Sensitivities of the runaway current in JET disruptions to massive gas injection and initial plasma current
Typ
Examensarbete för masterexamen
Master's Thesis
Master's Thesis
Program
Physics (MPPHS), MSc
Publicerad
2024
Författare
Gustavsson, Christian
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
The Joint European Torus (JET) tokamak, located at the Culham Centre for Fusion
Energy in the UK, has been a leader in magnetic confinement fusion (MCF) research
for decades. As the world’s largest operational tokamak until 2023, JET has sig nificantly advanced the understanding and technology needed for controlled fusion
energy, which aims to provide a clean, large-scale energy source by replicating the
processes that power the Sun. A primary challenge in tokamak operation is man aging plasma disruptions, which can terminate plasma confinement and generate
runaway electrons (REs). These high-energy electrons can damage reactor compo nents, thus studying REs is vital for the viability of fusion energy. As the fusion
community progresses towards advanced reactors like ITER in France and SPARC
in the USA, understanding and controlling REs becomes even more important.
This study uses the Disruption Runaway Electron Analysis Model (DREAM) to
investigate the conditions under which REs form during tokamak disruptions. The
main objective of this thesis is to model the conditions for the existence of REs
in JET massive gas injection (MGI) discharges, focusing on their dependence on
magnetic field strength, initial plasma current, as well as the ratio of injected argon
to deuterium. Furthermore, we are interested in how much current is carried by
the REs after a disruption. The analysis is conducted through a series of parameter
scans using the simulation tool DREAM. Our simulation results show that the RE
current is influenced by the initial plasma current and the ratio of injected argon
to deuterium, with only a very weak dependence on magnetic field strength. More over, our findings suggest that the injection profile of argon significantly affects the
parametric trends of the maximum RE current. A uniform injection profile yields
an inverted current trend compared to an edge-peaked injection profile, where the
latter yields results that are more in line with experimental results.
Beskrivning
Ämne/nyckelord
: fusion plasma, runaway electron, massive material injection, massive gas injection, disruption mitigation, JET