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The Plasma Microturbulence Project

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Four GK 'kernels' (which we have GS2, GYRO, Summit, and GTC) ... 18th International Conference on Numerical Simulation of Plasmas, Cape Cod, MA. ... – PowerPoint PPT presentation

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Title: The Plasma Microturbulence Project


1
The Plasma Microturbulence Project
UCI
  • W.M. Nevins ( )
  • For the
  • Plasma Microturbulence Project Team

UCLA
2
Summary of Progress on Achieving Scientific
Deliverables
  • The (partially funded) PMP proposal promised
  • A unified framework with
  • Four GK kernels (which we have GS2, GYRO,
    Summit, and GTC)
  • A common front end ? Morphed to two front ends
  • GS2 and GYRO
  • PG3EQ, UCAN, and GTC united under SUMMIT
    framework
  • A common back end (which we have GKV)
  • And users beyond the code development groups
    (which weve done)
  • Kinetic electrons and (at least) ?B? in all four
    codes
  • Have ?B , ?B? kinetic electrons in GS2
  • Have ?B? kinetic electrons in GYRO
  • PIC algorithms for ?B? kinetic electrons
    demonstrated in GEM(but not yet installed in
    SUMMIT framework )
  • Kinetic electrons in GTC
  • To do LOTS of good science with our codes (which
    weve done)

3
Four GK kernels a 2x2 Matrix ofPlasma
Turbulence Simulation Codes
  • Why both Continuum and Particle-in-Cell (PIC)?
  • Cross-check on algorithms
  • Continuum currently most developed (already has
    kinetic es , ?B?, ?B )
  • Proponents of PIC-codes believe they will
    ultimately be more efficient
  • If we can do Global simulations, why bother with
    Flux Tubes?
  • Electron-scale (?e, ?ec/?pe) physics (ETG modes,
    etc.)
  • Turbulence on multiple space scales (ITGTEM,
    TEMETG, ITGTEMETG, )
  • Efficient parameter scans

4
A PIC algorithm for kinetic es and
?B??Benchmarking GEM against GYRO and GTC
Turbulent Transport
Linear Growth Rates
5
The PMP Supports User Communities for both GS2
and GYRO Codes
  • Strong user community trained and working to
    validate gyrokinetic codes against experimental
    data, including
  • Bourdelle, Bravenec, Budny, Ernst, Hallatschek,
    Hill, Jenko, Mikkelsen, Redi, Ross, Yuh, and
    others
  • Workshops to educate user community (December
    2002, )
  • Websites for code distribution and documentation
  • http//gs2.sourceforge.net/ and
    http//fusion.gat.com/comp/parallel/gyro.html
  • Work by these Gyrokinetic code users has led to
    publications and talks at major meetings,
    including
  • D. W. Ross, TTF 2004 B. N. Rogers, Sherwood
    2004
  • D. Ernst, APS 2003 F. Jenko, IAEA 2002
  • K. Hallatschek, APS 2002 H. Yuh, ICOPS 2002

6
PMP Codes Scale to large numbers of
processorsGYRO is a benchmark code for the ORNL
Cray X-1GTC ported to both ORNL Cray X-1and
Japanese Earth Simulator
GTC problem size ?with Nprocessors
GYRO constant problem size
For details on GYRO performance, see
http//fusion.gat.com/comp/parallel/performance.ht
ml
For details on GTC performance, see
http//gk.ps.uci.edu/zlin/parallel/index.html
7
SciDAC Computing ResourcesEnabled Studies of
Plasma Micro-turbulence
  • NERSC (LBNL)
  • FY 01 usage 1.36M node-hrs
  • FY 02 usage 2.63M node-hrs
  • FY 03 usage 4.78M node-hrs
  • Accounting unit re-normalized (by a factor of
    2.5)
  • FY 04 allocation 2M node-hrs(and we will
    certainly use it all)
  • CCS (ORNL)
  • FY 03 usage 3.5M node-hrs
  • FY 04 allocation 1 M node-hrs(but CCS doesnt
    seem to mind if you exceed your allocation )

