ITER Research Needs. Report by David Campbell Plasma Operation Directorate

Transcription

1 ITER Research Needs Report by David Campbell Plasma Operation Directorate Acknowledgements: Members of PO and CHD directorates, together with many experts in the international fusion community The views and opinions expressed herein do not necessarily reflect those of the ITER Organization. ITPA Coordinating Committee, Cadarache, 12 December 2011 ITER Page 1

2 Synopsis Current status of the ITER Research Plan development Implications of deferrals and recent design decisions Key elements of ITER s Physics R&D needs ITPA contributions to ITER activities Recent ITPA contributions to ITER design and physics basis Preparations for 24 th IAEA Fusion Energy Conference, October 2012 ITPA Coordinating Committee, Cadarache, 12 December 2011 ITER Page 2

3 ITER Research Plan - Status ITPA Coordinating Committee, Cadarache, 12 December 2011 ITER Page 3

4 Boundary Conditions I Phased assembly and commissioning of tokamak, as in the Baseline OPS/ Level-0 Reference Schedule IRP consistent with proposed OPS/ Level-0 Reference Schedule: First Plasma scheduled for late 2020 with minimal in-vessel components target DT operation by end-2027 H&CD systems: H&CD mix of ECRH (20 MW), ICRF (10 15 MW), NBI (33 MW, 870 kev H) installed after Assembly Phase II (P inj ~ 63 MW) 2 nd ICRF antenna and 2 nd HNB installed in pre-nuclear shutdown before deuterium operations phase Diagnostic systems: Construction Phase procurement will focus primarily on in-vessel components principal diagnostic systems required for essential elements of plasma control and protection available (equilibrium control, density control, power exhaust monitoring, DMS etc) this element still under review ITPA Coordinating Committee, Cadarache, 12 December 2011 ITER Page 4

5 Boundary Conditions II Divertor configuration: all-tungsten divertor from First Plasma Central Solenoid: CS3L module to be fabricated from existing CSJA2 conductor, while improved conductor meeting ITER performance requirements developed Tritium Plant: installation and commissioning plan for Tritium Plant follows basic logic developed for Baseline Schedule initial 50:50 DT operation possible in late 2027, with full throughput gradually increasing through subsequent 6-12 operational months Operations scheduling based essentially on RAMI analysis: 2-shift operation during first H/ He campaign 3-shift operation possible for remainder of experimental programme TBM testing programme is constrained by needs of experimental programme towards DT operation ITPA Coordinating Committee, Cadarache, 12 December 2011 ITER Page 5

6 Summary of Operational Implications H&CD capability: reduced headroom for achieving H-mode in non-active phase, but current estimates indicate helium H-mode access remains viable at half-current and field foreseen H-mode and ELM-control testing programme remains possible, subject to results of ongoing physics R&D Diagnostics: Diagnostic installation programme is being adapted to ensure required measurement capability is available as required by experimental programme Central Solenoid: recent calculations indicate that new scenarios can be developed to mitigate possible performance limitations of CS3L module Tungsten divertor: use of tungsten divertor from start of non-active phase will necessitate adaptation of plasma scenarios adequate mitigation measures against transient heat loads will be required ITPA Coordinating Committee, Cadarache, 12 December 2011 ITER Page 6

7 ITER H-mode Power Threshold The latest H-mode threshold power scaling for deuterium plasmas: P thresh = 0.05n 0.72 e B 0.8 T S 0.94 (Y Martin, HMW-2008) The isotope dependence based on JET results in H, D, and DT indicates that P thresh 1/A for hydrogen isotopes Possible helium H-mode access half-field/ half current H-mode development Q=10 Full-field/ full current H-mode development H-mode access path in DT needs 40MW No H-mode access in D for full Q=10 simulation No H-mode access in H at full field Note: margins may be required for (i) core radiation and (ii) access to good confinement (H 98 = 1) ITPA Coordinating Committee, Cadarache, 12 December 2011 ITER Page 7

