EFDA EUROPEAN FUSION DEVELOPMENT AGREEMENT Task Force S1 J.Ongena 19th IAEA Fusion Energy Conference, Lyon Towards the realization on JET of an integrated H-Mode scenario for ITER 19th IAEA Fusion Energy Conference 14 to 19 October 2002 Lyon, France J.Ongena and EFDA-JET work programme contributors Task Force Leader Scenario 1 at JET Ecole Royale Militaire / Koninklijke Militaire School Association “EURATOM-Belgian State” Brussels, Belgium

EFDA EUROPEAN FUSION DEVELOPMENT AGREEMENT Task Force S1 J.Ongena 19th IAEA Fusion Energy Conference, Lyon O U T L I N E ITER Q=10 ELMy H-Mode operational requirements for high density, confinement and beta simultaneously realized in JET discharges Towards the realization of acceptable heat loads on the ITER divertor target plates Summary and Outlook

EFDA EUROPEAN FUSION DEVELOPMENT AGREEMENT Task Force S1 J.Ongena 19th IAEA Fusion Energy Conference, Lyon High Confinement and high density in ELMy H-Mode discharges Obtained in three different ways : 1. Plasma Shaping : High triangularity 2. Impurity seeding : Low and High  plasmas 3. High Field Side pellet injection Peaked density profiles can be seen Modified confinement scaling taking into account influence of density peaking, triangularity, proximity to Greenwald density

EFDA EUROPEAN FUSION DEVELOPMENT AGREEMENT Task Force S1 J.Ongena 19th IAEA Fusion Energy Conference, Lyon Plasma Shaping High Confinement and High Density at High  Confinement of high performance high  discharges : Type I ELMs with indications for Type II ELMs at high density Simultaneously for ~ 4 sec (~ 9  E ) : High density n/n GW > 1 High  N,th > 1.8 High Confinement H 98(y,2) = 1

EFDA EUROPEAN FUSION DEVELOPMENT AGREEMENT Task Force S1 J.Ongena 19th IAEA Fusion Energy Conference, Lyon JET Confinement depends on  and ELM Type Degradation versus density for all triangularities At high  : n/n GW, H 98(y,2) and  N for ITER obtained simultaneously Confinement in lower  plasmas improved by increasing P in /P L-H Best points : n/n GW > 1 with H 98(y,2) = 1  N ~ 1.9 Black diamonds from new HT3 configuration designed for high current/field operation See also J.Pamela, OV/1-4

EFDA EUROPEAN FUSION DEVELOPMENT AGREEMENT Task Force S1 J.Ongena 19th IAEA Fusion Energy Conference, Lyon Impurity Seeding combines High Confinement and High Density with Radiating Mantle Result of Ar seeding : Increased radiation : P rad /P tot = 0.65 Increased density (f   p  ) Density up to 1.15 n/n GW (with H 98(y,2) = 0.9 and  N,th = 2.1) Effects on ELMs Reduction of ELM frequency Higher D  between ELMs Moderate increase of Z eff :  Z eff ~ 0.2 and  C Ar (  0.2) = 0.05% Lack of central heating terminates pulse

EFDA EUROPEAN FUSION DEVELOPMENT AGREEMENT Task Force S1 J.Ongena 19th IAEA Fusion Energy Conference, Lyon Radiating Mantle and ITG stabilization with Ar Seeding Radiating Mantle in Plasma Edge  Reduction of ITG growth rate  Improvement of core confinement For both high and low  discharges : High  discharges #53149 #53146 Calculated with Weiland model (I.Voitsekhovitch) Larger mantle in high  discharge Without Ar With Ar #53146 #50473

EFDA EUROPEAN FUSION DEVELOPMENT AGREEMENT Task Force S1 J.Ongena 19th IAEA Fusion Energy Conference, Lyon High Field Side Pellet Injection Applied to discharges with medium  = 0.32 Fast Pellet Sequence to raise density Slow Sequence to keep density and confinement Strongly Peaked Density Profiles: n(0)/n ped ~ 2

EFDA EUROPEAN FUSION DEVELOPMENT AGREEMENT Task Force S1 J.Ongena 19th IAEA Fusion Energy Conference, Lyon Density Peaking Obtained with High Field Side Pellet Injection But also without Pellet Injection on JET : Tuning of gas dosing and heating Impurity seeding in low  discharges

EFDA EUROPEAN FUSION DEVELOPMENT AGREEMENT Task Force S1 J.Ongena 19th IAEA Fusion Energy Conference, Lyon New ELM behaviour leading to reduced ELM losses at high n and high  (inter ELM losses correlated with MHD, appearance of ELMs similar to Type II ELMs) : ELM Mitigation Studies How to reach acceptable heat loads in the ITER divertor ? Loss of Power due to ELMs : P ELM = f ELM   W ELM Low n High n Determined by edge transport, P sep / edge parameters Tools : , D puff, Ar, power Beneficial influence of impurities See also A.Loarte, EX/P1-08

EFDA EUROPEAN FUSION DEVELOPMENT AGREEMENT Task Force S1 J.Ongena 19th IAEA Fusion Energy Conference, Lyon Reduction of  W ELM /W ped at high density and high  With increasing density : Reduction of  W ELM /W ped Reduction of (  T e /T e ) ped Weak decrease of (  n e /n e ) ped ‘Minimum’ Type I ELMs found (at  U = 0.5 and reduced  L = 0.3) with (  T e /T e ) ped = 0 and  W ELM /W ped = 4.5% See also A.Loarte, EX/P1-08