Plus substantial use of Linux Clusters at PPPL,
GA, MIT and U of MD ? The PMP is largest user of
computer time among OFES-funded activities(and
this counts only usage by our PIs, not that of
our user-community)
8
Has the PMP produced good science?Judge for
yourselves
  • Refereed publications
  • 2004
  • J. Candy, R. E. Waltz, and W. Dorland, Phys.
    Plasmas 11.
  • J. Candy, R.E. Waltz, and M.N. Rosenbluth, Phys.
    Plasmas 11, 1879.
  • V. K. Decyk and Charles D. Norton, Scientific
    Programming 12, 45.
  • D. R. Ernst, P. T. Bonoli, P. J. Catto et al.,
    Phys. Plasmas .
  • S. Ethier and Z. Lin, Computer Physics
    Communications .
  • T. S. Hahm, P.H. Diamond, Z. Lin et al.,
    Plasma Phys. Controlled Fusion .
  • F.L. Hinton, R.E. Waltz, and J. Candy, Phys.
    Plasmas 11, 2433.
  • W. W. Lee, Comput. Phys. Comm. .
  • Z. Lin and T. S. Hahm, Phys. Plasmas 11, 1-99.
  • S.E. Parker, Y. Chen, W. Wan et al., Phys.
    Plasmas 11, 2594.
  • M. Romanelli, C. Bourdelle, and W. Dorland,
    Phys. Plasmas .
  • R.E. Waltz, Fusion Science and Technology
  • W.X. Wang, W.M. Tang, et al., Computational
    Physics Communication .
  • 2003
  • C. Bourdelle, W. Dorland, X. Garbet et al.,
    Phys. Plasmas 10, 2881.
  • J. Candy and R.E. Waltz, Phys. Rev. Lett. 91,
    045001.
  • J. Candy and R.E. Waltz, J. Comp. Phys. 186, 545.
  •  
  • 2002
  • R. V. Budny, R. Andre, et al., Plasma Phys.
    Control. Fusion 44, 1215.
  • Y. Chen, Samuel T. Jones, and Scott E. Parker,
    EEE Tran. Plasma Sci. 30, 74.
  • B.I. Cohen, A.M. Dimits, W.M. Nevins et al.,
    Phys. Plasmas 9 (1), 251-262.
  • Bruce I. Cohen, Andris M. Dimits, et al., Phys.
    Plasmas 9 (5), 1915-1924.
  • T. S. Hahm, Plasma Phys. Controlled Fusion 44,
    A87.
  • F. Jenko and W. Dorland, Phys. Rev. Lett. 89,
    225001.
  • Z. Lin, S. Ethier, T. S. Hahm et al., Phys.
    Rev. Lett. 88, 195004.
  • D. W. Ross, R. B. Bravenec, W. Dorland et al.,
    Phys. Plasmas 9, 177.
  • D. W. Ross and W. Dorland, Phys. Plasmas 9, 5031.
  • E. J. Synakowski, M. G. Bell, et al., Phys.
    Control. Fusion 44, A165.
  • R. E. Waltz, J. Candy, and M.N. Rosenbluth, Phys.
    Plasmas 9, 1938.
  • 2001
  • A.M. Dimits, B.I. Cohen, W.M. Nevins et al.,
    Nuclear Fusion 41, 1725-1732.
  • I. H. Hutchinson, R. Boivin, P. T. Bonoli et
    al., Nucl. Fusion 41, 1391.
  • F. Jenko, W. Dorland, and G. W. Hammett, Phys.
    Plasmas 8, 4096.
  • W. W. Lee, J. L. V. Lewandowski, T. S. Hahm et
    al., Phys. Plasmas 8, 4435.
  • Z. Lin and L. Chen, Phys. Plasmas 8, 1447.

