Masahito Tagawa

Kobe University | Shindai · Department of Mechanical Engineering

Utilizing wood in space-based applications poses challenges because the lack of electrical conductivity of this material can lead to local charging while off-gassing under high vacuum can potentially also have adverse effects. However, carbonized wood exhibits electrical conductivity and does not produce gases in a vacuum, making it a potential can...

Atomic oxygen (AO) is one of the dominant components of the residual atmosphere in low Earth orbit. AO collides with spacecraft with a translational energy of 5 eV, forming nanoscale protrusions on polymeric materials. To clarify the influences of a polymer's chemical structure on the formation of AO-induced microstructures, this study investigated...

Atomic oxygen (AO) is the main component of the residual atmosphere in a low Earth orbit. AO with a translational energy of 5 eV colliding with artificial satellites forms nano- and microscale protrusions on polymeric materials. This study investigated the influences of AO (fluence and velocity distribution) and a polymer's chemical structure on su...

The effect of the micro-structure surface on the passive compression performance of the intake system of an air-breathing ion engine (ABIE) system is proposed and analysed. The scattering distributions of the thermal Ar beam pulses at the microstructure surface were measured experimentally. The scattering process at the microstructure surface demon...

A more detailed understanding of the role of N2 in very low Earth orbit (VLEO) on atomic oxygen (AO)-induced material erosion is necessary for future development of the sub-LEO region. Accordingly, a laser-detonation source capable of capturing two different beams is developed. A dual-pulsed supersonic valve (dual-PSV) system is designed to form tw...

At Japan Aerospace Exploration Agency (JAXA), the Super Low Altitude Test Satellite (SLATS), named “TSUBAME” was successfully launched in 2017. In this work, we investigate rarefied aerodynamic characteristics for the SLATS geometry by carrying out free molecular (FM) and direct simulation Monte Carlo (DSMC) computations, and SLATS aerodynamic data...

The role of N 2 in the upper atmosphere on the atomic oxygen (AO)-induced erosion of polyimide in low Earth orbit (LEO) and sub-LEO is investigated through ground-based experiments and flight data. The experiment is performed by adding an Ar beam at the same collision energy as an undecomposed O 2 component in the AO beam formed by laser detonation...

In space operation of the microwave discharge ion thruster μ10 on the asteroid explorers Hayabusa and Hayabusa2, the propellant utilization efficiency deteriorated much more than in the ground endurance test. In this study, a fault tree analysis and experimental simulations of space operation were performed, focusing on the grid-derived internal ca...

Numerical simulations of plasma processes taking place near spacecraft require fully-kinetic modeling of plasmas, proper particle and field conditions at spacecraft surfaces, and sound parallelization strategy adapted for modern supercomputers. Some relevant techniques are presented, with particular focus on the use of the particle-in-cell approach...

The irradiation effect on fluorinated diamond-like carbon (F-DLC) film was investigated by measuring the dose dependence of various film properties using synchrotron radiation (SR) in the soft X-rays in the SR dose region from 0 to 2000 mA h. Film flatness was maintained but various film properties and surface properties were found to be changed by...

Polyimide or fluorine polymer that are used as heat-control materials on structures in LEO and GEO orbits, if not protected from the atomic oxygen (AO) may be severely degraded by the formation of microcracks. Carbonized materials are suitable for use in low Earth orbit (LEO) as they have excellent mechanical strength, electrical insulation, and th...

We investigated the effect of hyperthermal atomic oxygen beam irradiation on hydrogenated Si-doped Diamond-Like Carbon (hydrogenated Si-DLC) films for the purpose of use as a solid lubrication material in space. We found that film thickness of hydrogenated Si-DLC was constant after the exposure to atomic oxygen beam. From this result, the hydrogena...

The effect of irradiation by a hyperthermal-atomic-oxygen beam on hydrogenated titanium-doped diamond-like carbon (hydrogenated Ti-DLC) films, applied as a solid lubricant for equipment used in low-earth orbit was investigated. Unlike the film thickness of hydrogenated non-doped DLC films, that of hydrogenated Ti-DLC films was found to be constant...

