Present Status of TRANSP and PTRANSP for Fusion Energy Experiments

1. Status of TRANSP and PTRANSP Presented at APS-DPP 2008, Nov. 17--21, 2008 *Supported by U.S. DOE Contract No. DE-AC02-76CH03073 D. McCune

2. Abstract – BP6.0055 D. McCune, R. Andre, E. Feibush, K. Indireshkumar, C. Ludescher-Furth, L. Randerson, PPPL*, H. St. John, General Atomics, G. Bateman, F. Halpern, A. Kritz, Lehigh University, L. Lodestro, W. Meyer, D. Pearlstein, LLNL**– The PPPL TRANSP code suite is a set of tools for time dependent simulation of axisymmetric tokamak plasmas. While the code has historically been used primarily for analysis of experimental results, predictive modeling enhancements to TRANSP have been carried out under the PTRANSP project. TRANSP and PTRANSP are now both deployed as Fusion Grid services at PPPL, supporting an international user base. The status of TRANSP and PTRANSP code development, as well as trends in production use, are presented here. New and developing features, such as the solution of free boundary MHD equilibria, the use of advanced solvers for prediction of the evolution of plasma density, angular momentum, and temperature profiles, are emphasized. The status of MPI parallelizatoin of TRANSP components is described. A recent positive development has been the beneficial collaboration between TRANSP/ PTRANSP and SciDAC FSP prototype projects SWIM and FACETs, with code components being shared effectively across all of these efforts. *PPPL work performed under auspices of DOE contract DE-AC02-76CH03073 **LLNL work performed under auspices of DOE contract DE-AC52-07NA27344 D. McCune

3. TRANSP: Vision Statement Provide a comprehensive end-to-end modeling capability for magnetic confinement fusion energy experiments of today and tomorrow. D. McCune

4. Traditional TRANSP: Overview Experiments (Asdex-U, C-Mod, DIII-D, ITER, JET, KSTAR, MAST, NSTX) MDS+ 20-50 signals {f(t), f(x,t)} Plasma position, Shape, Temperatures, Densities Field, Current, RF and Beam Injected Powers. Preliminary data Analysis and Preparation (largely automated) Diagnostic Hardware Pre- and Post-processing at the experimental site… MDS+ TRANSP Analysis*: Current diffusion, MHD equilibrium, fast ions, heating, current drive; power, particle and momentum balance. Experiment simulation Output Database ~1000-2000 signals {f(t), f(x,t)} Visualization Load Relational Databases Detailed (3d) time-slice physics simulations: GS2, ORBIT, M3D… *FusionGrid TRANSP on PPPL servers D. McCune

5. PPPL TRANSP Run Production* Fusion Grid TRANSP *Not shown in graphic: independent run production at JET site (approximately 1000 runs); quasi-production use of development versions in PTRANSP project (estimated to be 100s of runs). D. McCune

6. PPPL TRANSP SERVICEFY-2005 through FY-2008 *~3000 additional JET runs on JET production server. 12868 Total Runs D. McCune

7. FY-2008 PPPL TRANSP Team Color code: Physics, Visualization, Engineering/ Operational Support D. McCune

8. TRANSP Staffing Level • Staff levels found to be insufficient: • Cannot promptly meet code development requests of production users; • Long term development projects have lagged. • Main reason: production system support. • 100s of crashed TRANSP runs per year, each requiring individual, detailed investigation. • New hire in FY-2009: Marina Gorelenkova. • Financed by experimental projects. D. McCune

9. TRANSP Development • Plasma State Module (collaboration with SWIM SciDAC). • MPI Parallelization of code components. • NUBEAM Upgrades. • Monte Carlo RF Operator. • TORIC. • GENRAY / CQL3D. • User interfaces (ElVis; web services). D. McCune

10. Standardized repository for tokamak simulation data: MHD Equilibrium Profiles Species Lists, etc. Used in PTRANSP, SWIM, FACETS. NUBEAM coupled. GENRAY in progress. SciDAC Plasma State Module Simulation Driver ECH/LH Module NBI module ICRF module Instance of Plasma State Control Channel Data Channel D. McCune

