Investigation of turbo-molecular pumps in strong magnetic fields

In modern particle and accelerator physics as well as in nuclear fusion experiments turbo-molecular pumps (TMP) are used in close proximity to super-conducting magnets. This can cause considerable heating of the fast moving rotor by eddy currents, which can ultimately lead to the destruction of the pump. Motivated by the KATRIN neutrino experiment, where TMPs are operated close to super-conducting magnets, a measurement programme has been elaborated to investigate the effect of magnetic fields on TMPs. An infra-red pyrometer has been used to measure the temperature of the revolving rotor. In addition the effect of different gas loads on the temperature was investigated. With these data a simplified model has been developed to predict the evolution of the rotor temperature over time, using easy to measure parameters. Here we introduce the new model and present first measurements and their application in predicting the rotor temperature in the pulsed field of a nuclear fusion experiment.

► We investigated turbo-molecular pumps in strong magnetic fields.
► An experimental setup measures the rotor temperature for different fields and gas flows.
► An empirical model with 5 easy to measure parameters describe the rotor temperature.
► The model can predict the temperature when designing a vacuum system.
► The rotor temperature in a pulsed field of a fusion reactor is calculated.