9
Has the PMP produced good science?Judge for
yourselves
  • 2003
  • Y. Chen, Electromagnetic gyrokinetic
    simulations, presented at the International
    Sherwood Fusion Theory Meeting.
  • W. Dorland, Sheared flows and boundary layer
    physics in tokamak plasma, presented at the New
    Themes in Plasma and Fusion Turbulence, London.
  • W. Dorland, Anomalous heating in a kinetic
    Alvfen wave cascade, presented at the 7th
    Workshop on the Interrelationship between Plasma
    Experiment in Laboratory and Space.
  • W. Dorland, US Plasma Microturbulence Project,
    presented at the Eighth International Symposium
    on Simulation Science, Hayama, Japan.
  • D.R. Ernst, Role of Trapped Electron Mode
    Turbulence in Internal Transport Barrier Control
    in Alcator C-Mod, presented at the 45th Annual
    Meeting of the Division of Plasma Physics,
    Albuquerque, NM.
  • F.L. Hinton, Electromagnetic turbulence effects
    in the neoclassical Ohm's law, presented at the
    45th Annual meeting of the Division of Plasma
    Physics, Albuquerque, NM.
  • S. Klasky, S. Ethier, Z. Lin et al.,
    Grid-Based Parallel Data Streaming implemented
    for the Gyrokinetic Toroidal Code, presented at
    the SC2003, Phoenix, AZ.
  • W. W. Lee, Thermodynamic and numerical
    properties of a gyrokinetic plasma implications
    on transport scale simulation, presented at the
    18th International Conference on Numerical
    Simulation of Plasmas, Cape Cod, MA.
  • Z Lin, presented at the 10th European Fusion
    Theory Conference, Helsinki, Finland.
  • S.E. Parker, Electromagnetic Turbulence
    Simulations with Kinetic Electrons, presented at
    the 45th Annual Meeting of the Division of Plasma
    Physics, Albuquerque, NM.
  • M. H. Redi, R. Bell, P. Bonoli et al.,
    Gyrokinetic Calculations of Microturbulence and
    Transport on NSTX and Alcator-CMOD H-modes,
    presented at the 30th European Physical Society
    Conference on Plasma Physics and Controlled
    Fusion, St. Petersburg, Russia.
  • Talks at major meetings
  • 2004
  • Ron Bravenec, Synthetic Diagnostics, presented
    at the 15th Topical Conference on
    High-Temperature Plasma Diagnostics.
  • V. K. Decyk, UCLA Parallel PIC Framework A
    Toolkit for new PIC Codes, presented at the SIAM
    Conference on Parallel Processing for Scientific
    Computing, San Francisco, CA.
  • W. Dorland, Resonant Heating in the Alfven
    Cascade, presented at the Fields Institute.
  • P.N. Guzdar, Pedestal Physics, to be presented
    at the 20th IAEA Fusion Energy Conference,
    Vilamoura, Portugal.
  • T.S. Hahm, to be presented at the 20th IAEA
    Fusion Energy Conference, Vilamoura, Portugal.
  • W. W. Lee, MFE Simulation Data Management,
    presented at the DoE Data Management Workshop,
    SLAC, Palo Alto, CA.
  • Z. Lin, to be presented at the 20th IAEA Fusion
    Energy Conference, Vilamoura, Portugal.
  • B.N. Rogers, Non-Curvature Driven Modes in the
    H-Mode Pedestal, presented at the Sherwood
    Conference, Missoula, MT.
  • D.W. Ross, Experimental Comparisons with
    Gyrokinetic Codes (preview talk), presented at
    the Transport Task Force Meeting, Salt Lake, UT.
  • R.E. Waltz, Advances in Comprehensive
    Gyrokinetic Simulations of Transport in
    Tokamaks", to be presented at the 20th IAEA
    Fusion Energy Conference, Vilamoura, Portugal.

