Impact of avalanche type of transport on internal transport barrier formation in tokamak plasmas.

In magnetic fusion plasmas, a transport barrier is essential to improve the plasma confinement. The key physics behind the formation of a transport barrier is the suppression of the micro-scale turbulent transport. On the other hand, long-range transport events, such as avalanches, has been recognized to play significant roles for global profile formations. In this study, we observed the impact of the avalanche-type of transport on the formation of a transport barrier for the first time. The avalanches are found to inhibit the formation of the internal transport barrier (ITB) observed in JT-60U tokamak. We found that (1) ITBs do not form in the presence of avalanches but form under the disappearance of avalanches, (2) the surface integral of avalanche-driven heat fluxe is comparable to the time rate change of stored energy retained at the ITB onset, (3) the mean E × B flow shear is accelerated via the ion temperature gradient that is not sustained under the existence of avalanches, and (4) after the ITB formation, avalanches are damped inside the ITB, while they remain outside the ITB.

3D metal powder additive manufacturing phased array antenna for multichannel Doppler reflectometer.

Measuring the time variation of the wavenumber spectrum of turbulence is important for understanding the characteristics of high-temperature plasmas, and the application of a Doppler reflectometer with simultaneous multi-frequency sources is expected. To implement this diagnostic in future fusion devices, the use of a phased array antenna (PAA) that can scan microwave beams without moving antennas is recommended. Since the frequency-scanning waveguide leaky-wave antenna-type PAA has a complex structure, we have investigated its characteristics by modeling it with 3D metal powder additive manufacturing (AM). First, a single waveguide is fabricated to understand the characteristics of 3D AM techniques, and it is clear that there are differences in performance depending on the direction of manufacture and surface treatment. Then, a PAA is made, and it is confirmed that the beam can be emitted in any direction by frequency scanning. The plasma flow velocity can be measured by applying the 3D manufacturing PAA to plasma measurement.

Prediction of a single Gaussian shape of spectral line measured with low-dispersion spectrometer by using machine learning.

We have developed a denoising autoencoder based neural network (NN) method to determine a spectral line intensity with an uncertainty lower than the uncertainty determined by fitting the spectral line. The NN method processes the measured raw spectral line shape, providing a single Gaussian shape based on the training dataset, which consists of synthetically prepared Doppler shift and broadening free spectral lines in the present work. It is found that the uncertainty reduction level significantly depends on the training dataset. Limitations originating from the training dataset are also discussed.

Design of JT-60SA core Thomson scattering diagnostic system.

An incoherent Thomson scattering diagnostic will be installed in the JT-60SA tokamak to measure electron temperature and electron density profiles. The target radial spatial resolution is 25 mm with 46 spatial channels. The accuracy in electron temperature and density is a few percent at ne = 7.5 × 1019 m-3, which is the expected value in the plasma core. This paper presents the designs of collection optics, fibers with their alignment system, and polychromators. The collection optics overcomes unique issues for superconducting fusion devices, i.e., limited design space, high-temperature measurements, and harsh radiation condition. When in several years the more performing plasma will generate intense nuclear radiation, the lens materials of the optics can be replaced by radiation resistant glasses without major changes in the lens holder. It will prevent transmission degradation and keep stable measurement accuracy.

Conceptual design of a collimator for the neutron emission profile monitor in JT-60SA using Monte Carlo simulations.

Materials and structures of a collimator for a new neutron emission profile monitor in JT-60SA are examined through Monte Carlo simulations using the Monte Carlo N-Particle transport code. First, the shielding properties of various material combinations are compared in order to determine a combination with high shielding performances against both neutrons and gamma-rays. It is found that a collimator consisting of borated polyethylene and lead has a high shielding performance against neutrons. Moreover, a high shielding performance against gamma-rays is obtained when a lead pipe with a radial thickness of 0.01 m is inserted into a collimation tube. Second, we demonstrate that it is possible to improve the spatial resolution to a desired level by installing a thin tubular extension structure that fits into the limited space available between the main collimator block and the tokamak device. Finally, the collimator structures that meet both the targeted spatial resolutions (<10% of the plasma minor radius) and the targeted counting rate (105 cps order) are discussed.

