Split and Segmented-Type Helical Coils for the Heliotron Fusion Energy Reactor

Yanagi, N.; Nishimura, K.; Bansal, G.; Sagara, A.; Motojima, O.

doi:10.1585/pfr.5.s1026

Cited by 13 publications

(24 citation statements)

References 17 publications

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“…Helical coils in a heliotron-type fusion reactor, FFHR [3], and toroidal field coils in a component test machine (a small tokamak), Vulcan [4], are the examples of application with remountable HTS magnet. The HTS could enable mechanical (electrical) joints of conductors constituting the magnet because of its high critical current, critical field and heat capacity at relatively high operating temperature (> 20 K).…”

Section: Introductionmentioning

confidence: 99%

Characteristic evaluation of cooling technique using liquid nitrogen and metal porous media

Tanno

Hashizume

2014

AIP Conference Proceedings

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Abstract.A remountable high-temperature superconducting magnet, whose segments can be mounted and demounted repeatedly, has been proposed for construction and maintenance of superconducting magnet and inner reactor components of a fusion reactor. One of the issues in this design is that the performance of the magnet deteriorates by a local temperature rise due to Joule heating in jointing regions. In order to prevent local temperature rise, a cooling system using a cryogenic coolant and metal porous media was proposed and experimental studies have been carried out using liquid nitrogen. In this study, flow and heat transfer characteristics of cooling system using subcooled liquid nitrogen and bronze particle sintered porous media are evaluated through experiments in which the inlet degree of subcooling and flow rate of the liquid nitrogen. The flow characteristics without heat input were coincided with Ergun's equation expressing single-phase flow in porous materials. The obtained boiling curve was categorized into three conditions; convection region, nucleate boiling region and mixed region with nucleate and film boiling. Wall superheat did not increase drastically with porous media after departure from nucleate boiling point, which is different from a situation of usual boiling curve in a smooth tube. The fact is important characteristic to cooling superconducting magnet to avoid its quench. Heat transfer coefficient with bronze particle sintered porous media was at least twice larger than that without the porous media. It was also indicated qualitatively that departure from nucleate boiling point and heat transfer coefficient depends on degree of subcooling and mass flow rate. The quantitative evaluation of them and further discussion for the cooling system will be performed as future tasks.

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Section: Introductionmentioning

confidence: 99%

Characteristic evaluation of cooling technique using liquid nitrogen and metal porous media

Tanno

Hashizume

2014

AIP Conference Proceedings

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“…For FFHR, the ∼40-m diameter helical coils are required [1,2]. There are three options for the superconductor selection: the cable-in-conduit (CIC) conductor using lowtemperature superconducting (LTS) strands such as Nb 3 Al or Nb 3 Sn [3], the indirectly-cooled solid-type conductor using LTS [4] and the indirectly-cooled solid-type conductor using high-temperature superconductors (HTS) represented by YBCO [5][6][7][8]. Presently, the well-established LTS conductors are being used in fusion devices like the Large Helical Device (LHD), and this could be the primary option for the FFHR magnet.…”

Section: Introductionmentioning

confidence: 99%

“…method using the HTS conductors has been proposed for FFHR [6][7][8]. Figure 1 shows a schematic illustration of the segment-fabricated HTS helical coils.…”

Section: Introductionmentioning

confidence: 99%

Measurement of the Joint Resistance of Large-Current YBCO Conductors

Terazaki

Yanagi

Tomida

et al. 2012

Plasma and Fusion Research

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Feasibility studies on applying high-temperature superconductors (HTS) to the LHD-type heliotron fusion energy reactor FFHR are being carried out. Because the HTS conductor has high cryogenic stability at elevated temperature operations (e.g. 20 K) and the refrigeration power has enough margins, it is considered that Joule heating dissipation generated at joints of conductors is acceptable to facilitate the segmented fabrication of the helical coils of FFHR. In this study, the joint resistance with 10-kA class YBCO conductors has been measured to evaluate the joule heating dissipation in the FFHR magnet. The experiment has been carried out by fabricating a soldered lap joint and a mechanical lap joint. The feasibility of segmented fabrication is examined by the measured results.

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“…To facilitate the winding of large complex coils, such as the helical coils of FFHR-d1, one possibility is segmented fabrication using HTS conductors [26,[28][29][30][31] instead of continuous winding using LTS conductors. Segmented fabrication was first proposed for helical reactors in the 1980's with the so-called "demountable" concept [28], which is illustrated in Fig.…”

Section: Segmented Fabrication Of Large Complex Coils Using Hts Condumentioning

confidence: 99%

Feasibility of HTS Magnet Option for Fusion Reactors

Yanagi

Terazaki

Natsume

et al. 2014

Plasma and Fusion Research

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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.

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Split and Segmented-Type Helical Coils for the Heliotron Fusion Energy Reactor

Cited by 13 publications

References 17 publications

Characteristic evaluation of cooling technique using liquid nitrogen and metal porous media

Characteristic evaluation of cooling technique using liquid nitrogen and metal porous media

Measurement of the Joint Resistance of Large-Current YBCO Conductors

Feasibility of HTS Magnet Option for Fusion Reactors

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