8 ITER H-mode Threshold - Implications Hydrogen/ Helium Operations: it has long been recognized that achievement of H-mode in hydrogen is at best marginal, requiring essentially full (100%) H&CD power routinely IRP plans call for initial studies of H-modes and ELM control in helium plasmas: ~ 50 MW required for reliable H-mode access at 7.5 MA/ 2.65 T Deuterium Operations: at least 30 MW required for H-mode access at 7.5 MA/ 2.65 T P inj ~ 63 MW might provide just enough headroom for H-mode access at full current and field, but at reduced density Deuterium-Tritium Operations: P inj ~ 50 MW required for access to H-mode at 15 MA/ 5.3 T, but alpha heating power ensures H-mode operation at Q=10 operating point ITPA Coordinating Committee, Cadarache, 12 December 2011 ITER Page 8

9 H&CD Operation Range H&CD access with NB shinethrough protection armour provides considerable flexibility in selecting appropriate operation strategy ITPA Coordinating Committee, Cadarache, 12 December 2011 ITER Page 9

10 ITER Experimental Programme Complete Tokamak Core First Plasma Hydrogen/ Helium Phase Complete Deuterium Phase Complete Plasma Restart Start Torus PumpDown First Plasma Assembly Phase II Plasma Development, H&CD Commissioning, Diagnostics, Control, DMS Commissioning Short Shutdown 15 MA and Disruption Forces, H&CD Commissioning, He H-modes, ELM Mitigation Pre-Nuclear Shutdown Full Heating capability T-Plant Commissioning Hydrogen Commissioning Tritium Introduction ~10% T-throughput D Plasmas, D H-modes D H-mode Studies Trace-T Studies Q=10 Long Pulse Short Pulse Q=10 DT Hybrid DT Non-inductive Scheduled Shutdowns ITPA Coordinating Committee, Cadarache, 12 December 2011 ITER Page 10

11 Operations: 1. Non-Active Phase Hydrogen/ helium operation consists of months of plasma operation over 2 campaigns two-shift operation assumed in Campaign 1 and three-shift operation in Campaign (360) (360) ITPA Coordinating Committee, Cadarache, 12 December 2011 ITER Page 11

12 Non-Active Phase - Deferral Implications Operational Schedule: detailed analysis of effective operational time indicates that it is within 10% of original operational schedule: scheduling of shutdowns and installation; partial utilization of 3 rd shift due to technical constraints etc Experimental Programme: both hydrogen and helium plasmas will be required for efficient commissioning of auxiliary systems (particularly H&CD) all-tungsten divertor may require more cautious experimental approach than originally foreseen to avoid melting, particularly at transients Some planned activities might not be accomplished during this phase, but this may compensate loss of operational time and slower start-up with tungsten divertor: full-power testing of divertor long-pulse commissioning of all H&CD systems - partial loss ITPA Coordinating Committee, Cadarache, 12 December 2011 ITER Page 12

13 Operations: 2. Deuterium Phase Focus is on inductive ELMy H-mode scenario to allow rapid transition to DT operation: new systems commissioned initially with H/ He plasmas Nuclear readiness demonstration for tokamak and auxiliary systems performed Tritium Plant commissioned with tritium in parallel with pre-nuclear shutdown and plasma operation trace tritium experiments precede transition to full DT operation (1100) (880) 5170 ITPA Coordinating Committee, Cadarache, 12 December 2011 ITER Page 13

14 Deuterium Phase - Deferral Implications Operational Schedule: proposed schedule foresees similar operational time in deuterium as previous IRP Experimental Programme: Major additional activity to be incorporated relative to original IRP is the commissioning of the 2 nd ICRF antenna Use of tungsten divertor in non-active phase means commissioning time for tungsten divertor originally foreseen would be saved to maintain early transition to DT operation, emphasis must be given to short pulse operational scenarios ITPA Coordinating Committee, Cadarache, 12 December 2011 ITER Page 14

15 Operations: 3. Deuterium-Tritium Phase 1 Initial DT phase focusses on achievement of Q = 10 scenario at up to 500MW for at least several 10s of seconds emphasis in initial campaign on development of necessary control techniques to allow quasi-stationary production of several 100MW of fusion power at Q~ Achievement of long pulse (several 100s) Q=10 milestone would be pursued in the subsequent DT experimental campaign allocation of time also to development of hybrid and non-inductive scenarios demonstration of Q=5, 3000s likely to require several years of experiments ITPA Coordinating Committee, Cadarache, 12 December 2011 ITER Page 15

