June 3, 2004W.M. Nevins1 The Plasma Microturbulence Project W.M. Nevins ( ) For the Plasma Microturbulence Project Team

June 3, 2004W.M. Nevins2 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 we’ve 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 we’ve done)

June 3, 2004W.M. Nevins3 Four GK “kernels” — a 2x2 Matrix of Plasma Turbulence Simulation Codes Why both Continuum and Particle-in-Cell (PIC)? –Cross-check on algorithms –Continuum currently most developed (already has kinetic e’s,  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,  e =c/  pe ) physics (ETG modes, etc.) –Turbulence on multiple space scales (ITG+TEM, TEM+ETG, ITG+TEM+ETG, …) –Efficient parameter scans

June 3, 2004W.M. Nevins4 A PIC algorithm for kinetic e’s and  B  Benchmarking GEM against GYRO and GTC Linear Growth Rates Turbulent Transport

June 3, 2004W.M. Nevins5 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: and 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

June 3, 2004W.M. Nevins6 PMP Codes Scale to large numbers of processors: GYRO is a benchmark code for the ORNL Cray X-1 GTC ported to both ORNL Cray X-1and Japanese Earth Simulator For details on GYRO performance, see GYRO constant problem size GTC problem size  with N processors For details on GTC performance, see

June 3, 2004W.M. Nevins7 SciDAC Computing Resources Enabled 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 allocation2M 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 doesn’t 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 PI’s, not that of our user-community)

June 3, 2004W.M. Nevins8 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, 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, W. W. Lee, Comput. Phys. Comm.. Z. Lin and T. S. Hahm, Phys. Plasmas 11, S.E. Parker, Y. Chen, W. Wan et al., Phys. Plasmas 11, 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 C. Bourdelle, W. Dorland, X. Garbet et al., Phys. Plasmas 10, J. Candy and R.E. Waltz, Phys. Rev. Lett. 91, J. Candy and R.E. Waltz, J. Comp. Phys. 186, 545. Y. Chen and S.E. Parker, Journal of Computational Physics 189 (2), Y. Chen, S.E. Parker, B.I. Cohen et al., Nucl. Fusion 43, 1-7. Y. Chen, S.E. Parker, B.I. Cohen et al., Nuclear Fusion 43, C. Holland, P.H. Diamond, S. Champeaux et al., Nuclear Fusion 43 (8), 761. W.W. Lee and H. Qin, Phys. Plasmas 10, J. L. V. Lewandowski, Phys. Plasmas 10, J. L. V. Lewandowski, Plasma Phys. Controlled Fusion 45, L39. T. S. Pedersen, A. H. Boozer, et al., J. Phys. B: At. Mol. Opt. Phys. 36, R. V. Budny, R. Andre, et al., Plasma Phys. Control. Fusion 44, 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), Bruce I. Cohen, Andris M. Dimits, et al., Phys. Plasmas 9 (5), T. S. Hahm, Plasma Phys. Controlled Fusion 44, A87. F. Jenko and W. Dorland, Phys. Rev. Lett. 89, Z. Lin, S. Ethier, T. S. Hahm et al., Phys. Rev. Lett. 88, D. W. Ross, R. B. Bravenec, W. Dorland et al., Phys. Plasmas 9, 177. D. W. Ross and W. Dorland, Phys. Plasmas 9, 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, A.M. Dimits, B.I. Cohen, W.M. Nevins et al., Nuclear Fusion 41, I. H. Hutchinson, R. Boivin, P. T. Bonoli et al., Nucl. Fusion 41, F. Jenko, W. Dorland, and G. W. Hammett, Phys. Plasmas 8, W. W. Lee, J. L. V. Lewandowski, T. S. Hahm et al., Phys. Plasmas 8, Z. Lin and L. Chen, Phys. Plasmas 8, 1447.

June 3, 2004W.M. Nevins9 Has the PMP produced good science? Judge for yourselves 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 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.

June 3, 2004W.M. Nevins10 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 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.

June 3, 2004W.M. Nevins11 Code Benchmarking Requires Error Bars on our “Measurements” Is the difference between the red and black curves significant?

