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Large Helical Device(LHD)Project

The Large Helical Device (LHD) Project conducts research on the confinement of high-temperature, high-density plasmas using the Large Helical Device (LHD), which employs a confinement magnetic field called the heliotron configuration. The LHD is one of the world's largest helical devices with superconducting coils that can generate a strong magnetic field on a regular basis. We are working on research issues related to core plasma physics, steady-state maintenance, and reactor engineering, which are necessary to realize future fusion reactors, by taking advantage of the excellent stability and steady-state characteristics of the LHD.

Heliotron Coordination

In order to stably confine plasma in a magnetic field container (a basket of magnetic field lines), an infinitely circulating magnetic field line with no end is required to close an escape route for particles. In addition, in order to create a donut-shaped cage with these lines of magnetic force, it is necessary to add a twist to the lines of magnetic field. The LHD is a helical device that employs a magnetic field configuration called heliotron configuration. Heliotron configuration has excellent steady-state operation capability because the magnetic field configuration necessary for confining the plasma can be formed using only a pair of helical external coils.

Outline of Large Helical Device

In the LHD project, academic research is being promoted to improve plasma performance and to understand the physics common to torus plasmas, including tokamaks, by using helical plasmas that do not require current flowing in the plasma, leading to the design of helical fusion reactors. The LHD consists of the main body of the device using superconducting coils, various plasma heating devices, and various instruments to measure various physical quantities such as the temperature and density of the plasma.

Device parameter of LHD
Outside diameter13.5 m
Height9.1 m
Weightapprox. 1500 t
Major radius3.9 m
Minor radius0.6 m
Plasma volume30 m3
Magnetic field strength3 T
Total heating power36 MW