Conference Report on the 7th International Symposium on Liquid metals Applications for fusion (ISLA-7)

Supported by the world magnetic fusion research community, a series of International Symposia on Liquid metals Applications for fusion (ISLA) have been held biannually since 2010. The 7th edition (ISLA-7) was held for the period from 12 December through 16 December 2022, at Chubu University located in Kasugai, Aichi, Japan. For the first time in the history of this series of symposia, ISLA-7 was held in a hybrid fashion, due to the COVID-19 situation. The total number of the participants was 60, 34 out of whom attended the symposium in person, and the rest participated online. As to the presentation statistics, 29 papers were presented in person, whereas 21 presentations were delivered online but real-time by the presenters in China, Spain, the UK, and the USA. Both of the presentations delivered in person and online were recorded, and the video has been shared by all participants. These participants represent 11 countries: China, Czech, Italy, Japan, Latvia, Netherlands, Russia, Thailand, the UK, and the USA. All these numbers are among the largest in this series of symposia. Covered by these presentations are; in session-2, program overviews and liquid metal research review; in session-3, liquid metal flows, and MHD issues; in session-4, liquid metal facilities; in sessions-5 and 6, liquid metal experiments and modeling; in session-7, divertor physics and heat flux mitigation; in session-8, plasma and liquid metals interactions; in session-9 liquid metal plasma-facing components, erosion, and wettability. In addition, there were an opening session whereby several opening addresses were delivered and also a closing session where all technical session summaries were presented by the respective session chairs.journal articl

Impact of HBV Infection on Outcomes of Direct-Acting Antiviral Therapy of Chronic Hepatitis C

Background: Most clinical trials of direct-acting antiviral (DAA) therapy for hepatitis C virus (HCV) infection have excluded hepatitis B virus (HBV) coinfection, and little is known about the effects of DAA on chronic hepatitis C patients with HBV coinfection. Recent studies have reported that DAA therapy for HCV can also cause HBV reactivation in patients with HBV and HCV coinfection. The aim of this study was to assess the effects of DAA on sustained virologic response (SVR) and HBV reactivation in patients with chronic hepatitis C. Methods: Participants comprised 199 chronic hepatitis C patients who received DAA therapy (96 men, 103 women; mean age, 66.7 ± 12.0 years). Results: Twelve patients were coinfected with HCV and HBV. Sixty patients were HBV surface antigen negative but positive for hepatitis B core antibody and/or hepatitis B surface antibody, and one hundred and twenty-seven patients had not been exposed to HBV. Rates of SVR in HBV and HCV coinfected patients, HBV prior infection, and no exposure to HBV were 100, 95, and 97%, respectively. Significant differences were seen between each group. No case showed HBV reactivation. Conclusions: DAA treatments were effective in patients with HBV coinfection or HBV prior infection, as well as HCV monoinfection. As the number of cases was small, we still suggest caution regarding HBV reactivation in HCV and HBV coinfected patients undergoing treatment with DAA

