In recent deuterium–tritium experiments on the Tokamak Fusion Test Reactor (TFTR), both the pellet charge exchange (PCX) [Phys. Rev. Lett. 75, 846 (1995); Nucl. Fusion 35, 1437 (1995)] and the alpha charge exchange recombination spectroscopy (α-CHERS) [Phys. Rev. Lett. 75, 649 (1995)] diagnostics indicate that sawtooth oscillations can cause significant broadening of the fusion alpha radial density profile. Investigation of this sawtooth mixing phenomenon was performed by applying a Hamiltonian guiding center approach. A model of time evolution of the Kadomtsev-type sawtooth [Sov. J. Plasma Phys. 1, 389 (1976)] is constructed. The presence of more than one mode in the nonlinear stage of the sawtooth crash is necessary to cause significant broadening of the alpha density profile. Use of numerical equilibria allows us to perform detailed comparisons with TFTR experimental data. The simulation results are in reasonable agreement with α-CHERS and show a broadening of alpha particles similar to that seen in PCX measurements.
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Zhao et al. (1997) studied this question.