"Overview of CMSO Center for Magnetic Self-Organization in"
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 nonlinear energy source plasma phy sics se lf-o r g aniz at io n large-scale st ruct ure magnet ic inst abilit ies The nonlinear plasma physics dy namo magnet ic reconnect ion angular moment um t ransport magnet ic chaos and t ransport magnet ic helicit y conserv at ion energy source ion heat ing se lf-o r g aniz at io n large-scale st ruct ure magnet ic inst abilit ies Magnetic self-organization in the lab ˜ B~ .04 magnetic fluctuations b .02 B B(a) 0 (reconnection) flux toroidal magnetic a2 .07 (T) dynamo .06 1.5 heat flux Q 1.0 (MW/m2) (MW/m2) 0.5 energy transport 0 30 rotation 20 V (km/s) (km/s) 10 momentum transport 0 0.4 ion temperature Tion C4+ (keV) 0.2 (KeV) ion heating 0 –2 –1 0 1 2 Time (ms) time (ms) CMSO goal: understand plasma physics needed to solve key laboratory and astrophysical problems • linking laboratory and astrophysical scientists • linking experiment, theory, computation 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 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 Cooperative Agreements (International) Ruhr University/Julich Center, Germany(04) Torino Jet Consortium, Italy (05) Experimental facilities Facilit y Inst it ution Descript ion MST Universit y of Wisco nsin Reversed Field Pinch ( Madison Symme tr ic Torus) MRX Princet on Universit y Merging Plasmas ( Magnet ic Reconnect ion Exp t ) SSPX Lawrence Livermore Nat ional Sphero mak ( St eady St at e Spheromak Exp t ) Lab SSX Swart hmore College Merging Plasmas ( Swa rth more Spheromak Exp t ) MRI experime nt Princet on Universit y Flow ing liquid gallium •yields range of topologies and critical parameters •Joint experiments and shared diagnostics MRX: Magnetic Reconnection SSX: Swarthmore Spheromak Experiment (Princeton) Experiment MST: Madison SymmetricTorus SSPX: Sustained Spheromak Physics (Wisconsin) Experiment (LLNL) MRX Inductively produced plasmas, Spheromak or annular plasmas Locailzed reconnection at merger SSX Electrostatically - produced spheromaks (by plasma guns) Two spheromaks reconnect and merge SSPX Electrostatically - produced spheromak MST Reversed field pinch Liquid gallium MRI experiment (Princeton) To study the magnetorotational instability Major Computational Tools Code Inst it ution Descript ion NEK Universit y of Chicago Spect ral f init e elements incomp ressible resistiv e MHD ( Any 5000 geomet ry ) Li2 Los A lamos Nonlinear, 3 D, ideal HD/ MHD, Cart esian, Cylind rical, Spherical Universit y of Wisconsin Third ord er hyb rid, essenti ally non- oscillat ory ( ENO) isoth erm al code f or comp ressible MHD Universit y of Chicago Fully spect ral, incomp ressible, resistiv e MHD ( slab or t riply periodic) DEBS SAIC, U. Wisconsin Nonlinear, 3 D, resistiv e MHD , cyl ind rical geo met ry NIMROD Multi -instit uti onal Nonlinear, 3 D, resistiv e, t wo -f luid , (W isconsin, SAIC, Los A lamos) t oro idal g eomet ry VPIC Los A lamos Nonlinear, 3 D relat ivi sti c PIC •Not an exhaustive list •Codes built largely outside of CMSO •Complemented by equal amount of analytic theory 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) Reconnection • Two-fluid Hall effects • Reconnection with line tying not foreseen in • Effects of coupled reconnection sites proposal • Effects of lower hybrid turbulence 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 Observation of Hall effects Observed quadrupole B component, MRX SSX QuickTime™ and a TIFF (LZW) decompressor are neede d to see this picture. radius also observed in magnetosphere 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) Linear theory for mode resonance in cylinder v periodic line-tied radius radius Effects of multiple, coupled reconnections Many self-organizing effects in MST occur ONLY with multiple reconnections Effects of multiple, coupled reconnections Many self-organizing effects in MST occur ONLY with multiple reconnections core reconnection only multiple reconnections core reconnection core edge edge reconnection •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) Lower hybrid turbulence Detected in MRX Magnetic fluctuations QuickTime™ an d a TIFF (LZW) decomp resso r are need ed to see this picture. 