核融合科学研究所 核融合工学研究プロジェクト 全体報告書

On the basis of the outstanding progress in high-density and high-temperature plasma experiments in the Large Helical Device (LHD) at National Institute for Fusion Science (NIFS), the conceptual design studies on the LHD-type helical fusion reactor, the FFHR series, have been conducted since 1993. In order to strongly promote this research activity in parallel with the acceleration of the related technological R&D for reactor components, the Fusion Engineering Research Project (FERP) was launched at NIFS in FY2010. The FERP consists of 13 tasks and 44 sub-tasks, each strongly assisted by domestic and international collaborations. The reactor design studies have focused on FFHR-d1, the demo-class reactor having a major radius of 15.6 m, which is four times larger than that of LHD. The similar heliotron magnetic configuration is employed to ensure steady-state operation with 3 GW self-ignited fusion power generation. The design activity has proceeded with the staged program, named “round,” that defines iterative working. The first round is to determine the basic core plasma parameters, the second is to compose all of the three-dimensional designs, the third focuses on construction and maintenance schemes, and the fourth is dedicated to passive safety. Since 2015, a multi-path strategy has been taken to include various options in the design, with FFHR-d1A as the base option. As a remarkable achievement of the reactor design, the Direct Profile Extrapolation (DPE) method is included in the helical systems code, HELIOSCOPE, in order to predict the confinement capability. The radial-build was successfully fixed and the neutronics calculation was carried out for the determined three-dimensional structure. The cost evaluation is also being conducted using these outcomes. The related R&D works in FERP are categorized into five key subjects: (1) large-scale superconducting (SC) magnet, (2) long-life liquid blanket, (3) low-activation structural materials, (4) high heat & particle-flux control, and (5) tritium and safety. Using the remarkable achievements of the related R&D works, the engineering design of FFHR-d1 defines the basic option and challenging option. While the basic option is an extension of the ITER technology, the challenging option includes innovative ideas from the following three purposes: (1) to overcome the difficulties related with the construction and maintenance of three-dimensionally complicated large structures, (2) to enhance the passive safety, and (3) to improve plant efficiency. For the superconducting magnet, the high-temperature superconductor (HTS) using ReBCO tapes is considered as an alternative (challenging) option to the cable-in-conduit conductor using low-temperature superconducting Nb3Sn strands. One of the purposes for selecting the HTS is to facilitate the three-dimensional winding of the helical coils by connecting prefabricated segmented conductors. A mechanical lap joint technique with low joint resistance has been developed and a 3 m-long short-sample conductor has successfully achieved 100 kA- current at a magnetic field of 5 T and temperature of 20 K. Further tests will be carried out in the world-largest 13 T, 700-mm bore superconducting magnet facility. For the tritium breeding blanket, we have chosen, as a challenging option, the liquid blanket with molten salt FLiNaBe from the viewpoint of passive safety. To increase the hydrogen solubility, an innovative idea to include powders of titanium was also proposed. An increase of hydrogen solubility over five orders of magnitude has been confirmed in an experiment, which makes the tritium permeation barrier less necessary for the coating on the walls of cooling pipes. The “Oroshhi-2” testing facility was constructed as a platform for international collaborations, having a twin-loop for testing both molten-salt (FLiNaK) and liquid metal (LiPb) under the perpendicular magnetic field of 3 T, the world’s largest for this purpose. For the structural material of blankets, a dissimilar bonding technique has been developed to join the vanadium alloy, NIFS-HEAT2, and a nickel alloy. For the helical built-in divertor, the diverter tiles could be placed at the backside of the blankets where the incident neutron flux is sufficiently reduced by an order of magnitude. It is thus expected that a copper-alloy could be used for cooling pipes under the bonded tungsten tile, since the maximum neutron fluence is limited to be lower than the allowable limit of ~1 dpa for copper within the operation period. We note that the peak heat flux on the helical divertor is expected to reach or exceed ~20 MW/m² because of the non-uniform strike point distributions, and effective removal of this heat flux is a concern. The maintenance scheme for the full-helical divertor is also a critical issue. To solve these problems, a new concept of liquid divertor has been proposed as a unique idea. Ten units of molten-tin shower jets (falls) are proposed to be installed on the inboard side of the torus to intersect the ergodic layer. It is considered that the vertical flow of tin jets could be stabilized using an internal flow resistance such as wires, chains, and tapes imbedded. In case the liquid divertor actually works, the full-helical divertor would become less necessary, though it should still be situated at the rear. Neutral particles are expected to be efficiently evacuated through the gaps between liquid metal showers. The mission of the NIFS FERP is to establish the scientific and technological basis that demonstrates the engineering feasibility of the helical fusion reactor and to promote the entire fusion engineering research toward the realization of fusion reactors in the mid-21st century. The progress of the NIFS FERP during the second six-year mid-term period in Japan for FY2010-2015 is overviewed in this full report. The numerical targets for the major components, which are the SC magnet, the in-vessel components, and the blanket, were compiled in FY2016,and its summary is also added in this report.research repor

First Wall Particle Flux Measurements by an F82H Permeation Probe in QUEST

0000-0001-9773-8121First wall particle flux measurements in the QUEST spherical tokamak have been conducted, using a permeation probe that employs a first wall candidate ferritic steel alloy F82H as the membrane and also SUS304 as a comparative reference membrane. Permeation measurements have been done during the conditioning steady-state discharges heated with 2.45 GHz and 8.2 GHz ECR. Diffusion and recombination coefficients measured in a laboratory-scale plasma device: VEHICLE-1 are used to interpret the results from the permeation probe measurements in QUEST. These permeation membranes have been analyzed with XPS to evaluate the effects of surface impurities

