ETD system

Electronic theses and dissertations repository


Tesi etd-08152010-211337

Thesis type
Tesi di dottorato di ricerca
Monte Carlo and Molecular Dynamics Simulations of Plasma-Material Interactions
Settore scientifico disciplinare
Corso di studi
tutor Prof. Aquaro, Donato
correlatore Prof. Cerullo, Nicola
correlatore Prof. Forasassi, Giuseppe
Parole chiave
  • Monte Carlo
  • Nuclear Fusion
  • Molecular Dynamics
  • Plasma Facing Materials
  • Density Functional Theory
Data inizio appello
Data di rilascio
Riassunto analitico
The design of a suitable interface between plasma heated at millions of kelvin<br>and the environment is one of the most critical areas within nuclear fusion research.<br>The surface of interface components should sustain the energy delivered<br>by plasma as electromagnetic radiation and transported through charge carriers<br>such as ions and electrons.<br>The ratio between available plasma energy and heated surface increases with<br>device dimension, so that for ITER and future fusion reactors the energy density<br>striking the tokamak walls will be order of magnitude higher compared to what<br>happens in current facilities.<br>Several plasma material interaction phenomena are relevant for PFCs design.<br>The high energy heavy particles striking the chamber walls produce sputtering.<br>The magnetic con nement su er from frequent plasma instabilities, which result<br>in a fast release of plasma energy on Plasma Facing Components. The ensuing<br>thermal and mechanical actions produce material damage, erosion, thermal<br>ablation and melting. Components lifetime is strongly limited by such extreme<br>phenomena and require careful design and material selection to avoid unwanted<br>maintenance stops and replacements.<br>The main aim of this research activity is to evaluate the PFMs erosion due to<br>thermal ablation, to understand how material properties are a ected by plasma<br>interactions and how correctly select PFMs, without relying simply on empiric<br>correlations with limited validity.<br>The main part of the performed work consist in the development of Molecular<br>Dynamics and Monte Carlo Simulation aimed to evaluate the thermal properties<br>of PFMs and to investigate how high energy electrons produced within the<br>plasma carry energy towards tokamak chamber walls.<br>The analysis of Plasma Material Interactions has been historically carried<br>out by putting together experimental activity and empiric relationships accounting<br>for complex physical e ects in an approximate fashion. The current research<br>activity wants to investigate such phenomena starting from the underlying physical<br>basic principles and through a comparison with experimental data with<br>minimum employ of empiric relationship.