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Overview of CMSO Center for Magnetic Self-Organization in Laboratory and Astrophysical Plasmas

Overview of CMSO Center for Magnetic Self-Organization in Laboratory and Astrophysical Plasmas. S. Prager May, 2006. Outline. Physics topics Participants Physics goals and highlights Educational outreach Management structure Funding. Magnetic self-organization.

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Overview of CMSO Center for Magnetic Self-Organization in Laboratory and Astrophysical Plasmas

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  1. Overview of CMSOCenter for Magnetic Self-Organization in Laboratory and Astrophysical Plasmas S. Prager May, 2006

  2. Outline • Physics topics • Participants • Physics goals and highlights • Educational outreach • Management structure • Funding

  3. Magnetic self-organization

  4. The nonlinear plasma physics

  5. Magnetic self-organization in the lab magnetic fluctuations (reconnection) toroidal magnetic flux dynamo heat flux (MW/m2) energy transport rotation (km/s) momentum transport ion temperature (keV) ion heating time (ms)

  6. CMSO goal: understand plasma physics needed to solve key laboratory and astrophysical problems • linking laboratory and astrophysical scientists • linking experiment, theory, computation

  7. Original Institutional Members Princeton University The University of Chicago The University of Wisconsin Science Applications International Corp Swarthmore College Lawrence Livermore National Laboratory ~25 investigators, ~similar number of postdocs and students ~ equal number of lab and astrophysicists

  8. With New Funded Members Princeton University The University of Chicago The University of Wisconsin Science Applications International Corp Swarthmore College Lawrence Livermore National Laboratory Los Alamos National Laboratory (05) University of New Hampshire (05) ~30 investigators, ~similar number of postdocs and students ~ equal number of lab and astrophysicists

  9. Cooperative Agreements (International) Ruhr University/Julich Center, Germany(04) Torino Jet Consortium, Italy (05)

  10. Experimental facilities • yields range of topologies and critical parameters • Joint experiments and shared diagnostics

  11. MRX: Magnetic Reconnection Experiment (Princeton) SSX: Swarthmore Spheromak Experiment MST: Madison SymmetricTorus (Wisconsin) SSPX: Sustained Spheromak Physics Experiment (LLNL)

  12. MRX Inductively produced plasmas, Spheromak or annular plasmas Locailzed reconnection at merger SSX Electrostatically - produced spheromaks (by plasma guns) Two spheromaks reconnect and merge

  13. SSPX Electrostatically - produced spheromak MST Reversed field pinch

  14. Liquid gallium MRI experiment (Princeton) To study the magnetorotational instability

  15. Major Computational Tools • Not an exhaustive list • Codes built largely outside of CMSO • Complemented by equal amount of analytic theory

  16. Sample Physics Highlights • New or emerging results • Mostly where center approach is critical We are pursuing much of the original plans, but new investigations have also arisen (plans for next 2 years discussed later)

  17. Reconnection • Two-fluid Hall effects • Reconnection with line tying • Effects of coupled reconnection sites • Effects of lower hybrid turbulence not foreseen in proposal

  18. Hall effects on reconnection • Identified on 3 CMSO experiments (MRX, SSX, MST) • Performed quasilinear theory • Will study via two-fluid codes (NIMROD, UNH) and possibly via LANL PIC code

  19. Observation of Hall effects Observed quadrupole B component, MRX SSX radius also observed in magnetosphere

  20. Reconnection with line-tying • Studied analytically (UW, LANL) and computationally(UW) • Compare to non-CMSO linear experiments • Features of periodic systems survive (e.g.,large, localized currents)

  21. Linear theory for mode resonance in cylinder v periodic line-tied radius radius

  22. Effects of multiple, coupled reconnections Many self-organizing effects in MST occur ONLY with multiple reconnections

  23. Effects of multiple, coupled reconnections Many self-organizing effects in MST occur ONLY with multiple reconnections core reconnection only multiple reconnections core core reconnection edge edge reconnection

  24. Applies to magnetic energy release, dynamo, momentum • transport, ion heating • Related to nonlinear mode coupling • Might be important in astrophysics where multiple • reconnections may occur • (e.g., solar flare simulations of Kusano)

