Search Results (20)

Tungsten (W) spectroscopy has attracted significant attention because W is one of the major impurities in ITER and future DEMO reactors. W²²⁺–W³³⁺ spectra at 15–45 Å have been useful for impurity diagnostics. Unresolved Transition Array (UTA) spectra around 200 Å, which contain W¹⁷⁺–W²³⁺, have potential for diagnostics tungsten ions in even lower charge states. Because multiple charge states overlap with very similar wavelengths, it is challenging to evaluate impurity spatial profiles from UTA spectra around 200 Å. In this study, we conducted tungsten pellet injection experiments in Large Helical Device (LHD) and attempted to evaluate the spatial profiles of UTA spectra around 200 Å, observed at 0.3–0.8 keV of central electron temperature. The results indicated that tungsten ions around W²⁰⁺ were locally profiled in a radial region, r_eff = 0.38 m, where the local electron temperature decreases by 30% to 40% with respect to more central and outer temperatures. These results suggested that the UTA spectrum around 200 Å would be useful for diagnostics of tungsten impurities in lower charge states than the charge states contained in UTA spectra around 15–45 Å. Full article

In this work, a krypton gas impurity seeding experiment was conducted in a Large Helical Device. Emission lines from the Na-like Kr ion in the extreme ultraviolet wavelength region, such as 22.00 nm, 17.89 nm, 16.51 nm, 15.99 nm, and 14.08 nm, respective to $2{\mathrm{p}}^{6}3\mathrm{p}{(}^2{\mathrm{P}}_{1/2}^{\mathrm{o}})-2{\mathrm{p}}^{6}3\mathrm{s}{(}^2{\mathrm{S}}_{1/2})$, $2{\mathrm{p}}^{6}3\mathrm{p}{(}^2{\mathrm{P}}_{3/2}^{\mathrm{o}})-2{\mathrm{p}}^{6}3\mathrm{s}{(}^2{\mathrm{S}}_{1/2})$, $2{\mathrm{p}}^{6}3\mathrm{d}{(}^2{\mathrm{D}}_{3/2})-2{\mathrm{p}}^{6}3\mathrm{p}{(}^2{\mathrm{P}}_{3/2}^{\mathrm{o}})$, $2{\mathrm{p}}^{6}3\mathrm{d}{(}^2{\mathrm{D}}_{5/2})-2{\mathrm{p}}^{6}3\mathrm{p}{(}^2{\mathrm{P}}_{3/2}^{\mathrm{o}})$, and $2{\mathrm{p}}^{6}3\mathrm{d}{(}^2{\mathrm{D}}_{3/2})-2{\mathrm{p}}^{6}3\mathrm{p}{(}^2{\mathrm{P}}_{1/2}^{\mathrm{o}})$ transitions, are observed. In order to generate a theoretical synthetic spectrum, an extensive calculation concerning the excitation of the ${\mathrm{Kr}}^{25+}$ ion through electron impact was performed for the development of a suitable plasma model. For this, the relativistic multiconfiguration Dirac–Hartree–Fock method was employed along with its extension to the relativistic configuration interaction method to compute the relativistic bound-state wave functions and excitation energies of the fine structure levels using the General Relativistic Atomic Structure Package-2018. In addition, another set of calculations was carried out utilizing the relativistic many-body perturbation theory and relativistic configuration interaction methods integrated within the Flexible Atomic Code. To investigate the reliability of our findings, the results of excitation energies, transition probabilities, and weighted oscillator strengths of different dipole-allowed transitions obtained from these different methods are presented and compared with the available data. Further, the detailed electron impact excitation cross-sections and their respective rate coefficients are obtained for various fine structure resolved transitions using the fully relativistic distorted wave method. Rate coefficients, calculated using the Flexible Atomic Code for population and de-population kinetic processes, are integrated into the collisional-radiative plasma model to generate a theoretical spectrum. Further, the emission lines observed from the ${\mathrm{Kr}}^{25+}$ ion in the impurity seeding experiment were compared with the present plasma model spectrum, demonstrating a noteworthy overall agreement between the measurement and the theoretical synthetic spectrum. Full article