10
Has the PMP produced good science?Judge for
yourselves
  • More Talks at major meetings
  • 2002
  • J. Candy, Comprehensive Gyrokinetic Simulations
    of Turbulent Transport in DIII-D with the GYRO
    Code, presented at the 44th Meeting of the
    Division of Plasma Physics.
  • J. Candy, GYRO Modeling of Anomalous Transport
    in Tokamaks, presented at the International
    Sherwood Fusion Theory Conference.
  • W. Dorland, Secondary instabilities in ETG
    Turbulence, presented at the VII Easter Plasma
    Meeting, Turin.
  • W. Dorland, Collisionless plasma turbulence,
    presented at the 29th Annual IoP Plasma Physics
    Group Conference.
  • W. Dorland, Gyrokinetic Turbulence in
    Magnetically Confined Plasmas, presented at the
    European Physical Society, Montreux.
  • F. Jenko, Simulations of finite-beta turbulence
    in tokamaks and stellarators, presented at the
    19th IAEA Fusion Energy Conference, Lyon, France.
  • Z. Lin, S. Ethier, T. S. Hahm et al., Size
    Scaling of Turbulent Transport in Tokamak
    Plasmas, presented at the 19th IAEA Fusion
    Energy Conference, Lyon, France.
  • W.M. Nevins, The Experiment/Theory Dialogue in
    the Age of Simulations, presented at the 2002
    Transport Task Force Meeting, Annapolis, MD.
  • 2001
  • B.I. Cohen, "Kinetic electron closures for
    electromagnetic simulation of drift and
    shear-Alfven waves" B.I. Cohen, et al., Phys.
    Plasmas 9, 1915 (2002)., presented at the 43rd
    Annual meeting of the Division of Plasma Physics,
    Long Beach, CA.
  • W. Dorland, Numerical Simulations and Burning
    Plasma Concepts in 2004, presented at the Fourth
    Symposium on Current Trends in International
    Fusion Research, Washington, DC.
  • T. S. Hahm, Gyrokinetic Simulation of Transport
    Scalings and Turbulent Structure, presented at
    the 43rd Annual Meeting of the Division of Plasma
    Physics, Long Beach, CA.
  • R.E. Waltz, Gyrokinetic Turbulence Simulation of
    Profile Shear Stabilization and Broken GyroBohm
    Scaling, presented at the 43rd Annual Meeting of
    the Division of Plasma Physics, Long Beach, CA.

11
Code Benchmarking RequiresError Bars on our
Measurements
Is the difference between the red and black
curves significant?
12
Uncertainty in the Estimate of the Mean (a
short detour into statistics)
Definitions
Then
13
Code Comparisons (GYRO vs. GTC)Scaling of Heat
Transport with Machine Size
14
?i(t) from GYRO GTC differ due to long-lived
transient
15
?i(t) from GYRO GTC differ due to long-lived
transient
16
The Local Transport Conjectureand the role of
flux-tube codes
  • In the limit a/??? and at each radius, ?i(r)
    from a global simulation approaches ?i from a
    flux-tube simulation with the equilibrium
    parameters evaluated at that radius.
  • Test conjecture using micro-turbulence simulation
    data
  • Strong radial variation in ?i(r) even at constant
    ?T/T
  • GS2 simulations track ?i(r) from GYRO (Candy, et
    al)
  • PG3EQ simulations also track ?i(r) from GYRO.

17
The Local Transport Conjectureand the role of
flux-tube codes
  • In the limit a/??? and at each radius, ?i(r)
    from a global simulation approaches ?i from a
    flux-tube simulation with the equilibrium
    parameters evaluated at that radius.
  • Test conjecture using micro-turbulence simulation
    data
  • Strong radial variation in ?i(r) even at constant
    ?T/T
  • GS2 simulations track ?i(r) from GYRO (Candy, et
    al)
  • PG3EQ simulations also track ?i(r) from GYRO.

18
Can local conjecture flux tube codes resolve
late-time behavior of ??? for a/??? ?
19
Can local conjecture flux tube codes resolve
late-time behavior of ??? for a/??? ?
20
Can local conjecture flux tube codes resolve
late-time behavior of ??? for a/??? ?
21
Can local conjecture flux tube codes resolve
late-time behavior of ??? for a/??? ?
Lesson We need to be humble about assigning
error bars!
22
Why long-lived transients, and why does ?i depend
on a/??Turbulence Spreading and the 4-wave model
  • PMP a/?-scan motivated series of papers on
    turbulence spreading
  • Chen et al, Phys. Plasmas 7, 3129 (2000)
  • Guzdar et al, Phys. Plasmas 8, 459 (2001)
  • Chen et al, PRL 92, 075004 (2004)
  • Zonca et al, Phys. Plasmas 11, 2488 (2004)
  • Basic plot ITG pump at kr ?i0 couples to
    sideband at finite kr ?ito produce zonal
    flow and radial propagation of ITG turbulence

