Dokument: Measurements of ion temperatures and fast particles in the scrape-off layer of W7-X stellarator and EAST tokamak
| Titel: | Measurements of ion temperatures and fast particles in the scrape-off layer of W7-X stellarator and EAST tokamak | |||||||
| URL für Lesezeichen: | https://docserv.uni-duesseldorf.de/servlets/DocumentServlet?id=56517 | |||||||
| URN (NBN): | urn:nbn:de:hbz:061-20210819-111551-8 | |||||||
| Kollektion: | Dissertationen | |||||||
| Sprache: | Englisch | |||||||
| Dokumententyp: | Wissenschaftliche Abschlussarbeiten » Dissertation | |||||||
| Medientyp: | Text | |||||||
| Autor: | Henkel, Marion [Autor] | |||||||
| Dateien: |
| |||||||
| Beitragende: | Prof. Dr. Liang, Yunfeng [Gutachter] Prof. Dr. Pretzler, Georg [Gutachter] | |||||||
| Dewey Dezimal-Klassifikation: | 500 Naturwissenschaften und Mathematik » 530 Physik | |||||||
| Beschreibung: | Considering the fusion research achievements of the past fifty years, one of the most important challenges of fusion plasma devices is understanding and handling power exhaust. The knowledge of the physics of scrape-off layer plasma is particularly essencial. Amongst other parameters, the ion temperature is a key value for understanding the characteristics of the scrape-off layer and divertor region. However, during the limiter campaign and first divertor campaign on the stellarator W7-X, no measurements for ions in the the scrape-off layer were availible. Therefore a multi-channel retarding field analyzer was developed for the second divertor campaign on stellarator W7-X. This multi-channel retarding field analyzer and its commissioning are presented in this thesis. The challenges and optimisations were discussed, starting with a simple 2-dimentional probe for a feasibility test on the linear plasma device PSI-2, continuing with the first multi-channel retarding field analyzer in the 2016 and 2017 campaigns of the tokamak EAST and finishing with the optimised probe on the stellarator W7-X in the second divertor campaign.
In the past, it was shown that the fast ions have a strong role in the stability of ELMy plasmas. Therefore, fast particle measurements in the scrape-off layer region of the tokamak EAST during ELMs were done. Using additional diagnostics, the preceding precursors are shown. The formation and propagation of fast particles in the plasma core and the apppearance in the scrape-off layer, measured with the multi-channel retarding field analyzer, showed, that the confinement of fast ions is less stable than the confinement of fast electrons during the ELM crash and they already get lost earlier. Furthermore, it is shown, that fast ions propagate locally in the horizontal midplane. Further, the knowledge about ion temperatures in the scrape-off layer is essential for several transport processes, like the ambipolar diffusion in the plasma edge, heat flux rise time during ELM and the plasma collisionality. Because no ion temperature measurements in the scrape-off layer of the stellarator W7-X were available in the previous campaigns, ion and electron temperature profile measurements were done during the second divertor campaign. It could be shown, that the island structure in the scrape-off layer leads to a peaking in the electron temperature profile, whereas the ion temperature profile attened. First studies about the ion to electron temperature ratio were conducted. Summarised, this thesis demonstrates the feasibility and the exibility of the multichannel retarding field analyzer, as well as in the tokamak and stellarator case. | |||||||
| Lizenz: |  Urheberrechtsschutz | |||||||
| Fachbereich / Einrichtung: | Mathematisch- Naturwissenschaftliche Fakultät » WE Physik » Laser- und Plasmaphysik | |||||||
| Dokument erstellt am: | 19.08.2021 | |||||||
| Dateien geändert am: | 19.08.2021 | |||||||
| Promotionsantrag am: | 15.08.2020 | |||||||
| Datum der Promotion: | 08.10.2020 |
