Experimental and numerical analysis of the air inflow technique for dust removal from the vacuum vessel of a tokamak machine

摘要

In fusion facilities, the dust production inside the plasma chamber is a concern from the viewpoint of both machine performance and safety. To the purpose of a correct handling of the experimental devices the problem of its removal must be properly solved. This work deals with the experiments carried out in the STARDUST facility by using as dust removal technique an air inflow into the volume representing the vacuum vessel. The goal was to evaluate the effectiveness of such an approach, less invasive as compared to all the others so far. These experiments, performed by using characterized carbon, tungsten and stainless steel dusts, show that the mobilization capability of the air inflow is between few percent and 100%, mainly depending on dust type of and deposit shape. The capture efficiency in a filter reached a maximum of about 7.5% in the STARDUST geometrical configuration. In conclusion, this simple and clean (from the radioactive point of view) removing technique needs particular care to be more effective and is not the perfect solution due to its low efficiency in the collection of removed powder in proper surfaces (i.e., filters). Nevertheless improvements are possible and worthwhile.