1D. McCune

PTRANSP

Predictive Upgrades for TRANSP

2D. McCune

US Predictive Modeling Effort

• R. Budny, S. Jardin, C. Kessel, L. P. Ku, D. McCune (PPPL).

• H. St. John (GA).

• D. P. Grote, L. Lodestro, L. D. Pearlstein, T. D. Rognlien (LLNL).

• G. Bateman, F. Halpern, A. Kritz (Lehigh).

• J. Carlsson (Tech-X).

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PTRANSP Plan• Leverage TRANSP:

– Well validated source models (NBI, alphas, ICRF, LH, ECH/ECCD).

– Strong connection to experimental data.– Fusion Grid production facility.

• Add predictive capabilities to TRANSP:– Robust transport equation solver.– Free boundary equilibrium.– Connection to edge model.

• Reuse existing software to extent possible.

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Design Principles - 1

• Reuse TRANSP and Fusion Simulation Project (FSP) software (to minimize costs).

• Two driver configurations:– Free boundary: (TRANSP computes sources;

analyzes free boundary code results).– Prescribed boundary: traditional TRANSP

with:• New transport solvers (FSP Solver, GCNM-P).• New MHD equilibrium solvers (FSP, TEQ).

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Design Principles - 2

• Modular design: interchangeability of critical parts (create/use NTCC modules):– Transport solvers.– MHD equilibrium solvers.– Sources.

• Leverage TRANSP archives:– Access to experimental data for validation.– NTCC module provided for data access.

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Solver Equilibrium Sources

GCNMP

FSP-Sol

Controller

TEQ

FSP-Equ

ESC

TRANSP

Plasma State

TRDATBUF (access to experimental data)

FSP-Src

XPLASMA (FSP upgrade in progress)

Edge AnalysisStability Analysis

Postprocessing (initially)

Sawtooth

Edge Pedestal

Bootstrap Curr

NCLASS

Hirsh-Sig.

Lehigh

PPPL

Porcelli-L

Porcelli-P

UEDGE

DEGAS-2

DCON

PEST-2

PTRANSP Schematic

TRANSP-based controller

FSP-based controller

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Transport Solver Dilemma

• Current predictive transport models (e.g. GLF-23) are very stiff.

• Standard numerical integration methods suffer severe oscillations and instability.

• Attempts to “smooth” GLF-23 directly significantly changes prediction results.

• Therefore: serious solver upgrade effort.– GCNM-P (General Atomics) & FSP (PPPL).

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Transport Solvers

• GCNM – Globally Convergent Newton Method – ONETWO Solver (St. John, GA).– Very general stiff PDE integrator.– Use of Jacobian, O(n**2) execution cost.

• FSP Solver (Jardin & Ku, PPPL).– “Local” Newton method– forward implicit use

of dependence of transport on grad(Ti,Te,…).– O(n) but may not be as stable as GCNM.

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The PTRANSP FSP Solver - 1This has been implemented in the full solver in the FSP:

Without linearization With linearization

• ITER simulation• Linearization of dependence of GLF-23 fluxes on temperature gradients.• Behavior reproducible in simplified single-T analytic transport model.• Caveat: DIII-D experimental data validation attempt– not yet fully stable.

S. Jardin / L. P. Ku

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The PTRANSP FSP Solver - 2Convergence Tests:

3 Newton iterations per timestep

Double # of zones Reduce timestep by 3

Base case: 1 Newton iteration per timestep

S. Jardin / L. P. Ku

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Results for a 500s ITER run:

Profiles at 250s

Chi Values for entire run

Powers vs time

ions

electrons

Chi vs radius at 250s

ions

electrons

S. Jardin / L. P. Ku

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PTRANSP Progress - 1

• Predictive Solver Improvement (as shown).– Both FSP solver and GCNM at GA.

• TRANSP Improvements:– Export of source calculation results.– Accommodation of free boundary equilibrium.– Modification of internal loop structure to allow

import of stiff transport solver results.

• Trdatbuf_lib NTCC module– access to TRANSP input data (experimental data).

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PTRANSP Progress - 2

• LLNL’s TEQ free boundary solver module in TRANSP.– NTCC module standards with error handling

enhancement.– Time dependent NSTX test results look good.

• UEDGE/TRANSP coupling:– LLNL design and prototype in place.– Includes TRANSP/UEDGE data exchange

schema.

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PTRANSP Progress - 3

• NTCC PEDESTAL module– predictive boundary condition option.– Lehigh University team making direct

modifications to TRANSP (in progress).– Prototype installation in BALDUR.– Experience with L to H transition dynamics.

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PTRANSP’s Next Step – APSPTRANSP’s Next Step – APS

• Drive TRANSP with ITER free boundary simulation:– TRANSP provides heating and current drive.– TRANSP uses free boundary simulation

predicted temperatures and equilibria.• Architecture compatible with density prediction but

testing of this capability likely to be postponed.

– TRANSP archive produced:• Available as input to UEDGE, linear stability

solvers, etc.

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Summary

• The PTRANSP project will provide a community predictive transport code with state-of-the-art capabilities.

• Like TRANSP itself, it will run as a Fusion Grid production service with world wide access.

• Control options will be provided for prescribed boundary or free boundary operation.

• Example of integrated ITER simulation with realistic sources by APS-2006.