11. Common Coupling to NUBEAM • Based on SWIM SciDAC Plasma State: • call nubeam_ctrl_init(ps_in,init_ctrl,status) • call nubeam_ctrl_step(ps_in,ps_out,step_ctrl,status) • Plasma State objects: ps_in, ps_out. • NUBEAM-specific control objects: init_ctrl, step_ctrl. • integer return code: status. • Interface used now by TRANSP. • Expected to be used by SWIM & FACETs SciDAC projects. D. McCune

12. Plasma State Provides Infrastructure for Module Coupling • TRANSP now provides Plasma States for use by heating and current drive codes. • GENRAY and CQL3D use this interface now in SWIM project. • Plan to leverage this development to import GENRAY and CQL3D into TRANSP. • Beneficial collaboration with SciDACs! D. McCune

13. TRANSP MPI Parallelization Methods Investigated • Client-Server: Single MPI server serves multiple serial clients: • Advantage: shared use of MPI machines. • Drawbacks: complexity, performance (file transport). • MPI Subprocess Coupled by Plasma State: • Advantage: simplicity, process level code sharing. • Drawback: performance (use of file I/O); load balance*. • Single MPI image: • Advantage: MPI module performance (avoid file I/O). • Drawback: interface / build complexity; load balance*. *MPI machines idle during execution of serial sections of TRANSP. D. McCune

14. NUBEAM Upgrades • MPI Parallelization – BP6.0057 (Kumar) • Planned: Diagnostic Simulation Upgrades: • GC f(E,vpll/v,x,theta) based NPA simulator. • 3d Halo Neutral Density. • Investigations: • Orbit averaging techniques (reduce variance in momentum sources and charge exchange loss model). • Beam-resolved outputs & other requests… D. McCune

15. MPI for more Particles, Better Statistics in Distribution Functions 10K particles 100K particles Plots provided by MAST Team D. McCune

16. Monte Carlo RF Operator in NUBEAM • Method based on TORIC wave fields was investigated by visiting Post Doc last year. • Model was able to couple power to MC fast ion population. • Statistics: MPI absolutely required. • Post Doc (Dr. Jae-Min Kwon) returned to Korea. • We don’t have the staff to pursue this… D. McCune

17. TORIC Full Wave ICRF Code • Collaboration with CMod, JET, NSTX, and TORIC authors at IPP/Garching. • TRANSP now coupled to IPP/Garching TORIC svn repository; up-to-date TORIC version now available in TRANSP. • Plasma State upgrade– HHFW TORIC can now be run: • Support NSTX experiments • Permit scenarios other than minority heating. D. McCune

18. GENRAY/CQL3D Coupling • Plasma State interface built for standalone GENRAY and CQL3D operation. • Effort by B. Harvey supported by PPPL TRANSP team as part of SWIM SciDAC Collaboration. • Foundation Laid for coupling GENRAY and CQL3D into TRANSP. D. McCune

19. Development of User Interfaces • Web-based NSTX Between Shots Analysis user interface. • Prototypes for time-slice post-analysis: • Linear stability: Balloon, Pest, Nova-K. • Turbulent transport: GTS • Methods based on extraction of TRANSP time slices as Plasma States; MHD equilibrium refinement by JSolver. • Poster by E. Feibush: BP6.0054 D. McCune

20. Between Shots TRANSP Service D. McCune

21. PTRANSP Developments: General Atomics, Lehigh U., LLNL, PPPL • Production Use. • MHD Equilibrium Solvers: • Free Boundary Solutions; rotation pressure modification. • Coupled Poloidal Field Diffusion: NTCC module under development by LLNL. • Transport Equation Solvers: • Density Prediction. • Incorporation of TGLF Transport Model. D. McCune

22. PTRANSP Production Use • 263 Full Discharge ITER PTRANSP Simulations In FY-2008. • Accounted for nearly 60% of cpu-time usage of entire PPPL TRANSP service. • PTRANSP-based Publications: • Four ITER papers in FY-2007 and FY-2008. • Four more currently in preparation. • IAEA validation study using JET, DIII-D data. • Authors: R. Budny, G. Bateman, F. Halpern, A. Kritz (PPPL / Lehigh University collaboration). D. McCune