An Electrodynamic tether (EDT) is an attractive propulsion device for active debris removal systems. One of the key components of the EDT system is an electron emission device, and we have studied a field emission cathode (FEC) using carbon nanotubes (CNTs) because of its simplicity and potential capabilities. Since EDT systems are operated in low...

A multiple-composition beam with a velocity of 8 km s(-1) was formed using a laser detonation source in order to simulate the physical and chemical effects of neutral gas collisions on a material in the sub-low earth orbit (LEO). A premixed target gas was applied in the laser detonation beam technique. It was found that atoms of different masses, O...

Surface structural changes of Ti-doped diamond-like carbon (Ti-DLC) film exposed to a hyperthermal atomic oxygen beam were investigated using near-edge X-ray absorption fine structure (NEXAFS) spectroscopy using synchrotron radiation. The spectral shape of the C K NEXAFS spectrum of as-deposited Ti-DLC film resembled that of DLC film. After exposur...

Oxidation reaction efficiency of the embedded Si atoms in the diamond-like carbon (DLC) film was studied with a combination of the broad O-atom beam, high-speed chopper wheel and synchrotron radiation photoelectron spectroscopy (SR-PES). The high-speed chopper wheel converted the translational energy distribution of O-atom into spatial distribution...

The materials used in the exterior surfaces of spacecraft encounter severe erosion due to hyperthermal (8 km/s) collisions with chemically reactive O-atoms, which are the major composition of the Earth’s upper atmosphere. Laser-induced plasma has been used to simulate these atom/surface reactions in the ground-based facilities. A 5-7 J/pulse CO2 la...

Extreme ultraviolet (EUV) spectrum emitted from laser-sustained oxygen plasma in a laser detonation atomic oxygen beam source was investigated. In order to measure EUV spectra, specially designed flat-field grazing-incidence EUV spectrometer was designed. The EUV spectra were recorded on an imaging plate which provides quantitative analysis capabil...

Spacecraft in low Earth orbit (LEO) are exposed to atomic oxygen (AO). It is thus important to develop an environmentally friendly material that can be applied to the outer surfaces of spacecraft in LEO to protect them against AO. Carbonized material containing electroconductive graphitic microlayers is promising for this purpose. We produced carbo...

The interaction mechanism of continuous soft X-rays with irradiated in vacuum diamond-like carbon (DLC) films, to simulate space environment conditions, was investigated using synchrotron radiation (SR). The thickness of the highly hydrogenated DLC film was found to decrease with increasing SR dose. The variation of local structure of DLC film was...

Volatile products were measured from two types of diamond-like carbon films under the hyperthermal atomic oxygen (AO) beam bombardment. It was clearly observed that CO and CO2 were formed at the conventional hydrogenated DLC surface when exposed to hyperthermal AO beam. Desorption rates of CO and CO2 are constant with AO fluence which reflects the...

Macroscopic and microtribological properties of MoS2 films exposed to atomic oxygen, ultraviolet rays and radiation both in low earth orbit (LEO) and in ground-based facility were evaluated. The MoS2 samples are exposed to LEO space environment in the Space Environment Exposure Device (SEED) experiment on International Space Station (ISS). Laser-de...

The basic properties of an air breathing ion engine, which uses upper atmospheric gases as a propellant, were experimentally investigated. The N-2 environment in a sub-low Earth orbit (altitude of 140-200 kin) was simulated by a laser detonation beam source, which has been previously used in studies on atomic oxygen-induced material degradation. Th...

Ground-based tests involving atomic-oxygen-induced erosion, which are intended to simulate the neutral gas environment in low Earth orbit, often result in disagreement between ground-based data and space data for certain materials. This disagreement is due to differences in the atomic oxygen test environments in space and in the laboratory. The ima...

The relative ionization probabilities of laser-detonation hyperthermal O, O2, and Ar components in Ar+O2 mixed molecular beams were evaluated for investigation of the effect of the space environment. In a high-energy beam, the complete decomposition of O2 was observed from the time-of-flight (TOF) spectra, which was due to high-energy collisions be...

