Incremental effects of near-atmospheric-pressure low-temperature air plasma jet irradiation on polyphenol content in harvested onions


Plasma-Assisted Annealing of Pt-Doped Rutile TiO2 Nanoparticles for Enhanced Decomposition and Bacterial Inactivation under General Lighting

Journal of Vacuum Science and Technology. B, Nanotechnology & Microelectronics : Materials, Processing, Measurement, & Phenomena : JVST B


Remote Bactericidal Effect of Anatase TiO2 Photocatalytic Nanoparticles Annealed with Low-Temperature O2 Plasma

The remote bactericidal effect of TiO photocatalyst, i.e., the bactericidal effect away from the photocatalyst, was successfully achieved using a humidified airflow. The TiO photocatalyst used was anatase-type TiO nanoparticles (NPs) annealed with a low-temperature O plasma. For comparison, anatase-type TiO NPs annealed in the air were used. The bacteria, Bacillus subtilis, were placed away from the TiO NPs. The plasma-assisted-annealed TiO NPs significantly inactivated 99% of the bacterial cells in 5 h, whereas the pristine and air-annealed TiO NPs inactivated 88-90% of the bacterial cells. The remote bactericidal effect of plasmaassisted-annealed TiO NPs would be attributed to a larger amount of HO molecules traveled by the airflow from the TiO NPs. The molecules were generated by chemically reacting more photoexcited carriers on the TiO surface with HO and O in the airflow. These photoexcited carriers originated from more oxygen-based species adsorbed and more oxygen vacancies introduced on the TiO surface by the plasma-assisted-annealing.


Bactericidal Effects of Low-Temperature Atmospheric-Pressure Air Plasma Jets with No Damage to Plant Nutrient Solutions


Photocatalytic Activity Enhancement of Anatase/Rutile-Mixed Phase TiO2 Nanoparticles Annealed with Low-Temperature O2 Plasma

Physica Status Solidi (A) Applications and Materials Science


Effects of Nonequilibrium Atmospheric-Pressure O2 Plasma-Assisted Annealing on Anatase TiO2 Nanoparticles


Effects of Air-Based Nonequilibrium Atmospheric Pressure Plasma Jet Treatment on Characteristics of Polypropylene Film Surfaces


Steady-state and time-resolved optical properties of multilayer film of titanium dioxide sandwiched by gold nanoparticles and gold thin film

We proposed metal insulator (MI) and metal insulator metal (MIM) structures of titanium dioxide (TiO2) sandwiched by gold nanoparticles (AuNPs) layer and gold sputtered thin film (only for the MIM film) to couple localized plasmon mode of AuNP with multi reflection mode and/or cavity resonator mode of TiO2. The optical extinctions of MI and MIM with differing TiO2 thickness were studied theoretically by finite element method simulation and experimentally by optical spectrometry. The extinction peaks of MI and MIM shifted by exchanging the surrounding medium from air to TiO2. The interference of TiO2 in MI structure also affected the extinction spectra showing the oscillation along the spectrum of AuNP in TiO2. Then, the extinction degree of MIM was higher than that of MI because of the coupling between cavity resonance mode with localized plasmon mode and interband transition in AuNPs. In addition, the cross section of MI and MIM films were observed by scanning electron microscopy. The surface of thinner film was rough because TiO2 heterogeneously grew from AuNP. The irregular growth of TiO2 might have induced the wide range extinction in 300 2500 nm after Au thin film deposition. The transient absorption spectra using a femtosecond laser were also carried out under the condition of 800 nm for excitation laser and 950 nm for probe laser. The long lived electron (∼1 ns) was observed in thick MIM film as a result of hot electron transfer from the gold nanostructure in the film.

