Description
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\begin{document}
\title{Fast transient initiation in tokamaks}
\author{Wayne Arter, UKAEA Culham Campus\
Alasdair Roy, University of Leeds}
\date{\today}
\maketitle
Magnetically confined plasmas exhibit sudden violent transients, such as sawteeth and ELMs, that occasionally
cause complete discharge disruption. Better understanding of these phenomena and in particular
their avoidance is crucial to economic energy generation from tokamaks. To this end, a range of theories has been
proposed, mostly nonlinear and invoking rapid magnetic field evolution in a highly conducting plasma,
hence demanding challenging numerical simulations to compare
directly with experiment. Since probably different theories anyway apply under different plasma regimes,
a catalogue of possible triggering mechanisms has been made, producing parametric surrogates for direct
comparison with, and fitting to, experiment by techniques such as SINDy and Data Assimilation~\cite{roy}.
The catalogue is interesting in itself
for containing examples of both polynomial and exponential growth, enabling intercomparison of severity that
assigns less significance to the (fold) catastrophe invoked in most textbooks. Preliminary application of
of the ANAET model~\cite{Ar25Spik} to experimental data will be described.
Work supported by EPSRC.
\begin{thebibliography}{1}
\bibitem{roy}
A.~Roy.
\newblock {\em {Data driven construction of MHD surrogates using sparse
regression and data assimilation}}.
\newblock PhD thesis, {University of Leeds}, 2025.
\bibitem{Ar25Spik}
W.~Arter.
\newblock {Spiking without and with blue-sky catastrophe}.
\newblock {\em {International Journal of Bifurcation and Chaos}},
{35}(13):{2550157}, 2025.
\newblock \url{https://doi.org/10.1142/S0218127425501573}.
\end{thebibliography}
\end{document}