Optimal strategies for time-dependent plasma edge simulations for nuclear fusion reactors

Sánchez Luis, Alejandro (2020). Optimal strategies for time-dependent plasma edge simulations for nuclear fusion reactors. Thesis (Master thesis), E.T.S.I. Industriales (UPM).

Description

Title: Optimal strategies for time-dependent plasma edge simulations for nuclear fusion reactors
Author/s:
  • Sánchez Luis, Alejandro
Contributor/s:
  • Velarde Mayol, Pedro
Item Type: Thesis (Master thesis)
Masters title: Ingeniería Industrial
Date: 2020
Subjects:
Faculty: E.T.S.I. Industriales (UPM)
Department: Ingeniería Energética
Creative Commons Licenses: Recognition - No derivative works - Non commercial

Full text

[img]
Preview
PDF - Requires a PDF viewer, such as GSview, Xpdf or Adobe Acrobat Reader
Download (2MB) | Preview

Abstract

One of the main issues in the study of magnetically confined nuclear fusion is the design of the divertor, a device near the reactor walls that has to withstand great amounts of heat and particle fluxes while acting as a pump. Simulations of the so-called plasma edge are very useful to study the performance of this kind of devices, but they can be very expensive and time consuming. The most advanced codes solve the fluid equations for the plasma, composed of electrons and ions, using a finite volume (FV) method coupled with a Monte Carlo (MC) code to compute the trajectories of the neutral particles. This adds statistical noise to the spatial and time discretization errors that arise in the model. There has been extensive research in the topic of assessing these errors in the code known as SOLPS-ITER, which is used among others to simulate the experimental reactor being built in Cadarache (France). However, study of the transient behaviour of this code has only been done in approximated models. The aim of this thesis is to properly analyse the characteristics of transient phenomena in SOLPS-ITER in comparison to the previous work in simpler models, as well as studying the different timescales present and particularly the algorithm used for the time integration of the equations. It was found that the spatial discretization error does in fact evolve linearly with the number of cells in the grid. Also the time integration error changes almost linearly with varying time step size, consistent with the first order time integration scheme based on an implicit Euler scheme. Also, a Dual Time Stepping scheme (DTS) is implemented in the code, to resolve the non-linear coupling between the plasma equations in each time step. However, unexpected behaviour was observed in the SOLPS-ITER code, where the transient behaviour became slower with increasing number of dual-time steps, as if the false-time is measured instead of the physical time. To further study this behaviour, DTS has been applied to several zero-dimensional and one-dimensional models representative of the plasma models in SOLPS-ITER, confirming that DTS should be able to correctly resolve the non-linearities in the equations. Unfortunately, the problem with the DTS scheme implemented in the code could not be detected, and should be subject of further research. The results obtained from simulations with the coupled FV-MC code indicate that the introduction of a Monte Carlo code does not change the general transient behaviour of the code, but a specific treatment to reduce the statistical noise could greatly improve this assessment.

More information

Item ID: 64970
DC Identifier: http://oa.upm.es/64970/
OAI Identifier: oai:oa.upm.es:64970
Deposited by: Biblioteca ETSI Industriales
Deposited on: 02 Dec 2020 11:17
Last Modified: 30 Dec 2020 23:30
  • Logo InvestigaM (UPM)
  • Logo GEOUP4
  • Logo Open Access
  • Open Access
  • Logo Sherpa/Romeo
    Check whether the anglo-saxon journal in which you have published an article allows you to also publish it under open access.
  • Logo Dulcinea
    Check whether the spanish journal in which you have published an article allows you to also publish it under open access.
  • Logo de Recolecta
  • Logo del Observatorio I+D+i UPM
  • Logo de OpenCourseWare UPM