ChemNanoMat : Chemistry of Nanomaterials for Energy, Biology and More


Effects of Ultraviolet Wavelength and Intensity on AlGaN Thin Film Surfaces Irradiated Simultaneously with CF4 Plasma and Ultraviolet


Characteristics of TiO2 Thin Films Surfaces Treated by O2 Plasma in Dielectric Barrier Discharge with the Assistance of External Heating


Characteristics of N2 and O2 Plasma-Induced Damages on AlGaN Thin Film Surfaces


Generation of Electrical Damage in n-GaN Films Following Treatment in a CF4 Plasma


AlGaN Surfaces Etched by CF4 Plasma with and without the Assistance of Near-Ultraviolet Irradiation


Damage Characteristics of n-GaN Crystal Etched with N2 Plasma by Soft X-Ray Absorption Spectroscopy

e-Journal of Surface Science and Nanotechnology


Surface Analysis of AlGaN Treated with CF4 and Ar Plasma Etching


Comparison between AlGaN Surfaces Etched by Carbon Tetrafluoride and Argon Plasmas: Effect of the Fluorine Impurities Incorporated in the Surface


Ar+-Irradiation-Induced Damage in Hydride Vapor-Phase Epitaxy GaN Films

Journal of Vacuum Science & Technology A


Recovery of X-ray Absorption Spectral Profile in Etched TiO2 Thin Films


Electrical Investigation of Deep-Level Defects Introduced in AlGaN/GaN Heterostructures by CF4 Plasma Treatments


Optical and Electrical Investigation of Ar+-Irradiated GaN


Damage Characteristics of n-GaN Thin Film Surfaces Etched by Ultraviolet Light-Assisted Helium Plasmas


Surface Damage of 6H-SiC Originating from Argon Plasma Irradiation

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms


Damage characteristics of n-GaN thin film surfaces etched by N2 plasmas

Physica Status Solidi (C) Current Topics in Solid State Physics


Characteristics of TiO2 Surfaces Etched by Capacitively Coupled Radio Frequency N2 and He Plasmas


Comparison between Damage Characteristics of p- and n-GaN Surfaces Etched by Capacitively Coupled Radio Frequency Argon Plasmas

Damage characteristics of p-GaN surfaces etched by capacitively coupled radio frequency Ar plasma at various gas pressures have been studied in terms of the ultraviolet (UV) light irradiation effect. The UV light corresponding to Ar II is emitted from the plasma at high gas pressures from 50 to 100 mTorr, whereas no UV light is emitted at a low gas pressure of 10 mTorr. The result of the etched p-GaN surface is compared with that of the etched n-GaN surface. The difference between the results of the p- and n-GaN surfaces depends strongly on the gas pressure. Both the experimental N/Ga ratios at the p- and n-GaN surfaces etched at the low gas pressure decrease with increasing etching time. The decreases in the experimental N/Ga ratios agree with the simulation results that N atoms at the p- and n-GaN surfaces are preferentially removed by Ar<sup>+</sup>ions. The morphologies of the p- and n-GaN surfaces etched at the low gas pressure are similar to those of the as-grown surfaces. The damage characteristic of the p-GaN surface induced in the absence of the UV light irradiation also appears at the high gas pressures, although the p-GaN surfaces etched at the high gas pressures are irradiated with the emitted UV light. In contrast, both the experimental N/Ga ratios and morphologies of the n-GaN surfaces etched at the high gas pressures change with increasing etching time. The changes in the n-GaN surfaces probably result from the UV light irradiation.


Etching Damage and Its Recovery by Soft X-ray Irradiation Observed in Soft X-ray Absorption Spectra of TiO2 Thin Film


Effect of UV Irradiation on Ar-Plasma Etching Characteristics of GaN

ECS Journal of Solid State Science and Technology


Damage Analysis of n-GaN Crystal Etched with He and N2 Plasmas

To understand the details of etching-induced damage on a GaN surface, n-GaN crystals were plasma-etched with He and N2 gases. The etched surfaces were analyzed by X-ray photoelectron spectroscopy (XPS) and soft X-ray absorption spectroscopy (XAS) methods. The composition of the surface etched with He plasma changed significantly to being Ga-rich with the N/Ga ratio nearly equaling 0.4--0.5. The ratio of the surface etched with N2 plasma was about 0.6. The shape of the near-edge X-ray absorption fine structure (NEXAFS) of the N-K edge deformed with increasing gas pressure and processing time. The deformation can be explained by the increase in the band widths of a number of peaks in the NEXAFS spectra owing to the increase in the degree of structural disorder in the crystal. The increase in band width for the surface etched with N2 plasma was larger than that for the surface etched with He plasma. The above results can be explained with the model of the elastic energy transfer ratio of He+ and N2+ ions incident on the solid surface.