Mitochondrial dysfunction and respiratory function changes have been consistently associated with the initiation and progression of cancer. The purpose of this study was to retrospectively investigate the expression of mitochondrial tumor-suppressor and DNA-repair proteins in patients with oral squamous cell carcinoma (OSCC) and to evaluate the relationship between their expression and prognosis. We enrolled 197 patients with OSCC who underwent surgical resection between August 2013 and October 2018. Clinical, pathological, and epidemiological data were retrospectively collected from hospital records. The expression of peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α), mitochondrial transcription factor A, mitochondrial tumor suppressor gene 1, silent information regulator 3, and 8-hydroxyguanine DNA glycosylase was investigated using immunochemistry. The 3-year disease-specific survival (DSS) rates of patients showing positive expression of all selected proteins were significantly higher than those of patients showing a lack of expression. Multivariate analysis revealed that the expression of PGC-1α (hazard ratio, 4.684) and vascular invasion (hazard ratio, 5.690) can predict the DSS rate (p < 0.001). Low PGC-1α expression and vascular invasion are potential clinically effective predictors of the prognosis of OSCC. Full article

To provide spectroscopic data for W${}^{13+}$, the present work is focused on the analysis of spectra observed in the visible range, using a compact electron beam ion trap (CoBIT). Line identification is done by using a collisional radiative model, along with sophisticated structure calculations from FAC and GRASP2018. Most of the identified lines belong to magnetic dipole (M1) transitions between the levels of the $4f^{12}5p^1$ and $4f^{13}$ configurations. Full article

The origin of heavier elements than iron is still under discussion, and recent studies suggest that the contribution of the r-process in neutron star mergers is dominant. Future modeling of such processes will require a huge amount of spectroscopic data on multiply charged ions of heavy elements. However, these experimental data are extremely scarce for heavy elements. In this work, we have performed the measurements of charge exchange spectroscopy for multiply charged Er ions in the visible light range. We report observed emission lines from multiply charged Er ions and their identification based on theoretical estimates. Full article

This study has systematically investigated the atomic number (Z) dependence of spectra from gallium-like (Ga-like) ions of heavy elements. We have mainly analyzed the experimental spectra recorded in high-temperature plasmas produced in the Large Helical Device (LHD) for various elements with atomic numbers from 57 onward. The measured wavelengths are compared with theoretical values calculated with a multi-configuration Dirac Fock code. As a result, we have successfully obtained Z-dependent wavelengths of several prominent transitions of Ga-like ions, including a magnetic dipole (M1) transition. Many of them have been experimentally identified for the first time in this study. The present results manifest the significant effects of configuration interaction and spin–orbit interaction for highly charged heavy ions. Full article

A standard treatment for osteoradionecrosis (ORN) has not yet been established because of the diversity. Therefore, identifying the risk factors for a poor prognosis is essential. This study retrospectively investigated the factors associated with the prognosis of ORN in 68 patients. Relevant clinical data of all patients were obtained. Of the patients, 16 who underwent extensive surgery underwent histopathological analysis. The necrotic changes of the anterior and posterior margins in the cortical and cancellous bones were investigated. Multivariate analyses showed statistically significant associations between poor prognosis in patients with ORN and high radiation dose (hazard ratio [HR] 1.15), orocutaneous fistula (HR 2.93), and absence of sequestration (HR 2.49). Histopathological analysis showed a viable anterior margin of the middle portion of the cortical bone for all recovered cases; in contrast, most cases (75%) with a poor prognosis showed necrotic changes. The anterior margin of the cancellous bone was viable and resilient to high irradiation, regardless of the prognosis. These results suggest that patients with orocutaneous fistula should receive early surgical intervention, even if the affected area is limited or asymptomatic. In extensive surgery, a sufficient safety margin of necrotic bone, particularly in the anterior region, is required to improve the prognosis. Full article

We present a laser induced breakdown spectrum of Er II in the near ultraviolet region. To use the spectrum for the evaluation of the transition probabilities, an alloy target with a low content of Er was used to suppress the self-absorption. From the linearity of the Boltzmann plot obtained by using the sensitivity corrected experimental intensity and existing transition probability data, the local thermal equilibrium condition of the plasma and the reliability of the transition probability data are confirmed. The linear function obtained in the Boltzmann plot is used for the determination of a previously unreported transition probability for the line at 393.863 nm. Full article

