| AVS 59th Annual International Symposium and Exhibition | |
| Vacuum Technology | Tuesday Sessions |
| Session VT-TuM |
| Session: | Pumping, Gas Dynamics and Modeling |
| Presenter: | S. Varoutis, Karlsruhe Institute of Technology, Germany |
| Authors: | S. Varoutis, Karlsruhe Institute of Technology, Germany Chr. Day, Karlsruhe Institute of Technology, Germany X. Luo, Karlsruhe Institute of Technology, Germany H. Haas, Karlsruhe Institute of Technology, Germany F. Sharipov, Federal University of Parana, Brazil |
| Correspondent: | Click to Email |
The main duty of the vacuum pumping system of fusion devices is to pump out the fusion exhaust gas. Due to the fact that very high throughputs have to be coped with, large pumping speeds are required. This is typically provided by cryogenic pumping, supplied with cryogen medium at 4 K and 80 K. The concept for the cryosorption vacuum system of ITER, the next generation fusion experiment currently being built in Europe, has been developed at the Karlsruhe Institute of Technology (KIT). As a result to the large gas flows, which are unusually high for a cryopump, the pumps are operated in the transitional regime. A further development and improvement of the system requires a corresponding numerical modelling of the gas flow inside the pump housing and near the cryopanel section.
The aim of the present work consists of the computational investigation of a 2D axisymmetric complex geometry of a model cryopump by the Direct Simulation Monte Carlo (DSMC) method. Since the flow close to the cryopanels can be assumed free molecular due to low pressure levels, the capture coefficient of the cryopanels can be estimated by applying the Test Particle Monte Carlo method. Then, this information can be used as input data to the corresponding DSMC simulations. The macroscopic parameters of practical interest as the bulk velocity, the pressure and the temperature in the whole flow field, have been calculated as a function of the incoming gas throughput and of the pump inlet valve position. Furthermore, the present numerical results have been thoroughly compared with corresponding experimental results obtained at KIT for the case of an ITER model cryopump.
The importance of these calculations is based on the fact that they can provide information for quantities which are not accessible for measurement during pump operation and that they can be used for prediction of the pump behavior. This paper describes a post-operational investigation of a built pump and is thought as a proof-of-principle test to include this approach in the design process of a future pump development.