Capacitively Coupled Radio Frequency Nitrogen Plasma Etch Damage to N-Type Gallium Nitride


Characteristics of TiO2 Thin Film Surfaces Treated by Helium and Air Dielectric Barrier Discharge Plasmas

The characteristics of TiO2 thin film surfaces treated with He and air dielectric barrier discharge (DBD) plasmas at different gas pressures are investigated. There is a difference between the two DBD plasma characteristics: for He-DBD, which is an atmospheric pressure glow discharge (APGD), the breakdown voltage and discharge current hardly change with increasing gas pressure, whereas for air-DBD, which is basically a filamentary discharge, they increase with increasing gas pressure. There is also a difference between the characteristics of TiO2 surfaces treated with the two DBDs. The surface roughness for He-DBD is lower than the roughness of the as-grown surface, whereas that for air-DBD is higher. The surface hydrophilicity for He-DBD is more enhanced than the hydrophilicity of the as-grown surface regardless of UV irradiation. The hydrophilicity for air-DBD is dependent on UV irradiation. It is more enhanced with UV irradiation; it is not improved adequately without UV irradiation.

Japanese Journal of Applied Physics, Part 1 (Regular Papers & Short Notes)


Damage Analysis of Plasma-etched n-GaN Crystal Surface by Nitrogen K-edge NEXAFS Spectroscopy

The surface of an n-GaN crystal etched with an Ar, Kr, or Xe plasma was analyzed by nitrogen K near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. The NEXAFS spectroscopy was carried out with the total electron yield (TEY) method in a sample current mode and the total fluorescence yield (TFY) method by measuring the amount of fluorescence using a photodiode. The shapes of the spectra of Ar plasma-etched samples obtained by the TEY method became smooth (blunt) with increasing Ar pressure from 10 to 200 mTorr. However, those obtained by the TFY method did not change with pressure. These results indicate that the etching damage was restricted in the shallow region of less than a few nm from the surface. A change in the NEXAFS spectral shape of Kr or Xe plasma-etched samples was not observed even when measured by the TEY method. This result indicates that the surface damage in Kr or Xe plasma-etched samples was less pronounced than that in Ar plasma-etched samples.


Photoluminescence Study of Damage Introduced in GaN by Ar- and Kr-Plasmas Etching

Materials Research Society Symposia Proceedings


Damage Characteristics of TiO2 Thin Film Surfaces Etched by Capacitively Coupled Radio Frequency Helium Plasmas


Synergy Effect of Xenon Plasma Ions and Ultraviolet Lights on GaN Etch Surface Damage and Modification

Transactions of the Materials Research Society of Japan


Surface analysis of n-GaN crystal damaged by RF-plasma-etching with Ar, Kr, and Xe gases

Physica Status Solidi (C) Current Topics in Solid State Physics


Etch-induced damage characteristics of n-GaN surfaces by capacitively coupled radio frequency He and Ar plasmas


Effect of DBD Air Plasma Treatment on TiO2 Thin Film Surfaces

Surface treatment effect on TiO2 thin films with the anatase phase by dielectric barrier discharge (DBD) air plasmas has been investigated for a variety of gas pressures and treatment times. At a low gas pressure (100 hPa) at which a glow-like discharge plasma occurs, hydrophilicities of TiO2 thin films treated at 5 and 30 min are enhanced compared with that of the as-grown thin film. For the 5 min treatment, this trend is more pronounced probably due to oxygen absorbed on the surface from the air plasma. For the 30 min treatment, the enhanced hydrophilicity is probably due to oxygen vacancy created on the surface by a high fluence of the plasma. When the gas pressure increases to 400 hPa at which a streamer discharge plasma occurs, the hydrophilicity is more weakened than that of the as-grown thin film: the plasma-induced damage occurs regardless of the treatment time. This result would probably result from the higher discharge current and UV light intensity caused by the higher breakdown voltage based on Paschen's law.


