Since lasers were first realized in 1960, significant amounts of resources have been invested in order to develop opto-electronics technologies. After about 30 years of such efforts, the opto-electronics industry has grown to an important partner of micro-electronics in supporting our society to advance into an information-intensive society. A technological overview on opto-electronics, including a variety of applications with respect to communication, switching, information processing and other uses, as well as device technology, is described.
Application of ceramics needs to join ceramics to metals. The addition of active element such as titanium which reacts with ceramics necessitate for applying filler metals to join ceramics to metals. Several methods such as amorphous active filler metals method, molten aluminum method and ultrasonic brazing method are described. The filler metals for joining ceramics to metals have to the high chemical reactivity and the ability to relax the thermal stress in the ceramic/metal joints.
It has been found that the oxidation process in heat treatment of Fe-Co double-layer films is different depend upon whether the films are Fe/Co or Co/Fe type. The relations between the magnetic properties and the microscopic structures oxide of films have been studied by X-ray diffraction, Auger erectron spectroscopy (AES) and Vibrating sample magnetometer (VSM). Both types of films have perpendicular magnetic anisotropy. When the upper Fe layer of Fe/Co film was oxidized by heat treatment, oxide grains growing perpen-dicularly to the substrate are considerd to cause the anisotropy. In the case of the Co/Fe film, the Fe layer had a greater affinity for oxygen than Co, so that the layer diffused to the surface and was preferentially oxidized. The anisotropy can be attributed to weakening of magnetic interaction among grains by the oxides formed at the Co grain boundaries.
In the present study, the effects of TiC coating with or without post heat treatment on fatigue strength and wear characteristics of coated steel specimen were investigated. And also the conspicuous factors of fatigue strength and wear characteristics were studied by detecting residual stresses and hardness. For the specimen, two kinds of steels which were coated with TiC by the chemical vapor deposition (CVD) method, were used. The fatigue property was tested by a bending fatigue test machine. It was found that quench-tempering heat treatment was very important from the point of view of strength of fatigue and wear, and also found that fatigue strength and wear of TiC coated steels depended on substrate hardness and residual stress of TiC layer and the substrate region adjacent to the interface.
Propagation of nonlinear ion-acoustic waves in a three-component plasma which consists of electrons and positive and negative ions have been investigated theoretically and experimentally. The Korteweg-de Vries (K-dV) equation is obtained by the reductive perturbation of the plasma taking the ion temperature into consideration. The dispersion term of the K-dV equation is positive for the concentration r of the negative ion considered here. On the other hand, the coefficient of the nonlinear term becomes negative at a critical concentration rc which depends on the mass ratio of the negative to positive ions and the temperature ratio of electrons to ions. Therefore, positive (electric potential), compressive (positive ion and electron density) solitons can exist when 0<r<rc and negative and rarefactive solitons can propagate when r>rc. When r=rc, the nonlinear term in the K-dV equation disappear so that a higher-order term should be considered, which results in the modified K-dV equation. The modified K-dV equation has also soliton solutions which are irrespective of the sign, i.e., both positive and negative solitons coexist. The K-dV and the modified equations are obtained under the assumption that the amplitude is small. When the amplitude is large, original fluid equations are integrated numerically. The result is that when rc<r<rm, positive solitary waves exist if the amplitude is larger than a threshold. Experiments were carried out in a multi-dipole double-plasma device. The inner diameter of the device is 40cm and its total length is 90cm. The device is separated into a driver and a target section with an electrically floating mesh grid. The chamber was evacuated to 1×10-6Torr with a turbo-molecular pump. Argon and sulfur hexafluoride were introduced into the chamber under continuous pumping. Plasma parameters measured with a probe and a retarding energy analyzer were the electron density=108-109cm-3, the electron temperature=0.6-1eV and the ion temperature=0.05-0.1eV. Experimental results are compared with the theoretical results described above.
