The hot cathode ionization gauges used in magnetic confinement fusion consist of a linear electrode array forming a triode. These accelerate electrons and confine them, to facilitate electron impact ionization of residual gas. The resulting ions are collected as a current, which is proportional to the gas density and can be converted into a pressure.

The triode grid potentials, distances and transparency ratios were determined experimentally, but never systematically documented. A flexible gauge head with movable grids was designed as an internship project, and manufactured in-house for systematic testing of these properties.

Main topic of this work is a systematic scan of grid distances and potentials to verify the current working point and document the behavior of the triode. A recently commissioned test facility with a permanent magnet array producing a high magnetic field of ~1.4 T will serve as the experimental device.

The experimental work is to be accompanied with simulations of the trap. After reproducing the basic measurements to validate and refine the model we will use it to investigate features found in gauges fielded at Wendelstein 7-X, such as electron current jumps.

A close collaboration with the manometer development group at IPP Garching is foreseen, with mutual visits and regular coordination meetings.