1. Multiple reconnections and explosive events and in MST and solar flares Gennady Fiksel CMSO workshop, Princeton, NJ, Oct 5-8, 2005

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

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

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

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.

6. CMSO We can control position of resonances (somewhat) Control q(a)

7. CMSO We can control position of resonances (somewhat) Control q(a)

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

9. CMSO Core plasma rotation remains unaffected without m=0 modes non reversed

10. CMSO Ion heating reduced for non-reversed shots

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)

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

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.

14. CMSO What about fluctuation induced drive terms? MHD dynamo EM torque Ion heating

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)

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

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

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 )?

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)

20. CMSO eruption internal collapse numerical simulation tearing instability eruption time kinetic energy magnetic energy