Buffer gas flow simulations for a Paul trap in MIRACLS

MIRACLS is a novel experimental approach to perform collinear laser spec- troscopy (CLS) within a Multi-Reflection Time-of-Flight device (MR-ToF). This combination promises large gains in sensitivity for CLS in order to probe the most exotic nuclides synthesized at ISOLDE at CERN. However, this combination also has very strict requirements in terms of the ion beam emittance. Hence, a next generation buffer gas filled Paul trap is required to cool down the ions very ef- fectively. This is achieved by the use of helium as buffer gas at cryogenic temperatures. Knowledge about the gas flow in and around the trap is crucial to minimize the so-called reheating effect, i.e. when ions are colliding with helium atoms during extraction and reacceleration their emittance will be increased again. With use of the simulation software COMSOL, two simulation approaches of the helium gas flow inside the Paul trap are investigated whose results are discussed.