The next European torus (NET): Objectives, design approach, and planning

Abstract

The performance requirements of NET are defined by its main objectives. These are the demonstration of controlled ignited burn of a D-T plasma over times of at least 100 s, the demonstration of reliable operation of a fusion plant, and the provision of a test bed for the development of the plasma facing and nuclear components needed for the initial operation of a DEMO reactor. A design approach has been developed on the basis of present experience while considering the extent to which an improved data base can be obtained from the investigations now under way and that can be completed within the next few years. In particular, the machine parameters and design solutions have been selected such that—to the extent possible—uncertainties in plasma performance and plasma-wall interaction can be accommodated. A reference set of basic machine parameters has been defined which is consistent with a range of plasma parameters and configurations: a plasma current up to 15 MA, elongations up to 2.2, as well as single and double null configurations. The current can be ramped-up and driven inductively for burn pulses of 200 s or more; noninductive current drive allows the pulse duration to be extended, if used for current ramp-up assist, and may be used for steadystate operation in a nonignited mode. This flexibility is an essential feature of the NET device. The predesign of NET is now in an advanced stage and the design solutions adopted are being verified by an extensive technology program in the Associated European Institutions and in industry. Upon completion of the predesign, taking into account the improvements expected in the physics and technology data bases by the end of 1989, the next major milestone of the NET program is the decision on the detailed design phase and its support by major prototype construction and tests.