  In this paper, the major upgrades and technical improvements of the buffer
gas handling system for the cryogenic stopping cell of the FRS Ion Catcher at
GSI/FAIR (in Darmstadt, Germany) are described. The upgrades include
implementation of new gas lines and gas purifiers to achieve a higher buffer
gas cleanliness for a more efficient extraction of reactive ions as well as
suppression of the molecular background ionized in the stopping cell.
Furthermore, additional techniques have been implemented for improved
monitoring and quantification of the purity of the helium buffer gas.

Instrumentation and Detectors;Nuclear Experiment