Search

The Large Helical Device (LHD) is an experimental device for helical type fusion plasma in National Institute for Fusion Science and plasma experiments over 150,000 shots have been successfully conducted during twenty long-term plasma experimental campaigns. The LHD has two kinds of superconducting magnets and nine flexible superconducting bus lines with an average length of 55 m, which are utilized as a part of the current feeder system between the coils and the power sources. The superconducting bus lines consist of a pair of aluminum stabilized NbTi/Cu compacted stranded cable insulated electrically and coaxial five corrugated stainless steel tubes with two layers of vacuum insulations. The nominal current is 32 kA and the withstand voltage is 5 kV in 77 K gas helium. From the first experimental campaign, the superconducting bus lines have been stably operated at steady state by using automatic control. It is also confirmed that the status of the superconducting bus lines are kept good thanks to appropriate maintenances. As the results, the reliable operation of the superconducting bus lines has been achieved during the plasma experimental campaigns without any serious failure and the total operational time of the steady state cooling is approximately 58,000 hours.

Based on the successful plasma experiments in the Large Helical Device (LHD), design activities of the LHD-type helical fusion reactor FFHR-d1 are progressing at National Institute for Fusion Science (NIFS). A 100 kA current capacity is required for the winding conductor under the maximum magnetic field of ~12 T. The high-temperature superconductor (HTS) is a promising option for the helical coil conductor. For the development of such a HTS conductor suitable for the helical fusion reactor, we fabricated 30 kA-class HTS conductor samples, and the excitation tests were successfully carried out. We then fabricated and tested a 100-kA class HTS conductor. The conductor sample is a one-turn short-circuit coil with a race-track shape having a bridge-type mechanical lap joint. The transport current of the sample was induced by changing the external magnetic field, then the critical current of the sample was measured. A numerical analysis of the critical current is being performed by self-consistently solving the spatial distributions of the current density and magnetic field among the simply-stacked HTS tapes to verify the measured critical current of the samples. The critical current characteristics of a single HTS tape is evaluated by the percolation model in the precise analysis.

Transcatheter angiographic embolization (TAE) has been widely accepted as a treatment for hemorrhagic shock associated with pelvic fracture. Gluteal muscle necrosis is a rare but potentially fatal complication of TAE. This study aimed to clarify factors associated with safer embolization procedures by evaluating relationships between embolic site and risk of gluteal skin injury. We classified embolized arteries into six groups: group A, nonselective embolization from the main internal iliac artery; group B, selective embolization including the superior gluteal artery but excluding the inferior gluteal artery; group C, selective embolization including the inferior gluteal artery but excluding the superior gluteal artery; group D, selective embolization including both the superior and inferior gluteal arteries; group E, selective embolization excluding both the superior and inferior gluteal arteries; and group F, no embolization. We assessed the frequency of gluteal injuries, relationships between gluteal injuries and embolized arteries, and the contributions of selective embolization, conservation of the superior or inferior gluteal artery, and conservation of both the superior and inferior gluteal arteries to reducing the risk of gluteal injury. Gluteal skin injuries were seen at 15 of 160 sites (9.4%). A significant difference was noted between the nonselective embolization group (group A: 10/82, 12.2%) and selective embolization excluding both the superior and inferior gluteal arteries (group E: 1/39, 2.6%) (p = 0.042). If possible, we recommend selective embolization avoiding the superior and inferior gluteal arteries.

The statistical properties of impurity transport in the edge tokamak plasma modeled by the Hasegawa-Wakatani system are investigated using the structure function analysis. The impurities are considered as a passive scalar advected by the plasma flow. The use of extended self-similarity (ESS) enables us to show that in the quasiadiabatic regime, the impurity density and the vorticity of the electric drift velocity exhibit similar multifractal scaling. However, potential fluctuations are self-similar and exhibit a monofractal scaling in agreement with Kolmogorov-Kraichnan theory for two-dimensional turbulence. Long-range spatial correlations have also been studied using Hurst exponent. The latter has been calculated by structure function method. The values of Hurst exponents for impurity and vorticity show that spatial anti-persistency dominates these quantities. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Classical molecular dynamics (MD) simulations of Si and SiO 2 etching by halogens (Cl or F) have been performed to study surface reaction mechanisms for plasma etching. The interatomic potentials for Si–O–Cl and Si–O–F systems are constructed based on potential energy data obtained from ab initio quantum mechanical calculations. The etch rates and selectivities obtained from these MD simulations are in good agreement with presently available experimental observations. We have also observed in MD simulations that surface conditions under reactive ion etching (RIE), where low-energy neutral halogens play important roles in enhancing etch rates, differ significantly from those under beam etching.