Plasma based particle accelerators have potentiality to produce much higher gradient of acceleration fields compared with the one in the conventional accelerators, if the high power laser and the plasma are combined together. The accelerators can be divided into major three categories, depending on the accleration principle: 1) Potential acceleration, 2) Cross field acceleration (CFA) or VpxB acceleration, and 3) Synchronized acceleration. In the potential acceleration, the energy of the particles is decided by the potential difference between two points, even in the travelling wave frame, and this system is a “limited acceleration” scheme. The cross field acceleration is the mechanism which is newly found in the plasma, and is possible to have higher acceleration efficiency. The charged particles are accelerated very efficiently along the wave front, but across the static magnetic field. The particle energy is decided mainly by the wave width and this is an “unlimited acceleration” scheme. The VpxB accelerator and the Surfatron are typical examples of this scheme. The energy in the synchronized acceleration is proportional to the acceleration duration with a power of α which is less than unity. This is a “quasi-limited acceleration” scheme. The synchrotron and the cyclotron are typical examples. The present status of the experimental investigations on the advanced accelerators with plasma, and some of them without plasma, are reviewed, including new accelerators which use new accelertion principle such as the cross field acceleration.
Plasma wakefield accelerator experiments carried out at ANL and KEK are reviewed, where driver bunches excite electron wave in a plasma, whose electric field accelerates trailers. The principle was first verified at ANL. Accelerating gradient of approximately 4Mev/m was observed at KEK.
One dimensional nonlinear evolution and localized structure of a high frequency beam mode were experimentally studied. Test waves were first linearly unstable, but stabilized in the nonlinear stage. The wave envelope behaved such as ki sech [ki(z-zo)] as a function of position z along the beam path, where ki is the linear growth rate. The results are discussed by a nonlinear theory on unstable beam waves in an electron beam plasma.
A high brightness, compact plasma x-ray source for x-ray lithography employing a gas-puff z-pinch plasma is developed. This source is designed to direct the x-ray downward into the atmosphere by connecting a diode with a condenser bank through a parallel transmission line and to easily link to a conventional aligner. High x-ray output power is attained by high-repetition-rate discharge (3Hz), developing a fast-acting gas valve. When pinched plasma is formed, the x-rays are emitted from the pinched columnar plasma region (20mm in length and 2mm in diameter). Axial x-ray exposure is achieved by a newly developed x-ray extraction method to reduce the blur in pattern replication caused by the penumbral effect. The x-rays are efficiently extracted through a window highly transparent to x-rays. With this x-ray source, 9-14 A x-rays with 200 J per pulse (600W average power) are obtained using Ne gas plasma in a 3Hz operation. The x-rays through x-ray extraction window (15-μm-thick Be) and x-ray mask (1-μm-thick SiN) have a peak intensity at 12 A wavelengths. The x-ray wavelength is longer than that of a conventional electron impact source. In addition, hard x-rays are not emitted by this plasma x-ray source. High contrast sufficient to replicate fine patterns can be obtained using a mask with a thin absorber, such as 0.4-μm-thick Ta. A 0.2μm resist pattern can be easily replicated.
Recent development of plasma diagnostics by laser spectroscopy are reviewed. In paticular, some current studies by use of dye-laser are presented; the method of laser-induced fluorescence (LIF) and beam-probe spectroscopy. A new diagnostic method using both techniques of neutral beam probing and LIF has been developed to measure the spatial electron density distribution. A novel technique to measure the magnetic field is also demonstrated, which is determined from the Zeeman splitting of the LiI resonance line with good time and spatial resolutions.
Much work has been done to understand basic properties of plasma due to hollow cathode discharges. However, these various work are almost specialized either in the hollow cathode glow or in the hollow cathode arc. Since the discharge characteristics are largely dependent on experimental conditions, such as device configuration, species of working gas, gas pressure, and discharge current, it is difficult to discuss in both types of the discharge regime. A new type of a simple LaB6 hollow cathode tube allows us to have very stable discharge even in the regime of the glow-arc transition at the low temperature operation. Because of the relatively large size of our device (25mm diameter) and stable discharge, we were able to investigate various plasma parameters of our plasma in detail by employing a standard Langmuir probe technique and flowing ion current from the cathode orifice (1mm diater). In particular, we have made an extensive investigation of the electron energy distribution function (EEDF) in order to understand the basic characteristics of the hollow cathode discharge. Also, we clarified the critical point which are distinguished the discharge conditions of the abnormal glow, transition, and arc regime. The EEDF of the center of this tube measured by a standard Langmuir probe is the anomalous properties in this transition: another peak appears and disappears in the range of 1-4eV.