16 ITER Research Plan - Summary An initial analysis has been performed of the possible ITER Research Plan towards early DT operation based on planning endorsed by IC-9: no showstoppers have been identified to achieving proposed experimental programme towards short-pulse Q=10 operation in 2028, though there are increased risks to achievement of programme goals on proposed timescale major impact of deferral proposal is associated with (i) reduced H&CD power (63 MW) in non-active phase and (ii) use of tungsten divertor in nonactive phase proposed deferral of diagnostic systems is still to be analyzed in detail to ensure required capabilities are available at required time proposed installation of all-tungsten divertor may necessitate more cautious approach to development of operational scenarios redeveloped plasma scenarios indicate that possible limitations in CS3L module have limited impact on satisfying ITER mission goals any limitations in operational time can be compensated to some extent by deferring elements of long-pulse scenario development until achievement of short pulse (several 10s of seconds) Q=10 ITPA Coordinating Committee, Cadarache, 12 December 2011 ITER Page 16

17 Key elements of ITER s Physics R&D Needs ITPA Coordinating Committee, Cadarache, 12 December 2011 ITER Page 17

18 Key ITER Physics R&D Needs I Key issues for ITER Physics R&D remain: development of integrated operational scenarios with all metallic PFCs in particular, resolution of outstanding issues related to use of tungsten divertor fuel retention with all-metallic walls tritium removal techniques heat fluxes in limiter/ divertor configurations and under stationary/ transient conditions Disruptions/ VDEs: characterization and understanding of rotation of halo current asymmetries following disruptions/ VDEs processes determining current quench time extrapolation to ITER improved quantitative analysis of disruption heat loads improved physics basis for choice of disruption/re mitigation techniques improved understanding of processes influencing confinement and losses of REs improved physics basis for ELM control exploitation of extended RMP coil capabilities to improve specification of requirements for ELM control in ITER studies of potential alternative ELM control techniques ITPA Coordinating Committee, Cadarache, 12 December 2011 ITER Page 18

19 Key ITER Physics R&D Needs II Key issues for ITER Physics R&D remain: experimental validation of ITER plasma scenarios validation of revised current ramp-up scenarios on tungsten divertor development of hybrid/ steady-state scenarios implications for H&CD upgrades extended physics basis for helium H-mode operation understanding of 3-D ripple effects such as produced by TBMs, RMP coils improved diagnosis of hydrogenic retention and dust production Issues highlighted in red are discussed in more detail later in presentation ITPA Coordinating Committee, Cadarache, 12 December 2011 ITER Page 19

20 Divertor and PWI: R&D Needs I The project s decision to give priority to installation of a tungsten divertor from the start of the experimental programme gives added urgency to R&D in this area (IC-9 recommendation delays final implementation of the decision for up to 2 years) demonstration of robust integrated scenarios power load control in longpulse operation over range of scenarios by low-z seeding development of helium plasma scenarios (H-modes, ELM control) impurity generation and core contamination in ELM-controlled regimes effect of divertor target damage on device operability fuel retention with all-metallic walls role of material erosion and migration dust generation Further emphasis is required on model validation activities ITPA Coordinating Committee, Cadarache, 12 December 2011 ITER Page 20

21 Divertor and PWI: R&D Needs II Heat fluxes in limiter/ divertor configurations and under stationary/ transient conditions: development of quantitative description of λ q in limiter plasmas remains critical for first wall design is recent indication that 1/I p is good ordering parameter for λ q in H-mode confirmed? problematic for ITER? characterization of transient heat loads at controlled ELMs and at disruptions/vdes key for estimating PFC lifetime and dust production T. Eich Structured workprogramme of Divertor and SOL TG appears welladapted to addressing and resolving these issues ITPA Coordinating Committee, Cadarache, 12 December 2011 ITER Page 21

