Description
The sawteeth preventing self-regulating magnetic flux pumping mechanism has already been modelled to date with the aid of various perturbed MHD simulating codes [1]-[4]. A new dynamic approach is proposed using a quasi-analytic solution of the plasma perturbed equations in terms of a perturbed flux function [5] to assess the peculiar 1/1 mode non-axisymmetric effect on the broadening of the plasma central current profile. This quantity is straightforwardly used to derive the low local dynamo loop voltage induced by the 1/1 perturbation as part of the self-regulating flux pumping effect. The calculated dynamo validity relies on the best possible match between the modelled and the experimental 1/1 mode amplitude, frequency and location that basically proves the perturbed solution correctness. Finally, based on this, the n=1 dynamo magnitude is compared against its induction equation counterpart, the electric field term due to the change of the experimental core plasma toroidal current density. It has been found a good agreement between the both terms for different plasma discharges, such as to highlight the flux pumping mechanism occurrence via the proposed model.
References
[1] Jardin S.C. et al, Phys. Rev. Letters 115 215001 (2015)
[2] Krebs I. et al, Phys. Plasmas 24 102511 (2017)
[3] Burckhart I. et al, Nucl. Fusion 63 126056 (2023)
[4] Zhang H. et al Nucl. Fusion 65 066001 (2025)
[5] Miron I.G. et al, Nucl. Fusion 61 106016 (2021).