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Design, Construction and Initial Experiments of Internal-Coil Divertor Experimental Device SOLEIL

Takaaki FUJITA*, Atsushi OKAMOTO, Yuichi KAWACHI, Taketo OSHIRO, Hisato KIZU, Shungo KAMBARA

Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan

(Received 27 December 2025 / Accepted 27 February 2026 / Published 3 July 2026)

Abstract

A new torus device named SOLEIL, equipped with a copper internal coil (IC), has been constructed and plasma experiments have been initiated. A unique feature of SOLEIL is that the magnetic field structure of the divertor tokamak plasma, with either a single null point or double null points, can be generated without plasma current. Various shapes of the last-closed flux surface (LCFS) can be formed including both positive and negative triangularity. The primary objective of the device is to study the dependence of the scrape-off layer (SOL) flow and impurity transport in the SOL and divertor regions on the LCFS shape. In the design of the device, it was intended to make the IC as compact as possible, to minimize its impact on the plasma confinement. Dismountable toroidal field coils were also designed to be compact taking into account space constraints. The main parameters are as follows: the major radius of the IC is 0.18 m, the minor radius of the IC cover is 0.031 m, the nominal IC current is 8 kA⋅turns, and the nominal toroidal field is 0.0875 T at R = 0.18 m. The assembly was completed in January 2025 and the first plasma was generated in February 2025.

Copyright (c) 2026 The Japan Society of Plasma Science and Nuclear Fusion Research

Keywords

internal coil, divertor configuration, SOL flow, impurity transport, negative triangularity

DOI: 10.1585/pfr.21.1302036

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References

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