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We have performed 59 Co spin-echo NMR measurements on Ce n +1 Co 3 n +5 B 2 n ( n = 0, 1, 2, 3) at T= 1.4 K. The NMR spectra corresponding to the inequivalent crystallographic sites were obtained. The resonance frequencies of the 2c-Co have been observed in the range 60-80 MHz, and those of the 6i-Co(6i 1 -Co) around 32 MHz. In addition to the zero-field spectra, the field-swept spectra from non-magnetic Co have also been observed for Ce 3 Co 11 B 4 and Ce 2 Co 7 B 3 . These spectra arise from the 3g-Co in Ce 3 Co 11 B 4 and the 6i 2 -Co in Ce 2 Co 7 B 3 . From the Co hyperfine field analysis, the Co magnetic moments at the inequivalent crystallographic sites are estimated. Magnitude of the spin moment for the 2c-Co is estimated to be μ B for Ce n +1 Co 3 n +5 B 2 n (n = 0, 1, 2, 3), and to be about 0.4 μ B for the 6i 1 -Co in Ce 3 Co 11 B 4 and Ce 2 Co 7 B 3 , while the orbital moment of the 2c-Co varies from μ B in CeCo 5 to μ B in Ce 2 Co 7 B 3 , and those for the 3g-Co and 6i 1 -Co are found to be 0.08 and 0.01 μ B , respectively. The Co magnetic moments are found to be strongly influenced by the crystallographic environment around the Co site.

A preliminary experiment for producing narrow-photon-energy cone-beam X-rays using a silicon single crystal is described. In order to produce low-photon-energy X-rays, a 100-μm-focus X-ray generator in conjunction with a (1 1 1) plane silicon crystal is employed. The X-ray generator consists of a main controller and a unit with a high-voltage circuit and a microfocus X-ray tube. The maximum tube voltage and current were 35 kV and 0.50 mA, respectively, and the X-ray intensity of the microfocus generator was 48.3 μGy/s at 1.0 m from the source with a tube voltage of 30 kV and a current of 0.50 mA. The effective photon energy is determined by Bragg's angle, and the photon-energy width is regulated by the angle delta. Using this generator in conjunction with a computed radiography system, quasi-monochromatic radiography was performed using a cone beam with an effective energy of approximately 17 keV.

The tungsten plasma flash X-ray generator is useful in order to perform high-speed enhanced K-edge angiography using cone beams because K-series characteristic X-rays from the tungsten target are absorbed effectively by gadolinium-based contrast media. In the flash X-ray generator, a 150 nF condenser is charged up to 80 kV by a power supply, and flash X-rays are produced by the discharging. The X-ray tube is a demountable diode, and the turbomolecular pump evacuates air from the tube with a pressure of approximately 1 mPa. Since the electric circuit of the high-voltage pulse generator employs a cable transmission line, the high-voltage pulse generator produces twice the potential of the condenser charging voltage. At a charging voltage of 80 kV, the estimated maximum tube voltage and current were approximately 160 kV and 40 kA, respectively. When the charging voltage was increased, the characteristic X-ray intensities of tungsten K α lines increased. The K α lines were clean, and hardly any bremsstrahlung rays were detected. The X-ray pulse widths were approximately 110 ns, and the time-integrated X-ray intensity had a value of approximately 0.35 mGy at 1.0 m from the X-ray source with a charging voltage of 80 kV. Angiography was performed using a film-less computed radiography (CR) system and gadolinium-based contrast media. In angiography of non-living animals, we observed fine blood vessels of approximately 100 μm with high contrasts.

In the plasma flash X-ray generator, a 200 nF condenser is charged up to 50 kV by a power supply, and flash X-rays are produced by the discharging. The X-ray tube is a demountable triode with a trigger electrode, and the turbomolecular pump evacuates air from the tube with a pressure of approximately 1 mPa. Target evaporation leads to the formation of weakly ionized linear plasma, consisting of nickel ions and electrons, around the fine target, and intense K α lines are left using a 15-μm-thick cobalt filter. At a charging voltage of 50 kV, the maximum tube voltage was almost equal to the charging voltage of the main condenser, and the peak current was about 18 kA. The K-series characteristic X-rays were clean and intense, and higher harmonic X-rays were observed. The X-ray pulse widths were approximately 300 ns, and the time-integrated X-ray intensity had a value of approximately 1.0 mGy at 1.0 m from the X-ray source with a charging voltage of 50 kV.

