All major JET systems have been fully commissioned for D-T and the DTE
1 series of experiments has started with the D-T fuel mixture and oper
ating conditions foreseen for ITER. In the area of ITER physics, signi
ficant results have been produced in both D-D and D-T. In D-D, the LH
threshold power database has been extended, the bounds on edge-electro
n temperature and density in ELMy H-modes have been defined and the ad
vantages of Types I and III ELMy discharges have been compared. In D-T
plasmas, the isotope effect on H-mode threshold power and transport h
as been determined so that a more accurate assessment can be made of t
he ignition margin and heating requirements for ITER. Trace tritium ex
periments have provided first particle transport measurements and an a
ssessment of the ITER reference ion-cyclotron resonance-frequency heat
ing scenarios has been started, In the area of fusion performance, rec
ord D-D neutron yields have been obtained by controlling the plasma an
d current profiles in hot ion ELM-free H-modes and optimized shear mod
es. In D-T, internal transport barriers have been readily established
in optimized shear discharges and Alfven eigenmodes have been observed
.