Stability of hydrogen in diamond-like carbon (DLC) film under simulated space environment, i.e., hyperthermal atomic oxygen, vacuum ultraviolet (VUV) and soft X-ray exposures has been studied. Hydrogen in DLC was released by exposure to low-energy atomic oxygen beam, whereas the gasification reaction of carbon atom needed collision energy above 3 e...

In order to simulate physical and chemical effects of neutral gas collisions on a material in super-low earth orbit, where the altitude around 200 km from sea level, multiple composition beams with velocity of 8 km/s were formed by a laser detonation source. Ar+O2 target gas was used for the laser detonation beam source. N2 was not used for prevent...

The origin of FEP (and other fluoropolymers) erosion in space environment is still in question; atomic oxygen, UV or high-energy particle such as N2. In the recent ground-based study, role of high-energy impact of chemically inert atoms/molecules is addressed. In order to verify this ground-based result in space, materials test in super-low earth o...

The goals of the 10th International Space Conference on “Protection of Materials and Structures from Space Environment” ICPMSE-10J, since its inception in 1992, have been to facilitate exchanges between members of the various engineering and science disciplines involved in the development of space materials, including aspects of LEO, GEO and Deep S...

The super-low altitude test satellite (SLATS) is the first Japanese satellite orbiting the altitude of 200 km assisted by an ion engine. Because of its low altitude, atomic oxygen flux at ram facing surface of SLATS is more than two to three orders greater than that of the International Space Station. Material Degradation Monitor (MDM) is the first...

Surface modification of diamond-like carbon (DLC) film was performed using a hyperthermal atomic fluorine beam on the purpose of production of hydrophobic surface by maintaining the high hardness of DLC film. By the irradiation of atomic fluorine beam of a 1.0×1020atoms/cm2, the contact angle of a water drop against the DLC surface increased from 7...

The effect of soft X-ray irradiation of diamond-like carbon films in vacuum was investigated using synchrotron radiation (SR). Etching and the desorption of hydrogen upon SR exposure in vacuum occurred in highly hydrogenated diamond-like carbon (H-DLC) films; these processes were not observed in the irradiation of a low-hydrogenated DLC film. The e...

The effect of soft X-ray irradiation of diamond-like carbon films in vacuum was investigated using synchrotron radiation (SR). Etching and the desorption of hydrogen upon SR exposure in vacuum occurred in highly hydrogenated diamond-like carbon (H-DLC) films; these processes were not observed in the irradiation of a low-hydrogenated DLC film. The e...

Hydrogenated amorphous silicon carbide (a-SiCx:H) films were prepared by the decomposition of tetramethylsilane (TMS) with microwave discharge flow of Ar. When radio-frequency (RF) bias voltage (− VRF) was applied to the substrate, the film hardness increased as (2.39 ± 1.12)–(9.15 ± 0.55) GPa for − VRF = 0–100 V. The a-SiCx:H films prepared under...

Macro- and microtribological properties of the MoS2 film exposed to atomic oxygen, ultraviolet rays and radiation both in low earth orbit (LEO) and in ground-based facility were evaluated relevance to micro/nano satellites. MoS2 samples are exposed to LEO space environment by the space environment exposure device experiment on international space s...

抄録 An analysis of the erosional properties of carbonized lignin with a Si content of 0 to 40% under the simulated atomic oxygen (AO) conditions found in low earth orbit was carried out. The AO environment was produced using a laser detonation atomic oxygen beam source. X-ray photoelectron spectroscopy revealed an increase in the atomic concentratio...

In Japan, the largest material exposure program “SM/MPAC&SEED (Service Module/ Micro-Particles Capturer and Space Environment Exposure Device) Experiment” has been completed. This program is quite ambitious among the other Japanese materials exposure tests; 3 sets of samples have been exposed for 1, 2 and 3 years in orbit in order to discover the f...

Surface structural changes of a hydrogenated diamond-like carbon (DLC) film exposed to a hyperthermal atomic oxygen beam were investigated by Rutherford backscattering spectroscopy (RBS), synchrotron radiation photoelectron spectroscopy (SR-PES), and near-edge X-ray absorption fine structure (NEXAFS). It was confirmed that the DLC surface was oxidi...

