Prospect Toward Steady-State Helical Fusion Reactor Based on Progress of LHD Project Entering the Deuterium Experiment Phase

Abstract

Large Helical Device (LHD) is one of the world largest superconducting fusion experiment devices, having demonstrated its inherent advantage for steady-state operation since the start of experiments in 1998. LHD has also demonstrated reliable operation of the large-scale superconducting magnet system for almost two decades. Development of the challenging heating systems, such as negative-ion-based NBI, high-power and high-frequency ECH and steady-state ICH, have led to wideranging physics and engineering achievements.LHD has progressed to the next stage, that is, the deuterium experiment starting in March 2017, which should further extend plasma parameters towards reactor-relevant regime. For establishing firm basis for designing steady-state helical fusion reactor, advanced physics research, such as on isotope effect, energetic particle confinement, and plasma-wall interaction, will be intensively performed in the deuterium experiments. In an engineering aspect, the upgrade of NBI system has been carried out in preparation to the deuterium experiment, and it should contribute to future NBI development for fusion reactors including ITER. For enhancement of the particle control, the closed divertor system has been installed with pumping capability. Diagnostics for neutron measurements are newly developed and installed for the deuterium experiment.Aligned with all the progress of LHD project in terms of engineering and physics aspects, the conceptual design activity of the LHD-type helical fusion reactor, FFHR-d1, has been programmatically conducted. In parallel to the design study, engineering R&Ds for the component development have been performed, including those based on employing challenging ideas such as high-temperature superconductor, liquid metal ergodic divertor, and molten salt breeder blanket.The present status of LHD project entering the deuterium experiment phase is overviewed with putting emphasis on the engineering aspects, and then the engineering R&D activities towards steady-state helical fusion reactor are described.

Evaluation of Neutron Emission Rate with FIT3D-DD Code in Large Helical Device

“…In the Large Helical Device (LHD), deuterium experiments have been performed by using tangentially-injected neutral beams (NBs) with the ∼ 180 keV deuterium and perpendicularly-injected NBs with the 60 -80 keV deuterium [1][2][3][4]. In the deuterium experiments, the 2.45 MeV neutrons are generated by the D-D nuclear fusion.…”

Analysis of Energetic Particle Confinement in LHD Using Neutron Measurement and Simulation Codes

“…The deuterium plasma experiment in the Large Helical Device (LHD) started in March 2017 [1][2][3][4]. In general, deuterium fusion plasmas yield fast neutrons due to the deuterium-deuterium (DD) fusion reaction.…”

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

“…Progress in both the physics and engineering aspects of hydrogen experiment phase of LHD has been summarized in recent reviews [6,7]. More specifically, engineering aspects which were the focus of Ref.…”

“…More specifically, engineering aspects which were the focus of Ref. [6] include the reliable operation of the LHD's large-scale superconducting magnetic system, progress in heating systems, the closed helical diverter, and the successful development and installation of a tritium removal system (installed for use in deuterium experiments). Conversely, in Ref.…”