Multiple reconnections and explosive events and in MST and solar flares Gennady Fiksel CMSO...

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Transcript of Multiple reconnections and explosive events and in MST and solar flares Gennady Fiksel CMSO...

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Multiple reconnections and explosive events and in MST and solar flares Gennady Fiksel CMSO workshop, Princeton, NJ, Oct 5-8, 2005 Slide 2 CMSO Outline Explosive character of many MST plasma parameters is associated with abrupt growth of internally resonant resistive tearing modes. Presence of non-linearly driven poloidally symmetrical (m=0) modes is crucial. Some new data and observations. Similarity with solar flares models by Kusano et al Slide 3 CMSO MST Reversed Field Pinch Toroidal, current-carrying Density, n ~ 10 13 cm 3 Temperature, T e,i ~ 1 keV B / B ~ 2% ( B 0.5 T) ~ MST Slide 4 CMSO MST equilibrium field and resonances m - poloidal mode number n - toroidal mode number Multiple resistive tearing modes can exist non-linearly driven linearly unstable Slide 5 CMSO Toroidal flux Continuous dynamo and discrete events RFP magnetic configuration is generated and supported against resistive decay by continuous coherent action of multiple tearing modes. On top of that regular discrete events are observed during which mode amplitude explodes and additional flux is generated. Slide 6 CMSO We can control position of resonances (somewhat) Control q(a) Slide 7 CMSO We can control position of resonances (somewhat) Control q(a) Slide 8 CMSO Discrete events of modes amplitude burst Core mode m=1 n=6 Edge mode m=0 n=1 m = 0 is small in non reversed plasmas m = 1 remains the same ReversedNon reversed Slide 9 CMSO Core plasma rotation remains unaffected without m=0 modes non reversed Slide 10 CMSO Ion heating reduced for non-reversed shots Slide 11 CMSO Ti (eV) Flux generation Magnetic energy released m=1, n=6 m=0, n=1 Abnormal events in reversed plasmas Abnormal events - the core modes amplitude remains high but there is no burst in edge m=0 modes even in reversed plasmas. Why? No change in Ti Toroidal flux Mag energy (kJ) Modes amplitude (G) Slide 12 CMSO Fusion neutrons with and without m=0 Toroidal flux Mag energy (kJ) Modes amplitude (G) Flux generation Magnetic energy released m=1, n=6 m=0, n=1 Fusion d-d neutrons Slide 13 CMSO Without m=0 the changes in equilibrium B and E are small ==> no free energy source No generation of toroidal flux and equilibrium electric field. No release of magnetic energy. Ion temperature (impurities and bulk) and core rotation remain unaffected. Slide 14 CMSO What about fluctuation induced drive terms? MHD dynamo EM torque Ion heating Slide 15 CMSO Fluctuation induced torque is low in the core without m=0... Fluctuation induced torque is measured in the plasma core by FIR polarimeter (Weixing Ding) Slide 16 CMSO... and edge The torque is also measured at the edge by insertable probes (with A. Almagri) 300 events with m=015 events without m=0 m=0,n=1 m=1,n=6 Slide 17 CMSO... and edge The torque is also measured at the edge by insertable probes (with A. Almagri) 300 events with m=015 events without m=0 m=0,n=1 m=1,n=6 Slide 18 CMSO Conclusions Plasmas without m=0 edge resonant fluctuations do not exhibit bursts of ion heating and abrupt change in the rotation even that the core resonant m=1 fluctuations are large. In addition - no change in the energy of equilibrium B and no induced equilibrium E. Fluctuation induced torque Jx B also remains small. The phase shift is close to /2. Is this the case for other quadratic fluctuation terms (e.g. ion heating J i x E, MHD dynamo vx E )? Slide 19 CMSO mutual excitation of reconnections (observation) 1 2 3 CS1 CS2 CS1 B tearing reconnection B collapsing flare spontaneous driven (Kusano et al. 2004, ApJ) Slide 20 CMSO eruption internal collapse numerical simulation tearing instability eruption time kinetic energy magnetic energy