Plasma D-dimer levels and ischaemic lesions in multiple vascular regions can predict occult cancer in patients with cryptogenic stroke.

BACKGROUND AND PURPOSE: Cancer patients with cryptogenic stroke often have high plasma D-dimer levels and lesions in multiple vascular regions. Hence, if patients with cryptogenic stroke display such characteristics, occult cancer could be predicted. This study aimed to investigate the clinical characteristics of cryptogenic stroke as the first manifestation of occult cancer and to determine whether plasma D-dimer levels and lesions in multiple vascular regions can predict occult cancer in patients with cryptogenic stroke. METHODS: Between January 2006 and October 2015, data on 1225 patients with acute ischaemic stroke were extracted from the stroke database of Osaka University Hospital. Among them, 184 patients were classified as having cryptogenic stroke, and 120 patients without a diagnosis of cancer at stroke onset were identified. Clinical variables were analyzed between cryptogenic stroke patients with and without occult cancer. RESULTS: Among 120 cryptogenic stroke patients without a diagnosis of cancer, 12 patients had occult cancer. The body mass index, hemoglobin levels and albumin levels were lower; plasma D-dimer and high-sensitivity C-reactive protein levels were higher; and lesions in multiple vascular regions were more common in patients with than in those without occult cancer. Multiple logistic regression analysis revealed that plasma D-dimer levels (odds ratio, 3.48; 95% confidence interval, 1.68-8.33; P = 0.002) and lesions in multiple vascular regions (odds ratio, 7.40; 95% confidence interval, 1.70-39.45; P = 0.01) independently predicted occult cancer. CONCLUSIONS: High plasma D-dimer levels and lesions in multiple vascular regions can be used to predict occult cancer in patients with cryptogenic stroke.

Small ion-temperature-gradient scale length and reduced heat diffusivity at large hydrogen isotope mass in conventional H-mode plasmas.

The dependence of the ion-temperature-gradient scale length on the hydrogen isotope mass was examined in conventional H-mode plasmas in JT-60U tokamak. While identical profiles for density and temperature were obtained for hydrogen and deuterium plasmas, the ion conductive heat flux necessary for hydrogen to sustain the same ion temperature profile was two times that required for deuterium, resulting in a clearly higher ion heat diffusivity for hydrogen at the same ion-temperature-gradient scale length. On the other hand, the ion-temperature-gradient scale length for deuterium is less than that for hydrogen at a given ion heat diffusivity.

Observation of a complex multistage transition in the JT-60U H-mode edge.

A complex multistage transition of the edge radial electric field is observed in JT-60U H-mode phase without edge localized mode. An interesting feature is that the poloidal rotation velocity of the carbon impurity ions changes in the later H-phase without a comparable change in the main ion pressure gradient, indicating a change in the parallel momentum (and particle) balance channel.

Measurement of type-I edge localized mode pulse propagation in scrape-off layer using optical system of motional Stark effect diagnostics in JT-60U.

Propagation of plasma ejected by type-I edge localized mode (ELM) has been measured in scrape-off layer (SOL) of the JT-60U tokamak, using optical system of motional Stark effect (MSE) diagnostics as beam emission spectroscopy (BES) diagnostics through a new technique developed. This MSE/BES system measures Dalpha emission from heating neutral beam excited by collisions with the ejected plasma, as well as background light (e.g., bremsstrahlung). While spatio-temporal change in the beam emission gives information on propagation of the ejected plasma, the background light that is observed simultaneously in all spatial channels veils the information. In order to separate the beam emission and the background light, a two-wavelength detector is newly introduced into the MSE/BES system. The detector observes simultaneously at the same spatial point in two distinct wavelengths using two photomultiplier tubes through two interference filters. One of the filters is adjusted to the central wavelength of the beam emission for the MSE diagnostics, and the other is outside the beam emission spectrum. Eliminating the background light, temporal change in the net beam emission in the SOL has been evaluated. Comparing conditionally averaged beam emission with respect to 594 ELMs in a discharge at five spatial channels (0.02-0.3 m outside the main plasma near equatorial plane), radial velocity of the ELM pulse propagation in SOL is evaluated to be 0.8-1.8 km/s (approximately 1.4 km/s for least-mean-squared fitting).