The origin of the inconsistency in the erosion phenomena of fluorocarbon polymers between a ground-based atomic-oxygen test environment and the low Earth orbital space environment has been investigated. A detailed experiment was performed in order to study the effect of the high-energy component in the atomic-oxygen beam pulses on the erosion. The...

Silicon containing polyimide is proposed as an atomic-oxygen (AO)-tolerant material for Low Earth Orbit flight. For this study, commercially available polysiloxane-block-polyimide film is selected for investigation. An AO beam is irradiated on the polysiloxane-block-polyimide film at the Combined Space Effects Test Facility of JAXA in Tsukuba, Japa...

The contribution of extreme ultraviolet (EUV) and vacuum ultraviolet (VUV) from a laser-sustained plasma on mass loss phenomenon of fluorinated polymer in the ground-based laser-detonation atomic oxygen (AO) beam source was evaluated. The AO beam and EUV/VUV from an oxygen plasma were separated by a high-speed chopper wheel installed in the beam so...

Real-time measurement of the erosion rate of a commercially available Si-containing polyimide (BSF30) under hyperthermal atomic oxygen (AO) beam exposure condition, which simulates the AO environment in low Earth orbit (LEO), was performed. It was found that the erosion rate of BSF30 decreased with increasing AO fluence and it reached as low as 4%...

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This article focuses on mechanistic aspects of hyperthermal atomic oxygen reactions with polymers, which are the major contributor to material degradation in low Earth orbit. Due to the importance of well-controlled experiments in the understanding of the reaction mechanisms, ground-based experimental results obtained by a hyperthermal atomic oxyge...

The importance of space environmental effect on material is addressed. Some examples of the material degradation in a particular space environment are introduced. In order to endorse the material properties requested in a mission, ground-based studies are quite important. However, present deficient ground-based simulation technology cannot perform...

The effect of hyperthermal atomic oxygen (AO) exposure on a surface property of Si-doped DLC was investigated. Two types of DLC were tested which contain Si atoms approximately 10 at% and 20 at%. Surface analytical results of high-resolution x-ray photoelectron spectroscopy using synchrotron radiation (synchrotron radiation photoemission spectrosco...

Hyperthermal (kinetic energy of 10 eV) fluorine atom beam interaction with highly oriented pyrolytic graphite (HOPG) was studied. Surface analytical results of atomic fluorine-exposed HOPG using synchrotron radiation photoelectron spectroscopy showed that the fluorine reaction was limited at the topmost HOPG(0001) layer. This is due to the fact tha...

This study evaluated effects of a low earth orbit (LEO) space environment on properties of a solid lubricant used for space applications. The tested lubricant was a bonded MoS2 film with organic binder. The film was exposed to a real LEO space environment aboard the International Space Station (ISS) by the Space Environment Exposure Device (SEED) e...

The electronic structure in hydrogenated amorphous carbon (a-C:H) thin films as a function of annealing temperature was investigated by photoemission spectroscopy. The photoemission results of the valence band and the C 1s core level suggested that the graphitization of a-C:H films proceeds by annealing at more than 400 °C. From the photoemission s...

The densities of hydrogen and carbon atoms in a hydrogenated diamond-like carbon (DLC) film exposed to a hyperthermal atomic oxygen beam were investigated by Rutherford backscattering spectroscopy (RBS) and elastic recoil detection analysis (ERDA). The hydrogen density in DLC decreased upon atomic oxygen beam exposure with collision energy as low a...

Atomic oxygen concentration technology was investigated with two types of concentrators. One is a "horn-type" and the other is a "multiple ring-type" concentrator. Both of them were designed with a computer simulation using a hard-cube model. It was made clear that the primary factor for limiting the concentration factor is the gas buildup near the...

A combination of beam-surface-scattering, quartz-crystal-microbalance, and surface-recession experiments was conducted to study the effects of various combinations of O atoms [in the O((3)P) ground state], Ar atoms, and vacuum ultraviolet (VUV) light on fluorinated ethylene-propylene copolymer (FEP) Teflon and poly(methyl methacrylate) (PMMA). A la...

