Abstract
In a tokamak-based fusion power plant, possible scenarios may include regulated sawtooth oscillations to remove thermalized
helium from the core of the plasma. During a sawtooth crash, the helium ash and other impurities trapped in the core are driven
by the instability to an outer region. However, in a fusion plasma, high energy ions will represent a significant population. We
thus study the behaviour of these energetic particles during a sawtooth. This paper presents the modelling of the redistribution
of fast ions during a sawtooth reconnection event in a tokamak plasma. Along the lines of the model for the evolution of the
flux surfaces during a sawtooth collapse described in Ya.I. Kolesnichenko and Yu.V. Yakovenko 1996 Nucl. Fusion 36 159, we
have built a time-dependent electromagnetic model of a sawtooth reconnection. The trajectories of the ions are described by
a complete gyro-orbit integration. The fast particles were evolved from specific initial parameters (given energy and uniform
spread in pitch) or distributed initially according to a slowing-down distribution created by fusion reactions. Our modelling is
used to understand the main equilibrium parameters driving the motions during the collapse and to determine the evolution of
the distribution function of energetic ions when different geometries of reconnection are considered.
Original language | English |
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Pages (from-to) | 104013-1/12 |
Number of pages | 12 |
Journal | Nuclear Fusion |
Volume | 54 |
DOIs | |
Publication status | Published - 2014 |