Etch Damage Characteristics of TiO2 Thin Films by Capacitively Coupled RF Ar Plasmas


Effects of Capacitively Coupled Radio Frequency Krypton and Argon Plasmas on Gallium Nitride Etching Damage

GaN etching damage characteristics by capacitively coupled radio frequency Kr and Ar plasmas have been found to differ significantly, on the basis of experimental and simulation results. The morphology of a GaN surface etched by Kr plasma is as smooth as that of the as-grown surface, and is independent of gas pressure and etching time. The agreement between the experimental and simulated etching depths for the Kr plasma, which are lower than those for the Ar plasma, indicates a significant contribution to the GaN damage of the physical etching effect. In contrast, Ar plasma etching produces a rough surface, which is dependent on gas pressure and etching time, and appears to be due to a chemical effect. The difference in the GaN surface morphologies etched by the Kr and Ar plasmas may be attributed to the different depths etched for these two plasmas. Moreover, the simulation shows that, for the Kr plasma, Ga is preferentially etched from GaN, whereas the preferential etching of N occurs for the Ar plasma. The difference in preferential etching between the Kr and Ar plasmas may be related to the difference between the GaN surface morphologies etched by these two plasmas.


Synergy Effect of Particle Radiation and Ultraviolet Radiation from Capacitively Coupled Radio Frequency Argon Plasmas on n-GaN Etching Damage

The change in the morphology of n-GaN surfaces etched by capacitively coupled RF Ar plasmas has been studied from the viewpoint of a synergy effect of particle radiation and UV radiation from the RF plasmas. The particle radiation (in particular, the energy of Ar+ impinging on n-GaN) is intensified with decreasing gas pressure from 200 to 10 mTorr, whereas the intensity of the UV radiation (whose peak wavelength corresponds to the GaN band-gap energy) is significantly weakened. The reverse result occurs when the gas pressure increases. Each type of radiation brings about a smooth surface morphology similar to that of the as-grown surface. However, at 50 or 100 mTorr, at which both types of radiation are expected to coexist, the surface morphology shows various types of pits (defects or dislocations), which seem to be induced by the synergy effect.

Japanese Journal of Applied Physics, Part 1 (Regular Papers & Short Notes)


Effect of Argon Plasma Etching Damage on Electrical Characteristics of Gallium Nitride


Analysis of GaN Etching Damage by Capacitively Coupled RF Ar Plasma Exposure


Simulation Study of Carbon Impurity Dynamics on Tungsten Surfaces Exposed to Hydrogen Ions


Simulation study of carbon impurity dynamics on reduced-activation ferritic/martensitic steel material at elevated temperatures under hydrogen exposure


Simulation Study on Effects of Chemically Eroded Methane and Ethylene Molecules on Carbon Impurity Transport and Net Erosion of Carbon Materials

Journal of Plasma and Fusion Research SERIES


Influence of Carbon Impurity on Net Erosion of Reduced-Activation Ferritic/Martensitic Steel and Tungsten Materials Exposed to Hydrogen and Carbon Mixed Ion Beam Relevant to Fusion Plasma Boundary

Using a simulation code for dynamic interactions between energetic ions and solid materials, the influence of C impurity concentration on net erosion of reduced-activation ferritic/martensitic steel, RAF (Fe in the simulation), and W materials exposed to a 0.33 keV H+ and 1 keV C+ impurity mixed ion beam relevant to a fusion plasma boundary has been studied. A comparison of the simulation results between the Fe and W materials at C impurity concentrations less than C: 1.00% is described and discussed. In particular, emphasis is paid to a quantitative comparison between depth profiles of C impurity deposited on the materials and the experimental data, which were obtained by the H and C mixed ion beam exposure experiments of RAF (F82H in the experiment) and W materials. For the W material, chemical erosion (CH4 emission) of the deposited C impurity by the H+ impact is taken into account in the simulation. The C impurity concentration causes a significant difference in net erosion between the two materials. For the Fe material, net erosion is suppressed with increasing C impurity concentration. In contrast, for the W material, net erosion is enhanced. In the depth profile, there is also a significant difference between the two materials. At C: 0.11%, the impinging C impurity is hardly deposited on the Fe material. For the W material, the depth profile at C: 0.11% shows a local peak around a certain depth, which is in good agreement with the experimental data at 653 K. This agreement indicates no contribution of the chemical erosion in the H-C-W system, which is quite different from that in the H-C system where the chemical erosion occurs. The difference seems to indicate that the chemical erosion in the H-C-W system is dependent upon amounts of the deposited C impurity or the binary alloy phase change between W and C. When the C impurity concentration increases to C: 0.84%, the impinging C impurity is deposited on the Fe material. The depth profile shows a maximum at the top surface, which reproduces the experimental data at 453 K. For the W material, the depth profile at C: 0.84% shows almost the same tendency as that at C: 0.11%, but shows a larger amount of the deposited C impurity. The simulation result at C: 0.84% is in disagreement with the experimental result at 653 K, which shows a maximum at the top surface. This disagreement is not fully explained by only the chemical erosion.


