Advanced Helical Plasma Research towards a Steady-State Fusion Reactor by Deuterium Experiments in Large Helical Device

Yasuhiko Takeiri

doi:10.3390/atoms6040069

Abstract

The Large Helical Device (LHD) is one of the world’s largest superconducting helical system fusion-experiment devices. Since the start of experiments in 1998, it has expanded its parameter regime. It has also demonstrated world-leading steady-state operation. Based on this progress, the LHD has moved on to the advanced research phase, that is, deuterium experiment, which started in March 2017. During the first deuterium experiment campaign, an ion temperature of 10 keV was achieved. This was a milestone in helical systems research: demonstrating one of the conditions for fusion. All of this progress and increased understanding have provided the basis for designing an LHD-type steady-state helical fusion reactor. Moreover, LHD plasmas have been utilized not only for fusion research, but also for diagnostics development and applications in wide-ranging plasma research. A few examples of such contributions of LHD plasmas (spectroscopic study and the development of a new type of interferometer) are introduced in this paper.

Highlights

The Large Helical Device (LHD) [1] is one of the world’s largest magnetically-confined fusion-experiment devices and is categorized as a helical system
During the first deuterium experiment campaign, an ion temperature of 10 keV was achieved. This was a milestone in helical systems research: demonstrating one of the conditions for fusion. All of this progress and increased understanding have provided the basis for designing an LHD-type steady-state helical fusion reactor
The main goals of the LHD are to establish a scientific basis for a steady-state helical fusion reactor and to promote academic study for a comprehensive physics-based understanding of toroidal plasmas

Summary

Introduction

The Large Helical Device (LHD) [1] is one of the world’s largest magnetically-confined fusion-experiment devices and is categorized as a helical system. The LHD has the critical advantage and engineering capability of steady-state operation. It has played a complementary and alternative role to the tokamak approach. It is worth noting that helical fusion research has been performed worldwide, as shown in Figure 1 [2]. Another large-scale superconducting device, Wendelstein 7-X, started operation in 2015 [3]. Atoms 2018, 6, 69 as a platform for wide-ranging plasma research by describing two examples of its use within such research These examples are the LHD’s use in spectroscopic study, and the development of a new type 2019, of interferometer that is applicable to atmospheric pressure plasmas

LHD Project Entering Deuterium Experiment Phase

The deuterium campaign

Conceptual of the LHD-Typeplasmas

Elements

Conclusions