In Japan, second-screen services are provided separately by the program or by the broadcasting station, which causes great inconvenience to viewers. Under the circumstance, we-the multiscreen broadcasting study group that has a membership of 78 companies as of June, 2014 -have successfully established a platform for the second screen in a situation where broadcasting stations take leadership and cooperate with one another. We believe this is the only example in the world. We named this second-screen platform SyncCast and launched the second-screen service in actual broadcasting nationwide in February and March 2014 with 48 programs and 27 commercial messages in service. This time, we have employed a simple system based on Internet, which will allow viewers to enjoy second-screen services only with a smartphone or tablet. Also, broadcasting stations do not need new equipment.

During the first two years of the LHD experiment the following results have been achieved: (i) higher Te (Te(0) = 4.4 keV at ne = 5.3 × 1018 m-3 and Pabs = 1.8 MW); (ii) higher confinement (τE = 0.3 s, Te(0) = 1.1 keV at ne = 6.5 × 1019 m-3 and Pabs = 2.0 MW); (iii) higher stored energy, Wpdia = 880 kJ at B = 2.75 T. High performance plasmas have been realized in the inward shifted magnetic axis configuration (R = 3.6 m) where helical symmetry is recovered and the particle orbit properties are improved by a trade-off of MHD stability properties due to the appearance of a magnetic hill. Energy confinement was systematically higher than that predicted by the International Stellarator Scaling 95 by up to a factor of 1.6 and was comparable with the ELMy H mode confinement capability in tokamaks. This confinement improvement is attributed to configuration control (inward shift of the magnetic axis) and to the formation of a high edge temperature. The average beta value achieved reached 2.4% at B = 1.3 T, the highest beta value ever obtained in a helical device, and so far no degradation of confinement by MHD phenomena has been observed. The inward shifted configuration has also led to successful ICRF minority ion heating. ICRF powers up to 1.3 MW were reliably injected into the plasma without significant impurity contamination, and a plasma with a stored energy of 200 kJ was sustained for 5 s by ICRF alone. As another important result, long pulse discharges of more than 1 min were successfully achieved separately with an NBI heating of 0.5 MW and with an ICRF heating of 0.85 MW.

In order to understand the mechanism of unequal division, polar body formation was investigated using the oocytes of the starfish, Asterina pectinifera. Cortical actin filaments were quantitatively measured after staining the maturing oocytes with fluorescently labeled phalloidin using a computer and image-processing software. Before polar body formation, at first the actin filaments at the animal pole decreased and subsequently the animal pole bulged. On the other hand, actin filaments surrounding the animal pole increased gradually and made a cleavage furrow around the animal pole as the bulge grew. Then the furrow ingressed and finally a polar body formed. When the surface force was calculated according to the cell shape, the surface force decreased at the animal pole but the force at the contractile ring increased. When by micromanipulation the mitotic apparatus was detached and translocated to the cortex other than the animal pole, polar body formation occurred all over the cortex of the oocyte, which indicates that the response of the whole cortex to the mitotic apparatus is equal. These results indicate that the decrease in the actin filaments and surface force near the centrosome of the mitotic apparatus as well as the increase in the actin filaments and surface force at some distance of the centrosome is important for cytokinesis.

Meiotic maturation is essential for the reproduction procedure of many animals. During this process an oocyte produces a large egg cell and tiny polar bodies by highly asymmetric division. In this study, to fully understand the sophisticated spatiotemporal regulation of accurate oocyte meiotic division, we focused on the global and local changes in the tension at the surface of the starfish (Asterina pectinifera) oocyte in relation to the surface actin remodeling. Before the onset of the bulge formation, the tension at the animal pole globally decreased, and started to increase after the onset of the bulge formation. Locally, at the onset of the bulge formation, tension at the top of the animal pole began to decrease, whereas that at the base of the bulge remarkably increased. As the bulge grew, the tension at the base of the bulge additionally increased. Such a change in the tension at the surface was similar to the changing pattern of actin distribution. Therefore, meiotic cell division was initiated by the bulging of the cortex, which had been weakened by actin reduction, and was followed by contraction at the base of the bulge, which had been reinforced by actin accumulation. The force generation system is assumed to allow the meiotic apparatus to move just under the membrane in the small polar body. Furthermore, a detailed comparison of the tension at the surface and the cortical actin distribution indicated another sophisticated feature, namely that the contraction at the base of the bulge was more vigorous than was presumed based on the actin distribution. These features of the force generation system will ensure the precise chromosome segregation necessary to produce a normal ovum with high accuracy in the meiotic maturation.

