Improvement of Automatic Physics Data Analysis Environment for the LHD Experiment

The physical data of the Large Helical Device (LHD) project have been serviced by the Analyzed Data Server system, and approximately 600 kinds of physical data are served. In order to execute simulation programs for the LHD experiment, one must gather sets of physical data. Because the Automatic Analyzed Server (AutoAna) calculates the physical data automatically, it eases the scientist’s task of collecting these physical data. The AutoAna has provided better computing environments for the scientists. Thus, the scientists, having recognized its benefits, make various requests as issues arise. In this paper, the authors introduce the current status of the AutoAna system

NIFS Atomic and Molecular Numerical Database for Collision Processes

The National Institute for Fusion Science (NIFS) has compiled and developed atomic and molecular numerical databases for various collision processes and makes it accessible from the internet to the public. The database contains numerical data of cross sections and rate coefficients for electron collision or ion collisions with atoms and molecules, attached with bibliographic information on their data sources. The database system provides query forms to search data, and numerical data are retrievable. The graphical output is helpful to understand energy dependence of cross sections and temperature dependence of rate coefficients obtained by various studies. All data are compiled mainly from published literature, and data sources can be tracked by the bibliographic information. We also have data of sputtering yields and back-scattering coefficients for solid surfaces collided by ions in the database. All data in the database are applicable to understand atomic and molecular processes in various plasmas, such as fusion plasma, astrophysical plasma and applied plasma, as well as for understanding plasma–surface interaction in plasmas

Inter-application communication during LHD consecutive short pulse discharge experiment

LHD short pulse experiments are executed every three minutes. After the end of the discharge, the scientists must collect, analyze, visualize the last acquired data of the discharge, and prepare for the next discharge. From the beginning, the computer environment of the LHD (Large Helical Device) experiment has been built as a network distributed system, and various computers have been used for data acquisition or physical analysis. When one program is finished on one computer, that computer must send the results in order to the other computers to run programs. Smooth communication is required in order to finish all the tasks before the next discharge. To exchange the information among the applications running on the different computers, the authors have tried various methods, such as a commercial software to share the memory over the network, simple network file sharing method, IP multicast, web interfaces, and others. The purpose of this paper is to share our experiences of trial and error to build the network distributed systems for the consecutive plasma discharge experiments

A patient with spontaneous rupture of the esophagus and concomitant gastric cancer whose life was saved: case of report and review of the literature in Japan

A 71-year-old man suddenly developed abdominal pain and vomiting on drinking soda after a meal, and visited a physician. Cervical subcutaneous and mediastinal emphysemas were observed on CT, and the patient was transferred to the emergency medical center of our hospital on the same day. Esophagography was performed at our department. A ruptured region was identified on the left side of the lower thoracic esophagus, and surgery was emergently performed employing sequential left thoracoabdominal incision. The chest wall was adhered due to inflammation, and large amounts of residual food and sloughing were present in the thoracic cavity and mediastinum. Moreover, necrotic changes were noted in the superior through inferior mediastinum. An about 2-cm rupture site was confirmed on the left side of the lower thoracic esophagus and closed by suture and filling with pediculate omentum. The presence of a tumorous lesion located mainly in the body of the stomach and lymph node enlargement were also diagnosed before surgery, for which gastric and intestinal fistulae were inserted to prepare for the second-stage surgery. The patient was admitted to an ICU after surgery. ARDS and MRSA-induced pneumonia and enteritis concomitantly developed but remitted. Curative surgery for gastric cancer was performed at 40 POD. Spontaneous rupture of the esophagus is relatively rare and that complicated by gastric caner is very rare, with only six cases being reported in Japan. Herein, we report the case

W-band millimeter-wave back-scattering system for high wave number turbulence measurements in LHD

A 90 GHz W-band millimeter-wave back-scattering system is designed and installed for measuring electron scale turbulence (kρs ∼ 40). Ametal lens relay antenna is used for in-vessel beam focusing, and a beam diameter of less than 40mm is achieved in the plasma core region.This antenna can be steered at an angle of 159○ ± 6○, which almost covers the plasma radius. The estimated size of the scattering volume is ∼105mm at the edge and 135mm at the core, respectively. A 60m corrugated waveguide is used to achieve a low transmission loss of ∼8 dB. A heterodyne detection system for millimeter-wave circuits with probing power modulation can distinguish the scattered signal frombackground noise

Extended capability of the integrated transport analysis suite, TASK3D-a, for LHD experiment

The integrated transport analysis suite, TASK3D-a (Analysis), has been developed to be capable for routine whole-discharge analyses of plasmas confined in three-dimensional (3D) magnetic configurations such as the LHD. The routine dynamic energy balance analysis for NBI-heated plasmas was made possible in the first version released in September 2012. The suite has been further extended through implementing additional modules for neoclassical transport and ECH deposition for 3D configurations. A module has also been added for creating systematic data for the International Stellarator–Heliotron Confinement and Profile Database. Improvement of neutral beam injection modules for multiple-ion species plasmas and loose coupling with a large-simulation code are also highlights of recent developments

Particle control in long-pulse discharge using divertor pumping in LHD

Density control is crucial for maintaining stable confined plasma. Divertor pumping, where neutral particles are compressed and exhausted in the divertor region, was developed for this task for the Large Helical Device. In this study, neutral particle pressure, which is related to recycling, was systematically scanned in the magnetic configuration by changing the magnetic axis position. High neutral particle pressure and compression were obtained in the divertor for a high plasma electron density and the inner magnetic axis configuration. Density control using divertor pumping with gas puffing was applied to electron cyclotron heated plasma in the inner magnetic axis configuration, which provides high neutral particle compression and exhaust in the divertor. Stable plasma density and electron temperature were maintained with divertor pumping. A heat analysis shows that divertor pumping did not affect edge electron heat conductivity, but it led to low electron heat conductivity in the core caused by electron-internal-transport-barrier-like formation

Impurity emission characteristics of long pulse discharges in Large Helical Device

Line spectra from intrinsic impurity ions have been monitored during the three kinds of long-pulse discharges (ICH, ECH, NBI). Constant emission from the iron impurity shows no preferential accumulation of iron ion during the long-pulse operations. Stable Doppler ion temperature has been also measured from Fe XX, C V and C III spectra

Integrated radiation monitoring and interlock system for the LHD deuterium experiments

The Large Helical Device (LHD) successfully started the deuterium experiment in March 2017, in which further plasma performance improvement is envisaged to provide a firm basis for the helical reactor design. Some major upgrades of facilities have been made for safe and productive deuterium experiments. For radiation safety, the tritium removal system, the integrated radiation monitoring system, and the access control system have been newly installed. Each system has new interlock signals that will prevent any unsafe plasma operation or plant condition. Major interlock extensions have been implemented as a part of the integrated radiation monitoring system, which also has an inter-connection to the LHD central operation and control system. The radiation monitoring system RMSAFE (Radiation Monitoring System Applicable to Fusion Experiments) is already operating for monitoring γ(X)-rays in LHD. Some neutron measurements have been additionally applied for the deuterium experiments. The LHD data acquisition system LABCOM can acquire and process 24 h every day continuous data streams. Since γ(X)-ray and neutron measurements require higher availability, the sensors, controllers, data acquisition computers, network connections, and visualization servers have been designed to be duplicated or multiplexed for redundancy. The radiation monitoring displays in the LHD control room have been carefully designed to have excellent visual recognition, and to make users immediately aware of several alerts regarding the dose limits. The radiation safety web pages have been also upgraded to always show both dose rates of γ(X)-rays and neutrons in real time