22 Stability: R&D Needs I Quantitative characterization of disruption/ VDE parameters and specification of adequate mitigation system for ITER remain critical issues: VDE horizontal forces - improved basis for prediction of ITER loads, including guideline on rotation of asymmetry determination of heat load characteristics at disruptions/ VDEs JET: halo current asymmetry rotates up to 4 revolutions with frequency 100Hz (T Hender) ITPA Coordinating Committee, Cadarache, 12 December 2011 ITER Page 22

23 Design and R&D activity on DMS/ RE mitigation hardware moving forward: Stability: R&D Needs II responsibility allocated to US DA timeschedule under review, but PA signature/ CDR likely in 2013 Key issues: need to finalize species, amount and number of locations (radiation asymmetries important) tests of concepts for RE mitigation most critical issue at present improved understanding of RE production, confinement and losses required Request for allocation of 4 upper port plugs (shown) for DMS and 2 horizontal port plugs for RE mitigation under study ITPA Coordinating Committee, Cadarache, 12 December 2011 ITER Page 23

24 Stability: R&D Needs III Additional high priority issues specification of criteria for tolerable level of low-n resonant and nonresonant error fields at low and high beta - guidance on use of correction coils and in-vessel coils to correct error fields assessment of capability of in-vessel coils to control RWMs in steady-state scenarios Critical issues are being addressed by MHD TG through a series of WGs designed to address ITER key issues on a rapid timescale ITPA Coordinating Committee, Cadarache, 12 December 2011 ITER Page 24

25 Pedestal/ Confinement R&D Needs I Developing effective ELM control and establishing basis for its application in ITER remains the critical issue in this area Recently there has been a rapid expansion of experimental capability in this area: demonstration of ELM suppression with RMPs in AUG, KSTAR improvement of pellet pacemaking experiments in AUG, DIII-D detailed cross-device studies of ELM suppression studies of alternative approaches to ELM suppression continue with some success (eg QH-mode) detailed analysis of issues such as field penetration and impact of RMP coils on heat load distribution are also important contributions ITPA Coordinating Committee, Cadarache, 12 December 2011 ITER Page 25

26 Pedestal/ Confinement R&D Needs II Key priorities in ELM control: coordinated work to improve understanding of ELM suppression with B edge perturbation: DIII-D, AUG, KSTAR, MAST, NSTX, JET revised physics basis for empirical criterion for ITER (n and I coil ) improved understanding of edge power and particle fluxes with ELM control expand ELM control by pellet pacing and determination of effects on confinement and fluxes to PFC during mitigated ELMs quantify requirements for ELM control with schemes which may be useful in lower I p phases of ITER plasma (vertical kicks, edge ECRH) compatibility of plasma fuelling with ELM mitigation/ suppression (particle transport + pellets) access and exit from H ~ 1 H-mode with ELM mitigation further exploration of new methods for ELM control (solid pellets?) analysis of ELMs and ELM control in helium plasmas ITPA Coordinating Committee, Cadarache, 12 December 2011 ITER Page 26

27 Pedestal/ Confinement R&D Needs III Access to H-mode and high confinement in ITER reference H, He, D and DT regimes: more extensive analysis of H-mode characteristics of helium plasmas (ELMs, ELM control) essential for operational planning access to H-mode in current ramp-up phase particularly important to scenario development assessment of additional factors affecting H-mode access (torque, X-point geometry) also necessary studies of plasma performance, ELM behaviour, ELM control in regimes with input power just above H-mode threshold these issues will have a significant impact on planning for ITER operation and development of scenarios for all phases of operation, but are particularly critical in planning for non-active phase of operation likely to affect upgrade plan for heating systems after construction is finished ITPA Coordinating Committee, Cadarache, 12 December 2011 ITER Page 27

