No abstract

The magnetic field structure associated with edge localised ideal ballooning mode (ELM) bursts is analysed by nonlinear gyrofluid computation. The linear growth phase is characterised by the formation of small scale magnetic islands. Ergodic magnetic field regions develop near the end of the linear phase when the instability starts to perturb the equilibrium profiles. The nonlinear blow-out gives rise to an ergodisation of the entire edge region. The time-dependent level of ergodicity is determined in terms of the mean radial displacement of a magnetic field line. The ergodicity decreases again during the nonlinear turbulent phase of the blow-out in dependence on the degrading plasma beta in the collapsing plasma pedestal profile. This is a preprint version of an article published in:Plasma Physics and Controlled Fusion 55, 015002 (2013).

No abstract

The electromagnetic pulses of rare long (order of seconds) repetitive lightning discharges near strike point (order of 100 m) are analyzed and compared to magnetic fields applied in standard clin- APPENDIX: Erratum and AddendumThe comparison of electric fields transcranially induced by lightning discharges and by TMS brain stimulators via E = −∂ t A is shown to be inappropriate. Corrected results with respect to evaluation of phosphene stimulability are presented. For average lightning parameters the correct induced electric fields appear more than an order of magnitude smaller. For typical ranges of stronger than average lightning currents, electric fields above the threshold for cortical phosphene stimulation can be induced only for short distances (order of meters), or in medium distances (order of 50 m) only for pulses shorter than established axon excitation periods. Stimulation of retinal phosphene perception has much lower threshold and appears most probable for lightning electromagnetic fields.

No abstract