Simulation Study on Influence of Chemically Eroded Higher Hydrocarbons on SOL Impurity Transport and Effect of Dynamical Material Mixing on Erosion/Deposition of Tungsten Surfaces Exposed to Plasma Boundary


Simulation Study on Influence of Chemically Eroded Carbon Impurity Transport on Net Sputtering Erosion of Carbon Materials Exposed to Edge Fusion Plasmas

Regarding TEXTOR and ITER-FEAT fusion devices, the net sputtering erosion rate of C targets exposed to their edge fusion plasmas has been investigated using a simulation code for plasma surface interactions, EDDY. The influence of the transport of chemically eroded CD4 molecules on the net erosion rate is presented. Emphasis is put on the difference in the simulated results between the CD4 reaction chain with e-, the CD4 reaction chain with e- plus D+, and the sticking coefficients of CDx locally returned back to the targets, which are related closely to the local redeposition, for a variety of plasma densities and temperatures. In particular, at a high density such as $10^{19}$ m-3 and low temperatures of less than 10 eV, the net erosion rate is found to be suppressed by a significant contribution of the local redeposition resulting from the charge exchange reactions of CDx with D+ if all the locally returned CDx radicals stick. For the ITER-FEAT divertor plasma, the profile of the net erosion rate along the outer vertical target is significantly changed by the C impurity concentration in the plasma, which is eroded from other wall surfaces and then transported by the plasma. For the D+ plasma exposure only, the net erosion rate is highest around the separatrix strike point. On the other hand, it is highest at the private plasma region if a few percent of the C impurity concentration is added to the D+ plasma exposure. The local redeposition resulting from the charge exchange reactions significantly suppresses the net erosion rates at these plasma regions, but does not bring about a significant change in the erosion/deposition profile along the outer vertical target.


Carbon Behavior on Tungsten Surface after Carbon and Hydrogen Mixed Beam Irradiation


Effects of Carbon Impurity in Fusion Plasmas on Erosion of RAF First Wall


Simulation Study of Sputtering Erosion and Impurity Deposition on Carbon and Tungsten Surfaces Irradiated with Deuterium Plasmas Including Carbon Impurity


Simulation Study of Dynamical Material Mixing on Tungsten Surfaces at Elevated Temperatures due to Hydrogen and Carbon Mixed Ion Beam Irradiation


Temporal Evolution of Erosion/Deposition on Tungsten Surfaces Exposed to SOL Plasmas and its Impact on Plasma-Surface Interactions

Temporal evolution of erosion/deposition on W surfaces exposed to SOL plasma composed of D+ and C4+ impurities, and its impact on plasma-surface interactions such as ion reflection and physical sputtering have been calculated. In particular, changes in the thickness of the W targets due to (i) C impurity concentration in the SOL plasma, and due to the additional contribution of (ii) chemical sputtering (CD4 emission) and (iii) thermal diffusion of C impurity deposited on the target are focused on. Changes in the depth profile of the deposited C are also considered. The calculated results have been compared qualitatively with experimental data which were obtained in TEXTOR-94. (i) Erosion of Wnear exposed close to the LCFS and deposition of C impurity on Wfar exposed far from the LCFS are reproduced by assuming different C impurity concentrations at the two targets. The deposition is due to the high C impurity concentration and the low plasma ion temperature, whereas the erosion is due to the converse reasons. However, the depth profiles are in disagreement with the measured growth of the W-C contamination layers. (ii) By the weak contribution of the chemical sputtering, the erosion of Wnear and the deposition on Wfar are also reproduced. Since the amount of the deposited C is decreased by the chemical sputtering, the depth profiles are also in disagreement with the experimental data. (iii) By the significant contribution of the thermal diffusion, the erosion/deposition at the two targets is also reproduced. In addition, the depth profiles for Wnear and Wfar, which show there is a deep penetration of the deposited C due to the thermal diffusion, are in good agreement with the experimental ones.

