Sachiko Yoshihashi-Suzuki

Experimental Study on Wave Propagation Behavior on Free Surface of Lithium Flow for IFMIF

Velocity measurement of surface waves on high-speed liquid lithium (Li) flow was conducted by using the Li circulation loop at Osaka University to support target monitor and diagnostics applications for the International Fusion Materials Irradiation Facility (IFMIF). Free surface shapes were recorded with a high-speed video camera, and surface waves were tracked with the statistical correlations of image intensity patterns over a velocity range of 5 to 15 m/s. As a result, the velocity distribution of surface waves was measured. The development of surface velocity beyond the nozzle edge was clearly measured. The velocity measurement by this method might suffer from some influence from stationary waves, which were generated by a damaged nozzle edge. The measured velocity in a region free from stationary waves was seen to exceed the mean flow velocity, probably due to two-dimensional regular waves. For this case, the measured velocity may consist of the advection velocity of the Li flow and the phase velocity of the wave. For an irregular wave region, the measured velocity was shown to be approximately the same as the mean flow velocity. The present flow velocity measurement can be used in the high-velocity range where random waves are generated.

Engineering Design of Contact-Type Liquid Level Sensor for Measuring Thickness Variation of Liquid Lithium Jet in IFMIF/EVEDA Lithium Test Loop

Abstract In the Engineering Validation and Engineering Design Activities (EVEDA) on the International Fusion Materials Irradiation Facility (IFMIF), hydraulic stability of a liquid Li jet simulating the IFMIF Li target is planned to be validated in the EVEDA Li Test Loop (ELTL). This paper presents the engineering design of a contact-type liquid level sensor for use in ELTL. The sensor is going to be utilized to measure variation of jet thickness in the validation test on hydraulic stability of the Li jet, which is one of the major key tests to be performed in ELTL. A fundamental requirement for the engineering specification of the sensor is to ensure the position accuracy of the measurement probe against the pressure load of approximately 0.1 MPa between the inside and the outside of the test chamber. The calculation result on structural strength of the sensor with a Nastran code showed that the maximum displacement was 0.65 mm and that the sensor has adequate strength against the pressure load. The calculation result on the sensor temperature with an ABAQUS code showed that the probe tip’s temperature can be heated up to approximately the operation temperature with no heaters installed on the sensor.

Measurement of Wavy Surface Oscillations on Liquid Metal Lithium Jet for IFMIF Target

The International Fusion Materials Irradiation Facility (IFMIF) has been conceived as a high-flux 14 MeV neutron source for testing candidate fusion reactor materials. In the current design, neutrons are generated by irradiating a target with a deuteron beam and high-speed free-surface flow of liquid metal lithium (Li) is adopted as the target. To reveal the stability of the Li flow, we have examined characteristics of surface waves at a location 175 nm downstream from a nozzle exit, which corresponds to the center of the beam irradiated region. In this study, the characteristics of surface waves just downstream of the nozzle exit were measured experimentally, since the initial growth of surface waves exerts a definite influence on the surface behavior of the Li flow in the downstream region. Experiments were carried out with a focus on surface oscillations of the Li flow using the lithium circulation loop at Osaka University. These oscillations are measured using an electro-contact probe apparatus, which can detect electrically a contact between the probe tip and the Li surface and provide local height data of surface waves. The apparatus was installed at a location 15 mm downstream from the nozzle exit and scanned the Li surface by moving along the liquid-depth direction. The experiments were performed for the velocity range of 3-15 m/s under argon gas atmosphere at a pressure of 0.13 MPa. The contact signal recorded in the experiment was used to analyze the characteristics of surface waves, and then the root-mean-square wave amplitude and the frequency of surface waves were calculated. It was found that the root-mean-square wave amplitudes of surface waves increased with a rise in the flow velocity, and reached approximately 0.18 mm at 14-15 m/s. And also, obtained frequencies were analyzed using a linear stability theory, and the variation of frequencies was examined with the mean flow velocity.

Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry Using a Mid-Infrared Tunable Laser for Direct Protein Analysis

Matrix-assisted laser desorption/ionization (MALDI) using a mid-infrared (MIR) laser is a promising technique for the study of biomolecules. We achieved the measurement of an insoluble protein under strong denaturing conditions using two lasers, a UV laser and a free electron laser (FEL). The FEL is a powerful tool for the IR-MALDI; however, it is expensive and difficult to operate. We developed a MIR-MALDI time-of-flight mass spectrometer combined with a tunable MIR nanosecond pulsed laser, which was developed by the Institute of Physical and Chemical Research (RIKEN; Wako, Japan) and Kawasaki Heavy Industries, Ltd. (Tokyo, Japan). We evaluated the advantages of MIR-MALDI using this MIR nanosecond pulsed laser with a urea matrix and compared the results with that from previous study using the FEL. The molecular mass of insulin with urea was obtained at wavelength between 5.8 and 6.2 mum, which corresponds to the >C=O stretching vibration mode. In particular, a high SNR was observed at a wavelength of 5.9 mum. This technique produced a better SNR than that of a previous study that used the FEL.

