3D-simulation of ionisation gauges and comparison with measurements

3D-simulations using the Vector Fields OPERA 3D software have been carried out on the CERN-type modulated Bayard-Alpert gauge. The program allows to simulate the ion creation inside the gauge and takes into account space charge effects. Parameters such as sensitivity, ion and electron path lengths inside and outside the ionisation grid, location of ion creation, collection efficiency, and potential distribution were studied as a function of emission current. This investigation resulted in a deeper understanding about the behaviour of the gauge, in particular about the effect of space charge. The achieved results were compared with experimental measurements; the results are satisfactory and encourage further studies.