We discuss dynamical properties of Yukawa systems, i.e., systems of particles interacting through Yukawa (i.e., screened Coulomb) potentials. Self-diffusion coefficients and wave dispersion relations are obtained from time and space correlations of various physical quantities evaluated from molecular dynamics (MD) simulations. Yukawa systems are used as models for charged dust particles immersed in plasmas or colloidal particles suspended in electrolytes.

Methods used for the modeling and numerical simulation of the plasma processes used in semiconductor integrated-circuit fabrication are reviewed. In the first part of the paper, we review continuum and kinetic methods. A model based on the drift-diffusion equations is presented as an example of a continuum model; the model and associated numerical solutions are discussed. The most widely used simulation method for kinetic modeling is the Particle-ln-Cell/Monte-Carlo-Collision (PIC/MCC) method, in which the plasma is modeled by a system of charged superparticles (each of which represents a collection of a large number of ions or electrons) that move in self-consistent electromagnetic fields and collide via given collision cross sections. In the second part of the paper, we review the modeling and simulation of the evolution of surface topography in plasma etching and deposition.

The Yukawa system is a collection of particles interacting through two-body Yukawa (i.e. screened Coulomb) potentials. Yukawa systems are often used as models for charged dust particles immersed in plasmas or colloidal particles suspended in electrolytes. We review thermodynamical and dynamical properties of Yukawa systems, focusing on the recent development of molecular dynamics (MD) simulation methods for Yukawa systems.

The effect of slightly acidic intracellular pH (pHi) on the development of the sea urchin, Hemicentrotus pulcherrimus was investigated. At first cleavage, the fertilized eggs were treated with artificial sea water containing sodium acetate (Ac-pHSW) at pH 6.8 or 7.0 at the onset of nuclear envelope breakdown, and their pHi decreased from 7.30 to 6.68 or 6.78, respectively. When the eggs were observed after fixation by indirect immunofluorescence and differential interference contrast microscopy, the mitotic stage of the treated eggs was arrested at metaphase and the mitotic apparatus was maintained until more than 50 min after the treatment, although it was smaller in size than that of non-treated eggs. On the other hand, the number of the mitotic asters increased from 2 to 3-4, and further to 6-8 following prolonged exposure, suggesting that the centrosomes had divided and replicated. These results suggest that the centrosome cycle advanced at slightly acidic pHi, even when the mitotic cycle did not advance beyond metaphase.

In the medaka, Oryzias latipes, which does not have cytologically recognizable sex chromosomes, the sex is genetically determined and the mechanism of sex determination (XX/XY) can be revealed by genetic crosses using a particular pigment gene. In a previous study, we isolated a sex-linked DNA marker (SL1) using the genomic differences between inbred strains of medaka. In the present paper, we further isolated another sex-linked clone (pHO5.110). The pHO5.110-related sequences were tightly linked to sex in O. latipes. We designated the locus of the pHO5.110-related sequence on sex chromosomes of medaka as Sex-Linked 2 (SL2). Southern blot analyses suggested that the pHO5.110-related sequence was tandemly repetitive in the medaka genome. Using the clone as a probe for FISH analysis, strong hybridization signals were obtained in a couple of chromosomes that formed one of two large submetacentric chromosome pairs. The pHO5.110-related sequences were repetitive in the genomes of other species of Oryzias (O. curvinotus, O. luzonensis and O. mekongensis) that are karyologically related to O. latipes (all are members of the so-called biarmed group). By contrast, the sequences were not detected as repetitive in other Oryzias species. Hence, it is thought that pHO5.110-related sequences were amplified in the genome of a common ancestor of the biarmed group.

