Bremen 2017 – wissenschaftliches Programm
P 23.4: Poster
Mittwoch, 15. März 2017, 16:30–18:30, HS Foyer
Plasma formation in the KATRIN tritium source — •Laura Kuckert — for the KATRIN collaboration, KIT, Karlsruhe, Germany
The Karlsruhe Tritium Neutrino Experiment (KATRIN) aims to measure the neutrino mass with a sensitivity of 200 meV/c2 (90% C.L.) in a direct approach using the beta decay of molecular tritium. The neutrino mass is extracted from a fit of modelled beta decay spectra to the measured electron spectrum. Hence, it is important to consider all effects that impact the electron energy. The potential energy of the emitted electrons is set by the electrostatic potential at the position of beta-decay in the windowless gaseous tritium source (WGTS). The potential distribution in the WGTS is determined by a cold low-density plasma that forms inside the strong magnetic field of the WGTS through beta decay and secondary ionizations. To understand the formation and structure of the plasma potential, a comprehensive fluid plasma model has been developed that includes the creation, annihilation and motion of electrons and ions as well as neutral gas flow. The results of the plasma modelling are reviewed with regard to different surface conditions and a monitoring option for the potential distribution is presented that uses monoenergetic electrons from 83mKr. Implications on the systematics budget for the neutrino mass measurement are inferred. Supported by BMBF (05A14VK2), HAP and the Helmholtz Association.