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

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
SSX Swarthmore Spheromak Experiment
MRX Magnetic Reconnection Experiment
(Princeton)
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

• Detected in MRX

Magnetic fluctuations
0 10 f(MHz)

• Reconnection rate ? turbulence amplitude
• Instability theory developed,
• May explain anomalous resistivity
  

26
Lower hybrid turbulence

• Detected in MRX

Similar to turbulence in magnetosphere (Cluster)
Magnetic fluctuations
E
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
MRI in Gallium
Couette flow

• Experiment (Princeton)
• hydrodynamically stable,
• ready for gallium

V?
experiment
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 from current-driven
reconnection
experiment
Requires multiple tearing modes (nonlinear
coupling)
33
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

• 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
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)
51
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

52
Abstract dynamo theory

• Small-scale field generation (via turbulence)
• Computation dynamo absent at low ?/?
• Theory dynamo present at high Rm

Magnetic field fluctuations generated by
turbulent convection

• Large-scale field generation
• No dynamo via homogeneous turbulence,
• Large-scale flows sustains field

Dynamo action driven by shear and magnetic
buoyancy instabilities.
53
MHD computation of Jet production
Magnetically formed jet
J contours
54
MHD computation of Jet evolution
Magnetically formed jet
J contours
helical fields develop in jet
When kink unstable, flux conversion B? -gt
Bz Similarities to experimental fields
55
in experiment
Dynamo Effect in the Lab
?E?
??j?
radius
additional current drive mechanism (dynamo)
56
Hall dynamo is significant
Hall dynamo
(theory significant)
57
Hall dynamo is significant
Hall dynamo
experiment
Laser Faraday rotation
58
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)

59
CMSO Educational Outreach

• Highlight is Wonders of Physics program
• Supported by CMSO and DOE (50/50)
• Established before CMSO,
• expanded in quantity and quality

60
6 campus shows
150 traveling shows/yr
all 72 Wisconsin counties, plus selected other
states
61
Center Organization
62
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

63
CMSO Steering Committee

• F. Cattaneo
• H. Ji
• S. Prager
• D. Schnack
• C. Sprott
• P. Terry
• M. Yamada
• E. Zweibel

meets weekly by teleconference
64
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
65
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
66
CMSO Meetings

• 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 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)

67
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
68
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