T.A. Casper, ITPA IOS Kyoto Japan1

Summary of ITER scenario work

ITPA IOS MeetingOctober 18 – 21, 2011

Kyoto, Japan

T. A. Casper, D. Campbell, Y. Gribov, S.H. Kim*, T. Oikawa, A. Polevoi, J.A. Snipes, A. Winter, and L. Zabeo ITER Organization, Route de Vinon sur Verdon, 13115 St Paul Lez Durance, France

*Monaco post doctoral program at ITER

Acknowledgement: CORSICA supportR. Bulmer, L.L. LoDestro, W.H. Meyer, and L.D. Pearlstein,

Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, CA USA 94550

T.A. Casper, ITPA IOS Kyoto Japan2

Modeling development for ITER scenarios: 1D transport + 2D equilibrium only (does not include other modeling work at ITER) Scenario development that requires lots of parameter variation studies can

and often is done with prescribed boundary evolution Controller development and evaluation of engineering constraints require

free-boundary with coupling to external systems Scenarios of interest:

Full field scenarios at BT=5.3T in H-mode: Baseline inductive: IP=15MA, Q=10, Pfus=500MW, to 400s duration Advanced inductive or hybrid: IP=12.5MA, Q=5, 1000s duration Steady-state: IP=9MA, Q=5, steady state – likely internal transport barrier

Low-activation scenarios: DD at IP=7.5MA and BT=2.65T (half IP, BT) Under development and of current interest for early experiments

Non-activation scenarios: H or He operations at reduced IP, BT

New interest for modeling to minimize CS coil demands MHD evaluation for scenarios

T.A. Casper, ITPA IOS Kyoto Japan3

Approaches leading to development of ITER scenarios Internal at the IO

To develop internal ideas quickly and to test concepts Build on and supplement work done outside the IO Rapid response to committees and engineering design crises Provide data to external research efforts, e.g. equilibria, profiles, constraints, etc.

Funded ITER tasks Major efforts to scope out scenarios and/or design modifications – longer term Contracts and must be competed among the DAs, a somewhat slow process

Volunteer – many efforts in DA programs typically coordinated by ITPA Benchmarking with experimental data Model and code validation Modeling scenarios and detailed physics aspects – a few recent examples:

ISM coordinated effort in EU (Litaudon) – several codes and variety of topics Individual efforts in scenarios with both DINA(Russia) and TSC(US) Data sent for many physics studies: BOUT and ELITE edge stability, MHD evaluation,

ECH study, RMP study, first wall evaluation, runaways, ripple loss, etc. etc. etc.

T.A. Casper, ITPA IOS Kyoto Japan4

Recent ITER tasks and internal studies have advanced understanding of likely ITER performance: mostly CORSICA, DINA, and TSC Current modeling includes latest modifications to ITER systems

coil and first wall geometry (may change again) power systems and source design parameters Increasing awareness of the divertor and first wall

Baseline inductive modeling – successful scenarios within operating space Kessel, C.E. et al Nucl. Fusion 49 (2009) 085034 Casper, T. et al accepted Nuc. Fusion 51(2011) ; in Fusion Energy 2010 (Proc.

23rd Int. Conf. Daejeon, 2010) (Vienna: IAEA) CD-ROM file ITR/P1-19 http://www-naweb.iaea.org/napc/physics/FEC/FEC2010/html/index.htm

ITER tasks and efforts at the IO advanced modes: advanced inductive (hybrid) and steady-state scenarios (Gormezano, C. et al Nucl. Fusion 47 (2007) S285-S336) Kessel, C.E. et al in Fusion Energy 2010 (Proc. 23rd Int. Conf. Daejeon, 2010)

(Vienna: IAEA) CD-ROM file ITR/P1-22 and http://www-naweb.iaea.org/napc/physics/FEC/FEC2010/html/index.htm

EU/F4E modeling effort currently in progress – results later today? IO modeling effort started for hybrid mode: Sun Hee Kim presentation

T.A. Casper, ITPA IOS Kyoto Japan5

Voluntary efforts have contributed significantly to ITER scenario development understanding – for example, a recent STAC report:

TOPICS-1B: N. Hayashi et al., Final Report on the ITER Task Agreement C19TD26FJ ITER_D_48DP5Z, 24 February 2011.

CRONOS: J. Citrin et al., Nucl. Fusion 50 115007 (2010).

Code-code comparison for steady-state scenariosMurakami, M. et al. Nucl. Fus. 51 103006 (2011).

