NIFS

Research Report2020

LHD Research report December 22, 2020
Slowing-down mechanism of rotating fluctuation in magnetic confinement plasmas

In the magnetic confinement plasmas of the Large Helical Device (LHD), a rotating fluctuation is often observed and its frequency sometimes decreases to almost zero. ...

LHD Research report December 14, 2020
Impurity accumulation layer profiles in the Large Helical Device have been successfully reproduced by simulation

In the Large Helical Device (LHD), for every plasma discharge, impurity layers have accumulated on the in-vessel-components. The layers are very fragile and are characterized by an exfoliation property. ...

LHD Research report December 10, 2020
Remaining tritium in graphite divertor tiles were quantitatively analyzed by using a full-combustion method

To reveal the triton transport and the tritium migration in a deuterium plasma experiment in LHD, remaining tritium in divertor tiles made of graphite was investigated by using a combustion method. ...

LHD Research report November 23, 2020
Discovering Turbulence to Help Plasma Mixing

The mixing state of hydrogen and deuterium in plasma was measured for the first time in the world in a mixed plasma experiment using hydrogen and deuterium in a large helical device (LHD). ...

LHD Research report November 12, 2020
World's First Detection of Anisotropy in Electron Motion by Spectroscopic Measurement

In the Large Helical Device (LHD), the polarization of light emitted by hydrogen atoms has been measured with an accuracy of 1%. ...

LHD Research report October 19, 2020
Neutron measurement using an artificial diamond

We established a pulse shape discrimination method for evaluating thermal neutron flux using an artificial diamond detector. ...

LHD Research report September 14, 2020
Let the accumulated data talk about the state of plasma

We have developed a method for grasping the state of plasma using a large amount of data accumulated in experiments in the Large Helical Device (LHD) and have succeeded in demonstrating its practicality. ...

LHD Research report August 27, 2020
Investigating the cause of the disturbance in maintaining the high-ion temperature state

The Large Helical Device (LHD) has achieved ion temperatures above 120 million degrees Celsius. In high-ion temperature plasma discharges, magnetic field oscillations, generated by the pressure of the energetic ions, occur frequently. ...

Press ReleaseEurekAlert! June 29, 2020
Lose weight of fusion reactor component

The group of associate professor Hitoshi Tamura and others of the National Institute of Natural Sciences (NINS) National Institute for Fusion Science (NIFS) first applied topology optimization technique to the concept design of a helical fusion reactor which aims to demonstrate power generation. ...

Press ReleaseEurekAlert! June 29, 2020
An accurate simulation of high-pressure plasma for an economical helical fusion reactor

The research team of Assistant Professor Masahiko Sato and Professor Yasushi Todo of the National Institutes of Natural Sciences (NINS) National Institute for Fusion Science (NIFS) has succeeded using computer simulation in reproducing the high-pressure plasma confinement observed in the Large Helical Device (LHD). ...

LHD Research report June 17, 2020
Estimation of the beam ion confinement time in LHD

The confinement time of fast ions, which are generated by the neutral beam injection, has been estimated quantitatively in the LHD deuterium experiment by using neutron measurement and integrated simulation. ...

LHD Research report March 18, 2020
First observation of tritium distribution on plasma facing surfaces in stellarator/heliotron devices

Tritium distribution on plasma facing surfaces after the first deuterium plasma experimental campaign, conducted over four months, was investigated in the Large Helical Device (LHD) for the first time in stellarator/heliotron devices by using the tritium imaging plate technique. ...

Press ReleaseEurekAlert! February 26, 2020
Isotope movement holds key to the power of fusion reactions

Fusion may be the future of clean energy. The same way the sun forces reactions between light elements, such as hydrogen, to produce heavy elements and heat energy, fusion on Earth can generate electricity by harnessing the power of elemental reactions. ...

LHD Research report January 29, 2020
Mechanism of plasma radiation concentration at “knot”of magnetic field lines

It has been reproduced in the newly developed simulation code that plasma radiation concentrates at the “knot” of the magnetic field lines, and its mechanism is recognized as the same as thermal condensation instability, which also occurs at star formation in the universe. ...

LHD Research report January 22, 2020
Real-time control of millimeter-wave propagation for highly efficient plasma heating

We have developed a real-time control system for the millimeter-wave injection system for electron cyclotron heating and have shown that the system can heat the plasma efficiently by optimizing the injection for the time-varying plasma in the Large Helical Device (LHD)....

LHD Research report January 2, 2020
Ion measurement by millimeter and sub-millimeter in plasma

In high-temperature plasmas, it is not easy to diagnose the state of ions and fast ions because they cannot be measured directly by a thermometer. ...