Prof. F.Troyon“JET: A major scientific contribution...”25th JET Anniversary 20 May 2004 JET: A major scientific contribution to the conception and design

Prof. F.Troyon “JET: A major scientific contribution...” 25th JET Anniversary 20 May 2004

JET: A major scientific contribution to the conception and design of ITER

Prof. Francis TroyonEx Chairman of the JET Scientific CouncilEx Member of the ITER TACformer Director CRPP EPFL

25th JET Anniversary, Culham 20th May 2004


The Outstanding Features of the JET concept

• D-shaped configuration (vessel elongation =1.6)

• Largest size in the world (volume vacum vessel about 180x that in largest existing tokamak)

• Highest current (12x)

• Fully compatible with DT operation

• Conservative engineering


INTOR-Zero Parameters (1980)

• D-shaped plasma ( =1.6) with divertor

• R=5.2 m

• a=1.3 m

• I=6.4 MA

• B=5.5 T

• Density 1.4-1.5 1020m-3 (tentative)

• Beta=5-6% (tentative)


ITER Overall Objectives

• Demonstrate the scientific and technological feasibility of fusion energy for peaceful purposes


ITER-RC detailed technical objectives (extract)

• Achieve extended burn with Q>=10 during enough time to reach stationary conditions for plasma physics processes

• Aim at demontrating steady-state operation at Q>=5.

• Not preclude ignition


ITER Performance Specifications

• Adress issues of burning plasma experiments: confinement, stability, exhaust of helium ash and impurity contrôle in discharges with dominant alpha particle heating

• Profile control and all mean to control profile and burn

• Identify sufficiently reliable operating modes for nuclear testing


2.5%, 0.7T, P

10Q (Pfus/Pin)

80+P (MW)

40-90Paux (MW)

0.5, 1.85,

5.3Bt (T)

15(17)IP (MA)

850VP (m3)

2a (m)

6.2R (m)

ITER


Plasma cross section

Divertor


L-Mode scaling


Different tokamak operating modes


H-Mode scaling


Operational limits

• Elongation < ≈ 2 • Current I B a2/R2

• Pressure limit IB/a• Density limit n I/a2

But can these limits be pushed ?

Advanced scenarios

• The most favourable factors for confinement have limits. Performance will then depend on how close operation is possible near these limits:


ITER Operational diagrams


JET D-T Operation • Confirmation of good confinement scaling

• Effect on PL-H simple but good !!

• Demonstration of standard ITER scenario in steady state (ELMy H-Mode) without impurity accumulation • Fast particles heat the plasma without being lost

• Succesful demonstration of exhaust of thermal -particles on JET done


D-T Confinement scaling in JET


SCENARIO CHOSEN FOR Q ~ 10 OPERATION ON ITER

4.5 MWFusionPower

Demonstration of steady state ELMy H-Mode in D-T


From JET to ITER


• JET was a giant step when designed and built • JET served as the model for the design of all next step machines, including ITER • Without JET, what would ITER be today ?? • JET remains the essential machine to test any

new concept for ITER in which size and performance is important • JET is an essential tool to study the « high reward » concepts (Advanced Scenarios) to further increase the operational domain and

the identification of reliable operating modes for nuclear testing

Conclusions

Documents

Prof. F.Troyon“JET: A major scientific contribution...”25th JET Anniversary 20 May 2004 JET: A major scientific contribution to the conception and design