Japanese Journal of Applied Physics, Part 1 (Regular Papers & Short Notes)


Dynamic Behavior of Tungsten Surfaces due to Simultaneous Impact of Hydrogen and Carbon Ion Beam

By using a simulation code for ion-solid interactions, EDDY, the dynamical behavior of W surfaces irradiated simultaneously with H+ and C+ impurity has been studied. This code models the fluence evolution of composition changes between C and W at the irradiated surface, which results from sputtering erosion and impurity deposition. The result has been described in terms of C impurity concentration in the irradiation. It has been compared with experimental data obtained by an ion beam irradiation device. In particular, the C impurity concentration has an important role in erosion/deposition at the W surface. As the C impurity concentration increases, the erosion is enhanced. As the C impurity concentration exceeds 3.00%, there is a transition from erosion to deposition which is due to the formation of a C film on the W surface. Regarding the result that the erosion changes to deposition, the simulation qualitatively reproduces the experimental results measured by X-ray photoemission spectroscopy (XPS). There is a different tendency in the fluence dependence for the different C impurity concentrations. For C:0.11%, the erosion rate increases with increasing fluence. This results from a growth of a local peak at around a depth of 20 nm in the depth profile of the deposited C. The growth is in good agreement with the experimental result, which shows that there is a strong contribution from recoil implantation of the deposited C due to a synergetic effect of the H and C impurity. For C:0.84%, there are almost the same tendencies as for C:0.11% in the erosion rate and in the depth profile. However, the growth of the local peak at around a depth of 10 nm is in disagreement with the measured one, which occurs near the surface. The disagreement appears to be attributable to the contribution of the surface segregation.


Dynamic Behavior of Carbon Deposited on Tungsten Surface due to Carbon Ion Bombardment and Its Influence on Ion-Solid Interactions

動的プラズマ壁相互作用コードEDDYを用いて，タングステン表面への炭素イオンの照射時の表面組成と粒子放出特性の照射量依存性について，衝突ミキシングと熱拡散を考慮して研究した．低照射量では，物理スパッタ率は表面温度の上昇と共に減少するが，高照射量では逆に増加する．これは堆積Cの拡散のため混成層の顕著な成長が促進される結果と考えられる．


Sputtering Erosion and Redeposition at Divertor Surfaces Exposed to ITER-FEAT Edge Plasmas

B2-EIRENEコードによって計算されたプラズマパラメータ分布を用いて，ITER-FEATのダイバータ部品の正味の損耗を，動的プラズマ壁相互作用コードEDDYで予測した．WドームとC垂直なターゲットへの炭素堆積が化学スパッタリングによって放出された炭化水素分子の再付着によって起こることを示した．また，内側と外側の垂直ターゲットの損耗の非対称性について議論した．


Simulation Study of Material Mixing Process on Tungsten Surfaces at Elevated Temperatures due to Boundary Plasma Exposure and Its Influence on Plasma Wall Interactions

動的なプラズマ壁相互作用コードEDDYを用いて，プラズマに照射されたタングステンと炭素の材料混成について研究した．TEXTOR-94で観測されたW表面のW-C 混成層の変化と計算結果の比較はよく一致したことより，この変化がW表面への堆積炭素不純物の熱拡散のためであると考えられる．また，W-C混成層の化学損耗と放出されたCD4分子の輸送過程も調べた．


Dynamic Behavior of Sputtering of Tungsten Implanted in Carbon

炭素への高粒子束タングステンイオンの照射によって起こるスパッタ率の時間的な振動現象について，動的シミュレーションコードを用いて研究した．低原子番号材料に注入された高原子番号粒子の深さ分布の変化に起因する現象であり，材料温度による深さ分布の変化の影響についても調べた．


