haku: @keyword ASDEX Upgrade / yhteensä: 5
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| Tekijä: | Kåll, Pia |
| Työn nimi: | 3D Simulations of Impurity Transport in the Divertor Region of ASDEX Upgrade Tokamak |
| 3D Simuleringar av Orenheters Betende i ASDEX Upgrade Tokamakens Divertorområde | |
| Julkaisutyyppi: | Diplomityö |
| Julkaisuvuosi: | 2005 |
| Sivut: | 96 Kieli: eng |
| Koulu/Laitos/Osasto: | Teknillisen fysiikan ja matematiikan osasto |
| Oppiaine: | Ydin- ja energiatekniikka (Tfy-56) |
| Valvoja: | Salomaa, Rainer |
| Ohjaaja: | Airila, Markus |
| OEVS: | Sähköinen arkistokappale on luettavissa Aalto Thesis Databasen kautta.
Ohje Digitaalisten opinnäytteiden lukeminen Aalto-yliopiston Harald Herlin -oppimiskeskuksen suljetussa verkossaOppimiskeskuksen suljetussa verkossa voi lukea sellaisia digitaalisia ja digitoituja opinnäytteitä, joille ei ole saatu julkaisulupaa avoimessa verkossa. Oppimiskeskuksen yhteystiedot ja aukioloajat: https://learningcentre.aalto.fi/fi/harald-herlin-oppimiskeskus/ Opinnäytteitä voi lukea Oppimiskeskuksen asiakaskoneilla, joita löytyy kaikista kerroksista.
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| Sijainti: | P1 Ark TF80 | Arkisto |
| Avainsanat: | tokamak plasma-surface interactions impurity transport ERO ASDEX Upgrade plasma-vägg växelverkan ASDEX Upgrade orenheter randplasma |
| Tiivistelmä (eng): | The interactions between the hot fusion plasma and the surrounding vessel wallin magnetically confined fusion devices are not completely understood. The plasma-surface interactions give rise to impurity particles, i.e. atoms or molecules from the surfaces that are dislodged and transported into the piasma. The goal is to keep the impurity density in the main piasma as low as possible, since impurities that reach the central fusion-producing piasma will cool and dilute the piasma, thus reducing the power output. On the other hand, in the edge region impurities are desirable to some extent, since the radiation they eause disperses the piasma power, which otherwise would cause high heat fluxes on Iocalized areas of the surfaces, and potentially damage the surfaces. A balance between the wanted amount of impurities at the edge, and as few impurities as possible in the main piasma should be achieved, but to achieve this the transport of impurities from the surfaces, where they are produced, through the edge plasma to the main plasma have to be understood. The production of impurities at the surfaces, and the transport of impurities inside the main piasma are quite weIl understood. However, the impurity transport in the edge is stiil largely unexplored and it is not known how the amount of inipiirities produced at the walls is connected to the impurity density in the main piasma. In this work explanations to experimental observations about the transport of carbon in the divertor region of ASDEX Upgrade tokamak were sought through simulations with the ERO code. ERO is a Monte Carlo based Iocal impurity transport code that has been developed at Forschungszentrum Julich in Germany. What distinguishes ERO froni other impunty transport codes is the detailed way m which plasma-surface interactions are taken into account and the possibility to simulate external sources. As part of this work some improvements to ERO have been made and the previously 2D divertor version of ERO has been extended to a 3D version. Benchmarking of the 3D divertor version has been made and the new code has been found to work welI. Thereafter, the 3D divertor version has been used to simulate methane puffing experiments done at the outer divertor of ASDEX Upgrade during the 2003 campaign. Differences in the long-term erosion and deposition patterns ofcarbons, and the deposition patterns found by puffing marker-carbon into the piasma, have earlier been found experimentally. In this work an explanation to tbese differences were sought by investigating the influence of the puffed particles on the background plasma. If the puffing would have significant impact on the background piasma, this could explain why the puffed carbon behaves differently than the carbon eroded from the piasma facing components. It would also mean that ERO would not be suitable for simulating puffing experiments, since in ERO it is assumed that the impurities do not influence the background piasma. This assumption ean be questionable especially with strong impurity sources as in puffing experiments. From the simulations it can he concluded that the puffing does not influence neither the density nor the energy content of the background piasma with more than 10 %. The area affected by the puffing is vety centralized around the puffing hole and quite small, in most cases it has a diameter snialler than one centimeter. The simulations did not give an explanation to the differences in erosion and deposition patterns of carbon that have been found experimentally. However, from the simulations it can be concluded that siniilar puffing experiments can he used in the future to determine the transport ofcarbon in the edge piasma without affecting the background piasma parameters. Likewise the assumptions made in ERO are valid, and this type of simulations wiIl be continued. Some further improvements to ERO are aiready under way. |
| ED: | 2006-01-16 |
INSSI tietueen numero: 30498
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