The effect of change in intracellular pH (pHi) on mitosis was investigated in the sand dollar egg. The pHi in the fertilized egg of Scaphechinus mirabilis and Clypeaster japonicus, which was 7.34 and 7.31, respectively, changed by means of treating the egg at nuclear envelope breakdown with sea water containing acetate and/or ammonia at various values of pH. The mitotic apparatus at pHi 6.70 became larger than that of normal fertilized eggs; that is, the mitotic spindle had the maximal size, especially in length at pHi 6.70. The spindle length linearly decreased when pHi increased from 6.70 to 7.84. By polarization microscopy, the increase in birefringence retardation was detected at slightly acidic pHi, suggesting that the increase in size of the spindle is caused by the increase in the amount of microtubules in the spindle. At pHi 6.30, the organization of the mitotic apparatus was inhibited. Furthermore, slightly acidic pHi caused cleavage retardation or inhibition. By counting the number of the eggs at various mitotic stages with time after treating them with the media, it is found that metaphase was persistent and most of the S. mirabilis eggs were arrested at metaphase under the condition of pHi 6.70. It is concluded that at slightly acidic pH, the microtubules in the spindle are stabilized and more microtubules assembled than those in the normal eggs.

To establish a method of pHi regulation and to understand the pH regulation mechanism in the cell, we investigated the pHi response of unfertilized or fertilized eggs of sea urchin, applying sea water containing both weak permeant acid, acetic acid and/or base, ammonia, to eggs. Pyranine was employed as a pH indicator to measure intracellular pH (pHi) by microfluorometry. The unfertilized/fertilized eggs had a pHi of 6.80/7.34 and 6.81/7.32 for Schaphechinus mirabilis and Hemicentrotus pulcherrimus, respectively. With the addition of both acetic acid and ammonia to the media, pHi changed linearly against extracellular pH (pHo) between 6-8 and was almost equal to pHo at the concentration of 20 mM acetate and ammonia. This mixed application was proved to be available for regulating pHi at the desired value within a wide range involving the original pHi by a single solution system. pHi after the treatment was dependent on various factors, such as the concentration of the weak acid and base, the pHi before the treatment, and pH buffering power in the cytoplasm. The latter was estimated to be 43 mM and 58 mM in unfertilized and fertilized eggs, respectively, from the measurement of pHi change induced by microinjecting a HEPES solution, assuming that the pH buffering power is caused by phosphate.

S. Hamaguchi and S. M. Rossnagel, Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena 14, 2603 (1996) https://doi.org/10.1116/1.588993, The conformality of thin metal films (liners) formed on high-aspect-ratio trench structures in ionized magnetron sputter deposition processes is studied numerically and experimentally. The numerical simulator (SHADE) used to predict the surface topography is based on the shock-tracking method for surface evolution. The simulation results are in good agreement with experimentally observed thin-film topography. It is shown that combination of direct deposition and trench-bottom resputtering results in good conformality of step coverages and the amount of the resputtering needed for the good conformality is almost independent of trench aspect ratios. © 1996 American Vacuum Society.

A numerical algorithm and simulation results are presented for microscopic profile evolution of material surfaces subject to plasma etching (reactive‐ion etching) and surface passivation. Surface evolution is calculated by the shock‐tracking method, which accurately simulates formation and evolution of facet corners. The angle distribution for the reemission of sputtered materials is assumed to follow an arbitrary cosine law (i.e., ∝cosβ Θ, with Θ being the reemission angle and β≳0). Thickness of sidewall passivation layers and resulting etched profiles are shown to depend sensitively on both the reemission angular distribution and the sticking coefficient.

SummaryMagnesium ions as well as calcium ions are required for successful fertilisation in sea urchins. In the absence of Mg2+spermatozoa attached to the egg plasma membrane, their acrosomal processes passing through the vitelline envelope, but could not enter the egg cytoplasm (Sanoet al, Dev. Growth Differ.22, 531–41,1980). Such an individual spermatozoon was observed microscopically to resume entry into the egg immediately after the addition of a sufficient amount of Mg2+to the surrounding medium. Neither any change in membrane potential nor an increase in intracellular Ca2+concentration of the egg was observed after insemination in the absence of Mg2+, although both could be observed after the addition of Mg2+. The sperm heads did not show fluorescence when attached to the surface of an egg previously microinjected with mithramycin A in Mg-free seawater, indicating that there was no connection between the sperm and the egg. Therefore, occurrence of fertilisation potential must be a post-fusional event. These results suggest that Mg2+are indispensable for fusion between the sperm acrosomal membrane and the egg plasma membrane.

