# Presentation: 939326

## The Plasma Microturbulence Project

- W.M. Nevins (     )
- For the
- Plasma Microturbulence Project Team

- UCLA

- UCI

- W.M. Nevins

- June 3, 2004

## 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)

- W.M. Nevins

- June 3, 2004

## 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

- W.M. Nevins

- June 3, 2004

## A PIC algorithm for kinetic e’s and BBenchmarking GEM against GYRO and GTC

- Linear Growth Rates

- Turbulent Transport

- W.M. Nevins

- June 3, 2004

## 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.](http://gs2.sourceforge.net/)__[sourceforge](http://gs2.sourceforge.net/)__[.net/](http://gs2.sourceforge.net/)_     and    _[http://fusion.gat.com/comp/parallel/gyro.html](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

- W.M. Nevins

- June 3, 2004

## 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

- PMP Codes Scale to large numbers of processors:GYRO is a benchmark code for the ORNL Cray X-1GTC ported to both ORNL Cray X-1and Japanese Earth Simulator

- For details on GYRO performance, see http://fusion.gat.com/comp/parallel/performance.html

- GYRO
- constant problem size

- GTC
- problem size with Nprocessors

- For details on GTC performance, see http://gk.ps.uci.edu/zlin/parallel/index.html

- W.M. Nevins

- June 3, 2004

## 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 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 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)

- W.M. Nevins

- June 3, 2004

## 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.
- Y. Chen and S.E. Parker, Journal of Computational Physics **189** (2), 463-475.
- 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**, 1121.
- C. Holland, P.H. Diamond, S. Champeaux *et al*., Nuclear Fusion **43** (8), 761.
- W.W. Lee and H. Qin, Phys. Plasmas **10**, 3196.
- J. L. V. Lewandowski, Phys. Plasmas **10**, 3204.
- 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**, 1029.

** **
**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.

- W.M. Nevins

- June 3, 2004

## 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.

**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.

- W.M. Nevins

- June 3, 2004

## 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.

- W.M. Nevins

- June 3, 2004

## Code Benchmarking RequiresError Bars on our “Measurements”

- Is the difference between the **red** and **black** curves significant?

- W.M. Nevins

- June 3, 2004

## Uncertainty in the Estimate of  the Mean (a short detour into statistics)

- Definitions:

- Then:

- W.M. Nevins

- June 3, 2004

## Code Comparisons (GYRO vs. GTC)Scaling of Heat Transport with Machine Size

- W.M. Nevins

- June 3, 2004

## i(t) from GYRO & GTC differ due to long-lived transient

- W.M. Nevins

- June 3, 2004

## i(t) from GYRO & GTC differ due to long-lived transient

- W.M. Nevins

- June 3, 2004

## 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.

- W.M. Nevins

- June 3, 2004

## 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.

- W.M. Nevins

- June 3, 2004

## Can local conjecture & flux tube codes resolve late-time behavior of  for a/ ?

- W.M. Nevins

- June 3, 2004

## Can local conjecture & flux tube codes resolve late-time behavior of  for a/ ?

- W.M. Nevins

- June 3, 2004

## Can local conjecture & flux tube codes resolve late-time behavior of  for a/ ?

- W.M. Nevins

- June 3, 2004

## Can local conjecture & flux tube codes resolve late-time behavior of  for a/ ?

- Lesson:  We need to be “humble” about assigning error bars!

- W.M. Nevins

- June 3, 2004

## Why long-lived transients, and why does i depend on a/?Turbulence Spreading and the 4-wave model

- 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 *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, ...

- W.M. Nevins

- June 3, 2004

## 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

- W.M. Nevins

- June 3, 2004

## Perpendicular Spectral DensityEarly vs. Late-time Comparisons

- W.M. Nevins

- June 3, 2004

**Notes:**
Figure IV.G.2.  (a) A cut of the perpendicular spectral density at kr=0 from a GTC simulation of the CYCLONE base case at a/s=500 (black curve), from the early non-linear phase(red curve), and the late non-linear phase of the corresponding GYRO simulation.  For reference, the toroidal mode number, N = 209 ks.  (b) The perpendicular spectral density integrated over k is displayed as a  function of kr for the same simulations and time intervals.

## The Radial Correlation Function

- GYRO
- a/-scan

- PMP
- Code-scan

- W.M. Nevins

- June 3, 2004

**Notes:**
Fig. IV.A.1.  (a) The radial correlation function from GYRO simulations with a/s= (black), a/s=105 (blue), a/s=210 (red), a/s=375 (green), a/s=500(cyan) and a/s=700 (gold). (b) The radial correlation function from GYRO with a/s= (black), GYRO with a/s=500 (red), GTC with a/s=500 (blue), PG3EQ (green) and GS2 (cyan).  For global simulations the radial correlation function is averaged over the interval 0.42 < r/a < 0.58 r/a, while it is averaged the entire radial domain in flux-tube simulations

## The Transverse Correlation Function

- GYRO
- a/-scan

- PMP
- Code-scan

- W.M. Nevins

- June 3, 2004

**Notes:**
Figure IV.E.1.  The transverse correlation function. (a) The transverse correlation function is plotted vs. y for a sequence of GYRO simulations having a/s= (black), 105 (red), 210 (blue), 375 (green), 500 (cyan) and 700 (gold). (b) The transverse correlation function is plotted vs. y for simulations of the CYCLONE base case using different codes, including a GYRO flux-tube simulation (black), a GYRO global simulation with a/s=500 (red), a GTC global simulation with a/s=500 (blue), a GTC simulation with a/s=125 (green), a PG3EQ flux-tube simulation (cyan) and a GS2 flux-tube simulation (gold).

## The Lagrangian Correlation Function

- GYRO
- a/-scan

- PMP
- Code-scan

- W.M. Nevins

- June 3, 2004

**Notes:**
Figure IV.D.1. The Lagrangian correlation function vs. a/s.  The Lagrangian correlation function evaluated at =0 (the outboard mid-plane) and averaged over 0.42 < r/a < 0.58 (for global simulations with a/s finite) or over the entire radial domain (for flux-tube simulation with a/s=). Data from (a) a sequence of GYRO simulations having a/s= (black), 105 (red), 210 (blue), 375 (green), 500 (cyan) and 700 (yellow ); and (b) various PMP codes, including a GYRO at a/s= (black), GYRO at a/s=500 (red), GTC at a/s=500 (blue), PG3EQ (green) and GS2 (cyan).

## 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*,*** ***thenI’d know ***ExB*

- If I knew ***ExB**,* I’d know ******

- If I knew ******, thenmaybe I could estimate ***i *!

- The Eddy Turnover Time

- W.M. Nevins

- June 3, 2004

## 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

- W.M. Nevins

- June 3, 2004

## 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]

- W.M. Nevins

- June 3, 2004

## 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) 2433.  An invited talk at 2003 APS/DPP Meeting.

- W.M. Nevins

- June 3, 2004

## 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 tokamak[Ross and Dorland, Phys. Plasmas **9**, 5031 (2002)  and “preview” talk at 2004 DDT meeting]

- W.M. Nevins

- June 3, 2004

## 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

- W.M. Nevins

- June 3, 2004

## Electrostatic ETG and ITG  nearly homologous
ETG~ √me/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

- ETG~ √me/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

- Electron Thermal Transport & the ‘ETG’ Mode

- W.M. Nevins

- June 3, 2004