Simulation of Rarefied Gas Flow in the KATRIN Source

L. Kuckert[1]
[1]Karlsruhe Institute of Technology, Karlsruhe, Germany

The KATRIN experiment at the Karlsruhe Institute of Technology (KIT) will measure the neutrino mass on a sub-eV range. Therefore the electron spectrum of the beta decay of Tritium will be detected and compared with a simulated spectrum of the used windowless gaseous Tritium source (WGTS). In the WGTS tritium is injected with 0.33Pa through small orifices in the middle of a 10m long tube with a diameter of 90mm held at a constant temperature of 30K. This work presents the COMSOL Multiphysics® simulation of the density profile in the gas injection system, the beam tube and the first pumping port using the transitional flow interface. Further transport and pumping sections are simulated using the molecular flow interface.