A speech recognition processor CMOS LSI was developed as the processing element (PE) of a ring array processor previously proposed by the authors as architecture to carry out highly parallel recognition processing with array size flexibility. There are three key features for the LSI: (1) a highly parallel I/O structure of triple buffer with cyclical-mode transition control methods to solve the serious problem of inter-PE data transfer overhead versus the array processing; (2) a control structure with two direct memory access (DMA) controllers to realize inter-PE data I/O processing and intra-PE processing in parallel; and (3) a pipelined recognition processing at a high execution rate realized by a pipelined structure and a balanced clock distribution design technique. These effective designs for the PE LSI allow high-speed recognition processing without any inter-PE data transfer overhead in the ring array processor. Combining the PE-LSI architecture with the proposed array architecture for highly parallel dynamic time warping (DTW) processing, a real-time continuous speech recognition system based on continuous dynamic programming matching using the SPLIT method for a 1000-word vocabulary, can be constructed using a ring array processor consisting of 30 PEs. >

An increase in intracellular Ca2+ concentration ([Ca2+]) and morphological were simultaneously observed by epifluorescence and differential interference contrast (DIC) microscopy during fertilization of the sand dollar, Clypeaster japonicus. [Ca2+], which was detected by a Ca2+ indicator, Fluo-3, initially increased just beneath the sperm-attached site on the egg surface 8.6 sec after attachment. The increase spread into the egg as a concentric sphere to the egg center and, thereafter, propagated in the egg cytoplasm as a planar wave rather than a spherical wave. It reached the site opposite the initiation site across the egg 24.2 sec after initiation. The fertilization envelope (FE) began to elevate 10.3 sec after the initiation of the increase in [Ca2+] and 21.2 sec after sperm attachment.

Helical coils of the Large Helical Device (LHD) are large scale superconducting magnets for heliotron plasma experiments. The helical coils had been cooled by saturated helium at 4.4 K, 120 kPa until 2005. An upgrade of the cooling system was carried out in 2006 in order to improve the cryogenic stability of the helical coils and then it has been possible to supply the coils with subcooled helium at 3.2 K, 120 kPa. A designed mass flow of the supplied subcooled helium is 50 g/s. The subcooled helium is generated at a heat exchanger in a saturated helium bath. A series of two centrifugal cold compressors with gas foil bearing is utilized to lower the helium pressure in the bath. The supplied helium temperature is regulated by rotational speed of the cold compressors and power of a heater in the bath. The mass flow of the supplied helium is also controlled manually by a supply valve and its surplus is evaporated by ten heaters at the outlet above the coils. In the present study, the performance of the cooli...

To improve the stability of superconducting magnets cooled by He II, it is considered that the utilization of the porous media enhances the heat transport capability of He II. In the present studies, the thermal hydraulic characteristics of He II through porous media have been investigated experimentally and numerically. Experimental results are presented about 6 porous media with various porosity, thickness and average pore diameters. Numerical results are reported about 4 porous media among them. In the present numerical analysis, the two‐dimensional calculations have been performed for the turbulent Gorter‐Mellink regime to understand the heat and mass transfer of the He II through the porous media in the case of the large heat input. The present numerical model was based on the two‐fluid model with the Gorter‐Mellink mutual friction and dealt with the classical friction loss and the tortuosity in the porous media. This paper discusses the influence of these additional terms on the heat and mass flow o...

Summary form only given. To achieve high recognition performance for a wide variety of noise and for a wide range of signal-to-noise ratio, this paper presents the integration of four noise reduction algorithms: spectral subtraction with smoothing of time direction; temporal domain SVD-based speech enhancement; GMM-based speech estimation; and KLT-based comb-filtering. In this paper, we investigated the optimal suppression method for each noise condition, and then also developed the method of choosing the optimal method automatically for unknown noise. Recognition results on the AURORA-2J task show the effectiveness of our proposed method.

A PE (Processing Element) LSI for a DTW (Dynamic Time Warping) linear array processor has been designed. In designing this LSI, major effort has been focused on achieving regular data-flow among adjacent PEs maintaining pipelined operation in the array. A three data channel structure, a triple buffer structure and sophisticated control schemes make it possible for the designed LSI to carry out MIMD (Multiple Instruction and Multiple Data streams) and continuous pipelined DTW processing in sync with regular pattern input. Due to the high speed real time operation, and the versatile function of this PE-LSI, a high performance linear array processor can be constructed using a small number of PEs. The high speed operation of LSI is pursuited to achieve real time processing. Continuous speech recognition with an approximate vocabulary of 1000 words can be achieved using only 20 to 30 of these PE-LSIs.