Spectroscopic studies for emissions released from tungsten ions have been conducted in the Large Helical Device (LHD) for contribution to the tungsten transport study in tungsten divertor fusion devices and for expansion of the experimental database of tungsten line emissions. Tungsten ions are distributed in the LHD plasma by injecting a pellet consisting of a small piece of tungsten metal wire enclosed by a carbon tube. Line emissions from W⁰, W⁵⁺, W⁶⁺, W²⁴⁺–W²⁸⁺, W³⁷⁺, W³⁸⁺, and W⁴¹⁺–W⁴⁶⁺ are observed simultaneously in the visible (3200–3550 Å), vacuum ultraviolet (250–1050 Å), and extreme ultraviolet (5–300 Å) wavelength ranges and the wavelengths are summarized. Temporal evolutions of line emissions from these charge states are compared for comprehensive understanding of tungsten impurity behavior in a single discharge. The charge distribution of tungsten ions strongly depends on the electron temperature. Measurements of emissions from W¹⁰⁺ to W²⁰⁺ are still insufficient, which is addressed as a future task. Full article

Forbidden transitions in the near-UV and visible wavelength of highly charged tungsten (W) ions are potentially useful as novel tungsten diagnostics means of fusion plasmas. Emission lines in 290–360 nm from W${}^{q+}$ ions interacting with an electron beam of 540–1370 eV are measured, using a compact electron-beam-ion-trap. The charge states of 64 lines are identified as W${}^{20+}$–W${}^{29+}$. A magnetic-dipole (M1) line of W${}^{29+}$ between the excited states $\left(4d^{8}4f\right){\left[{\left(4d_{5/2}^{-2}\right)}_{4}4f_{7/2}\right]}_{13/2}\to {\left[{\left(4d_{5/2}^{-2}\right)}_{4}4f_{5/2}\right]}_{13/2}$ is newly identified; the wavelength is determined as 351.03(10) nm in air. The theoretical wavelength calculated using the multiconfiguration Dirac–Hartree–Fock method is in a good agreement with the measurement. Full article

The intensity ratio of Fe XIV 264.765A/274.203A is useful to determine the electron density of solar corona, and the relationship between the electron density and the intensity ratio obtained from a model should be evaluated using laboratory plasmas to estimate the electron density more precisely. We constructed a new collisional–radiative model (CR-model) for Fe XIV (an Al-like iron ion) by considering the processes of proton-impact excitation and electron-impact ionization to the excited states of a Mg-like iron ion. The atomic data used in the CR-model were calculated using the HULLAC atomic code. The model was evaluated based on laboratory experiments using a compact electron beam ion trap, called CoBIT, and the Large Helical Device (LHD). The measured Fe XIV 264.785 Å/274.203 Å line intensity ratio with CoBIT was 1.869 ± 0.036, and it agreed well with our CR-model results. Concurrently, the measured ratio using LHD was larger than the results of our CR-model and CHIANTI. The estimated electron densities using our CR-model agreed with those from CHIANTI within a factor of 1.6–2.4 in the range of $n_e\approx {10}^{10-11}{\mathrm{cm}}^{-3}$. Further model development is needed to explain the ratio in a high-electron density region. Full article

Extreme ultraviolet (EUV) spectra of highly charged praseodymium (Pr) and neodymium (Nd) ions have been investigated in optically thin high-temperature plasmas produced in the Large Helical Device (LHD), a magnetically confined torus device for fusion research. Discrete spectral lines emitted mainly from highly charged ions having 4s or 4p outermost electrons were observed in plasmas with electron temperatures of 0.8–1.8 keV. Most of the isolated lines of Ga-like to Cu-like Nd ions were identified by a comparison with the recent data recorded in an electron beam ion trap (EBIT). The isolated lines of Pr ions corresponding to the identified lines of Nd ions were easily assigned from a similarity of the spectral feature for these two elements. As a result, some of the lines of Pr ions have been newly identified experimentally for the first time in this study. Full article

This paper presents an overview of the current status of the Virtual Atomic and Molecular Data Centre (VAMDC) e-infrastructure, including the current status of the VAMDC-connected (or to be connected) databases, updates on the latest technological development within the infrastructure and a presentation of some application tools that make use of the VAMDC e-infrastructure. We analyse the past 10 years of VAMDC development and operation, and assess their impact both on the field of atomic and molecular (A&M) physics itself and on heterogeneous data management in international cooperation. The highly sophisticated VAMDC infrastructure and the related databases developed over this long term make them a perfect resource of sustainable data for future applications in many fields of research. However, we also discuss the current limitations that prevent VAMDC from becoming the main publishing platform and the main source of A&M data for user communities, and present possible solutions under investigation by the consortium. Several user application examples are presented, illustrating the benefits of VAMDC in current research applications, which often need the A&M data from more than one database. Finally, we present our vision for the future of VAMDC. Full article

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. Full article