June 3, 2004W.M. Nevins12 Uncertainty in the Estimate of the Mean (a short detour into statistics) Definitions: Then: Real data has “trends” which must be  Removed from   Added back to our error estimate (and I’m still not completely satisfied …)

June 3, 2004W.M. Nevins13 Code Comparisons (GYRO vs. GTC) Scaling of Heat Transport with Machine Size

June 3, 2004W.M. Nevins14  i (t) from GYRO & GTC differ due to long-lived transient

June 3, 2004W.M. Nevins15  i (t) from GYRO & GTC differ due to long-lived transient

June 3, 2004W.M. Nevins16 The Local Transport Conjecture and 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.

June 3, 2004W.M. Nevins17 The Local Transport Conjecture and 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.

June 3, 2004W.M. Nevins18 Can local conjecture & flux tube codes resolve late-time behavior of  for a/  ?

June 3, 2004W.M. Nevins19 Can local conjecture & flux tube codes resolve late-time behavior of  for a/  ?

June 3, 2004W.M. Nevins20 Can local conjecture & flux tube codes resolve late-time behavior of  for a/  ?

June 3, 2004W.M. Nevins21 Can local conjecture & flux tube codes resolve late-time behavior of  for a/  ? Lesson: We need to be “humble” about assigning error bars!

June 3, 2004W.M. Nevins22 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, (2004) Zonca et al, Phys. Plasmas 11, 2488 (2004) Basic plot: ITG “pump” at k r  i ≈0 couples to “sideband” at finite k r  i to produce “zonal flow” and radial propagation of ITG turbulence: Model exhibits long time-scales, intermittency, fixed-points, …

June 3, 2004W.M. Nevins23 Is the ITG Turbulence the Same (or similar) in PMP Codes? Turbulence is stochastic  trying to reproduce time/space dependence is a fool’s errand Need realization-independent way to characterize turbulence –Correlation functions –Spectral density GYRO GTC

June 3, 2004W.M. Nevins24 Perpendicular Spectral Density Early vs. Late-time Comparisons

June 3, 2004W.M. Nevins25 The Radial Correlation Function GYRO a/  -scan PMP Code-scan

June 3, 2004W.M. Nevins26 The Transverse Correlation Function GYRO a/  -scan PMP Code-scan

June 3, 2004W.M. Nevins27 The Lagrangian Correlation Function GYRO a/  -scan PMP Code-scan

June 3, 2004W.M. Nevins28 Eddy Turn-over Time Tracks Eddy Life-time  ITG turbulence saturates due to onset of ExB trapping Suggesting that:  If I could predict  Eddy, then I’d know  ExB  If I knew  ExB, I’d know     If I knew   , then maybe I could estimate  i ! The Eddy Turnover Time

June 3, 2004W.M. Nevins29 Amazingly, this program actually succeeded, yielding (almost) everything you wanted to know about the “Cyclone”  T-Scan in 7 parameters Model assumes: –ITG turbulence saturates by 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

June 3, 2004W.M. Nevins30 Validation of GYRO against 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]

June 3, 2004W.M. Nevins31 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 Ohm’s Law,” Phys. Plasmas 11 (2004) An invited talk at 2003 APS/DPP Meeting.

June 3, 2004W.M. Nevins32 Validation of GS2 against Experiments Comparisons to EDA H-mode in C-Mod tokamak –Nonlinear upshift in critical  T (i.e., R/L T ) –Importance of e in retaining this shift w/kinetic electrons [D. Mikkelsen, Invited talk at 2002 IAEA Mtg.] Comparisons with L-mode in DIII-D tokamak [Ross and Dorland, Phys. Plasmas 9, 5031 (2002) and “preview” talk at 2004 DDT meeting]

June 3, 2004W.M. Nevins33 Is  decreasing with V EXB /  max a viable paradigm?  i Does not scale with V EXB /  max Toroidal flow-shear does not suppress transport PG3EQ results presented by A. Dimits at 2001 APS/DPP Meeting

June 3, 2004W.M. Nevins34 Electrostatic ETG and ITG nearly homologous –  ETG ~ √m e /M i  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 Electron Thermal Transport & the ‘ETG’ Mode