Speaker
Thomas Giegerich
(Institute for Technical Physics)
Description
The reduction of tritium inventories is a key challenge for DEMO and future fusion power plants. As large amounts of tritium have to be processed in the inner fuel cycle, an inventory-optimized vacuum pumping process – the KALPUREX process – has been developed at KIT. Here, continuously working and non-cryogenic vacuum pump trains will be used in order to keep the tritium residence times and thus the inventories in the pumps small. These pump trains comprise a combination of diffusion pumps and liquid ring pumps, both using the same working fluid mercury.
Liquid ring pumps are typically used with a non-tritium compatible working fluid (e.g. water or oil) and at relatively high inlet pressures (some kPa, defined by the vapour pressure of the working fluid). As roughing pumps in fusion, they have to be made fully tritium compatible and optimized in inlet pressure. Both can be done when using mercury as working fluid, as it is perfectly tritium compatible and has a low vapour pressure. As no mercury ring pump was existing on the market and no performance predictions could be made for such a high density working fluid, a commercially available pump has been modified and used for proof-of-principle experiments in the THESEUS facility.
In this paper, the design of the KIT mercury ring pump will be described and performance curves, like pump down- und pumping speed curves for different gases, will be presented. Furthermore, operational limits (e.g. ultimate pressure, thermal limitations) will be discussed and suggestions for the design of future mercury ring pumps will be made. Also methods to avoid the migration of mercury vapour outside the pumping system will be shown and validated by corresponding measurements.
Co-authors
Christian Day
(Institute for Technical Physics, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany)
Martin Jager
(Institute for Technical Physics, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany)
Thomas Giegerich
(Institute for Technical Physics, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany)