23. PTRANSP Implementation of TEQ Free Boundary Solver– see BP6.056 (Andre). Limiter • TRANSP/PTRANSP has successfully been using the TEQ fixed boundary solver for over two years. • Reasonably robust and very accurate • Has become the preferred fixed boundary solver • The TEQ free boundary solver is invoked over the fixed solver by a single namelist change. • NTEQ_MODE=102 causes <J.B> to be used in a free boundary solution when TEQ (LEVGEO=11) is being used. • The prescribed boundary given as input to PTRANSP is used to select fuzzy boundary points for TEQ. The coil currents are constrained in a least squares manner so that the plasma boundary lies on the fuzzy boundary points. • To startup the run an existing free boundary solution of the tokamak is read into TEQ and perturbed through multiple invocations of TEQ to the starting conditions of the shot. • A q mode free boundary solution will be made available after further development of the magnetic field diffusion in PTRANSP. • An alternate free boundary solution is available in TRANSP through the PPPL ISolver code. This has been used to test the effects related to plasma toroidal rotation. Coil Plasma Fuzzy Boundary Point X point D. McCune

24. LLNL Report: RMHD (Resistive MHD Code) Coupling TEQ & Bpol Diffusion. • 1D transport (C++) and its connection logic to F90. Includes the diffusion equations’ numerical coef.’s and sources; and 1D solver. • Corsica F90 source (tor.f90) • Provides the transformations btw the equilibrium coordinates (poloidal flux) and the independent transport coordinate. • Logic to obtain the conductivity and bootstrap current using either neoHS (LLNL) or NCLASS (NTC). • Corsica run-time scripts --> transStep.f90 • Provides time step logic, restart capability, and time history of selected variables. In addition, contains the circuit-equation logic. Work in Progress: Parts 1 and 2 are complete. Part 3 remains. D. McCune

25. New PTRANSP Features Added by Lehigh Group - 1 • Expanded choice of theory-based transport models: • New MMM08 model for particle, momentum and thermal transport • Posters BP6.00059 and BP6.00060 Monday morning by F.D. Halpern, A.H. Kritz, et al. • GLF23 particle, momentum and thermal transport • MMM95 particle and thermal transport • NCLASS neoclassical particle and thermal transport as well as computation of radial electric field and neoclassical electrical resistivity • Improved choice of predictive sawtooth oscillation models: • Porcelli model for triggering sawtooth crashes and partial mixing • Porcelli sawtooth trigger can also be used with older Kadomtsev sawtooth mixing model • Park-Monticello model for triggering sawtooth crashes • Prescribed sawtooth period D. McCune

26. New PTRANSP Features Added by Lehigh Group - 2 • Predictive transport modeling for density, momentum and temperature • Unified system of predictive transport equations are advanced in time using consistent numerical algorithms and time-step control • See poster BP6.00058 Monday morning by G. Bateman et al. • Boundary conditions from predictive pedestal model or experimental data • Can select subset of profiles to be obtained from experimental data • Gas puffing feedback loop implemented for predictive particle transport • Controls average electron density with prescribed Zeff profile vs time • Implemented choice of techniques in the new combined system of transport equations to control numerical problems : • Pereverzev-Corrigan numerical technique provides fast, simple controlsee Comput. Phys. Comm. 179 (2008) 579 • Tends to slow down transient behavior • Newton’s method, see Jardin et al., J. Comp. Phys. 227 (2008) 8769 • More computational effort than the Pereverzev-Corrigan method, but Newton’s method can provide improved treatment of transient conditions • Older time-averaging methods D. McCune

27. Access to TGLF via GCNMP (General Atomics) • Holger St. John – poster TP6.0026 • Will need to use TRANSP’s new Plasma State based MPI module coupling method. • TGLF very computationally expensive! • Ongoing PPPL/GA collaboration: Plasma State pairs define prediction problem. • Human iterations needed to complete definition and agree on interface methods. D. McCune

28. Summary • Important new capabilities– MPI, Free MHD Boundary, PTRANSP, NUBEAM Upgrades. • Ambitious development program– more MPI, PTRANSP, access to SciDAC RF codes via Plasma State. • Labor Constraint: budget << $25M/year! • All fusion transport codes = FSP wannabes. • Operation of production system delivers V&V of (P)TRANSP simulations to user community but imposes a heavy labor burden (FSP take note!). D. McCune