  25. Lower hybrid turbulence Magnetic fluctuations Detected in MRX 0 10 f(MHz) • Reconnection rate  turbulence amplitude; • Instability theory developed, • May explain anomalous resistivity

  26. Lower hybrid turbulence Similar to turbulence in magnetosphere (Cluster) Magnetic fluctuations E Detected in MRX B 0 10 f(MHz) • Reconnection rate ~ turbulence amplitude; • Instability theory developed, • May explain anomalous resistivity

  27. Momentum Transport radial transport of toroidal momentum In accretion disks, solar interior, jets, lab experiments, classical viscosity fails to explain momentum transport

  28. Leading explanation in astrophysics MHD instability Flow-driven (magnetorotational instability) momentum transported by j x b and v.v Leading explanation in lab plasma resistive MHD instability current-driven (tearing instability) momentum transported by j x b and v.v

  29. Momentum Transport Highlights • MRI in Gallium: experiment and theory • MRI in disk corona: computation • Momentum transport from current-driven reconnection

  30. --- Couette flow + diff. endcaps + end caps rotate with outer cyl. vq r MRI in Gallium Couette flow V experiment • Experiment (Princeton) hydrodynamically stable, ready for gallium radius • Simulation (Chicago) • underway

  31. MRI in disk corona • Investigate effects of disk corona on momentum transport; possible strong effect • Combines idea from Princeton, code from SAIC initial state: flux dipole ...after a few rotations

  32. Momentum transport fromcurrent-driven reconnection experiment Requires multiple tearing modes (nonlinear coupling)

  33. resonant surface r  Theory and computation of Maxwell stress in MHD quasilinear theory for one tearing mode computation for multiple, interacting modes An effect in astrophysical plasmas? reconnection and flow is ubiquitous raises some important theoretical questions (e.g., effect of nonlinear coupling on spatial structure)

  34. Ion Heating

  35. Ion heating in solar wind thermal speed km/s r/Rsun Strong perpendicular heating of high mass ions

  36. Ion heating in lab plasma Observed during reconnection in all CMSO experiments Ti (eV) MST t = +0.50 ms t = -0.25 ms radius

  37. Conversion of magnetic energy to ion thermal energy ~ 10 MW flows into the ions

  38. change in ion thermal energy (J) MRX reconnected magnetic field energy (J)

  39. Magnetic energy can be converted to Alfvenic jets magnetic energy SSX Energetic ion flux time (s)

  40. Ions heated only with core and edge reconnection MST core reconnection core edge edge reconnection Ti (eV) time (ms)

  41. What is mechanism for ion heating? • Still a puzzle • Theory of viscous damping of magnetic fluctuations has been developed

  42. Magnetic chaos and transport Magnetic turbulence Transport in chaotic magnetic field

  43. Magnetic chaos and transport Magnetic turbulence • Star formation • Heating via cascades • Scattering of radiation • Underlies other CMSO topics Transport in chaotic magnetic field • Heat conduction in galaxy clusters (condensation) • Cosmic ray scattering

  44. Magnetic turbulence • Properties of Alfvenic turbulence • Intermittency in magnetic turbulence • Comparisons with turbulence in experiments Sample results: Intermittency explains pulsar pulse width broadening, Observed in kinetic Alfven wave turbulence computation Measurements underway in experiment for comparison

  45. Transport in chaotic field Experiment measure transport vs gyroradius in chaotic field

  46. Transport in chaotic field Result Small gyroradius (electrons): large transport Large gyroradius (energetic ions): small transport Experiment measure transport vs gyroradius in chaotic field Ion orbits well-ordered Transport measured via neutron emission from energetic ions produced by neutral beam injection Possible implications for relativistic cosmic ray ions

  47. The Dynamo

  48. Why is the universe magnetized? • Growth of magnetic field from a seed • Sustainment of magnetic field • Redistribution of magnetic field

  49. Why is the universe magnetized? • Growth of magnetic field from a seed primordial plasma • Sustainment of magnetic field e.g., in solar interior in accretion disk • Redistribution of magnetic field e.g., solar coronal field extra-galactic jets

  50. The disk-jet system Field produced from transport Field sustained (the engine)

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