28 Pedestal/ Confinement R&D Needs IV Improved physics basis for particle transport in SOL, pedestal and core (in hydrogenic and helium plasmas): a critical issue for establishing the viability of ITER operational scenarios need to develop an improved physics basis for predicting realistic fuelling requirements, core density, impurity content and fusion performance Development of physics basis for momentum transport: prediction of plasma rotation has several implications for confinement properties and mhd stability in ITER operational scenarios can determine tolerance to error fields, use of RMPs, impact of TF ripple particularly 3-D effects Influence of toroidal field ripple on plasma performance: specification of ferromagnetic inserts now complete understanding 3-D ripple effects remains an issue (is ripple or error field/ magnetic braking important?) potential impact on TBM design ITPA Coordinating Committee, Cadarache, 12 December 2011 ITER Page 28

29 Operational Scenarios: R&D Needs I In recent years there has been a significant R&D activity aimed at strengthening the physics basis for the redevelopment of the ITER 15MA baseline scenario There are several outstanding issues which would further improve the predictive capability for this scenario: validation of plasma initiation models validation of transport models for various phases of the scenario, particularly the ramp-up/ ramp-down/ transient phases - quantification of density behaviour is of particular importance characterization of plasma transport with significant electron heating and T e ~ T i re-definition of standard plasma disturbances, particularly L-H and H-L transition experimental simulation and model validation of ITER non-active scenarios ITPA Coordinating Committee, Cadarache, 12 December 2011 ITER Page 29

30 Operational Scenarios: R&D Needs II Recent qualification tests of CS conductor indicate that present samples may only achieve ITER lifetime requirements if Lorentz force (internal stress) is limited to ~70% of reference value To maintain ITER schedule, IC-9 has endorsed decision to proceed with manufacture of CS3L from this conductor while developing improved conductor for other CS modules 15 MA scenario has been reanalyzed with DINA code: - by re-optimizing initial magnetization, loss of flux limited to ~3 Wb - plasma heating during fast current ramp-up allows mission goals to be maintained ( s burn) - experimental validation of revised scenarios, particularly with tungsten divertor, necessary T, s burn Z eff Option 1 P aux : 5=>20MW P aux : 5MW T ramp-up, s DINA: burn duration vs current ramp-up time ITPA Coordinating Committee, Cadarache, 12 December 2011 ITER Page 30

31 Operational Scenarios: R&D Needs III An increased focus on validation of models of plasma control in ITER-relevant scenarios is essential for support of development of Plasma Control System ITER PCS will rely on multi-variable control with limited set of actuators - validated models of control functionality is required to provide an adequate basis for the design of the PCS novel functionality such as heat flux control, burn control etc needs to be addressed The fusion programme is devoting a significant fraction of its resources to the development of advanced scenarios - hybrid and steady-state A systematic approach to validation of simulation codes is required to improve physics basis for extrapolation of these scenarios to ITER, including access conditions optimization of H&CD mix and their use in plasma control is a key issue which will have a significant impact on choice of H&CD upgrades ITPA Coordinating Committee, Cadarache, 12 December 2011 ITER Page 31

32 Energetic Particles: R&D Needs There is a good basis for the calculation of EP losses in presence of TF ripple 3-D effects (eg TBMs, RMPs) need further analysis interaction between EP scattering due to MHD instabilities and TF ripple needs eventually to be addressed recent predictions of significant NBI fast ions in ITER in presence of RMP fields requires further study/ validation Validation of non-linear analysis of AEs to provide improved estimate of EP spatial redistribution and losses Simulation and validation of the generation, confinement and loss processes for (post-disruption) runaway electrons is essential: the potential impact of REs on PFCs in ITER justifies a significant allocation of resources to improve the physics basis for simulation of their behaviour in ITER ITPA Coordinating Committee, Cadarache, 12 December 2011 ITER Page 32

33 Diagnostic: R&D Needs I The Diagnostics TG has identified 6 high priority topics to support the development of ITER s measurement capability: 1. Development of methods of measuring the energy and distribution of alpha particles 2. Assess calibration strategy and calibration sources needed for neutron diagnostics (CLOSED) NEW: Review Measurement Requirements for Plasma Control 3. Determination of life-time of plasma-facing mirrors used in optical systems 4. Development of the measurement requirements for measurements of hot dust, and assessment of techniques for the measurement of hot dust (CLOSED) 5. Assessment of the impacts of wall reflections on diagnostics 6. Assessment of the measurement requirements for plasma initiation and identification of potential gaps in planned measurement techniques These issues reflect major needs supporting procurement activities ITPA Coordinating Committee, Cadarache, 12 December 2011 ITER Page 33