0 10 f(MHz) •Reconnection rate turbulence amplitude; •Instability theory developed, •May explain anomalous resistivity Lower hybrid turbulence Detected in MRX Similar to turbulence in magnetosphere (Cluster) Magnetic fluctuations E QuickTime™ and a QuickTime™ an d a TIFF (LZW) decompressor are neede d to see this picture. TIFF (LZW) decomp resso r are need ed to see this picture. B QuickTime™ and a TIFF (LZW) decompressor are needed to see this picture. 0 10 f(MHz) •Reconnection rate ~ turbulence amplitude; •Instability theory developed, •May explain anomalous resistivity Momentum Transport radial transport of toroidal momentum rotation momentum transport In accretion disks, solar interior, jets, lab experiments, classical viscosity fails to explain momentum transport 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 Momentum Transport Highlights • MRI in Gallium: experiment and theory • MRI in disk corona: computation • Momentum transport from current-driven reconnection MRI in Gallium --- Couette flow + diff. endcaps flow Couette • Experiment (Princeton) + end caps rotate with outer cyl. experiment hydrodynamically stable, V v ready for gallium r radius •Simulation (Chicago) underway QuickTime™ and a TIFF (LZW) decompressor are neede d to see this picture. 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 Momentum transport from current-driven reconnection experiment Requires multiple tearing modes (nonlinear coupling) Theory and computation of Maxwell stress in MHD quasilinear theory for computation for multiple, one tearing mode interacting modes j ˜ ˜B resonant j ˜ ˜B surface r An effect in astrophysical plasmas? reconnection and flow is ubiquitous raises some important theoretical questions (e.g., effect of nonlinear coupling on spatial structure) Ion Heating Ion heating in solar wind thermal speed km/s QuickTime™ an d a TIFF (LZW) decompressor are need ed to see this p icture. r/Rsun Strong perpendicular heating of high mass ions Ion heating in lab plasma Observed during reconnection in all CMSO experiments Ti (eV) MST t = +0.50 ms QuickTime™ and a TIFF (LZW) decompressor are neede d to see this picture. t = -0.25 ms radius Conversion of magnetic energy to ion thermal energy ~ 10 MW flows into the ions change in ion thermal energy (J) MRX reconnected magnetic field energy (J) Magnetic energy can be converted to Alfvenic jets magnetic SSX energy QuickTime™ and a TIFF (LZW) deco mpressor Energetic are neede d to se e this picture. ion flux time (s) Ions heated only with core and edge reconnection MST core ˜ B QuickTime™ anedge core da TIFF (LZW) decompressor reconnection edge are need ed to see this p icture . reconnection Ti (eV) QuickTime™ an d a TIFF (LZW) decompressor are need ed to see this picture. time (ms) What is mechanism for ion heating? • Still a puzzle • Theory of viscous damping of magnetic fluctuations has been developed Magnetic chaos and transport Magnetic turbulence Transport in chaotic magnetic field 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 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 QuickTime™ an d a TIFF (LZW) decompressor computation are need ed to see this p icture . Measurements underway in experiment for comparison Transport in chaotic field Experiment measure transport vs gyroradius in chaotic field Transport in chaotic field Experiment measure transport vs gyroradius in chaotic field Result Small gyroradius (electrons): large transport Large gyroradius (energetic ions): small transport Ion orbits well-ordered Transport measured via neutron emission from energetic ions produced by neutral beam injection Possible implications for relativistic cosmic ray ions The Dynamo Why is the universe magnetized? • Growth of magnetic field from a seed • Sustainment of magnetic field • Redistribution of magnetic field 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 The disk-jet system Field produced Field sustained (the from transport engine) CMSO Activity • Theoretical work on all problems the role of turbulence on the dynamo, flux conversion in jets, • Lab plasma dynamo effect: field transport, with physics connections to growth and sustainment Abstract