Installation and test of a helium centrifugal pump into the TOSKA facility

Up to now He piston pumps were used in the TOSKA facility of the Forschungszentrum Karlsruhe for circulating supercritical He in a secondary cooling loop. The performance of these pumps was a mass flow rate up to 150 g/s each, a pressure head of up to 0.3 MPa and an operation in the temperature range between 1.8 K and 5 K.For redundancy reasons, a centrifugal pump, developed by industry, was installed in an extension of the control cryostat, integrated into the existing cooling system, and tested in 2004. During the first tests, large oscillations and a huge heat input to the cooling circuit prevented operation of the pump. After some modifications by the supplying company, the pump was tested again with very promising test results. The results are in very good agreement with the predictions of the supplier. Details of the installation, the integration into the cooling system as well as the operational experience and test results will be outlined.