For testing constituent materials of nuclear fusion reactor structure it is highly desirable to install a 14MeV neutoron source which can produce a neutron flux of the density much higher than 1014n/cm2sec which is a value expected on the wall of the reactor in future. We made an evaluation that a flux of 1×1015n/cm2sec can be obtained if a D2O water jet target along the center axis of the bombarding chamber is bombarded, from all surrounding directions, with tritium ion current of 600keV and 2A. This new type irradiation system consists of an annular ion source, an annular accelerating gap and an annular magnetic lens. In this way the bombarding current density can be increased by about a facter of two hundreds compared to that at the exit of ion source. Difficulty of extracting and accelerating extremely high current ion beam from the ion source can then be greatly reduced. we are now testing the bombarding system above mentioned by using a model equipment of nearly the same scale in the dimension as the actual one in order to be able to obtain a full accelerating voltage of 600kV, but of 1/100 of the final design as for bombarding beam current. So far we obtained a reasonable design of the annular ion source which is strong enough to produce the extracted ion current of 2A which is required in the final system.
There is a great demand for ions of various kinds of refractory materials, such as molybdenum (Mo), nickel (Ni) and tungsten (W) for new material production and plasma processing. We have developed a hollow cathode ion source with which ion beams of refractory materials of high current can be produced using sputter technique. We call this ion source the Double Hollow Cathode Metal ion source, which is a joined two hollow cathode tubes with different cathode diameter. This ion source is compact construction and easy operation in a state. In this ion source, most solid materials can be sputtred and ionized by the cold hollow cathode discharge mode. This ion source consists of three parts: a first cylindrical hollow cathode (40mm diameter), a second narrow hollow cathode (4mm diameter) as a sputter target, and an anode. The main discharge of this ion source is established the anode and cathode (first hollow cathode). The discharge path between these electrodes is made narrower by inserting a hollow cathode (second hollow cathode) and by applying a magnetic field along the narrowed discharge path. With increasing the sputter voltage of the second hollow cathode (up to 1kV), this ion source can be effectively produced metallic ions of refractory materials to be sputtered these hollow cathode. Our preliminary experimental results of this ion source has shown that refractory materials (Mo) of the second hollow cathode can be sputtered and ionized by a high temperature, high density plasma formed inside a narrow canal applying the negative voltage (sputter voltage) to this electrode and the axial magnetic field (600G). The current of metal ion beams increases with increasing the sputter voltage Vs of this second hollow cathode. The argon pressure in the first hollow cathode tube is approximately 0.25Torr and the discharge current Id is fixed at 0.8A. The metal ion percentage α (Mo+/(Ar++Mo+)) reaches 25% at Vs=800V. The total ion beam current is obtain 1.6mA for a 10kV extraction voltage.
Polypropylene, non-polar polyolefin, has little wettability (30dyn/cm), and so polypropylene can't be printed or adhered by ordinary methods, Wettability had been given to a polypropylene sheet by treatment with argon-oxygen plasma (72dyn/cm). The wettabilyty, however, notably decreased after more than one month (48dyn/cm, nearly the same value by treatment of argon plasma); the reason was thought that the radical, involving oxygen and being formed on the surface, transformed to the inside of the sheet, but the smoothness of the surface was a little rough than virgin polypropylene. Finally, wettabilyty lasted for a long time in graft copolymers which were made by addition of various vinyl monomers-propylene oxide, glycidol, 2-hydroxyethyl methacrylate, vinyl acetate—to the sheet previously treated with argon-oxygen plasma (72dyn/cm, and 62dyn/cm after one month); the reason was thought that the long graft chains could not be transfered to the inside of the sheet.