Hydrogen fuel production for fuel cell from methane gas is studied by using the plasma reforming technology which is eco-friendly method without generating harmful gas of carbon monoxide or carbon dioxide. Hydrogen production rate became larger as increasing input power and it became smaller with increasing methane gas flow. The highest hydrogen rate obtained about 30% by the plasma reforming under conditions of input power of 290 W and methane gas flow of 100 mL/min. Moreover, it was found that high hydrogen production was attainable by using the plasma reactor having wide gap for the velocity control of gas flow at higher input power region.
SuperKEKB is an upgrade project of KEKB, which is a double ring collider of electron and positron beams. The vacuum control system has also been upgraded. Key changes related to the framework of the system are that Computer Automated Measurement And Control (CAMAC) system as a data logger and VME computer as an Input Output Controller (IOC) of Experimental Physics and Industrial Control System (EPICS) have been replaced with CompactRIO (cRIO) and a Linux CPU module of Programmable Logic Controller (PLC), respectively. As an integrative and practical test, we have executed the final evacuation process, including the baking of sputter ion pumps and the activation of Non-Evaporable Getter (NEG) pumps, in a section between two gate valves in the SuperKEKB main ring. The control system supervised the discharge currents of ion pumps, readings of Cold Cathode Gauges (CCGs), heating power for the activation and so on. The new control system is in preparation for a start of the beam commissioning on fiscal 2015 in Japan.
Field emission microscopy (FEM) is commonly used to observe patterns and intensities of electron emissions and to estimate the average work function from the emission current with respect to the applied voltage (F-N plots). However, it is difficult to observe the nanostructure at the apex of the tip using only field emission microscopy. In this research, we observed the nanostructure of a single crystal tungsten 〈100〉 electron emitter covered with barium aluminate by using scanning probe microscopy (SPM). We were able to observe the terrace structure at the top of single crystal tungsten 〈100〉 electron emitter tip. Furthermore, we investigated the correlation between field emission pattern by the FEM and nanostructure of the electron emitter tip by the SPM.
The usual way to reduce outgassing from a device in vacuum is to heat up a whole vacuum chamber containing the device. However, the situation, where this method can be applied, is limited due to the heat expansion of the chamber. Especially in accelerators, where the vacuum chambers are connected with nearby beam pipes, this normal bake-out method may not be applied. If a heat source and heat shields are appropriately installed inside the chamber, heat flux is directed to the device. Therefore the device can be baked out without raising the temperature of the vacuum chamber. One candidate for such bake-out method to be applied is kicker magnets in J-PARC RCS, which are installed in large vacuum chambers. We performed the heating tests with some types of heaters in order to examine the effectiveness of this method and to decide the material and configuration of the heater. As a result, the graphite heater was selected for in-situ bake-out of the kickers in the RCS beam line. Using the method, the each material of kicker magnet was heated up above 100℃ with keeping the temperature rise of the vacuum chamber below 30℃.
We introduce our handmade image intensifier for visualizing the beam profiles of accelerated ion beams having energy and current in the order of keV and nano-amperes, respectively. The simple image intensifier comprising stainless steel meshes and a fluorescent screen has been designed for the transport of mm-size ion beams. The intensifier is easy to install in the beamline of a vacuum setup, because it is designed to attach on a conflat flange of ICF70. We have used the image intensifier to observe the beam profiles of the ion beams transported from the ion source to an ultra-high vacuum chamber. Through the use of the image intensifier, bright images were obtained, and it was concluded that the intensifier is useful for observing the profiles of the beams having current densities greater than 0.1 nA mm−2.
We developed the optical fiber built-in type Kelvin probe, which was combined with the previously developed system. This system can be applied to measure band diagram included fermi level of organic/inorganic semiconductor, and photovoltage. This system is also applied to the wide range environment from ultra-high vacuum to the atmosphere. We demonstrated photovoltage measurement of polycrystalline Si solar cell. Obtained photovoltage was increasing with increasing photon power. As photovoltage is associated with open-circuit voltage, the obtained results are consistent with its trend. This system has a very wide range of applications ranging from band gap science and solar cell evaluation.
In the field of nuclear fusion technology, Er2O3 thin film is a candidate for the coating material of the blanket of thermonuclear fusion reactor. It is known that the luminescence of Er2O3 provides information on its crystallinity. We observed luminescence of Er2O3 during the irradiation with highly charged ions produced by an electron beam ion source (EBIS) as a function of charge state and kinetic energy of incident Ar ions. We found that the luminescence intensity non-linearly rises as the charge state increases and is independent of kinetic energy. This demonstrates that the luminescence of Er2O3 thin film arises from the potential energy of highly charged ions rather than the kinetic energy.
After approximately ten years of research and development (R&D), Matsumoto-Ohtsuka (MO)-type flanges have been practically applied on a large scale to the vacuum beam pipes of the SuperKEKB, a particle accelerator under construction since 2010. The MO-type flanges are expected to effectively and reliably mitigate the problems related to electromagnetic waves that have been typically observed in high-intensity accelerators. Approximately 4700 MO-type flanges made of a copper or an aluminum alloy have been newly manufactured for the beam pipes and the bellows chambers of the SuperKEKB. All the beam pipes are baked at 150℃ before being installed into the KEKB tunnel. Approximately 2300 flanges have been used in the baking procedure until mid-November, 2014, and the percentage of leaks at the first fastening was approximately 2-3% on average. After the installation in the tunnel, the beam pipes are connected with bellows chambers. Approximately 3800 flanges have been used so far. The percentage of leaks after the connection procedure was 10% at an early stage, but was then reduced to less than 5% on average after revising the procedure. It was found that the sealing property is very sensitive to scratches or traces of machining on the sealing surface. Once these issues are under control, however, the flange is able to serve as a reliable connection for the accelerator beam pipes.
This second lecture of “Basics of Vacuum measurement from viewpoint of Metrology” gives the concise explanation of the technical terms related to the pressure measurement such as a zero point, an offset, a residual current, a linearity, and so on. A calibration result of a hot-cathode ionization gauge is shown as an example. A difference between a calibration and an adjustment is also explained. Benefits of calibration are discussed.