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Unsteady reconnection session

Unsteady reconnection session. Working group coordinators: T. Intrator, J. Borovsky - LANL 30-40 participants Energy stored in stressed magnetic fields can produce large scale explosive events Unsteady , impulsive , multi time scale , probably requires 3D to exist

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Unsteady reconnection session

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  1. Unsteady reconnection session • Working group coordinators: T. Intrator, J. Borovsky - LANL • 30-40 participants • Energy stored in stressed magnetic fields can produce large scale explosive events • Unsteady, impulsive, multi time scale, probably requires 3D to exist • Reality is rarely steady state, but our concepts & models are • How and where does reconnection • Initiate? … Stagnate? SHINE2009 Intrator LA-UR-08-0324

  2. Unsteady solar reconnection • Surveys of solar flare energy release observations • L. Fletcher-Univ. Glasgow: Unsteady signatures in solar flares • J. Qiu- Univ. Montana: Reconnection in solar flares -- 2D to 3D • P. Bellan-Caltech: Alfven waves = field line twist = energy flow • Flare energy release is probably mediated by reconnection, but not yet definitively proven • No clean diagnostics for electron acceleration time scales • Hard to separate time and spatial scales • Overlapping time scales are not very distinct • measured data characteristic time scales evenly spread down to resolution ≈ 0.1-0.3 seconds, probably faster in future data • Proxy data: UV footpoints track reconnection inflow speed => “rcxn rate” SHINE2009 Intrator LA-UR-08-0324

  3. Unsteady 3D Reconnection • 3D geometry? • Sweet-Parker model is a 2D concept • T. Forbes - UNH: 3D models for reconnection in solar flares. • T. Intrator - LANL: 3D experiment • I. Roth - UCB-SSL: Generalized vorticity, asymmetric rcxn • Quasi separatrix layers and slip-squash reconnection seem practical alternatives to singular spine-fan-separator concepts. • Lab experiment invokes Sweet-Parker definition for onset threshold. Convenient but correct? • THEMIS Spacecraft observes asymmetric reconnection SHINE2009 Intrator LA-UR-08-0324

  4. Impulsive Magnetic Reconnection • Onset of reconnection? • A. Bhattacharjee - UNH: Tectonic model => unsteady rcxn dynamics • M. Yamada - Princeton: MRX data shows impulsive rcxn • T. Intrator - LANL: RSX data shows kink instigated rcxn • Unsteady dynamics can follow from 2D & 3D theories, definitely occurs in 3D lab data, nature SHINE2009 Intrator LA-UR-08-0324

  5. Impulsive Magnetic Reconnection • Flow fields? • Proxy flare measurements can back out in-flow, reconnection rate assuming MHD • magnetic flux conservation • photospheric line-tying • separatrices in motion • energy release/transport along the “line” • Dynamics? • Back reaction of flux pileup on initial state? • Compressibility? Stagnation flows? • Some laboratory data (RSX) SHINE2009 Intrator LA-UR-08-0324

  6. Impulsive Magnetic Reconnection • Boundary conditions? • Some discussion of line tying. Concluded that this is a boundary condition and applies to field lines at the boundary. But many presume it to be a stronger condition than this. SHINE2009 Intrator LA-UR-08-0324

  7. Scientific desires • Improved proxy data for flares, or more direct measurements • Faster time cadence • Improve measurements or estimates for B, velocity, reconnection rate • Deconvolve temporal and spatial scales • More attention to 3D concepts, theories • Some laboratory data SHINE2009 Intrator LA-UR-08-0324

  8. Unsteady Magnetic Reconnection SHINE2009 Intrator LA-UR-08-0324

  9. Unsteady rcxn session • Wednesday morning, Salon E • 10:05-11:05AM, 11:05-11:30-break, 11:30AM-1:00PM =>150min • Invited talks: ≈ 25 minutes each • Intrator intro - 5 min • L. Fletcher-Univ. Glasgow: Unsteady signatures in solar flares • J. Qiu- Univ. Montana: Reconnection in solar flares -- 2D to 3D • T. Forbes - UNH: 3D models for reconnection in solar flares • A. Bhattacharjee - UNH: Impulsive current sheets & rcxn • Roth, Intrator, Yamada, Bellan • Edmondson, Evans, Savage, … posters or talks? others?? • Posters P142-P146 SHINE2009 Intrator LA-UR-08-0324

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