Computer Simulation Study on Incident Fluence Dependence of Ion Reflection and Sputtering Processes from Layered and Mixed Materials

炭素(C)バルクとタングステン(W)上に堆積した炭素層，C上に堆積したW層とWxC1-x混合材料上のW層について，Dイオン反射とスパッタリングの照射量依存性を動的プラズマ壁相互作用コードEDDYを用いて研究した．層状材料において，反射率とスパッタ率の照射量による変化は層の厚さに依存する．Cのスパッタ率は照射ともに減少するが，D反射率とWのスパッタ率は増加する．


Simulation Study on Erosion and Redeposition at Tungsten Surface Exposed to Deuterium Plasma Including Carbon Impurity

炭素不純物を含む重水素プラズマに晒されたタングステン表面の損耗と再堆積を動的プラズマ表面相互作用コードEDDYを用いて研究した．計算結果を実験データ(TEXTOR-94プラズマ照射後のW試験リミタの端部におけるC堆積領域の明瞭な境界)と比較した．明瞭な境界は，プラズマ中の不純物炭素濃度と端部の低いプラズマ温度に関係し，照射量の増加とともに形成される．


Comparison between Static and Dynamic Simulations of Ion Reflection and Sputtering from Layered Materials

動的プラズマ壁相互作用コードEDDYを用いて，低イオン照射量と高イオン照射量における二層材料のイオン反射とスパッタリングの違いを研究した．低照射量では，上層の厚さの増加によってそれらは急激に変化するが，高照射量では，上層の大きい損耗とリコイルインプランテーションの効果によりゆるやかな変化を示す．

Japanese Journal of Applied Physics, Part 1 (Regular Papers & Short Notes)


A Modified EDDY Code to Simulate Erosion/Redeposition of Carbon Target in an ITER-FEAT Divertor

核融合装置内のプラズマ壁相互作用の解析のため開発しているEDDY計算機シミュレーションコードに化学スパッタリングによる壁材料の損耗と放出炭化水素分子のプラズマ中の原子分子過程を追加した．炭化水素分子の再付着も考慮した正味の損耗量を評価できるようになり，ITER-FEATのダイバータ黒鉛ターゲットの損耗分布の評価を行った．


Simulation calculations of mutual contamination between tungsten and carbon and its impact on plasma surface interactions

TEXTOR-94トカマクの周辺プラズマに挿入したタングステン·炭素ツイン試験リミタ近傍の不純物発光分布を実機条件でのEDDYコード計算と比較した．特に，タングステンと炭素材を核融合炉内で併用した場合の相互汚染の進展とプラズマ壁相互作用への影響について研究した．


Simulation Study on Influence of Mutual Contamination on Ion Reflection and Sputtering from Tungsten and Carbon Materials

動的プラズマ壁相互作用EDDYコードを用いて，ダイバータ内でタングステンと炭素を同時に使用したときの相互汚染について研究した．W上に堆積したC堆積はWのイオン反射率とスパッタ率を減少させる一方，C上に堆積したW堆積は，逆に反射率を増加し，させて，Cのスパッタリングを減少させる．

Journal of Plasma and Fusion Research SERIES


Time Evolution of Surface Topography of Plasma Facing Materials with Non-Uniform Impurity Deposition

高粒子束プラズマに照射された材料の表面凹凸の時間発展を計算するシミュレーションコードを開発した．表面にプラズマ炭素不純物が正弦波状に堆積したボロン被膜の表面変化の計算に適用し，炭素の非一様な堆積によって表面の平均的損耗が大きく変化することを示した．

Journal of Plasma and Fusion Research, SERIES


Simulation study of carbon and tungsten deposition on W/C twin test limiter in TEXTOR-94

タングステンと炭素で構成した試験リミタをTEXTOR-94トカマクの周辺プラズマに晒した時のリミタの不純物放出と表面変化について，動的プラズマ壁相互作用コードEDDYを用いて研究した．実験で観測されたリミタのW側のWI発光分布はWの物理スパッタリング，CII発光分布はCイオンの反射と再堆積Cの物理スパッタリングによって説明できた．