dynamo theory Small-scale field generation (via turbulence) Computation: dynamo absent at low / Theory: dynamo present at high Rm Magnetic field fluctuations Large-scale field generation generated by turbulent convection No dynamo via homogeneous turbulence, Large-scale flows sustains field Dynamo action driven by shear and magnetic buoyancy instabilities. MHD computation of Jet production Magnetically formed jet |J| contours QuickTime™ and a TIFF (LZW) decompressor are neede d to see this picture. MHD computation of Jet evolution Magnetically formed jet |J| contours QuickTime™ and a TIFF (LZW) decompressor are neede d to see this picture. helical fields QuickTime™ and a develop in jet TIFF (LZW) decomp resso r are need ed to see this picture. When kink unstable, flux conversion B -> Bz Similarities to experimental fields Dynamo Effect in the Lab in experiment E j 2.0 E || 1.5 E|| 1.0 V/m 0.5 neo j|| J|| (Zeff = 2) 0.0 -0.5 0.0 0.2 0.4 0.6 0.8 1.0 /a radius additional current drive mechanism (dynamo) Hall dynamo is significant j ˜ ˜B ˜ ˜ E || v B || || j || ne Hall dynamo (theory significant) Hall dynamo is significant j ˜ ˜B ˜ ˜ E || v B || || j || ne Hall dynamo experiment: j ˜ ˜B || Laser Faraday ne rotation Questions for the lab plasma, relevant to astrophysics • At what conditions (and locations) do two-fluid and MHD dynamos dominate? • Is the final plasma state determined by MHD, with mechanism of arrival influenced by two-fluid effects? • Is the lab alpha effect, based on quasi-laminar flows, a basis for field sustainment (possibly similar to conclusion from computation for astrophysics) CMSO Educational Outreach •Highlight is Wonders of Physics program •Supported by CMSO and DOE (50/50) •Established before CMSO, expanded in quantity and quality ~ 150 traveling shows/yr all 72 Wisconsin counties, QuickTime™ and a TIFF (LZW) decomp resso r are need ed to see this picture. plus selected other states ~ 6 campus shows Center Organization Topical Coordinators each pair = 1 lab, 1 astro person • Reconnection Yamada, Zweibel • Momentum transport Craig, Li • Dynamo Cattaneo, Prager • Ion Heating Fiksel, Schnack • Chaos and transport Malyshkin, Terry • Helicity Ji, Kulsrud • Educational outreach Reardon, Sprott CMSO Steering Committee F. Cattaneo H. Ji S. Prager D. Schnack C. Sprott P. Terry M. Yamada E. Zweibel meets weekly by teleconference CMSO Program Advisory Committee S. Cowley (Chair) UCLA P. Drake University of Michigan W. Gekelman UCLA R. Lin UC - Berkeley G. Navratil Columbia University E. Parker University of Chicago A. Pouquet NCAR, Boulder, CO D. Ryutov Lawrence Livermore National Lab CMSO International Liaison Committee M. Berger University College, London, UK A. Burkert The University of Munich, Germany K. Kusano Hiroshima University, Japan P. Martin Consorzio RFX, Padua, Italy Y. Ono Tokyo University, Japan M. Velli Universita di Firenze, Italy N. Weiss Cambridge University, UK CMSO Meetings Sept, 03 Ion heating/chaos (Chicago) Sept, 03 Reconnection/momentum (Princeton) Oct, 03 Dynamo (Chicago) Nov, 03 General meeting (Chicago) June,04Hall dynamo and relaxation (Princeton) Aug, 04 General meeting (Madison) Sept, 04 PAC meeting (Madison) Oct, 04 Reconnection (Princeton) Jan, 05 Video conference of task leaders March, 05 General meeting (San Diego) April, 05 Dynamo/helicity meeting (Princeton) June, 05 Intermittency and turbulence (Madison) June, 05 Experimental meeting (Madison) Oct, 05 General meeting (Princeton) Nov, 05 PAC meeting (Madison) Jan, 06 Winter school on reconnection (Los Angeles, w/CMPD) March, 06 Line-tied reconnection (Los Alamos) June, 06 Workshop on MSO (Aspen, with CMPD)) Aug, 06 General meeting (Chicago) Budget • NSF $2.25M/yr for five years • DOE ~$0.4M to PPPL ~$0.1M to LLNL ~$0.15M to UNH all facility and base program support • LANL ~$0.34M CMSO is a partnership between NSF and DOE Summary •CMSO has enabled many new, cross-disciplinary physics activities (and been a learning experience) •New linkages have been established (lab/astro, expt/theory, expt/expt) •Many physics investigations completed, many new starts •The linkages are strong, but still increasing, the full potential is a longer-term process than 2.5 years