PPP&T Power Exhaust Studies

Transcription

1 PPP&T Power Exhaust Studies Leena Aho-Mantila VTT Technical Research Centre of Finland Visiting researcher at the Max-Planck- Institut für Plasmaphysik (IPP), Garching, Germany Euratom-TEKES Annual Seminar 2012

2 2 Power Plant Physics and Technology (PPP&T) GOALS: Begin a coordinated effort in EU to quantify key physics/technology prerequisites for a demonstration fusion power plant, DEMO To define a set of technical characteristics for DEMO and, subsequently, to carry out the design work necessary to establish its conceptual design To define future R&D needs and to carry out specific validating R&D work supportive of the conceptual design activities All these activities are coordinated by the EFDA PPP&T department (head: G. Federici) G. Federici, Annual TEKES Fusion Seminar, Helsinki,

3 3 Organization of PPP&T Activities SYS (8) system code activities SERF (2) socio economic research on fusion PEX (12) power exhaust physics integration activities PPP&T MAT (14) materials R&D and engineering database DTM (6) design tools and methodologies DAS (28) design assessment studies

4 4 Organization of PPP&T Activities SYS (8) system code activities SERF (2) socio economic research on fusion PEX (12) power exhaust physics integration activities PPP&T MAT (14) materials R&D and engineering database DTM (6) design tools and methodologies DAS (28) design assessment studies

5 Power exhaust is among the most critical problems to be solved for a DEMO reactor 5 ITER is the first tokamak that can regularly exceed the technological limits of actively cooled PFCs (~10 MW / m 2 ) Already the particle fluxes may be high enough to heat the PFCs above the allowed limits => radiative cooling and divertor detachment are mandatory Significant uncertainties in extrapolating the power decay length and divertor detachment DEMO design: Maximize the total tolerable divertor power loading Minimize the device size (operation in H- mode) Q DT = 10 Reference magnetic equilibrium P IN = 50 MW P FUS = 500 MW P α = 100 MW P RAD = 50 MW ITER divertor λ q =? R. Pitts, seminar at VTT in 2011

6 6 Two approaches in PPP&T studies (A) Conventional divertor X-point configuration Metallic walls and impurity seeding Edge radiation pushed to the limit (B) Novel divertor designs Enhanced spreading of power: snowflake, super-x divertor High power handling: liquid metal walls ITER organization S. Lisgo et al, EPS 2009 V. Soukhanovskii (LLNL)

7 7 Organization of PEX activities & TEKES Contribution PEX-01: Power Exhaust Physics Plasma boundary modelling (TEKES, IPP, CEA) Erosion estimates (TEKES, FZJ) PEX-03: Bare Steel Wall Preparation and characterization of tiles/ markers (TEKES, IPP) Campaign-integrated erosion rate, comparison with spectroscopically measured fluxes, enrichment of high-z elements (TEKES, IPP) PEX-02: Novel Divertor Magnetic Configurations PEX-04: Novel PFC Material Solutions / Liquid Metals 11% of available PPY and 20% of total PEX-2012 budget allocated to TEKES

8 8 Organization of PEX activities & TEKES Contribution PEX-01: Power Exhaust Physics Plasma boundary modelling (TEKES, IPP, CEA) Erosion estimates (TEKES, FZJ) PEX-03: Bare Steel Wall Preparation and characterization of tiles/ markers (TEKES, IPP) Campaign-integrated erosion rate, comparison with spectroscopically measured fluxes, enrichment of high-z elements (TEKES, IPP) PEX-02: Novel Divertor Magnetic Configurations PEX-04: Novel PFC Material Solutions / Liquid Metals 11% of available PPY and 20% of total PEX-2012 budget allocated to TEKES

9 9 Numerical modelling to address power exhaust issues 2D fluid codes are most extensively used to model the edge, scrape-off layer and divertor plasmas SOL Parallel transport calculated for multiple fluid species (fuel and impurities) Calculation of cross-field drifts and kinetic treatment of neutrals possible in some code packages edge Require assumptions on anomalous transport and plasma-wall interaction Validation against existing devices needed divertor 2D calculation grid for ASDEX Upgrade

10 10 PEX studies aim to validate impurity radiation models Take into account the limited validity of nonseeded plasma solutions, namely: No agreement btw code and experiment for detached divertor plasma conditions Begin with the best understood nonseeded plasmas and study incremental effects of seeded impurities: Low-density L-mode plasmas in reactor-relevant devices SOLPS EXP Need dedicated experiments for model validation outer target low recycling Goal: provide simplified, validated incremental models for system codes (SYS)

11 11 Experiments at ASDEX Upgrade and JET AUG full-w wall JET Be + W (ILW) AUG: several characterization discharges with no seeding, N 2 seeding to be investigated JET: N 2 seeding effects characterized in horizontal target configuration (more planned)

12 12 A lot of physics to be understood Increasing N 2 seeding rate leads to: Reduction in D 2 fuelling efficiency Saturation of radiated power fraction at 60 % Asymmetric roll-over in particle fluxes at the two targets

13 13 with some promising first results from modelling Converged SOLPS5.0 simulations with impurities (C+N) and calculation of drifts and currents activated In-out asymmetry observed in simulations, similar to both ASDEX Upgrade and JET simulations

14 Future steps 14 Expand the investigated plasma regimes as soon as there is confidence in code calculations (high recycling, detachment) First DEMO simulations to investigate device scaling Use specialized PWI codes to estimate target erosion 2D SOLPS grid 3D ERO volume

15 15 Concluding remarks PPP&T activities have been launched on several key DEMO design areas Significant contribution from TEKES in PEX, focusing in particular on experiments at ASDEX Upgrade and JET Numerical simulations and post-mortem surface analyses Work done in close collaboration with other associations (IPP, FZJ, CEA) and with EFDA CSU