To deliver baseball highlight scenes broadcast live to baseball fans outside, image processings such as an online video analyzing, meta information extraction and automatic editing have to be performed in real time. This paper proposes a high-speed image processing to automatically extract PC (pitcher and catcher) scenes, based on feature mining, from a baseball live game broadcast in real time as a part of the baseball highlight scene delivery system. This method showed 95.5% accuracy in the F-measure score within 1/30 of real time.

Molecular dynamics (MD) simulations are used to study non-thermal-equilibrium reaction dynamics taking place on the surface during dry etching processes. In MD simulations, the motion of each atom is solved numerically based upon pre-determined interatomic potential functions and data of interest (such as sputtering yields, deposition rates, etch products, etc.) are evaluated from statistical averaging of relevant instantaneous data obtained from the simulations. In this paper, we review our recent MD simulations results on organic polymer etching. Similar simulations were also performed for selective etching processes of silicon and silicon dioxide substrates.

In order to understand the mechanism of unequal division, polar body formation was investigated using the oocytes of the starfish, Asterina pectinifera. Cortical actin filaments were quantitatively measured after staining the maturing oocytes with fluorescently labeled phalloidin using a computer and image-processing software. Before polar body formation, at first the actin filaments at the animal pole decreased and subsequently the animal pole bulged. On the other hand, actin filaments surrounding the animal pole increased gradually and made a cleavage furrow around the animal pole as the bulge grew. Then the furrow ingressed and finally a polar body formed. When the surface force was calculated according to the cell shape, the surface force decreased at the animal pole but the force at the contractile ring increased. When by micromanipulation the mitotic apparatus was detached and translocated to the cortex other than the animal pole, polar body formation occurred all over the cortex of the oocyte, which indicates that the response of the whole cortex to the mitotic apparatus is equal. These results indicate that the decrease in the actin filaments and surface force near the centrosome of the mitotic apparatus as well as the increase in the actin filaments and surface force at some distance of the centrosome is important for cytokinesis.

In the fertilization of sea urchin eggs, intracellular [Ca2+] (Cai) increases transiently and intracellular pH (pHi) elevates accordingly. Unlinking these two activating factors experimentally, the requirement of the increase in pHi for sperm aster formation in the sea urchin, Clypeaster japonicus, was investigated. When the eggs were injected with an EGTA or BAPTA solution, they incorporated sperm but did not organize the sperm aster. Using these sperm-incorporated eggs under the condition that an increase in Cai was blocked, pHi was regulated by two methods: (i) perfusing ammonium acetate-containing seawater; and (ii) injecting pH buffer solutions of various pH values. By either of the two methods, the sperm aster formed at pHi 7.0 or more and functioned in female pronuclear migration when the sperm aster reached the female pronucleus. Hence, the step of the transient increase in Cai at fertilization can be bypassed. In contrast, a pHi increase is indispensably required for sperm aster formation in sea urchin eggs. Moreover, under the condition that there was the transient increase in Cai, the threshold pHi value for sperm aster formation was pHi 7.0 or more. Consequently, whether a Cai increase on fertilization occurs or not, the threshold pHi value for sperm aster formation is constant in sea urchin eggs.

Molecular dynamics (MD) simulations have been used to study surface reaction dynamics of Si and Si02etching by halogens. To perform classical MD simulations for Si02 etching reaction by halogens (Cl or F), we have constructed new sets of two— and three—body interatomic potential functions based on potential energy data obtained fromab initioquantum mechanical calculations of the electronic states. Etching yields for Si and Si02targets are obtained from MD simulations for both beam etching and reactive ion etching (RIE). The obtained yields are in good agreement with experimental observations.

Publisher Summary This chapter studies the dynamical properties of strongly coupled dusty plasmas using molecular dynamics (MD) simulation. Systems of dust particles immersed in a plasma are modeled by a collection of particles interacting via Yukawa (screened Coulomb) potentials. Thermodynamic properties of Yukawa systems can be characterized by two parameters— қ (the ratio of the average interparticle distance to the Debye length of the background plasma) and F (the ratio of the interparticle Coulomb potential energy to the kinetic energy per particle). By examining velocity autocorrelation functions and mean square displacement for single particle diffusion, this chapter obtains self-diffusion coefficients of Yukawa systems for various қ and Γ values.

