Design activities on helical DEMO reactor FFHR-d1

Conceptual design studies are being carried out on the application of high-temperature superconducting (HTS) conductors and coils to the magnet systems of fusion reactors. A 100-kA-class HTS conductor is required to be applied at high magnetic fields of > 12 T. A simple stack of YBCO tapes embedded in copper and stainless-steel jackets is found to be a practical approach to producing large-scale conductors that exhibit high cryogenic stability and mechanical rigidity. The feasibility of the segmented fabrication method for large complex HTS coils, such as the helical coils in the LHD-type helical fusion reactor FFHR-d1, is being investigated by developing mechanical bridge-type lap joint technology of HTS conductors.

Section: Design Of a 100-ka-class Hts Conductor For DC Magnets Of Fusmentioning

confidence: 99%

Section: Design Of Hts Coil Winding Packmentioning

confidence: 99%

Feasibility of HTS Magnet Option for Fusion Reactors

Yanagi

Terazaki

Natsume

et al. 2014

“…On the basis of outputs from the LHD, design studies of the FFHR-d1 reactors have been performed. The FFHRd1 has a major radius of 15.6 m, a toroidal field of 4.7 T, and a fusion power of 3.0 GW [2,3]. Details of the threedimensional design of the superconducting magnets, consisting of two helical and four poloidal coils, and neutronics analyses have already been published [2].…”

Section: Introductionmentioning

confidence: 99%

A Cooling Concept for Indirectly Cooled Superconducting Magnets for the Fusion Reactor FFHR

Takahata

Tamura

Mito

et al. 2015

Helical fusion power reactors have competitive advantages for steady-state operation because they use a currentless plasma. This paper presents the cooling concept of the indirectly cooled superconducting helical coil for the helical fusion reactor FFHR-d1. The helical coil consists of continuously wound aluminum-alloy-jacketed Nb 3 Sn superconductors and intermediate metal plates that not only cool the conductor indirectly, but also support the electromagnetic force. The copper cooling panels are partially mounted in the stainless steel intermediate plate and cooled by cryogenic supercritical helium. The conductor is cooled by contact with the cooling panels through an insulation material with high thermal conductivity, such as a ceramic. Fundamental calculations show that this cooling concept is technically feasible. Experimental investigations yielded a candidate for the ceramic insulator with high thermal conductivity.

“…The FFHR-d1 heliotron-type fusion reactor requires 100-kA-class superconducting conductors for a pair of helical coils experiencing a maximum magnetic filed of 12 T [1]. The use of high-temperature superconducting (HTS) conductors can allow the coils to be operated at elevated temperatures (> 20 K), where the coils can have higher heat capacity and lower refrigeration energy than low-temperature superconducting (LTS) coils.…”

Section: Introductionmentioning

confidence: 99%

Bridge-Type Mechanical Lap Joint of a 100 kA-Class HTS Conductor having Stacks of GdBCO Tapes

Seino

Yanagi

Terazaki

et al. 2014

In this paper, we reported design, fabrication and test of a prototype 100-kA-class high-temperature superconducting (HTS) conductor, especially for joint section, to be used for segmented HTS helical coils in the FFHR-d1 heliotron-type fusion reactor. The conductor has a geometry of three rows and fourteen layers of Gadolinium Barium Copper Oxide HTS (GdBCO) tapes embedded in copper and stainless steel jackets and has a joint section with bridge-type mechanical lap joint. We introduced improved method to fabricate the joint based on pilot experiments and we were able to apply a current of ∼ 120 kA at 4.2 K, 0.45 T to the sample without quench at joint. The obtained joint resistance was ∼ 2 nΩ, which was lower than our previous data. Though joint resistance increased with a rise in current and magnetic field, predicted joint resistance in the environment of actual helical coil in the FFHR-d1 was small enough to properly run the cryoplant of the reactor.