First Wall Particle Flux Measurements by an F82H Permeation Probe in QUEST

0000-0001-9773-8121First wall particle flux measurements in the QUEST spherical tokamak have been conducted, using a permeation probe that employs a first wall candidate ferritic steel alloy F82H as the membrane and also SUS304 as a comparative reference membrane. Permeation measurements have been done during the conditioning steady-state discharges heated with 2.45 GHz and 8.2 GHz ECR. Diffusion and recombination coefficients measured in a laboratory-scale plasma device: VEHICLE-1 are used to interpret the results from the permeation probe measurements in QUEST. These permeation membranes have been analyzed with XPS to evaluate the effects of surface impurities.journal articl

Plasma-Wall Interactions Data Compendium-1 “Hydrogen Retention Property, Diffusion and Recombination Coefficients Database for Selected Plasma-Facing Materials”

A summary on the recent activities of the plasma-wall interactions database task group at the National Institute for Fusion Science is presented in this report. These activities are focused on the compilation of literature data on the key parameters related to wall recycling characteristics that affect dynamic particle balance during plasma discharges and also on-site tritium inventory. More specifically, in this task group a universal fitting formula has been proposed and successfully applied to help compile hydrogen implantation-induced retention data. Also, presented here are the data on hydrogen diffusion and surface recombination coefficients, both critical in modeling dynamic wall recycling behavior. Data compilation has been conducted on beryllium, carbon, tungsten and molybdenum, all currently used for plasma-facing components in magnetic fusion experiments.research repor

Cows painted with zebra-like striping can avoid biting fly attack

Experimental and comparative studies suggest that the striped coats of zebras can prevent biting fly attacks. Biting flies are serious pests of livestock that cause economic losses in animal production. We hypothesized that cows painted with black and white stripes on their body could avoid biting fly attacks and show fewer fly-repelling behaviors. Six Japanese Black cows were assigned to treatments using a 3 × 3 Latin-square design. The treatments were black-and-white painted stripes, black painted stripes, and no stripes (all-black body surface). Recorded fly-repelling behaviors were head throw, ear beat, leg stamp, skin twitch, and tail flick. Photo images of the right side of each cow were taken using a commercial digital camera after every observation and biting flies on the body and each leg were counted from the photo images. Here we show that the numbers of biting flies on Japanese Black cows painted with black-and-white stripes were significantly lower than those on non-painted cows and cows painted only with black stripes. The frequencies of fly-repelling behaviors in cows painted with black-and-white stripes were also lower than those in the non-painted and black-striped cows. These results thus suggest that painting black-and-white stripes on livestock such as cattle can prevent biting fly attacks and provide an alternative method of defending livestock against biting flies without using pesticides in animal production, thereby proposing a solution for the problem of pesticide resistance in the environment

Plasma-Wall Interactions Data Compendium-2 “Hydrogen Retention Property, Diffusion and Recombination Coefficients Database for Selected Plasma-Facing Materials”

This report will present additional data to those included in the previous report of this series. These new data are on the hydrogen (deterium) trapping properties of graphite materials. The units on the data on hydrogen (deterium) diffusion and surface recombination coefficients have been updated to adopt the SI unit system. Also, the graphic representations of previously compiled data on hydrogen (deterium) retention have been improved for better understanding. For the sake of completeness, this report will present all these data in the improved formatresearch repor

プラズマー壁相互作用関連データ集ー3 「プラズマ対向材料中の水素同位体リテンションと関連する拡散係数・再結合係数データベース」

This report will present additional data to those included in the previous report of this series. These new data are "effective" hydrogen (deuterium) recombination coefficients estimated under the assumption that hydrogen recombination occurs in the bulk of materials, followed by immediate desorption to vacuum. The SI units are used for all the data collected this report

Correction: Cows painted with zebra-like striping can avoid biting fly attack.

[This corrects the article DOI: 10.1371/journal.pone.0223447.]