Since the last IAEA conference, the scientific programme of JET has focused on the
qualification of the integrated operating scenarios for ITER and on physics issues
essential for the consolidation of design choices and the efficient exploitation of
ITER. Particular attention has been given to the characterization of the edge plasma,
pedestal energy and edge localized modes (ELMs), and their impact on plasma facing
components (PFCs). Various ELM mitigation techniques have been assessed for all ITER
operating scenarios using active methods such as resonant magnetic field perturbation,
rapid variation of the radial field and pellet pacing. In particular, the amplitude
and frequency of type I ELMs have been actively controlled over a wide parameter range
(q(95) = 3-4.8, beta(N) <= 3.0) by adjusting the amplitude of the n = 1 external perturbation
field induced by error field correction coils. The study of disruption induced heat
loads on PFCs has taken advantage of a new wide-angle viewing infrared system and
a fast bolometer to provide a detailed account of time, localization and form of the
energy deposition. Specific ITER-relevant studies have used the unique JET capability
of varying the toroidal field (TF) ripple from its normal low value delta(BT) = 0.08%
up to delta(BT) = 1% to study the effect of TF ripple on high confinement-mode plasmas.
The results suggest that delta(BT) < 0.5% is required on ITER to maintain adequate
confinement to allow Q(DT) = 10 at full field. Physics issues of direct relevance
to ITER include heat and toroidal momentum transport, with experiments using power
modulation to decouple power input and torque to achieve first experimental evidence
of inward momentum pinch in JET and determine the threshold for ion temperature gradient
driven modes. Within the longer term JET programme in support of ITER, activities
aiming at the modification of the JET first wall and divertor and the upgrade of the
neutral beam and plasma control systems are being conducted. The procurement of all
components will be completed by 2009 with the shutdown for the installation of the
beryllium wall and tungsten divertor extending from summer 2009 to summer 2010.
