A conceptual model of the magnetic topology and nonlinear dynamics of ELMs

• Published in: Journal of nuclear materials 2009-06, Vol.390, p.789-792
• Main Authors: Evans, T.E., Yu, J.H., Jakubowski, M.W., Schmitz, O., Watkins, J.G., Moyer, R.A.
• Format: Article
• Language: English
• Subjects: Applied sciences; Controled nuclear fusion plants; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Fission nuclear power plants; Fuels; Installations for energy generation and conversion: thermal and electrical energy; Nuclear fuels
• ISSN: 0022-3115; 1873-4820
• DOI: 10.1016/j.jnucmat.2009.01.209

A conceptual model is introduced describing the 3D magnetic topology and nonlinear evolution of Type-I edge localized modes (ELMs), which immediately follow the initial linear peeling-ballooning growth phase. The model requires feedback amplification of stable and unstable invariant manifolds that increases the helical perturbation. The amplification process is caused by a rapid growth of field-aligned helical thermoelectric currents that flow through relatively short pedestal plasma flux tubes connecting the inner and outer divertor target plates. It is shown that the model qualitatively agrees with the formation of global field-aligned emission filaments and with fast IR heat flux splitting patterns of the inner and outer strike points observed experimentally. In addition, the model predicts an increase in the size of the ELMs as the pedestal collisionality drops. Experimental data and modeling results are presented supporting the basic conceptual elements of the model.