Spatial coherence properties of 3 different kinds of coherent sources in extreme ultraviolet/soft x‐ray wavelength region, namely undulator, x‐ray laser and high harmonic generation source, are introduced. Advantage...
Spatial coherence properties of 3 different kinds of coherent sources in extreme ultraviolet/soft x‐ray wavelength region, namely undulator, x‐ray laser and high harmonic generation source, are introduced. Advantages of each source type and their potential applications are also discussed.
A Shack‐Hartmann wavefront sensor has been developed at the Laboratoire de l’Interaction du Rayonnement X avec la Matière, for a characterization of soft x‐ray laser beam. A mapping of the wave‐vectors pointi...
A Shack‐Hartmann wavefront sensor has been developed at the Laboratoire de l’Interaction du Rayonnement X avec la Matière, for a characterization of soft x‐ray laser beam. A mapping of the wave‐vectors pointing of laser‐pumped soft x‐ray laser (Optical Field induced and 100 ps laser pumped lasers) has been achieved. Capillary discharge soft X‐ray laser has been also investigated. The electromagnetic field has been reconstructed and the influence of the argon pressure in the capillary on the wave front regularity has been investigated.
This paper focuses on the development of an innovative nondestructive test procedure (system+algorithm) for characterizing defects in concrete sewer pipelines, using ultrasonic inspection. A signal processing techniqu...
This paper focuses on the development of an innovative nondestructive test procedure (system+algorithm) for characterizing defects in concrete sewer pipelines, using ultrasonic inspection. A signal processing technique is being developed that is invariant to changes in both concrete material properties and composition of wastewater. Development of such an inspection procedure will be the first step in the design of a mobile autonomous vehicle for inspecting wastewater pipeline systems. Results demonstrating the validity of the proposed approach are presented.
In this paper, an encircling outer diameter (OD) remote field eddy current (RFEC) probe is proposed to inspect the nuclear fuel rod. To force the electromagnetic energy from exciter coil to penetrate into the rod, shi...
In this paper, an encircling outer diameter (OD) remote field eddy current (RFEC) probe is proposed to inspect the nuclear fuel rod. To force the electromagnetic energy from exciter coil to penetrate into the rod, shielding by laminations of iron is applied outside the exciter coil. The operating frequency and effects of shielding are studied by the finite element analysis and modeling results show the existence of RFEC effects. Based on these results, the location for an encircling OD sensor coil is decided. However, predicted signals do not clearly show defect indications when the sensor passes a defect and exhibit certain symptoms that the fields from the exciter directly affect the sensor signal. To prevent direct contact with exciter fields, the sensor coil is also shielded. This shielding of sensor coil dramatically improves signal characteristics. The resulting signals have very similar characteristics to those of inner diameter RFEC signals and show almost equal sensitivity to inner diameter and outer diameter defects.
Pulsed sonic/ultrasonic excitation, combined with infrared imaging, is used to image the presence of cracks in metals. The technique is rapid (50–280 ms) and is sensitive to both surface-breaking and subsurface cracks.
Pulsed sonic/ultrasonic excitation, combined with infrared imaging, is used to image the presence of cracks in metals. The technique is rapid (50–280 ms) and is sensitive to both surface-breaking and subsurface cracks.
We report the results of thermal wave measurements of corrosion thinning on painted metal aircraft belly skins. We have developed algorithms to compensate for irregular variations in paint thickness. These algorithms ...
We report the results of thermal wave measurements of corrosion thinning on painted metal aircraft belly skins. We have developed algorithms to compensate for irregular variations in paint thickness. These algorithms have been successfully blind-tested on a DC-9 belly skin.
This paper discusses the three-dimensional (3-D) stability of carbon fiber sail structures (beam riders) that are being studied in a series of experiments at the Jet Propulsion Laboratory (JPL) and U.C. Irvine by a te...
This paper discusses the three-dimensional (3-D) stability of carbon fiber sail structures (beam riders) that are being studied in a series of experiments at the Jet Propulsion Laboratory (JPL) and U.C. Irvine by a team led by Microwave Sciences, Inc. The stability analysis is developed for a limited set of conical sail configurations, and the code described in this paper has been developed at JPL by one of the coauthors. The assumptions in the model and the principles behind the simulation, in addition to their relationship to earlier experiments utilizing disk configurations are discussed. Results of stability analyses for several beam rider configurations will be presented at the Forum.
Micro-Raman spectroscopy of an isolated single wall carbon nanotube is overviewed in connection with the recent observation of (1) the chirality-dependent G-band Raman intensity, (2) BWF line analysis and (3) D-band f...
Micro-Raman spectroscopy of an isolated single wall carbon nanotube is overviewed in connection with the recent observation of (1) the chirality-dependent G-band Raman intensity, (2) BWF line analysis and (3) D-band feature of an individual single wall carbon nanotube. The localized phonons appeared around a point defect of carbon nanotube might be relevant to D-band intensity.
This paper contains a thermodynamic analysis of electron emission from a micro-fabricated diamond tip array. The analysis is based on experimental measurements of the current-voltage characteristics of an actual devic...
This paper contains a thermodynamic analysis of electron emission from a micro-fabricated diamond tip array. The analysis is based on experimental measurements of the current-voltage characteristics of an actual device. Field enhancement, applied field, and electrical current density are shown to influence thermodynamic performance. The idealized thermodynamic analysis predicts cooling rates above 10 W/cm2 for an existing device under room temperature operation and that 100 W/cm2 may be possible for future devices.
Shock Hugoniot compression curve for water has been measured up to less than 1 GPa. Plane and steady shock wave is produced in water by the flat plate impact of a projectile accelerated up to 500m/s by a compressed ga...
Shock Hugoniot compression curve for water has been measured up to less than 1 GPa. Plane and steady shock wave is produced in water by the flat plate impact of a projectile accelerated up to 500m/s by a compressed gas gun. To measure shock Hugoniot in this pressure range in higher precision, a new experimental procedure was proposed, which is based on the very large pressure dependence of the refractive index of water upon compression. By using this method, shock compression curve was determined. It was confirmed that within the pressure range covered in this experiment, shock-particle velocity Hugoniot can be described by a linear relation with a large slope. Shock temperature was calculated by using the obtained Hugoniot data combined with the values of thermodynamical variables.
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