Study of Impurity Release from a W-C Twin Test Limiter Exposed to TEXTOR-94

Bulletin of Faculty of Engineering, The University of Tokushima


Calculation of Impurity Release from Walls and its Transport in Edge Plasmas

プラズマ壁相互作用コードEDDYを用いて相互汚染下での(つまりW上にCが堆積，またはC上にWが堆積)WとCの相互汚染下での損耗と不純物再堆積過程を研究した．スパッタ炭素原子の再堆積はW表面の損耗率の低下を引き起こし，C(W)表面に堆積したW(C)は実質的にはDと不純物イオンの反射係数を増加(わずかに減少)させる．


Anomalous Relaxation and Stopping Power for Electron Beam in Beam-Plasma System

ビームプラズマ放電において，電子ビームはソリトンを放射するが，そのとき特異な緩和や電子素子能をしめすことが理論的に解析されている．計算結果は実験と比較されている．ビーム電子がイオン波の急峻な負の波面，すなわち，減速場，に衝突するときソリトンを放射する．これはコヒーレントな相互作用を介しておこなわれる．


Nonlinear Dispersion Relation for Beam-Excited Plasma

ビームプラズマ放電における崩落ソリトンの発生について実験的に研究史，それに対する非線形理論と分散関係について調べた．ガウス型グリーン関数を用いて非線形分散関係を得ることに成功した．さらに，この非線形分散関係を数値的に解くことを試みた．結果として，ωーk面に2つの曲線が得られ，これらが電子ビームの分散である．これらの曲線は線形の分散から導かれる解に非常によく似ている．


Structure of Multi-dimensional Soliton and Generation of Caviton in the Nonlinear Beam-Plasma System

ソリトンとキャビトンの生成機構に関する実験結果を解析した．ソリトンが発生する際には，イオン花見(キャビトン)を伴っている．ガウス関数型グリーン関数に関して，繰り込み理論によって電子ビームによって作られる孤立波を描いた．すなわち，電子同士がフォノンを介してコヒーレントな相互作用をすることでソリトンを放射する．


Nonlinear Waves Observed in an Electron Beam-Plasma

Journal of Plasma and Fusion Research SERIES


Simultaneous Calculation of Reflection, Physical Sputtering and Secondary Electron Emission from a Metal Surface Due to Impact of Low-Energy Ions

アルミニウム中での10eVから10keVの低エネルギーイオン(原子番号1から17)の弾性，非弾性衝突過程を同時に取り扱う計算機シミュレーションコードを開発した．そのコードは励起電子の電子カスケードと反跳原子の衝突カスケードの計算を行い，固体からのイオン反射，物理スパッタリング，二次電子放出の計算ができる．

Japanese Journal of Applied Physics, Part 1 (Regular Papers & Short Notes)


Anomalous Electronic stopping and relaxation in the plasma and application of its theory to beam-surface interaction

電子ビームをガスプラズマに注入した場合の電子的青銅機構の新しい理論を提案し，高速家電粒子と固体表面のコヒーレントな相互作用理論に適用した．実験はミラー磁界を持つビームプラズマ装置でおこなった．電子ビームがアルゴンガスを電離させるような電子ビームプラズマ系を考える場合，電子励起を伴う非弾性散乱による電子的素子能をけいさんした．ビームのエネルギーの緩和が観測されたが，これは理論の予測とよく一致する．

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms


Cascade Collision of Fe-Atom Caused by Low Energy He-Incidence and Effect of Temperature to the Type of Defect

分子運動力学モデルシミュレーション法によって低エネルギーヘリウム原子が体心立方格子の鉄結晶に注入されたときにフォーカシングカスケード衝突が観測された．また，格子温度と欠陥の型が関連していることについて議論した．ヘリウム原子と鉄原子の質量比が大きいにもかかわらず，非常に小さいエネルギーで格子欠陥が生ずることを示した．


Monte Carlo Simulation of Ion Reflection, Physical Sputtering and Kinetic Electron Emission from Solid Due to Ion Impact

Bulletin of Takuma National College of Technology


Variation of Ion Transport Properties under Electric Field with Mass Ratios

Journal of the Physical Society of Japan


Variation of Reduced Mobilities of Ions in Gases under 12-4 Potentials


Ion Transport Properties in Model Gases Based on A dot r^{-n} Type Single Potential