T.A. Casper, ITPA IOS Kyoto Japan6

CORSICA: Current emphasis for modeling at the IO is control of scenarios and development of the plasma control system (PCS)

2D equilibrium + 1D transport predictive modeling code provides capability for controller simulations - applied to shape, vertical stability and profile control

Crotinger, J.A. et al LLNL Report UCRL-ID-126284,1997 NTIS #PB2005-102154 Full free-boundary GS solutions with various transport models - control of the

evolution of plasma shape, vertical position and kinetic profiles Simultaneously converges free-boundary equilibrium with transport at each

time step – solutions always self-consistent Calculates sources each time step - needed for feedback control applications

Monte-Carlo NBI with orbits and Toray-GA ECH/ECCD – previously used for DIII-D modeling and updated for ITER by Sun Hee Kim

ICH and LH capability recently added by Sun Hee Kim DCON for time-dependent MHD stability assessment Coupled with simulink control environment - independently executing and

connected with RPCs (Meyer, W. et al, IAEA-TM, San Francisco June 2011) Modular, customizable with interruptable work flows from interpretive

scripting language interface – flexible and extensible environment

T.A. Casper, ITPA IOS Kyoto Japan7

Elements in place at ITER for a PCS simulator: ITER control methods, JCT2001 controller, CORSICA implementation

(b) Corsica realization of control simulator Casper, T.A. et al, FED 83 (2008) 552-556

(c) ITER shape and vertical position control

(d) JCT2001 controller

T.A. Casper, ITPA IOS Kyoto Japan8

CORSICA (or any code, e.g. DINA, TSC) free-boundary capabilities are required for controller modeling and development

CORSICA modes of operation (Casper, T.A. et al, FED 83 (2008) 552-556) “backing-out”: fast, prescribed boundary evolution (no controller) with free-

boundary evaluation at each time step to couple to external systems Fast scenario development Most engineering constraints evaluated, e.g. currents, forces, limits Provides feed-forward waveforms for forward control

“forward” : full free-boundary shape and vertical stability evolution with controller – must run with dt ~ vertical growth time so lots of time-steps required

“hybrid”: free-boundary shape from controller in simulink with vertical stability internal to CORSICA – a new development done for speed in long pulse control simulations

Coupling to simulink provides a mechanism to test controllers (shape, vertical stability, and profile) during development JTC2001 controller +VS1,VS3 both in simulink and internal to CORSICA

Interpretive interface with interrupts provides a mechanism for simulating event handling

T.A. Casper, ITPA IOS Kyoto Japan9

CORSICA feedback-controlled evolution for baseline inductive case: IP=15MA, Q=10, 400s duration burn and Pfus=500MW

JCT-2001+VS1 controlled shape and vertical position, typically ~15,000 converged free-boundary solutions (700s discharge)

Performance results (a) Coil currents (b,c) and forces (g)

within operational limits Controller voltage demands for

vertical stability (d) and shape (e,f)

(g)

T.A. Casper, ITPA IOS Kyoto Japan10

Time-dependent evaluation (B,I)-limits and forces on coils

New diagnostic: UFC = utilization factor for superconducting coils – moved from equilibrium design to time-dependent

* Simulation from fast current ramp with 17%reduction in I*B ~ different initial magnetization state* Power ramp to control power to divertor

T.A. Casper, ITPA IOS Kyoto Japan11

Summary/Future: the tools are in place and we are simulating a variety of controller aspects for ITER

Controller development - simulations will support these efforts New controllers have been proposed for improving ITER performance The Plasma Control System (PCS) conceptual design in progress Shape

and vertical position Significant efforts have been done for the baseline 15MA case This needs to be extended to the alternative scenarios

Advanced inductive (hybrid) is being worked on The Steady-state control will be done Non- and low-activation scenario are being defined and developed

Kinetic control efforts for performance Feed-back control of q (current profile) Temperature and stored energy control Burn control Stabilization of islands

Event simulation, database and display testing

T.A. Casper, ITPA IOS Kyoto Japan12

Additional concerns/emphasis for scenario modeling with regards to experiments

More experimental validation of codes used for ITER scenario analysis Lots has been done to date, keep going Concepts that need to be integrated into scenarios, e.g. divertor and stability Effort to benchmark profile control between simulations and experiments

Specific studies of current ramp-up/ ramp-down scenarios under ITER-relevant conditions (i.e. potentially with a tungsten divertor)  Compatibility with tungsten divertor Now using power ramp (5-20MW) during current ramp

Characterization of MHD during the current ramp-up in X-pointconfigurations Fast, heated current ramp-up after X-point formation Stability boundary lurking somewhere

Non-activation or low activation DD scenarios IP/2 and BT/2 with ECH Full BT at reduced IP ~ 10 or 12MA

CS coil limitations for “reduced” operation