Makoto Matsui

Generation and diagnostics of atmospheric pressure CO2 plasma by laser driven plasma wind tunnel

Atmospheric pressure CO2 plasma was generated by a laser driven plasma wind tunnel. At an ambient pressure of 0.38u2009MPa, a stable plasma was maintained by a laser power of 1000u2009W for more than 20u2009min. The translational temperature was measured using laser absorption spectroscopy with the atomic oxygen line at 777.19u2009nm. The measured absorption profiles were analyzed by a Voigt function considering Doppler, Stark, and pressure-broadening effects. Under the assumption of thermochemical equilibrium, all broadening effects were consistent with each other. The measured temperature ranged from 8500u2009K to 8900u2009K.

A Contact Type Linear Photodiode Array Using an Amorphous Thin Film

A Contact type linearly arrayed imaging sensor not requiring an optical lens system has been successfully developed. This sensor array consists of 40 amorphous Saticon type photodiodes formed on an optical fiber plate, each of which measures 250 µm by 200 µm and the overall sensor length is 10 mm. This device has an advantage of easy fabrication which permits elongation of the total length without deteriorating the high resolution characteristics. Therefore, it may be useful as an imaging sensor for small size facsimile equipment. In this paper, a series of technical data on the proposed structure, the fabrication procedures and also the static and operational performances are described.

A 10×10 Polycrystalline-Silicon Thin-Film Transistor Matrix for Liquid-Crystal Display

A 10×10 thin-film transistor (TFT) matrix has been fabricated using a molecular beam deposited polycrystalline silicon film on a glass substrate by low-temperature (below 600°C) fabrication processes. The field-effect mobility of the TFT element is 40 cm2/Vs at a gate voltage of 10 V, and the response time is less than 10 ns. Combining the TFT matrix with a twisted-nematic liquid-crystal layer, a transmissive-type active matrix liquid-crystal display. It has been shown that the polycrystalline silicon TFT matrix is compatible with a liquid-crystal cell both from the viewpoint of device fabrication and of TFT characteristics.

Development of vacuum ultraviolet absorption spectroscopy system for wide measurement range of number density using a dual-tube inductively coupled plasma light source

A vacuum ultraviolet absorption spectroscopy system for a wide measurement range of atomic number densities is developed. Dual-tube inductively coupled plasma was used as a light source. The probe beam profile was optimized for the target number density range by changing the mass flow rate of the inner and outer tubes. This system was verified using cold xenon gas. As a result, the measurement number density range was extended from the conventional two orders to five orders of magnitude.

Development of an isotope analysis method based on diode laser absorption spectroscopy using an arc-jet plasma wind tunnel

Radioactive isotopes in nuclear fuel and radioactive waste must be quantified for safety control and management of various nuclear facilities. In this study, an isotope analysis method based on diode laser absorption spectroscopy by using an arc-jet plasma wind tunnel is developed for rapid analysis without sample preparation and sophisticated maintenance. The translational temperature and flow velocity downstream of a supersonic nozzle are measured using an atomic argon transition of 826.45xa0nm from an excited state, and then, the temperature upstream of the nozzle is estimated using the two measured values. Next, the trace gas measurement capability is verified by injecting natural xenon into argon plasma, and optical measurements are carried out at an atomic xenon transition to 823.16 nm from a metastable state. The detection limit of xenon over the argon molar ratio is estimated to be 140 parts per million downstream.

Combined VUV Absorption and Laser Absorption Spectroscopy for Atomic Oxygen Detection

A combined vacuum ultraviolet absorption (VUV AS) and near infrared laser absorption spectroscopy (LAS) system was developed to measure atomic number density. As a VUV light source, inductively coupled plasma was used and its beam profile was determined by LAS. Firstly, this system was evaluated using cold xenon gas. As a result, the measured number density agrees with the that estimated from the partial pressure considering the absorption between the ICP and the window. Then, this system was applied to the ECR oxygen plasma. The measured number density of atomic oxygen was found to increase with the increase in the microwave power.

High spectral resolution of diode laser absorption spectroscopy for isotope analysis using a supersonic plasma jet

Although high-temperature plasma sources have been used for direct isotope analysis of solid samples, the spectral resolution of diode laser absorption spectroscopy in high-temperature plasma is limited by the Doppler broadening of atomic absorption lines. Thus, a decrease in translational temperature is necessary to enhance the spectral resolution and distinguish isotope shifts due to the mass number. In this study, a supersonic plasma wind tunnel, also called an arc-jet plasma wind tunnel, was used to enhance the spectral resolution drastically, and a demonstration was carried out using natural stable xenon isotopes. As a result, the temperature was found to be about 180 K, and the spectral resolution was about one order of magnitude higher than that of the conventional high-temperature source. Additionally, the method proposed herein was verified by using two xenon isotopes.

Development of ICP Light Source for Wide Number Density Range Measurement by VUV Absorption Spectroscopy

A vacuum ultraviolet absorption spectroscopy system for a wide measurement range of atomic number densities is developed. Dual-tube inductively coupled plasma was used as alight source. The probe beam profile was optimized for the target number density range by changing the mass flow rate of the inner and outer tubes. This system was verified using cold xenon gas. As a result, the measurement number density range was extended from the conventional two orders to five orders of magnitude. Nomenclature A = Einstrein coefficient fprobe = line shape function of ICP ftube = line shape function of absorption profile in quartz tube ftarget = line shape function of target g = statistical weight i = lower state j = upper state I0 = incident beam intensity

Atomic Oxygen Generation by Laser Plasma as a LEO Environmental Simulator

High speed atomic oxygen flows were generated by a laser driven plasma wind tunnel to simulate low earth orbit environment. The flow velocity was measured by laser absorption spectroscopy using OI 777.19 nm line. Using pure oxygen as a working gas, the flow velocity was 5.4 km/s. To enhance the velocity, average molecular weight was reduced by mixing helium. As a result, the velocity increased to 6.2 km/s for the laser power of 1300 W, oxygen flow rate of 1.2 slm and helium flow rate of 0.3 slm.

Performance of Miniature Microwave Discharge Ion Thruster for Drag-free Control

Drag-free control systems have been studied to detect gravitational waves by measuring distortions in the fabric of space-time. The purpose of drag-free control is to counteract nongravitational forces such as residual aerodynamic drag or solar radiation pressure. The objective of this study is to use miniature microwave discharge ion thruster, uf06d1, for this propulsion system. In this experiment, the thrust dynamic range was between 7-100 %, and the thrust noise was less than 0.02 uf06dN/Hz 1/2 in the frequency range of 0.1-1.0 Hz. Although the design of uf06d1 thruster has not yet been optimized, we can expect that the uf06d1 thruster will be feasible for DPF thruster after optimization.