Rotation drive and momentum transport with electron cyclotron heating in tokamak plasmas.

The role of electron cyclotron resonance heating (ECRH) on the toroidal rotation velocity profile has been investigated in the JT-60U tokamak device by separating the effects of the change in momentum transport, the intrinsic rotation by pressure gradient, and the intrinsic rotation by ECRH. It is found that ECRH increases the toroidal momentum diffusivity and the convection velocity. It is also found that ECRH drives the codirection (co) intrinsic rotation inside the EC deposition radius and the counterdirection (ctr) intrinsic rotation outside the EC deposition radius. This ctr rotation starts from the EC deposition radius and propagates to the edge region.

[Immune-enhancing diet (IED) for acute respiratory distress syndrome].

A 63-year-old man who was involved in a traffic accident was transferred to our hospital. He was unconscious and had a flail chest. On chest X-ray, he had a left hemopneumothorax and multiple rib fractures. After endotracheal intubation, a 16 Fr chest tube was immediately inserted, and drainage was started with negative pressure suction. Intravenous administration of sivelestat sodium hydrate and methylprednisolone was ineffective, but the Pao2/Fio2 ratio improved rapidly after enteral nutrition with an immune-enhancing diet (IED, Oxepa) was started. The patient was extubated on hospital day 34. This case suggests that an IED may be useful for the treatment of acute respiratory distress syndrome.

Observation of an energetic-particle-driven instability in the wall-stabilized high-beta plasmas in the JT-60U tokamak.

We have observed a bursting mode in the high-beta plasmas above the ideal beta limit without a conducting wall. The mode frequency is chirping down as the mode amplitude increases, and its initial value is close to the precession frequency of the trapped energetic particle from the perpendicular neutral beams. The mode structure is radially extended with a peak around the q = 2 surface. This mode can finally trigger the resistive wall mode (RWM) despite enough plasma rotation for RWM stabilization. It is concluded that the mode is driven by trapped energetic particles. The mode is attributed to the interaction between the trapped energetic particles and a marginally stable mode in the wall-stabilized high-beta_{N} region.

ECM1 interacts with fibulin-3 and the beta 3 chain of laminin 332 through its serum albumin subdomain-like 2 domain.

The extracellular matrix protein 1 (ECM1) is an 85 kDa secreted glycoprotein, comprising four variants and playing a pivotal role in endochondral bone formation, angiogenesis, and tumour biology. A computational model for the three-dimensional structure of ECM1a was determined to identify the potential and/or concealed region(s) for binding with candidate partners in human skin. Multiple alignments for the secondary structure of ECM1a and b revealed similarity with serum albumin. The N-terminal domain of ECM1a consists mainly of alpha-helices (alphaD1), while the remaining three domains, namely serum albumin subdomain-like (SASDL) domains 2-4, were topologically comparable with the subdomain of the third serum albumin domain. Yeast-two-hybrid screening of a human foreskin cDNA library using both full-length ECM1a and the hot spot region for ECM1 gene mutations in lipoid proteinosis, an autosomal recessive genodermatosis (complete SASDL2 and the linker to SASDL3: aa177-aa361), as bait, isolated seven extracellular proteins. The site-specific interaction of ECM1a with two of these candidate binders, laminin 332 beta-3 chain and fibulin-3, was confirmed by in vitro and in vivo co-immunoprecipitation experiments. Immunohistologically both binders co-localized with ECM1 in human skin. Together, ECM1 is a multifunctional binding core and/or a scaffolding protein interacting with a variety of extracellular and structural proteins, contributing to the maintenance of skin integrity and homeostasis. Hence, disruption of the ECM1 function may cause the failure of multi-communication among the surrounding skin interstitial molecules, as seen in lipoid proteinosis pathology.

