After the 2001 shutdown the restart activity commenced as planned on November 26th with the torus pump down. In January and February 2002 a series of problems with leaking vacuum windows, faults in the cryogenic plant, and a water leak from a window on the Lower Hybrid System delayed the restart activities by a total of two weeks.

Following these delays, the start of EFDA experimental campaign C5 was moved to 18th March to allow the key systems to be commissioned. However, problems with the power supplies of Octant 8 Neutral Beam Injection (NBI) system delayed the availability of this system until the end of April.

Campaign C5 started on 18th March and finished on 31st May with a total of 101 experimental sessions planned and the participation of 200 scientists from 15 Associations. There was good progress with many aspects of the S/T programme, but various technical problems occurred during the campaign. This resulted in 21 sessions lost due to problems with various systems: failure of the baking plant control system; investigation of a suspected air leak (which turned out to be a false alarm); investigation of a suspected in-vessel water leak arising from the connection of an un-pumped volume to the torus; failure of a fan on the Poloidal Field (PF) flywheel generator; and problems with the Toroidal Field (TF) cooling circuit.

There were also constraints on the S/T programmes arising from the delayed availability and reduced power from the Octant 8 NBI system. This required significant reshuffling of the programme. Consequently, some experiments originally planned for C5 will not be completed until C7.

An analysis of the events and the relevant causes has been done by the operator and Culham CSU. Corrective actions have been defined. The urgent actions are being addressed in the August restart and campaign C6. The implementation of the full corrective plan is under discussion.

Although C5 was a difficult campaign, a number of interesting experimental results were obtained. The removal of the septum has increased the flexibility in terms of plasma shape. In ELMy H-mode plasmas there is preliminary evidence of higher confinement in the preparation of high current discharges; of mixed Type I-II ELMs in near double null configuration; and of reduction of target plate temperatures with Ar seeding. Diagnostic optimised configurations have been developed, with resolved pedestal and edge gradients. Electron heat modulation experiments using ICRF mode conversion in L mode indicate stiffness of electron profiles. The existence of a Neutral Point for density limit disruptions in JET was demonstrated and modelled: this has useful applications for disruption amelioration. Active control of advanced tokamak scenarios has been demonstrated with real time control of the plasma current profile. ITBs were obtained with the ITER shape. Pellets injected after the prelude phase lead to high density ITBs, with Te~Ti. Promising high current experiments were started by producing ITBs with 3.5 MA and 3.45 T.

Octant 8 Neutral Beam Injection (NBI) system: The JET torus is divided into 8 sectors. Three of them are equipped with a NBI system injecting beams of fast neutral particles, which become ionised in the plasma and heat it as they slow down.

S/T (Science and Technology) programme: The experimental programme on the JET facilities since 1 January 2000 has been organised and conducted by S/T task forces comprising staff from the European fusion Associations.

Belgian Minister of Science visited Culham

François-Xavier de Donnea, Belgian Minister of Science, visited Culham on May 7, accompanied by Professor Paul Vandenplas (Head of Euratom-Belgian State Association), Belgian journalists and a film crew. He had briefings from Derek Robinson, Head of the Research Unit of the Euratom/UKAEA Fusion Association and from Jérôme Paméla (EFDA Associate Leader for JET ) on the role of JET as a rehearsal for ITER operation. He toured the JET facilities and the MAST experiment and also visited the Culham Innovation Centre as part of his briefing on fusion’s outreach to industry.