Overview of CMSO Center for Magnetic Self-Organization in Laboratory and Astrophysical Plasmas S....
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Transcript of Overview of CMSO Center for Magnetic Self-Organization in Laboratory and Astrophysical Plasmas S....
Overview of CMSO
Center for Magnetic Self-Organization in Laboratory and Astrophysical Plasmas
S. PragerMay, 2006
Outline
• Physics topics
• Participants
• Physics goals and highlights
• Educational outreach
• Management structure
• Funding
Magnetic self-organization
large-scale structure magnetic instabilities
nonlinear plasma physicsenergy source
self-organization
The nonlinear plasma physics
large-scale structure magnetic instabilities
energy source
self-organization
dynamomagnetic reconnectionangular momentum transportmagnetic chaos and transportmagnetic helicity conservationion heating
Magnetic self-organization in the lab–2–1012Time (ms)1.50.50 Q
(MW/m2)
30200 V
(km/s)
100.40.20 Tion
(KeV)
C4+.07.06Φ/πa2
( )T
.04.020 bB(a)
~1.0
€
˜ B
B
toroidal magnetic flux
heat flux(MW/m2)
rotation(km/s)
ion temperature(keV)
dynamo
magnetic fluctuations
energy transport
momentum transport
ion heating
time (ms)
(reconnection)
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 UniversityThe University of ChicagoThe University of Wisconsin Science Applications International CorpSwarthmore CollegeLawrence Livermore National Laboratory
~25 investigators,
~similar number of postdocs and students
~ equal number of lab and astrophysicists
With New Funded Members
Princeton UniversityThe University of ChicagoThe University of Wisconsin Science Applications International CorpSwarthmore CollegeLawrence Livermore National LaboratoryLos 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)
•yields range of topologies and critical parameters•Joint experiments and shared diagnostics
Experimental facilities
Facility Institution DescriptionMST
(Madison Symmetric To rus)
University of Wisconsin Reversed Field Pinch
MRX(Magnetic Reconnection Expt)
Princeton University Merging Plasmas
SSPX(Steady State Spheromak Expt)
Lawrence Livermore NationalLab
Spheromak
SSX(Swarthmore Spheromak Expt)
Swarthmore College Merging Plasmas
MRI experiment Princeton University Flowing liquid gallium
SSPX: Sustained Spheromak Physics Experiment (LLNL)
SSX: Swarthmore Spheromak Experiment
MRX: Magnetic Reconnection Experiment (Princeton)
MST: Madison SymmetricTorus (Wisconsin)
SSX
Electrostatically - produced spheromaks (by plasma guns)
Two spheromaks reconnect and merge
MRX
Inductively produced plasmas,
Spheromak or annular plasmas
Locailzed reconnection at merger
MST
Reversed field pinch
SSPX
Electrostatically - produced spheromak
Liquid gallium MRI experiment (Princeton)
To study the magnetorotational instability
Major Computational Tools
•Not an exhaustive list•Codes built largely outside of CMSO•Complemented by equal amount of analytic theory
Code Institution Description
NEK5000
University of Chicago Spectral finite elementsincompressible resistive MHD (Anygeometry)
Li2 Los Alamos Nonlinear, 3D, ideal HD/ MHD,Cartesian, Cylindrical, Spherical
University of Wisconsin Third order hybrid, essentially non-oscillatory (ENO) isothermal codefor compressible MHD
University of Chicago Fully spectral, incompressible,resistive MHD (slab or triply periodic)
DEBS SAIC, U. Wisconsin Nonlinear, 3D, resistive MHD ,cylindrical geometry
NIMROD Multi-institutional(Wisconsin, SAIC, Los Alamos)
Nonlinear, 3D, resistive, two-fluid,toroidal geometry
VPIC Los Alamos Nonlinear, 3D relativistic PIC
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
• Effects of coupled reconnection sites
• Effects of lower hybrid turbulence
not foreseen in proposal
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
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MRX SSX
radius
also observed in magnetosphere
Observed quadrupole B component,
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
radius
v
radius
periodic
line-tied
Effects of multiple, coupled reconnectionsMany self-organizing effects in MST occur ONLY with multiple reconnections
core reconnection
edge reconnection
core
edge
core reconnection only
multiple reconnections
Effects of multiple, coupled reconnectionsMany self-organizing effects in MST occur ONLY with multiple reconnections
•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
•Reconnection rate turbulence amplitude;•Instability theory developed,•May explain anomalous resistivity
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Magnetic fluctuations
0 10 f(MHz)
Lower hybrid turbulence
Detected in MRX
•Reconnection rate ~ turbulence amplitude;•Instability theory developed,•May explain anomalous resistivity
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Similar to turbulence in magnetosphere (Cluster)
E
B
Magnetic fluctuations
0 10 f(MHz)
Momentum Transport
rotation
momentumtransport
radial transport of toroidal momentum
In accretion disks, solar interior, jets, lab experiments, classical viscosity fails to explain momentum transport
Leading explanation in lab plasmaresistive MHD instabilitycurrent-driven (tearing instability)momentum transported by j x b and v.v
Leading explanation in astrophysicsMHD instabilityFlow-driven (magnetorotational 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
• Experiment (Princeton)hydrodynamically stable,
ready for gallium
v
r
--- Couette flow + diff. endcaps + end caps rotate with outer cyl.
