| AVS 62nd International Symposium & Exhibition | |
| Vacuum Technology | Tuesday Sessions |
| Session VT-TuA |
| Session: | Gas Dynamics and Modeling, Pumping and Outgassing |
| Presenter: | Xueli Luo, Karlsruhe Institute of Technology (KIT), Germany |
| Authors: | X. Luo, Karlsruhe Institute of Technology (KIT), Germany T. Giegerich, Karlsruhe Institute of Technology (KIT), Germany C. Day, Karlsruhe Institute of Technology (KIT), Germany |
| Correspondent: | Click to Email |
In current nuclear fusion research, the cryopump in various designs has become the standard solution for pumping the plasma chamber. However, considerable amounts of accumulated tritium have been found the issues towards a fusion demonstration power plant (DEMO). A recent study has shown that the mercury diffusion pump has the potential to replace the cryopump, and KIT has been charged to develop a new linear mercury diffusion pump [1]. Obviously, a reliable simulation tool is essential in such a development.
The first mercury diffusion pump was invented by W. Gaede 100 years ago. In the fifties of last century, a large, linear mercury diffusion pump was built and tested in Livermore Research Laboratory [2]. In this paper, we will present the simulation of this pump by ProVac3D, which is a versatile Test Particle Monte Carlo simulation code developed by KIT [3-4]. Based on the fact that the profiles of the mercury jets are hardly changed by the gas load, the simulation was carried out in two steps. First, the background density of the mercury molecules established by the mercury jets was calculated. Secondly, the collision between the molecules of the gas load (N2 at 15°C) and the mercury molecules had been considered. In order to achieve high simulation precision, ProVac3D had been parallelized, and 1012 test molecules were simulated at a supercomputer. The calculated pumping probability, which is the ratio of the number of particles absorbed at the pump bottom to the number of the total simulated particles, was compared with the ratio without collisions between the gas load and the mercury jets. In this way, the pumping effect of the mercury gas jet had been clearly revealed and compared with the experimental data. The agreement is good and this novel simulation approach with ProVac3D will be employed in the development of such a pump for DEMO. Further investigation to combine the Monte Carlo simulation of the gas load with the CFD calculation of the mercury jet is in plan.
References
[1] Chr. Day, Th. Giegerich, Development of advanced exhaust pumping technology for a DT fusion power plant, IEEE Transactions on Plasma Science 42 (2014) 1058-1071.
[2] E. Lind, F. Steinhaus, Development of a large linear jet mercury diffusion pump, Report MTA-14, Livermore Research Laboratory, Livermore, CA, US, Jan. 1953.
[3] X. Luo, Chr. Day, H. Haas, St. Varoutis, Experimental results and numerical modelling of a high-performance large-scale cryopump I, Journal Vac. Sci. Technol. A 29 (2011) 041601/1-7.
[4] X. Luo, V. Hauer, Chr. Day, Monte-Carlo calculation of the radiation heat load of the ITER pre-production cryopump, Fusion Engineering and Design 87 (2012) 603-607.