Transport section of the Karlsruhe Tritium Neutrino experiment (KATRIN) must provide the dramatic reduction of tritium flow and gas density from the end of 10-m long windowless gaseous tritium source throughout a few stages of differential pumping system. The final stage of this section, cryogenic pumping section (CPS) base on pumping of tritium on argon frost at 4.5 K should provide the flow ratio between inlet and outlet in the range of 107.
Cryosorbed tritium may decay emitting a few keV electrons, these electrons in their turn cause the electron stimulated desorption of cryosorbed argon and tritium, which re-distributed along CPS (migration process). This effect was modelled with use of method of angular coefficients. The main result is that the tritium migration process does not affect the CPS performance at KATRIN for given inlet flow. Meanwhile has the flow chosen larger the migration effect could be dominant. |