Search for dissertations about: "Torbjörn Hellsten"

Showing result 6 - 10 of 10 swedish dissertations containing the words Torbjörn Hellsten.

  2. 6. Fast wave heating and current drive in tokamaks

    Author : Martin Laxåback; Torbjörn Hellsten; Raymond Koch; KTH; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Tokamak; JET; ITER; thermonuclear fusion; fast wave; heating; current drive; ion cyclotron resonance; polychromatic; finite orbit widths; RF-induced transport; neutral beam injection; fusion born alpha particles; magnetosonic eigenmodes; parasitic absorption; modelling; weighted Monte Carlo scheme; Fysik; Physics; Fysik;

    Abstract : This thesis concerns heating and current drive in tokamak plasmas using the fast magnetosonic wave in the ion cyclotron range of frequencies. Fast wave heating is a versatile heating method for thermonuclear fusion plasmas and can provide both ion and electron heating and non-inductive current drive. READ MORE

  4. 7. On Monte Carlo Operators for Studying Collisional Relaxation in Toroidal Plasmas

    Author : Qaisar Mukhtar; Torbjörn Hellsten; Tainia Kurki-Suonio; KTH; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Fusion plasma; thermonuclear fusion; tokamak; Coulomb collisions; stochastic differential equations with singular diffusion coefficients; Monte Carlo schemes; spatial diffusion; modelling; Fokker-Planck equation; RF-heating.;

    Abstract : This thesis concerns modelling of Coulomb collisions in toroidal plasma with Monte Carlo operators, which is important for many applications such as heating, current drive and collisional transport in fusion plasmas. Collisions relax the distribution functions towards local isotropic ones and transfer power to the background species when they are perturbed e. READ MORE

  5. 8. The dynamics of Alfvén eigenmodes excited by energetic ions in toroidal plasmas

    Author : Emmi Tholerus; Thomas Johnson; Torbjörn Hellsten; Duarte Borba; KTH; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Fusion plasma physics; Tokamak; Wave–particle interactions; Toroidal Alfvén eigenmodes; Bump-on-tail instabilities; Magnetohydrodynamics; Nonlinear dynamics; Quasilinear dynamics; Hamiltonian mechanics; Monte Carlo method; ICRH; FWCD; Electrical Engineering; Elektro- och systemteknik;

    Abstract : The future fusion power plants that are based on magnetic confinement will deal with plasmas that inevitably contain energetic (non-thermal) particles. These particles come, for instance, from fusion reactions or from external heating of the plasma. READ MORE

  6. 9. The dynamics of Alfvén eigenmodes excited by energetic ions in toroidal plasmas

    Author : Emmi Tholerus; Torbjörn Hellsten; Thomas Johnson; Lars-Göran Eriksson; KTH; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Fusion plasma physics; tokamak; wave-particle interactions; toroidal Alfvén eigenmodes; bump-on-tail instabilities; magnetohydrodynamics; nonlinear dynamics; quasilinear dynamics; Hamiltonian mechanics; Monte Carlo method; Electrical Engineering; Elektro- och systemteknik;

    Abstract : Experiments for the development of fusion power that are based on magnetic confinement deal with plasmas that inevitably contain energetic (non-thermal) particles. These particles come e.g. from fusion reactions or from external heating of the plasma. READ MORE

  7. 10. Modeling RF waves in hot plasmas using the finite element method and wavelet decomposition : Theory and applications for ion cyclotron resonance heating in toroidal plasmas

    Author : Pablo Vallejos; Thomas Jonsson; Torbjörn Hellsten; Philippe Lamalle; KTH; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Electrical Engineering; Elektro- och systemteknik;

    Abstract : Fusion energy has the potential to provide a sustainable solution for generating large quantities of clean energy for human societies. The tokamak fusion reactor is a toroidal device where the hot ionized fuel (plasma) is confined by magnetic fields. Several heating systems are used in order to reach fusion relevant temperatures. READ MORE