G. Agarici

Experience feedback from high heat flux component manufacturing for Tore Supra

Abstract Tore Supra is involved in flat tile carbon armoured plasma facing components (PFCs) since 1985. In 1997, a third generation of components, based on the original concept developed with Plansee Company, called active metal casting (AMC®), has been launched. Since 1998, 660 elementary components for the toroidal pump limiter (TPL) are in production. The route of the manufacture is rather complex and many controls were requested all along the fabrication to insure a high reliability of the elements. One of the main controls is the final infrared (IR) test allowing to determine the quality of the bonding between the carbon fibre composite (CFC) tiles and the heat sink made of copper–chromium–zirconium alloy (CuCrZr). Although results for the first batch of elements were as expected (less than 5% rejected at the final test), unexpected defects appeared with the followings batches. Investigations on the fabrication processes underlined the importance of having a better heat treatment of the pieces in copper alloy (CuCrZr), however this was not sufficient to completely explain the observed defects.

New advanced launcher for lower hybrid current drive on Tore Supra

Abstract A new actively cooled advanced launcher is being built for Tore Supra LHCD to inject 4 MW during 1000 s at 3.7 GHz, at a power density of 25 MW/m 2 (a conservative value observed in Tore Supra experiments). It is made from an array of 6×48 active and 6×9 passive waveguides. The design uses technologies which are relevant for a next step machine such that it can: (i) withstand a plasma radiated flux of 0.15 MW/m 2 ; (ii) radiate power with spectra having peak N// values of 2.02±0.35; (iii) withstand a total torque of 8.6 10 4 N m during disruptions; (iv) allow an antenna 20 cm radial stroke adjustable in real time, (v) withstand a convected power flux of 10 MW/m 2 on its guard limiter made of CFC tiles. A prototype of each new component of this antenna has been tested successfully at the nominal power with a pulse length of 1000 s.

First plasma experiments in Tore Supra with a new generation of high heat flux limiters for RF antennas

During the 1997 and 1998 Tore Supra shutdown, a first set of new antenna guard limiters was installed on one of the three ion cycloton resonance heating (ICRH) antennas of Tore Supra. This limiter, which was one of the main technological studies of the 1998 campaign, was widely experimented in real plasma conditions, thus allowing the validation in situ, for the first time, of the technology of active metal casting (AMC) for plasma facing components. The huge improvement in the thermal response of the new limiter generation, compared to the old one, is shown on plasma pulses made identical in terms of antenna position and injected RF power profile. By using the infrared cameras installed inside Tore Supra and viewing the antennas front, the power density fluxes received by the carbon fibre composite (CFC) surface of the limiter were evaluated by correlation with the heat load tests made on the electrons beam facility of CEA/Framatome.

Quality control of plasma facing components for Tore Supra

Abstract The high technology components used in fusion devices, especially high heat flux (HHF) plasma facing components, require high reliability. This can be only guaranteed by a very high level of quality control (QC) through rigorous acceptance inspection procedure. Qualification of the power exhaust capabilities of HHF components in normal operation requires control of their thermal and mechanical integrity. During the last 4 years, the Tore Supra QC team improved acceptance inspection procedures for HHF components, which have been 100% controlled before their installation in the Tokamak. Innovative investigations of non-destructive techniques, such as pressure drop test, helium leak testing procedure, infrared thermography, were performed and it was shown that these techniques are essential tools for QC of critical parts.

Tore supra ICRH antenna prototype for next step devices

ITER-like IC antennas, fulfilling or possibly exceeding ITER requirements and designed for long pulse operation (1000 s) are currently being developed at Cadarache. As part of these developments, a project of an IC antenna prototype obtained by modifying a tore supra (TS) resonant double loop (RDL) antenna is proposed, to assess in real working conditions the performance of this scheme. After a brief comparison between the new RF circuit version and the conventional RDL circuit, which has been tested in TS for 10 years, the paper focuses on the design and manufacturing aspects of the prototype.

High power density and long pulse operation with Tore Supra ICRF facility

Abstract Ten years after the first ion cyclotron range of frequency (ICRF) heated Tore Supra (TS) plasma shot, and as TS facility, now equipped with the new ‘CIEL’ high power handing in-vessel components (This SOFT), is progressing towards long pulse performances, the main results and experience gained from the ICRF system are reviewed. An overview of the present status of TS ICRF facility is given, with highlights on the main modifications made to the initial plant and associated results. TS ICRF system achievements are then reported from a large ICRF heated pulses database covering ten experimental campaigns (1991–2001). The main technological issues encountered, especially those relevant to next step ICRF system design, are also discussed. Finally, in view of extended pulse length performances on TS, the present limitations of the ICRF facility and future plans are outlined.

Tore Supra ICRH antennas for long pulse operation

The Tore Supra ICRH antennas, built in collaboration with ORNL according to the Resonant Double Loop concept, have been used for many years in various experimental schemes. In the frequency range between 35 to 80 MHg they have contributed to meet the initial aim of the Tore Supra tokamak: to operate at a plasma current up to 1.7 MA, over 30 seconds or with a heating power higher than 10 MW. Based on the experience gained, the next step, aiming at high power operation up to 25 MW with long pulse discharges (1000 s), is scheduled on Tore Supra.

High performance results with the LHCD system on Tore-Supra and new Launcher design for quasi continuous operation

High power and energy performance have been achieved by the Tore-Supra LH system during the last experimental campaign. Far distance coupling as well as plasma pulses up to 120 s in steady state conditions with a power density of 24 MW/m2 were obtained. A new launcher, made with RF components such as mode converters has been designed in order to extend the present TS performance towards quasi continuous operations.

A new internal matching impedance concept for ICRF antennas

As an alternative to commercial capacitors which have experienced reliability problems and are irrelevant to the next step, a new all-metal impedance concept has been elaborated for Tore Supra ICRF Resonant Double Loop (RDL) antenna. Two detailed design versions are presented, both based on the principle of a parallel LC transformer inserted in a coaxial structure. First low power measurement results on a full-scale mock-up are discussed.

Thermal behaviour of ICRH antennas on Tore Supra

The goal of the CIEL project on Tore Supra is to demonstrate a heat removal capability of 15MW convected plus 10MW radiated, over typical pulses of 1000s. Nearly all of this heating power will be delivered by RF systems, including ICRH. It is thus crucial to make sure that the RF system itself can sustain high thermal loads for long times. A systematic study of the thermal behavior of Tore Supra ICRH antennas has been undertaken, by means of visible and infrared light cameras. Experimental results demonstrate a variety of edge-antenna interaction phenomena, depending on the plasma configuration and the location on the plasma facing components (PFCs).