The contribution of extreme ultraviolet (EUV) from a laser‐sustained plasma on the mass loss phenomenon of fluorinated polymer in a ground‐based laser‐detonation atomic oxygen beam source was evaluated. The atomic oxygen beam and EUV from the oxygen plasma were separated by the high‐speed chopper wheel installed in the beam source. The mass changes...

Influence of a ground‐simulated space environment on a solid lubricant was compared to that of the real space environment. The tested lubricant that has been used for space applications was a bonded MoS 2 film with organic binder. The film was irradiated individually with atomic oxygen (AO), ultraviolet rays (UV), and electron beam (EB). The fl...

The effect of hyperthermal atomic oxygen (AO) exposure on the surface properties of Si-doped diamond-like carbon (DLC) was investigated. Two types of DLC were tested that contain approximately 10 at% and 20 at% of Si atoms. Surface analytical results of high-resolution x-ray photoelectron spectroscopy using synchrotron radiation (synchrotron radiat...

For the high-fluence atomic oxygen exposure tests, we have investigated atomic oxygen concentration technology. Based upon the previous results relating material selection or shape of the reflecting surface, two types of concentrators were designed. One is ``horn-type'' and the other is ``multiple ring-type'' concentrator. Both of them were designe...

O-atom has been well known that it reacts with many space materials used in low Earth orbit and induces severe erosion. One of the important points of this phenomenon is the impact energy of O-atom with materials. Due to the high-orbital velocity of a spacecraft, the impinging energy of O-atom reaches as high as 5-6 electronvolts, which is similar...

Effects of a low earth orbit (LEO) space environment on tribological characteristics of a solid lubricant film were evaluated. The tested lubricant, which has been used for space applications, was a bonded molybdenum disulfide (MoS2) film with organic binder. Three sets of the specimen were exposed to a real LEO space environment for about 1, 2 and...

Microtribological properties of vertically-aligned carbon-nanotube (VACNT) films have been studied. Adhesion forces were obtained by measuring force-displacement curves. Friction experiments were conducted in reciprocating sliding configurations. Effects of tip radius, applied force, scan speed, and relative humidity were investigated. A model of t...

Effect of relative intensity of atomic oxygen and vacuum ultraviolet (UV) in the synergistic effect of polyimide erosion was investigated. The relative intensity of atomic oxygen and UV was adjusted by rotating the polyimide sample at the crossover point of the beam axes of atomic oxygen and UV which crossed 90∘. The erosion rate of polyimide was m...

Surface modification of a diamond-like carbon (DLC) thin film was performed using hyperthermal fluorine beams. After the irradiation of fluorine beam, the contact angle of a water drop against the DLC surface increased from 73deg to 87deg. The formation of C-F bonding was confirmed from the carbon K-edge near-edge X-ray absorption fine structure (N...

Effect of 5 eV atomic oxygen beam exposure on the surface properties of sputter-deposited molybdenum disulfide (MoS2) and diamond-like carbon lubrication films is experimentally evaluated with relevance to space environmental effect in low Earth orbit. X-ray photoelectron spectra indicate that the loss of sulfur and oxidation of molybdenum at the a...

Metallization methods of polyimide by hyperthermal atomic oxygen and atomic fluorine beams were developed. An atomic fluorine beam with a translational energy of 6.2 eV modified the wettability of polyimide surfaces to provide an advancing water contact angle of 132 degrees. It was confirmed that in-air storage for 2 months did not alter the hydrop...

A direct oxidation reaction of Si atoms on a Si(001) surface was studied by ellipsometry and synchrotron radiation photoemission spectroscopy. In situ ellipsometry measurements when exposed to 2.7-5.0 eV O atom beams indicated that oxide growth follows a linear relationship with an O atom fluence up to an oxide thickness of 0.6-0.7 nm. In contrast,...

Synergistic effect on atomic oxygen-induced erosion of polyethylene and polyimide with 172 nm monochromatic ultraviolet exposure was compared. The erosion of these materials was measured by a quartz crystal microbalance under 5 eV simultaneous atomic oxygen and ultraviolet exposures. The effect of simultaneous ultraviolet exposure on the atomic oxy...

