EXPERIMENTAL INVESTIGATIONS OF THE CURRENT-MULTIPLICATION BEFORE THE ELECTRICAL BREAKDOWN

摘要

In the course of our work it is shown, how far the stochastic fluctuations of the electron avalanche leading to the breakdown can influence the breakdown itself. This can be seen in the different gradient of the current curve shortly before the breakdown. These fluctuations are responsible for the scattering of the breakdown voltage. These fluctuations were supposed to be neglectable due to the kind of the signal (not chaotic, but stochastic-deterministic). It is shown, why such fluctuations cannot be measured by the determination of the first Townsend coefficient. The electronic device used will be discussed as well as its extension for measurements under different voltage forms (ramp, HF). These measurements allow a deeper understanding of breakdown phenomena. Only such investigations can explain the micrometer breakdown. Besides, a Monte Carlo Simulation will confirm the fact, that the assumption of a constant ionisation coefficient in a constant electrical field, at least in the first phase of the discharge, is not correct.