Recent experiments and numerical simulations have shown that a system of small dust particles immersed in a plasma forms crystalline structures (Coulomb crystals) when its kinetic energy becomes sufficiently small compared with its potential energy. Employing Yukawa potential to model the interparticle potential between dust particles, we have performed molecular dynamics (MD) simulation to obtain the phase diagram of such charged dust systems.

H. L. Berk, Physics of Fluids B: Plasma Physics 2, 3212 (1990) https://doi.org/10.1063/1.859232, The general expression of the power transfer from a high-energy ion beam to a background electrostatic plasma wave is obtained for arbitrary wave amplitude. It is verified that phase space gradients produced by a finite amplitude wave enhance the power transfer significantly. © 1990 American Institute of Physics.

In the medaka, Oryzias latipes, which does not have cytologically recognizable sex chromosomes, the sex is genetically determined and the mechanism of sex determination (XX/XY) can be revealed by genetic crosses using a particular pigment gene. In a previous study, we isolated a sex-linked DNA marker (SL1) using the genomic differences between inbred strains of medaka. In the present paper, we further isolated another sex-linked clone (pHO5.110). The pHO5. 110-related sequences were tightly linked to sex in O. latipes. We designated the locus of the pHO5.110-related sequence on sex chromosomes of medaka as Sex-Linked 2 (SL2). Southern blot analyses suggested that the pHO5.110-related sequence was tandemly repetitive in the medaka genome. Using the clone as a probe for FISH analysis, strong hybridization signals were obtained in a couple of chromosomes that formed one of two large submetacentric chromosome pairs. The pHO5.110-related sequences were repetitive in the genomes of other species of Oryzias (O. curvinotus, O. luzonensis and O. mekongensis) that are karyologically related to O. latipes (all are members of the so-called biarmed group). By contrast, the sequences were not detected as repetitive in other Oryzias species. Hence, it is thought that pHO5.110-related sequences were amplified in the genome of a common ancestor of the biarmed group.

Summary We have discussed the theory of moving solid boundaries and numerical algorithms to simulate them. In Sec. II, the problem description (i.e., Hamilton-Jacobi type equation and entropy conditions) is presented. We have emphasized the fact that the Hamilton-Jacobi type equation (and therefore the ray-tracing method or method of characteristics) in itself cannot determine the physically plausible solid surface evolution. It is important to recognize that the additional physical mechanism (i.e., infinitesimal surface diffusion) is needed to derive the entropy conditions, which together with the Hamilton-Jacobi type equation determine the physical solution. A geometric method to construct the physical solution is presented in Sec. II.F, based on the entropy conditions of Eq. (20) or Oleinik construction. The shock-tracking algorithm (1) presented in Sec. III explicitly uses this geometric construction method to determine the correct moving boundary solution. Earlier work on etching/deposition topography simulation focused primarily on the method of characteristics or ray tracing (26-31), but paid little attention to the entropy conditions. Without the entropy conditions, however, some other procedures must be invoked to avoid seemingly unphysical solutions (32,33). In many cases, such procedures are introduced based on the modeler's intuition of what the correct physical solutions should be, rather than additional physical processes such as surface diffusion. In the latter half of this article, we have treated more specific applications, that is dry processes for etching and deposition, and presented some representative examples. The spatial scale treated in these problems is mesoscopic, that is, sufficiently smaller than macroscopic scales such as mean free paths of gaseous atoms, but sufficiently larger than molecular scales. For semiconductor dry processes, the representative scale for microfeatures is typically 1 or less, in which one can still approximate the solid by a continuum, rather than aggregates of molecules. In this mesoscopic continuum model, ion and neutral fluxes impinging on the surface are also treated as continuums. Under some realistic assumptions, such fluxes are easily evaluated, as shown in Sec. IV. For simplicity, we have only discussed the two-energy/single-species model, but extending this model to a multienergy/multispecies model is straightforward. Since the goal of this article is to present the basic theory of moving boundary problems in dry processes, no attempt was made to discuss details of various processes used in industry. For instance, readers interested in more details of the examples shown in Sec. V are referred to Refs. 4, 5, 19, and 20.

Numerical simulations are used to predict microscopic topography of deposited metal films in ionized magnetron sputter deposition experiments. The simulation takes into account ionized and neutral fluxes as deposition material sources and re–sputtering and re–deposition of the deposited material due to the ion bombardment. The shock-tracking algorithm is used to advance the moving surface boundary. Applications of this deposition technique include lining and filling of trenches, vias and dual damascene.