•Simulation (Chicago)
underway
Vexperiment
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radius
Couette flow
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)
-1.0-0.500.51.01.50102030-10Time (ms)Parallel Velocity (km/s)Core (toroidal)Edge (poloidal)
Theory and computation of Maxwell stress in MHD
r
resonantsurface
quasilinear theory for one tearing mode
€
˜ j × ˜ B
computation for multiple, interacting modes
€
˜ j × ˜ B
An effect in astrophysical plasmas?reconnection and flow is ubiquitousraises some important theoretical questions
(e.g., effect of nonlinear coupling on spatial structure)
Ion Heating
Ion heating in solar wind
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r/Rsun
Strong perpendicular heating of high mass ions
thermal speed km/s
Ion heating in lab plasma
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MST
Observed during reconnection in all CMSO experiments
t = -0.25 ms
t = +0.50 ms
Ti (eV)
radius
–2–1012Time (ms)110100Wm
(kJ)
90
Conversion of magnetic energy to ion thermal energy
~ 10 MW flows into the ions
MRX
reconnected magnetic field energy (J)
change in ion thermal energy
(J)
Magnetic energy can be converted to Alfvenic jets
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magnetic energy
Energetic ion flux
time (s)
SSX
Ions heated only with core and edge reconnection
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Ti (eV)
time (ms)
€
˜ B core reconnection
edge reconnection
MST
core edge
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
Measurements underway in experiment for comparison
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computation
Transport in chaotic fieldExperiment
measure transport vs gyroradius in chaotic field
Transport in chaotic fieldExperiment
measure transport vs gyroradius in chaotic field
ResultSmall gyroradius (electrons): large transportLarge 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 seedprimordial plasma
• Sustainment of magnetic fielde.g., in solar interior
in accretion disk
• Redistribution of magnetic fielde.g., solar coronal field
extra-galactic jets
The disk-jet system
Field sustained (the engine)
Field produced from transport
CMSO Activity
• Theoretical work on all problemsthe 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
Large-scale field generationNo dynamo via homogeneous
turbulence,Large-scale flows sustains field
Magnetic field fluctuations generated by turbulent convection
Dynamo action driven by shear and magnetic buoyancy instabilities.
MHD computation of Jet production
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|J| contours
Magnetically formed jet
MHD computation of Jet evolution
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|J| contours
Magnetically formed jet
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When kink unstable, flux conversion B -> Bz
Similarities to experimental fields
helical fields
develop in jet
in experiment
-0.5
0.5
1.0
1.5
2.0
V/m
0.0
0.0 0.2 0.4 0.6 0.8 1.0/a
E||
neo J||(Zeff = 2)
€
E ≠ η j
E||
j||
radius
additional current drive mechanism (dynamo)
Dynamo Effect in the Lab
Hall dynamo is significant
€
E||+ ˜ v × ˜ B
||+
˜ j × ˜ B ||
ne= η j
||
Hall dynamo
(theory significant)
Hall dynamo is significant
€
E||+ ˜ v × ˜ B
||+
˜ j × ˜ B ||
ne= η j
||
Laser Faraday rotation
Hall dynamo
€
˜ j × ˜ B ||
ne
experiment:
• 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)
Questions for the lab plasma, relevant to 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
~ 6 campus shows
~ 150 traveling shows/yr
all 72 Wisconsin counties,
plus selected other states
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Center Organization
Topical Coordinators
• 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
each pair = 1 lab, 1 astro person
CMSO Steering CommitteeF. Cattaneo
H. JiS. Prager
D. SchnackC. SprottP. Terry
M. YamadaE. Zweibel
meets weekly by teleconference
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 Program Advisory Committee
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
Sept, 03 Ion heating/chaos (Chicago)Sept, 03 Reconnection/momentum (Princeton)Oct, 03 Dynamo (Chicago)Nov, 03 General meeting (Chicago)June,04 Hall dynamo and relaxation (Princeton)Aug, 04 General meeting (Madison)Sept, 04 PAC meeting (Madison)Oct, 04 Reconnection (Princeton)Jan, 05 Video conference of task leadersMarch, 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)
CMSO Meetings
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