抄録 A quantitative analysis in erosion properties of polyimide and fluorinated ethylene propylene (FEP) under simulated low earth orbit space environment of atomic oxygen and ultraviolet was performed. An atomic oxygen environment was simulated by a laser detonation atomic oxygen beam source, whereas that of ultraviolet was made by a 172 nm-eximer l...

A detailed structural analysis and dielectric property measurements of silicon nitride films fabricated using atmospheric pressure (AP) plasma were carried out, and the results were compared to those of nitride films fabricated using a radio frequency plasma. Using AP plasma, 1.8-nm-thick silicon nitride films composed of Si3N3.5O0.7 were obtained...

Feasibility of atomic oxygen concentration in low Earth orbit space environment for material testing was studied. To maximize the concentration efficiency, trajectories of the atomic oxygen reflected at the reflector surface were computer-simulated based on the Hard-Cube model, which can deal with inelastic scattering events at the solid surface. T...

Synergistic effect on atomic oxygen-induced erosion of polyethylene and polyimide with 172 nm vacuum ultraviolet was investigated using a quartz crystal microbalance. In order to adjust the relative intensity of atomic oxygen and vacuum ultraviolet, the sample was rotated with an axis perpendicular both to the axes of atomic oxygen and ultraviolet....

Feasibility of atomic oxygen concentration using reflecting mirrors was studied. Pyrex was selected as a material of reflecting surface due to its low recombination yield of atomic oxygen. Efficiency of reflection at Pyrex surfacewas measured to be 87.1%. The focal point of atomic oxygen reflected by a concave mirror was predicted by a computer sim...

Synchrotron radiation photoelectron spectroscopy (SR-PES) and crystal truncation rod (CTR) scattering profiles were used to investigate an ultrathin SiO2 overlayer on a Si(001) surface formed by a 5 eV O-atom beam at room temperature. The SR-PES spectra indicated that the suboxides in the O-atom-beam oxidized film were concentrated on the SiO2 surf...

The effect of charging on the atomic oxygen-induced erosion of polyimide was investigated. A polyimide sample was spin-coated on the quartz crystal microbalance (QCM), and mass loss of the film was directly measured from the resonant frequency shift ofQCMduring atomic oxygen exposure. The experiment was carried out using the specially designed QCM,...

An ultrathin SiO2 overlayer on a Si(001) surface formed by a 5 eV O-atom beam at room temperature was analyzed by synchrotron radiation photoelectron spectroscopy (SR-PES). SR-PES spectra clearly indicated that the SiO2 layer formed by a hyperthermal O-atom beam at room temperature contains a small amount of suboxides compared with that formed by h...

Surface and tribological properties of molybdenum disulfide-based lubricants that were exposed to real low earth orbit space environment were analyzed. Organic binder-type MoS2 sample was exposed to space environment for one year and two years, and retrieved for analysis. Corresponding ground-based simulation tests were also carried out. XPS and ED...

Wear-life of the MoS2 film was evaluated by in situ tribological testing under 5eV atomic oxygen exposures which simulated atomic oxygen environment in low Earth orbit. A combination of a laser-detonation atomic oxygen source and a conventional pin-on-disk friction tester was used to perform tribological tests. It was confirmed that the friction co...

Service Module / Space Environment Exposure Device (SM/SEED) is experimental system aboard International Space Station (ISS) to evaluate the degradation of various materials for space application under the Low Earth orbit (LEO) space environment. Three sets of exposure pallets of SM/SEED with the same samples have been exposed to LEO since October...

The vertically aligned carbon nanotubes were synthesized using microwave plasma-enhanced chemical vapor deposition. The high growth rate was achieved by avoiding the direct plasma irradiation on a substrate, in which the growth of carbon nanotubes occurs, using a plasma shield. Transmission electron microscopy and scanning electron microscopy were...

Effect of 5 eV atomic oxygen beam exposure on the surface properties of sputter-deposited and single-crystal molybdenum disulfide (MoS2) were evaluated in the light of space environmental effects in low earth orbit. X-ray photoelectron spectra indicated that the loss of sulfur from the atomic oxygen exposed MoS2 surface was significant, especially...