High throughput analysis of proteins using mid-infrared laser

Large-scale analysis of proteins, which are functional biomolecules, has assumed an important role in the life sciences. Mass spectrometry is one of the techniques used to identify ptoreins. Direct desorption and ionization of proteins from polyacrylamide gel is expected to be a the high-throughput technique in proteomics, which will eliminate several problems such as sample loss, adduct formation, and contamination. In this study, we performed direct ionization of a protein, bovine insulin, in a polyacrylamide gel without matrix addition with a tunable MIR nanosecond pulsed laser. Mass spectra of insulin in an acrylamide gel and an acrylamide solution were recorded in the wavelength range 5.8-5.9 μm and at a wavelength of 6.0 μm, respectively. This wavelength corresponds to the >C=O stretching vibration mode of acrylamide.

Free-electron-laser-induced shock-wave control and mechanistic analysis using pulse control

The wavelength of the free electron laser (FEL) in Osaka University can be continuously varied in the range of 5.0-20.0 microm. The FEL has a double-pulse structure, consisting of a train of macropulses of pulse duration 12 micros. Each macropulse contains a train of 330 micropulses of pulse duration 5 ps. The tunability and picosecond pulses afford new medical and biological applications. However, a macropulse of long pulse duration leads to undesirable secondary effects. Precise control of the macropulse duration is essential for the high-precision applications of the FEL. An FEL pulse control system using acousto-optic modulators has been developed to investigate mechanical (shock-wave) effects of the FEL on living tissues. With this system, we have controlled photoinduced shock waves and determine the mechanism of interaction during FEL-induced tissue ablation.

Thermal effect control for biomedical tissue by free electron laser

An absorption characteristic and a thermal relaxation time of a target biomedical tissue is an important parameter for development of low-invasive treatment that considers of interaction between biomedical tissue and laser. Laser irradiations with a wavelength corresponding to the absorption characteristics of tissue enable selective treatment. Furthermore, the thermal effect to tissue can be controlled at the laser irradiation time which depends on the laser pulse width and reception rate. A free electron laser (FEL) can continuously vary the wavelength in the mid-infrared region, has a unique pulse structure; the structure at the Institute of the Free Electron Laser (iFEL) consist of train of macropulses with a 15 &mgr;s pulse width, and each macropulse contained a train of 300-400 ultrashort micropulse with a 5 ps pulse width. In a previous report, we have proposed a novel laser treatment such as soft tissue cutting, dental treatment and laser angioplasty using the tenability of the FEL. To investigate the thermal effect to the biomedical tissue, we developed a FEL pulse control system using an acousto-optic modulator (AOM). The AOM commonly are used the Q-switch for the pulse laser generation, has a high pulse control efficiency and good operationally. The system can control the FEL macropulse width from 200 ns. This system should be a novel tool for investigating the interaction between the FEL and biomedical tissue. In this report, the interaction between FEL pulse width and biomedical tissue will be discussed.

A novel laser angioplasty guided hollow fiber using mid-infrared laser

We have proposed selective removal of cholesterol ester by infrared laser of wavelength with 5.75 μm irradiation; the wavelength of 5.75 μm correspond with the ester bond C=O stretching vibration. The flexible laser guiding line and a compact light source are required for our proposal. We used a compact mid-infrared tunable laser by difference frequency generation; DFG laser was developed for substitute light source of free electron laser. In the present work, first, we have developed hollow optical fiber with a diamond lens-tip to deliver DFG laser in the blood vessel and evaluated the transmission of DFG laser from 5.5 μm to 7.5 μm. The transmission of 5.75 μm is about 65%, the DFG beam was focused on the tip of fiber by diamond lens-tip. Secondly, we performed the selective removal experiment of cholesterol ester using the hollow optical fiber with diamond lens-tip and DFG laser. The sample used a two layer model, cholesterol oleate and gelatin. The cholesterol oleate was decomposed by 5.75 μm DFG irradiation with 3.8 W/cm2.

Laser-dephosphorylation of phosphogelatin and its indirect quantitative analysis using FT-IR

Phosphorylation and dephosphorylation are considered to be important reactions that control the active and inactive factors of proteins. In regenerative medicine of the osteoconnective tissue (a tendon, a ligament), it has been reported that the biomaterial possessing phosphate groups promote formation of HAP, the main component of hard tissues. The noncontact measurement of phosphate groups and low-destructive controlling of phosphate groups allow for the accurate regeneration of the osteoconnective tissue, and the validation. Our objective is to propose the nondestructive controlling and measuring method of phosphorylation for regenerative medicine. In this study, as the indirect quantitative analysis of phosphate groups, we examine the correlation between the mid-infrared absorbance ratio and the ratio of phosphate groups introduction theoretically calculated from a colorimetric determination method. And the noncontact controlling method of the quantities of phosphate groups, we examine the selective and low-destructive bond cutting of phosphate groups in the phosphogelatin using a mid-infrared laser.

Design of synchronizing system of UV laser pulse and FEL micropulse for MALDI

Abstract Matrix-assisted laser desorpution ionization (MALDI) is a widely used technique for mass spectrometry (MS) of biological macromolecules. We have been developing a novel MALDI method (UV/FEL MALDI) based on simultaneous irradiation of a nitrogen laser and a free electron laser (FEL). There is a difference the pulse structure between the nitrogen laser and the FEL. To achieve the optimum irradiation condition for UV/FEL-MALDI, the length of the micropulse train and the timing of the optical pulse sequence have to be controlled arbitrarily. To control the length of the micropulse train, we set up the micropulse-picking system using the acousto-optic modulator. This paper reports designs of the opto-electric system which establishes the synchronicity for UV/FEL-MALDI. PACS codes: 82.80.Ms