EFDA EUROPEAN FUSION DEVELOPMENT AGREEMENT Task Force S1 J.Ongena 19th IAEA Fusion Energy Conference, Lyon ELM mitigation with impurity seeding Without Ar Reduced Target Surface Temperature with Ar seeding With Ar During ELMs in Between ELMs Unique feature of impurity seeding : Drop in base line target temperature will allow larger temperature excursions due to ELMs before reaching ablation limit See also J.Rapp, P.Monier-Garbet, EX/P1-09

EFDA EUROPEAN FUSION DEVELOPMENT AGREEMENT Task Force S1 J.Ongena 19th IAEA Fusion Energy Conference, Lyon Extrapolation to ITER is very different for both scalings Raises hope for a possibility of Type I ELMs operation on ITER with an acceptable divertor lifetime Further work ongoing to determine the correct parameter dependence  // front : char. time for heat front to reach the target Scaling of ELM size and extrapolation to ITER Correlation between ELM size and both  ped and  // front See also A.Loarte, EX/P1-08 and G.Matthews, EX/D1-1

EFDA EUROPEAN FUSION DEVELOPMENT AGREEMENT Task Force S1 J.Ongena 19th IAEA Fusion Energy Conference, Lyon Conclusions 1. ITER Q=10 ELMy H-Mode Requirements reached on JET with several techniques

EFDA EUROPEAN FUSION DEVELOPMENT AGREEMENT Task Force S1 J.Ongena 19th IAEA Fusion Energy Conference, Lyon Conclusions 2. New results on ELM physics and extrapolation to ITER : Decrease of ELM size at high density for ITER  Further alleviation of constraints due to ELM heat load possible with impurity seeding Hope for a possible window for Type I ELMs operation with an acceptable ITER divertor lifetime JET is an excellent testbed to prepare for ITER operation

EFDA EUROPEAN FUSION DEVELOPMENT AGREEMENT Task Force S1 J.Ongena 19th IAEA Fusion Energy Conference, Lyon OUTLOOK Continue preparation for ITER Operation using new ‘tools’ at JET New Pellet Track ITER deep fuelling New ITER relevant Discharge Shapes New very long divertor phase (50s) pulses Near Double Null Study of Type II ELMs Plasmas with reduced disruptive force Study of High Current Plasmas Optimisation of pellet fuelling for ITER Long time plasma and wall constants NEW!

EFDA EUROPEAN FUSION DEVELOPMENT AGREEMENT Task Force S1 J.Ongena 19th IAEA Fusion Energy Conference, Lyon

EFDA EUROPEAN FUSION DEVELOPMENT AGREEMENT Task Force S1 J.Ongena 19th IAEA Fusion Energy Conference, Lyon Very Long Divertor Phase Pulses On JET Study of Long time constants in wall and plasma parameters

EFDA EUROPEAN FUSION DEVELOPMENT AGREEMENT Task Force S1 J.Ongena 19th IAEA Fusion Energy Conference, Lyon Impurity Seeding Aim : Realize an integrated operational scenario combining : High density and high confinement Acceptable power exhaust In JET : using Ar seeding in low and high  discharges Cautious D and Ar dosing

EFDA EUROPEAN FUSION DEVELOPMENT AGREEMENT Task Force S1 J.Ongena 19th IAEA Fusion Energy Conference, Lyon Pellet Injection from the High Field Side In medium triangularity discharges Using an optimised pellet cycle High densities reached while keeping high confinement Peaked density profiles

EFDA EUROPEAN FUSION DEVELOPMENT AGREEMENT Task Force S1 J.Ongena 19th IAEA Fusion Energy Conference, Lyon Spontaneous Density Peaking Stationary peaked profiles : n(0)/n ped ~ 1.3 Tuning of gas dosing (flux, position) and plasma heating High and stationary n/n GW = 1,  N,th = 2 and H 98(y,2) = 1

EFDA EUROPEAN FUSION DEVELOPMENT AGREEMENT Task Force S1 J.Ongena 19th IAEA Fusion Energy Conference, Lyon Confinement and L-H Threshold Scaling Studies on JET Influence of plasma shaping, density peaking and proximity to the Greenwald limit H 98(y,2),corr = H 98(y,2)  F F = ln(q 95 /q cyl ) (n/n ped - 1) n/n GW BENEFICIAL : Plasma Shape and Density Peaking DETRIMENTAL : Proximity to Greenwald limit Effect on Confinement: He plasmas (purity C He / C D = 85%) show : Isotope scaling :  E  M 0.19 Z (from previous H and T data + He database) L-H Power Threshold in He : same I p B t and mass dependence as for D 50% higher in absolute value

EFDA EUROPEAN FUSION DEVELOPMENT AGREEMENT Task Force S1 J.Ongena 19th IAEA Fusion Energy Conference, Lyon Density Peaking with Impurity Seeding Low  plasmas (  ~ 0.3) High and stationary n/n GW = 1,  N,th = 2 and H 98(y,2) = 1 Peaked density profiles : n(0)/n ped ~ 1.3

EFDA EUROPEAN FUSION DEVELOPMENT AGREEMENT Task Force S1 J.Ongena 19th IAEA Fusion Energy Conference, Lyon Heat pulse delay of ELMs  IR from IR thermographic measurements Indications for non-determining role of *,ped