Overview of Fusion Engineering Research in Japan Focusing on Activities in NIFS and Universities

Muroga, T.; Fukada, Satoshi; Hayashi, T.

doi:10.1080/15361055.2019.1603499

Cited by 4 publications

(4 citation statements)

References 116 publications

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“…An overview of Japanese fusion engineering research activities focusing on those being carried out by the National Institute for Fusion Science (NIFS) and Japanese universities (Universities) is given by Muroga et al [11]. NIFS is promoting the Fusion Engineering Research Project (FERP) as one of three research projects.…”

Section: Introductionmentioning

confidence: 99%

Negative ion source operation with deuterium

Bacal

Wada

2020

Plasma Sources Sci. Technol.

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When the working gas of a negative ion source is changed from hydrogen to its isotope, deuterium, an ‘isotope effect’ is observed; namely, several plasma characteristics such as the electron energy distribution, the atomic fraction and the spectra of rovibrationally excited molecules change. The understanding of the effect becomes more important, as research and development aiming at ITER power level operation is being challenged with feeding deuterium to the ion sources. As a historical review of the effort to develop hydrogen/deuterium negative ion sources, several types of negative ion sources designed for the neutral beam plasma heating are described: double charge exchange sources, volume sources and surface-plasma sources. The early results with volume sources operated with and without cesium are introduced. The characteristics of the source charged with deuterium are compared to those of the source charged with hydrogen. The isotope effect did not appear pronounced as the negative ion density was measured in a small source but became more pronounced when the plasma source size was enlarged and the discharge power density was increased to higher values. Surface plasma sources were optimized for deuterium operation but could not achieve the same performance as a source operated with hydrogen at the same power and pressure. The lower velocity of negative deuterium ions leaving the low work function surface seemed to limit the production efficiency. Fundamental processes causing these differences in negative ion source operation are summarized. After explaining the current status of negative ion source research and development, the acquired knowledge is utilized to the development of large negative ion sources for nuclear fusion research and to the development of compact negative ion sources for neutron source applications.

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Section: Introductionmentioning

confidence: 99%

Negative ion source operation with deuterium

Bacal

Wada

2020

Plasma Sources Sci. Technol.

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“…All tests described were executed in the LMFREX channel of Kyoto University (see figure 3(a)) [21,22]. LMFREX is an acrylic channel equipped with a heater and thermocouple array to study heat flux within MHD flows.…”

Section: Methodsmentioning

confidence: 99%

“…where I 0 is the externally applied current, A is the surface area of the boundary and σ is the electrical conductivity of the LM. Assuming no electric current can enter or exit the domain through inlets and outlets, their boundary condition for the electric scalar potential is in equation (21):…”

Section: Appendix B Governing Equations and Boundary Conditions On Fr...mentioning

confidence: 99%

Experimental, numerical and analytical evaluation of j × B -thrust for fast-liquid-metal-flow divertor systems of nuclear fusion devices

Castro¹,

Fisher²,

Al-Salami³

et al. 2023

Nucl. Fusion

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Divertor systems of fusion devices exhaust intense heat loads from the plasma, which degrades solid plasma-facing components (PFCs). Fast liquid metal (LM) flow divertors may be more advantageous for this purpose. However, LMs have risk of piling due to intense magnetohydrodynamic (MHD) drag. Despite this, severe deceleration of the flow could be countered with the injection of currents that are transverse to external magnetic fields, allowing to thrust the flow with jxB forces. The injection of currents as an approach to propel LM-divertor flows has remained experimentally understudied. This article focuses on the evaluation of jxB-thrust and finding its drawbacks. This paper evidences that the simple operation of a LM-flow divertor with jxB-thrust, without any of the instabilities caused from reactor plasmas or parasitic currents, already presents intrinsic challenges.jxB-thrust was experimentally tested with free-surface-LM flows, a vertical magnetic field and and externally applied current. Experiments were reviewed with a theoretical model, showing agreement in the trends of theory and experiments. Full 3D-MHD-free-surface flow simulations were also performed with FreeMHD and confirmed the sensitivity to unstable flow behavior in LM systems when applying external currents. Furthermore, excessive power requirements are expected for the implementation of jxB-thrust at the reactor scale, making these systems inefficient for commercial devices.

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“…Such activities should be continued and extended in the future. This theme setting is a good example of the importance of basic research to strengthen DEMO-oriented fusion reactor development research [25].…”

Section: Proposals Regarding the Future Direction Of Irradiation Rese...mentioning

confidence: 99%

Challenge to Performance Evaluation of Fusion Reactor Materials by Fission Neutron and Charged Particle Irradiation

Muroga

2023

MSF

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Since there are no fusion reactors generating high-flux 14 MeV neutrons, it is necessary to evaluate materials’ performance in fusion reactors based on a correlation of fission neutron and charged particle irradiations. However, the irradiation tests involve various issues which prevent simple correlation and evaluation. In this paper, the issues related to irradiation temperature control and dose rate effects are pointed out and analyzed, and proposals regarding future irradiation tests are given.

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Overview of Fusion Engineering Research in Japan Focusing on Activities in NIFS and Universities

Cited by 4 publications

References 116 publications

Negative ion source operation with deuterium

Negative ion source operation with deuterium

Experimental, numerical and analytical evaluation of j × B -thrust for fast-liquid-metal-flow divertor systems of nuclear fusion devices

Challenge to Performance Evaluation of Fusion Reactor Materials by Fission Neutron and Charged Particle Irradiation

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