Electron motion and confinement in the orbitip vacuum gauge: II. Modelling results

The sensitivity of the “orbitip” ionization vacuum gauge has been studied, by modelling the electron motion and confinement inside the device. The orbitip has two electrodes shaped as coaxial cylinders, and the electrons are provided by a field emission array. Numerical solutions of the electron equations of motion are used to study the device sensitivity. The electrons have irregular helical trajectories greatly increasing their mean path and therefore the gauge sensitivity. It is shown that the device sensitivity is maximal when conditions are fulfilled to achieve a circular helical electron trajectory. Accordingly, a gauge design procedure is outlined. Under such conditions, the study predicts extremely high values of the gauge sensitivity, in the range of 102–103 Torr−1.