron and ion motion in combined electric and magnetic fields.
COBISS.SI-ID: 8654420
The motivation for this work comes from the field of over-voltage/surge protection devices called Gas Discharge Tubes (GDT). GDT’s can be installed in all levels of electric power distribution grids with the purpose of over-voltages in cases of atmospheric discharges, short circuits and other malfunctions/natural phenomena. In general they work as perfect high-voltage switches acting as infinite resistors during normal operation and as perfect conductors in case of external over-voltages. The nature of such gas discharge tubes allows them to carry extremely high currents when conducting and the return to their resistive mode when the surge wave passes. Our intention was to study the initial phenomena in that occurs during the breakdown inside the tube, namely the avalanche process in order to better understand it’s nature and find a way to optimize the way this class of devices are constructed. This paper deals with the effects of space-charge collected in the simulated area. This happens when the charged particles injected in the domain and additional charged gained through ionization process perturb the electric field enough to make impact on the potential profile and consequently on the avalanche process. This question is also important in the view of field enhanced emission from the boundaries.
COBISS.SI-ID: 8654676