Material migration in tokamaks: Studies of deposition processes and characterisation of dust particles
2015 (English)Licentiate thesis, comprehensive summary (Other academic)
Thermonuclear fusion may become an attractive future power source. The most promising of all fusion machine concepts is the tokamak. Despite decades of active research, still huge tasks remain before a fusion power plant can go online. One of these important tasks deals with the interaction between the fusion plasma and the reactor wall. This work focuses on how eroded wall materials of different origin and mass are transported in a tokamak device. Element transport can be examined by injection of certain species of unique and predetermined origin, so called tracers. Tracer experiments were conducted at the TEXTOR tokamak before its final shutdown. This offered an unique opportunity for studies of the wall and other internal components: For the first time it was possible to completely dismantle such a machine and analyse every single part of reactor wall, obtaining a detailed pattern of material migration. Main focus of this work is on the high-Z metals tungsten and molybdenum, which were introduced by WF6 and MoF6 injection into the TEXTOR tokamak in several material migration experiments. It is shown that Mo and W migrate in a similar way around the tokamak and that Mo can be used as tracer for W transport. It is further shown how other materials - medium-Z (Ni), low-Z (N-15 and F), fuel species (D) - migrate and get deposited. Finally, the outcome of dust sampling studies is discussed. It is shown that dust appearance and composition depends on origin, formation conditions and that it can originate even from remote systems like the NBI system. Furthermore, metal splashes and droplets have been found, some of them clearly indicating boiling processes.
Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2015. , 80 p.
TRITA-EE, ISSN 1653-5146 ; 2015:102
tokamak, fusion, plasma, material migration, particle transport, TEXTOR, PWI, plasma-wall interaction, plasma facing components, PFC, PFM, plasma facing materials, ALT limiter, MoF6, tracer experiment, molybdenum hexafluoride, future energy source, fuel retention, deuterium retention
Fusion, Plasma and Space Physics
IdentifiersURN: urn:nbn:se:kth:diva-178026ISBN: 978-91-7595-766-1OAI: oai:DiVA.org:kth-178026DiVA: diva2:876116
2015-12-15, Seminarierummet på plan 3, Teknikringen 31, KTH, Stockholm, 10:15 (English)
Primetzhofer, Daniel, Associate Professor
Rubel, Marek, ProfessorPetersson, Per, Doktor
QC 201512032015-12-032015-12-022015-12-03Bibliographically approved
List of papers