34 Diagnostic: R&D Needs II There are several additional R&D issues which would benefit from ITPA contributions: Gas puff modelling (affects many systems) Effect of gap changes on bolometry performance & bolometer R&D issues Lost alphas as soon as FW is frozen we will need to know localization of alpha losses in the new ITER FW geometry. MHD effects on lost alpha distribution on the FW (where, what energy and pitch angle range) S/N and performance dependence of proposed diagnostics on temperatures, neutron/gamma fluxes, etc. additional ideas on the diagnostic tools for lost alpha measurements Practical tests of erosion monitoring diagnostics for divertor components Interferometric (holographic or speckle interferometry) LIDAR type metrology ITPA Coordinating Committee, Cadarache, 12 December 2011 ITER Page 34

35 ITPA contributions to ITER activities ITPA Coordinating Committee, Cadarache, 12 December 2011 ITER Page 35

36 ITPA Contributions to ITER Design Basis The results of ITPA R&D activities have provided a substantial physics basis for the ITER design over the past decade formalized in Progress in ITER Physics Basis ITPA database activities have been fundamental to establishing guiding physics principles for the tokamak design (eg H-mode threshold, H-mode confinement) - Disruption database has provided crucial input to the ITER Load Specification and Preliminary Safety Report (RPrS - Licensing documentation) Supporting R&D implemented through ITPA made an important contribution to numerous aspects of physics analysis during ITER Design Review Plasma Performance Assessment Heat and Nuclear Load Specifications ITPA Coordinating Committee, Cadarache, 12 December 2011 ITER Page 36

37 ITPA Contributions to STAC Reports ITPA has been active in supporting IO s responses to Council s Charges to specific STAC Charges STAC-8: Plan for ELM Mitigation in ITER STAC-9: H-mode Physics and R&D for ITER STAC-9: Outstanding issues in transient and steady state heat loads to ITER plasma facing components STAC-10: Evaluation of ITER Baseline Scenarios STAC-10: Development of a Disruption Mitigation System for ITER The scope of the ITPA R&D activities has been essential to building a substantial physics case for ITER s approach to resolving key physics issues in these areas ITPA Coordinating Committee, Cadarache, 12 December 2011 ITER Page 37

38 Council Charge to STAC-12 IC-9 has issued a Charge to ITER STAC for the STAC-12 meeting in May 2012 which includes, inter alia, the following request: Assess whether the worldwide research program on carbon- and tungstendivertors, including tritium-retention and transient heat loads, is sufficient for making a timely decision on the ITER divertor, and suggest improvements in the program; The ITER Research Plan will also be revised to reflect in greater detail the implications of deferrals and design decisions: input from the ITPA on key aspects, such as operation with all-metal walls, disruption mitigation, ELM control, H-mode access and plasma scenarios would be invaluable A workprogramme is being drawn up to prepare reports in response to this Charge, with a deadline around end-april 2012: ITPA experts are welcome to contribute to the preparation of these reports ITPA Coordinating Committee, Cadarache, 12 December 2011 ITER Page 38

39 24 th IAEA Fusion Energy Conference 24 th IAEA Fusion Energy Conference will take place in San Diego in October 2012 As at previous conferences, the intention is to organize an ITER session integrating contributions from the IO, ITER DAs and ITPA - an ITER review committee will be established by IO and ITER DAs to review synopses and make recommendations for oral presentations ITPA TGs are welcome to submit papers to the ITER session - ITPA papers submitted to ITER session should be endorsed by TG Chair Formal announcement of conference deadlines is not yet available, but based on previous experience, the deadlines for the ITER system would be (approximately): submission of synopsis to ITER review committee: mid-february 2012 (following all necessary clearance) recommendation by review committee: early-march 2012 submission to conference website: start-april 2012 ITPA Coordinating Committee, Cadarache, 12 December 2011 ITER Page 39