The frictional behavior of a vertically aligned carbon-nanotube (VACNT) film against gold tips was studied in air. In these experiments, the film was 6 mum thick, the tip radii 4.5-30 mum, the applied forces smaller than 5 muN, and speeds were 0.15-24 mum/s. In spite of the null adhesion force to the gold tip, extremely high friction coefficients o...

Microtribological properties of diamond-like carbon (DLC) films in the presence of water molecule have been studied. The amount of water adsorbed on DLC films was measured by the quartz crystal microbalance (QCM), while microtribological properties of the film were evaluated by an environment-controlled microtribometer. The hydrogenated-DLC showed...

A quantitative study of the synergistic effect of 5 eV atomic oxygen and 172 nm vacuum ultraviolet radiation exposure was carried out on polyimide samples. The relative intensity of atomic oxygen and ultraviolet was adjusted by rotating the polyimide sample at the crossover point of the beam axes of atomic oxygen and ultraviolet which crossed 900....

Ground-based experimental results on atomic oxygen-induced erosion of polyethylene with simultaneous vacuum ultraviolet (VUV) are reported. In situ mass-loss measurement was made using a quartz crystal microbalance with a mass resolution of 2 ng. A laser detonation atomic oxygen beam source was used to simulate collision energy of atomic oxygen wit...

We have utilized a molecular beam-surface scattering technique to measure energy accommodation coefficients for the collisions of fast Ar atoms and CO 2 molecules with surfaces that are representative of materials on the solar panels of the Mars Global Surveyor and Magellan spacecraft. Pulsed beams of fast atoms or molecules, with nominal kinetic e...

In this study, cell micro-patterning on FEP substrate was studied by modifying its surface using atomic oxygen beam exposure. Osteoblastic cells tended to adhere on the boundary area between modified and pristine surfaces. AFM observation at the boundary area revealed the roughness of modified surface was larger than that of pristine surface. This...

Herein, the ground-based experimental results of temperature and impingement angle dependences of erosion rate of polyimide and polyethylene films under hyperthermal atomic oxygen beam exposures are reported. The in-situ mass loss measurement was made during the atomic oxygen exposure by using a quartz crystal microbalance (QCM). A 5 eV atomic oxyg...

Macro-scale and micro-scale tribological properties of MoS2 and diamond-like carbon (DLC) films were evaluated in hyperthermal atomic oxygen beam exposure conditions. A friction coefficient at the beginning of sliding increased with increasing atomic oxygen fluence. Appearance of the atomic oxygen-induced high friction on the in-situ macroscopic tr...

The fundamental properties of hyperthermal atomic oxygen or atomic fluorine-exposed polyimide and polyethylene surfaces, based on the analytical results by X-ray photoelectron spectroscopy and contact angle measurements, are reported. It was observed that CF, CF2 or CF3 moieties were formed at the atomic-fluorine-exposed polymer surfaces depending...

In order to measure precisely the circumferential profiles of small cylindrical and spherical objects, we have developed an atomic force microscope that consists of a cantilevered probe, an optical lever system for detecting the probe deflection, and an air bearing sample stage. This rotating atomic force microscope (R-AFM) provided a roundness pro...

Influence of relative humidity on tribology of diamond-like carbon (DLC) has been studied using an in-situ microtribometer. In order to simulate the relative humidity in tribological experiments, water vapor is often back-filled in a vacuum chamber at an appropriate pressure. However, the relation between vapor pressure and relative humidity has no...

This study aimed to develop a new cell micro-patterning method by controlling material surface affinity of the cell using atomic oxygen beam exposure. Surfaces of low-density polyethylene (LDPE) and tetrafluoroethylene-hexafluoropropylene (FEP) were exposed to the atomic oxygen beam. On the LDPE surface, the roughness measured by atomic force micro...

Wear-life of the MoS 2 film was evaluated by in-situ tribological testing under 5 eV atomic oxygen exposures which simulate LEO atomic oxygen environment. A combination of a laser-detonation atomic oxygen source and a conventional pin-on-disk friction tester was used to perform tribological tests. It was confirmed that the friction coefficient was...