Model exhibits long time-scales, intermittency,
fixed-points,
23
Is the ITG Turbulence the Same (or similar) in
PMP Codes?
GTC
  • Turbulence is stochastic
  • trying to reproduce time/space dependence is a
    fools errand
  • Need realization-independent way to characterize
    turbulence
  • Correlation functions
  • Spectral density

GYRO
24
Perpendicular Spectral DensityEarly vs.
Late-time Comparisons
25
The Radial Correlation Function
GYRO a/?-scan
PMP Code-scan
26
The Transverse Correlation Function
GYRO a/?-scan
PMP Code-scan
27
The Lagrangian Correlation Function
GYRO a/?-scan
PMP Code-scan
28
The Eddy Turnover Time
  • Eddy Turn-over Time Tracks Eddy Life-time
  • ITG turbulence saturates due to onset of ExB
    trapping
  • Suggesting that
  • If I could predict ?Eddy, thenId know ?ExB
  • If I knew ?ExB, Id know ?????
  • If I knew ?????, thenmaybe I could estimate ?i !

29
Amazingly, this program actually succeeded,
yielding (almost) everything you wanted to know
about the Cyclone ?T-Scan in 7 parameters
  • Model assumes
  • ITG turbulence saturatesby onset of ExB trapping
  • Nonlinear rates scale ?Max
  • Model successfully predicts
  • Eddy life-time
  • Eddy turn-over time
  • ExB Shearing rate
  • Correlation lengths
  • Turbulent intensity
  • ITG Transport
  • Fails to predict Dimits shift
  • Turbulence saturates before onset of ExB trapping

30
Validation of GYROagainst DIII-D Experiments
  • GYRO simulations with
  • Kinetic electrons
  • ExB shear
  • Collisions
  • Plasma shape
  • Reproduce magnitude, profile, and ?-dependence
    of DIII-D transport
  • J.Candy, Invited Talk at 2002 APS/DPP Meeting
  • Fixed-flux GYRO simulations
  • Enhance comparisons with Experiment
  • Key step toward transport time-scale and FSP
  • R. Waltz, Invited Talk at 2003 APS/DPP Meeting

31
GYRO Simulations of Turbulent Dynamo in DIII-D
L-Mode Plasma
See Hinton, F.L., R.E. Waltz, J. Candy, Effects
of Electromagnetic Turbulence in the Neoclassical
Ohms Law, Phys. Plasmas 11 (2004) 2433. An
invited talk at 2003 APS/DPP Meeting.
32
Validation of GS2 against Experiments
  • Comparisons to EDA H-mode in C-Mod tokamak
  • Nonlinear upshift in critical ?T (i.e., R/LT)
  • Importance of ?e in retaining this shift
    w/kinetic electrons
  • D. Mikkelsen, Invited talk at 2002 IAEA Mtg.
  • Comparisons with L-modein DIII-D tokamakRoss
    and Dorland, Phys. Plasmas 9, 5031 (2002)  and
    preview talk at 2004 DDT meeting

33
Is ? decreasing with V?EXB/?max a viable
paradigm?
Toroidal flow-shear does not suppress transport
?i Does not scale with V?EXB/?max
PG3EQ results presented by A. Dimits at 2001
APS/DPP Meeting
34
Electron Thermal Transport the ETG Mode
  • Electrostatic ETG and ITG nearly homologous
  • ?ETG vme/Mi ?ITG(so ETG not important?)
  • Zonal flows are nearly absent in ETG
    turbulence(so ETG is important?)
  • Absence of zonal flows
  • Streamers, significant ETG transport
  • Dorland et al, PRL 85, 5579 (2003)
  • Streamers, but no significant ETG transport
  • Lin et al, TTF04 oral talk at 2004 IAEA Mtg.
  • This issue yet to be resolved
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