Effect of amidoalkyl group as spacer on aggregation properties of guanidine-type surfactants.

Dodecanoyl amidoalkylguanidine hydrochlorides (C(12)A(m)G, m = 2, 3, 4, 6) are cationic surfactants that have an amidoalkyl group (A(m)) as spacer between the cationic guanidine and hydrophobic groups in the molecule. The effect of the A(m) group on the aggregation properties of the surfactants was evaluated through measurements of their critical micelle concentration (cmc) value, Krafft point, phase behavior, area occupied by one molecule at the air/water interface, and micellar aggregation number. Dodecylguanidine hydrochloride (C(12)A(0)G) with no A(m) group is a unique cationic surfactant because it exhibits a strong tendency for self-assembly when compared with common ionic surfactants, due to the hydrogen bonding between its guanidine groups in addition to the hydrophobic interaction between its alkyl chains [M. Miyake, K. Yamada, N. Oyama, Langmuir 24 (2008) 8527-8532]. In contrast, C(12)A(m)G showed a decreasing tendency for self-assembly with increasing alkyl chain length, m, of the A(m) group up to m = 3, above which the tendency increased. Such changes in aggregation tendency of the surfactants were suggested to arise from an increased bulkiness of the hydrophilic part caused by the A(m) group, resulting in a decrease in the hydrogen bonding between the guanidine groups and an increase in micellization through the cooperative hydrophobic interaction between the hydrophilic groups. From the balance of these effects, the area of the hydrophilic part of C(12)A(4)G was the largest and the hydrogen bonding between the guanidine groups in C(12)A(4)G was weakened. It is suggested in guanidine-type surfactant that A(4) gave a similar aggregation tendency to traditional ionic surfactants and a weak effect for skin.

Magnetic fluctuation profile measurement using optics of motional Stark effect diagnostics in JT-60U.

Motional Stark effect (MSE) diagnostics in JT-60U works as polarimeter to measure the pitch angle of magnetic field as well as beam-emission-spectroscopy (BES) monochromator simultaneously at 30 spatial channels. Fluctuation in the BES signal using MSE optics (MSE/BES) contains fluctuations in not only the density but also the pitch angle (or the magnetic field). Correlation analysis of the magnetic fluctuation between two spatial channels is applied to high-beta plasma with a magnetohydrodynamic activity at frequency of about 0.9 kHz. It has been found that the magnetic fluctuation measured by the MSE/BES is spatially localized near the magnetic flux surface having safety factor and that the phase of the fluctuation is inverted at about the surface, suggesting magnetic island structure by tearing mode. The phase of the magnetic fluctuation measured by the MSE/BES at outside of the q=2 surface is consistent with that by the pickup coil placed outside the plasma.

Transition between internal transport barriers with different temperature-profile curvatures in JT-60U Tokamak plasmas.

A spontaneous transition phenomena between two states of a plasma with an internal transport barrier (ITB) is observed in the steady-state phase of the magnetic shear in the negative magnetic shear plasma in the JT-60U tokamak. These two ITB states are characterized by different profiles of the second radial derivative of the ion temperature inside the ITB region (one has a weak concave shape and the other has a strong convex shape) and by different degrees of sharpness of the interfaces between the L mode and the ITB region, which is determined by the turbulence penetration into the ITB region.

Role of pressure gradient on intrinsic toroidal rotation in tokamak plasmas.

The toroidal plasma rotation generated by the external momentum input and by the plasma itself (intrinsic rotation) has been separated through a novel momentum transport analysis in the JT-60U tokamak device. The toroidal rotation, which is not determined by the momentum transport coefficients and the external momentum input, has been observed. It is found that this intrinsic rotation is locally determined by the local pressure gradient and increases with increasing pressure gradient. This trend is almost the same for various plasmas: low and high confinement mode, co and counterrotating plasmas.