Tests and Analyses of Two TF Conductor Prototypes for JT-60SA

Abstract

In the framework of the JT-60SA project, included inside the Broader Approach agreement, EU is expected to provide to JA the totality of the toroidal field (TF) magnet system. It consists in 18 coils, evenly shared for in-kind procurement between France and Italy while the TF conductor providing is under the responsibility of Fusion for Energy. The conductor is a rectangular-shaped, NbTi-based, cable-in-conduit (CICC) and will be wound in double-pancake inside the TF casing. In the paper, the experimental approach of conductor design validation process and the associated analyses of conductor samples test campaign in the SULTAN facility are shown. A design and manufacture action on full-size SULTAN-type short samples for the TF conductor have been launched in 2007 to allow an early gathering of relevant information enabling to proceed onto the conductor design qualification process. A series of two pre-prototypes was realized, based on a former conductor design which even if slightly different from the most up-to-date layout, includes all its important relevant features: square-shaped section, superconducting strands segregation with copper, no subwrapping. The samples are designed to allow comparative studies on shape influence (two types of sections) and on joint influence (presence or not of a bottom joint), and to provide a consolidated baseline for making decisions on conductor final design. A descriptive part of the samples manufacturing activity is included. The samples TFCS1 and TFJS1 were then characterized in the SULTAN facility (Villigen, CH) respectively in 2008 and 2009, experiencing DC tests, AC tests, mechanical cycling, and stability tests. The corresponding results and the associated analyses are shown and statements regarding the contribution of the present results to the assessment of the actual JT-60SA TF conductor design are also drawn.