Integrating core and edge performance at JET


Marco de Baar for the JET-EFDA contributors*

Operations Department

EFDA Close Support Unit


JET is the largest tokamak in the world, featuring unique scientific and
technical capabilities such as the ability to operate with plasma
currents up to 5 MA and the possibility of using a DT mixture. Since
2000 the JET facilities have been exploited under the European Fusion
Development Agreement (EFDA).

JET has made key contributions to the ITER design and plays a major role
in consolidating the ITER operating scenarios and auxiliaries such as
additional heating systems. In this colloquium, JET's latest results on
H-modes, ELM control, Hybrid scenarios and advanced scenario's will be
introduced. Having all the elements available, the next challenge is
integration: Can we engineer discharges that integrate

1) high core confinement,
2) low core impurity accumulation,
3) mild ELM's,
4) a high edge radiation fraction and
5) a large non-inductive current fraction?

One of the developmental lines for  scenario integration, The low q95
Nitrogen seeded type III Elmy H-mode, will be discussed in detail.

JET's experimental campaigns will benefit from a series of enhancements
that will be mounted in the shutdowns of 2005 and 2006. A load bearing
septum replacement plate in the divertor enables plasma configurations
with high triangularity under high heat-fluxes for considerable times.
The efficiency of the NBI neutralisers has been increased, bringing the
total NBI power to 25 MW. The conjugate T system in the ICRH enables
coupling under difficult ELMy conditions. A new ITER-like ICRH antenna
will be installed. In addition, a possible JET programme beyond 2006 is
being vigorously pursued. In particular a complete new Beryllium 1st
wall and Tungsten divertor a further major upgrade in NBI power and a
pellet injector for ELM control will be procured.


* See the Appendix of J. Pamela et al., Fusion Energy 2004 (Proc. 20th
Int. Conf. Vilamoura, 2004) IAEA, Vienna (2004)