Project

Modelling of L-H mode transition in magnetically confined plasmas

Publisher

Supervisor

Location

Greater Copenhagen area

Numerical simulations of the transition from the low confinement (L-) mode to the high confinement (H-) mode in magnetically confined plasmas - as, e.g., Tokamak devices.

The confinement of plasma particles and energy in magnetically confined plasmas and thereby the performance of a fusion reactor is strongly influenced by turbulent transport. This transport is generally increasing as the input power is ramped up until a threshold value, where the edge heat flux reaches a critical value. The confinement is then abruptly improved, and the plasma enters a state of high confinement, the so-called H – mode, contrasting the low confinement state - the L-mode.

The transition from L- to H-mode is routinely observed and controlled in fusion experiments for the last three decades, but still lacks a first principles explanation. It is thus one of the high-priority topics of fusion research.

The formation of a transport barrier limiting the transport at the plasma edge, as the transition occurs, is believed to be connected with the appearance of large scale shear flows. Insight into the L-H transition dynamics has been gained from simplified models of the predator-prey type, basically describing the self-regulation of the turbulence by means of the shear flow that is fed by the turbulence. Recent simulation results using the four field plasma fluid code, HESEL, have revealed L-H transitions recovering the transport barrier formation as described by the simplified models. The HESEL model governs the edge-region dynamics of magnetically confined plasma.

The topic of this project is to apply the HESEL model to investigate the L-H transition for different heating scenarios, e.g., different ratios between electron and ion power input using plasma parameters from experiments, specifically from selected JET shots. A power built-up is expected as the system enters H-mode and the system should be studied well after the transition to observe an eventual power burst and temporary returns to L-mode confinement. Comparisons with experimental data may also be envisaged.

Requirements

Knowledge of numerical solutions of coupled ordinary as well as partial differential equations.Some knowledge of continuum dynamics, plasma physics, and complex dynamics will be beneficial.

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Contact

Company / Organization

DTU Fysik

Name

Jens Juul Rasmussen

Position

Professor

Mail

jjra@fysik.dtu.dk

Supervisor info

MSc in Physics and Nanotechnology

Supervisor

Jens Juul Rasmussen

Co-supervisors

Anders Henry Nielsen

ECTS credits

30 - 35

Type

BSc project, MSc thesis

Technical University of Denmark

For almost two centuries DTU, Technical University of Denmark, has been dedicated to fulfilling the vision of H.C. Ørsted – the father of electromagnetism – who founded the university in 1829 to develop and create value using the natural sciences and the technical sciences to benefit society.


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