Development of full-scale conductors for the ITER Central Solenoid Scalable Model Coils

Abstract

Abstrad-Japan Atomic Energy Research Institute(JAERI)has been developing 13-T, 40-kA conductors for the ITER Central Solenoid Scalable Model Coil. The conductors are composed of high performance (NbTi)jSn strands and titanium conduit. In this development work, 15-km length strand fabrication from a 100-kg billet, chrome plating, cabling of 675 or 768 strands, jacketing of titanium conduit, and so on were conducted by two mass production lines. In this paper, several test results are reported such as critical current measurements of full-scale conductors and AC loss measurements of sub-scale conductors.Previously, experimental strands, which had an 800-Nmmz nonapper current density (Jc) at 12 T and a 6-pm effective filament diameter (De@ [2][3][4], were manufactured by a bronze process, using only a 10-kg billet. As the next step in strand technology, strands of 15-km length were fabricated using a 100-kg billet to provide a database for mass production. In practice, full-scale conductors of 20-m length were manufactured in order to evaluate the full-scale conductor, as shown in Fig. 1.In this paper, measurements of critical current (IC) of fullscale conductors and AC losses of sub-scale conductors are evaluated as an estimate of conductor performance.

Development and testing of 40-kA, 13-T Nb/sub 3/Sn cable-in-conduit conductors for a fusion reactor

“…Critical current (IC) measurements of the full-scale conductors were carried out at JAERI [2]. From these results, degradation due to fabrication was little, and the IC was close to estimated value from strand data.…”

“…At the critical current measurement in JAERI, obvious ramp rate limit was observed, whose sample conductor has a shorter length of 1.7 m and was operated in saturated liquid helium condition [2]. In a series of experiment at the FENIX test facility, no ramp rate limit appeared up to the charging speed of 10 kAh from 0 A to 40 kA in condition of supercritical helium of 4 bar and around 5 K.…”

“…The requirements of the CS conductor are (1) 13-T magnetic field, (2) 40-kA operating current, and (3) 0.3-Th pulse operation. The main technical issue is to achieve stable operation at 13 T and 40 kA.…”

First results of a parametric study on coupling loss in subsize NET/ITER Nb/sub 3/Sn cabled specimen

“…The contact pressure between the strands is hardly taken into account but may possibly play an important role [3,4,5]. Recent results of coupling current tests on a jacketed 48 (Cr coated) strands subcable without load, show a time constant of 27 ms [6] and no explanation is given for this high value. A parametric study, restricted to a limited variation of the reference cable lay out, is necessary to identify the quantitative impact of manufacturing parameters on the Manuscript received October 17, 1994.…”