The JET experimental campaign has focused on studies in support of the ITER
physics basis. An overview of the results obtained is given for the refere
nce ELMy H mode and advanced scenarios, which in JET are based on internal
transport barriers. JET studies for ELMy H mode have been instrumental in t
he definition of ITER FEAT. Positive elongation and current scaling in the
ITER scaling law have been confirmed, but the observed density scaling fits
a two term (core and edge) model better. Significant progress in neoclassi
cal tearing mode limits has been made showing that ITER operation with q(95
) around 3.3 seems to be optimized. Effective helium pumping and divertor e
nrichment is found to be well within ITER requirements. Target asymmetries
and hydrogen isotope retention are well simulated by modelling codes taking
into account drift flows in the scrape-off plasmas. Striking improvements
in fuelling effectiveness have been made with the new high field pellet lau
nch facility. Good progress has been made on scenarios for achieving good c
onfinement at high densities, both with radiation improved modes and with h
igh field side pellets. Significant development of advanced scenarios, in v
iew of their application to ITER, has been achieved. Progress towards integ
rated advanced scenarios is well developed with edge pressure control (impu
rity radiation). An access domain has been explored showing, in particular,
that the power threshold increases with magnetic field but can be signific
antly reduced when lower hybrid current drive is used to produce target pla
smas with negative shear. The role of ion pressure peaking on MHD has been
well documented. Lack of sufficient additional heating power and interactio
n with the septum at high beta prevents assessment of the beta limits (stea
dy plasmas achieved with beta (N) up to 2.6). Plasmas with a non-inductive
current (I-NI/I-p = 60%), well aligned with the plasma current, high beta a
nd good confinement have also been obtained.