The cerium-target x-ray tube is useful in order to perform cone-beam K-edge angiography because K-series characteristic x rays from the cerium target are absorbed effectively by iodine-based contrast media. The x-ray generator consists of a main controller, an x-ray tube unit with a high-voltage circuit and an insulation transformer, and a personal computer. The tube is a glass-enclosed diode with a cerium target and a 0.5-mm-thick beryllium window. The maximum tube voltage and current were 65 kV and 0.4 mA, respectively, and the focal-spot sizes were 1.2×0.8 mm. Sharp cerium K-series characteristic x rays were observed without using a filter, and the x-ray intensity was 209μGy/s at 1.0 m from the source with a tube voltage of 60 kV and a current of 0.40 mA. Angiography was performed with a computed radiography system using iodine-based microspheres 15 μm in diameter. In angiography of non-living animals, we observed fine blood vessels of approximately 100 μm with high contrasts.

Energy-selective enhanced K-edge angiography utilizing a conventional x-ray generator is described. The x-ray generator is SOFRON NST-1005, and the maximum tube voltage and current are 100 kV and 5 mA, respectively. In the present research, the tube voltage ranged from 45 to 65kV, and the tube current was regulated to optimum values. The exposure time is controlled in order to obtain optimum x-ray intensity. At a charging voltage of 60 kV, the x-ray intensity rate obtained using an aluminum and a barium sulfate filters were 58.4 and 51.6 μGy/s at 0.7m per pulse, respectively, and the dimensions of the focal spot were approximately 1×1 mm. Angiography was performed using both the aluminum and the barium sulfate filters with a charging voltage of 60 kV.

The high-voltage condensers in a polarity-inversion two-stage Marx surge generator are charged from -50 to -70 kV by a power supply, and the electric charges in the condensers are discharged to an x-ray tube after closing gap switches in the surge generator with a trigger device. The x-ray tube is a demountable diode, and the turbo molecular pump evacuates air from the tube with a pressure of approximately 1 mPa. Clean molybdenum K{alpha} lines are produced using a 20 {mu}m-thick zirconium filter, since the tube utilizes a disk cathode and a rod target, and bremsstrahlung rays are not emitted in the opposite direction to that of electron acceleration. At a charging voltage of -70 kV, the instantaneous tube voltage and current were 120 kV and 1.0 kA, respectively. The x-ray pulse widths were approximately 70 ns, and the generator produced instantaneous number of K{alpha} photons was approximately 3x10{sup 7} photons/cm{sup 2} per pulse at 0.5 m from the source of 3.0 mm in diameter.

The cerium target x-ray generator is useful in order to perform enhanced K-edge angiography using a cone beam because K-series characteristic x rays from the cerium target are absorbed effectively by iodine-based contrast mediums. The x-ray generator consists of a main controller, a unit with a Cockcroft-Walton circuit and a fixed anode x-ray tube, and a personal computer. The tube is a glass-enclosed diode with a cerium target and a 0.5−mm-thick beryllium window. The maximum tube voltage and current were 65kV and 0.4mA, respectively, and the focal-spot sizes were 1.0×1.3mm. Cerium Kα lines were left using a barium sulfate filter, and the x-ray intensity was 0.48μC/kg at 1.0m from the source with a tube voltage of 60kV, a current of 0.40mA, and an exposure time of 1.0s. Angiography was performed with a computed radiography system using iodine-based microspheres. In coronary angiography of nonliving animals, we observed fine blood vessels of approximately 100μm with high contrasts.

High-voltage condensers in a polarity-inversion two-stage Marx surge generator are charged from -40 to -60 kV using a power supply, and the electric charges in the condensers are discharged to an X-ray tube after closing the gap switches in the surge generator using a trigger device. The X-ray tube is a demountable diode, and the turbomolecular pump evacuates air from the tube with a pressure of approximately 1 mPa. Sharp K-series characteristic X-rays of molybdenum are produced without using a monochromatic filter, since the tube utilizes a disk cathode and a rod target, and bremsstrahlung rays are not emitted in the opposite direction to that of electron acceleration. The peak tube voltage increased with increasing charging voltage and increasing space between the target and cathode electrodes. At a charging voltage of -60 kV and a target-cathode space of 1.0 mm, the peak tube voltage and current were 110 kV and 0.75 kA, respectively. The pulse width ranged from 40 to 100 ns, and the maximum dimension of the X-ray source was 3.0 mm in diameter. The number of generator-produced K photons was approximately 7×1014 photons/cm2s at 0.5 m from the source.

In the plasma flash X-ray generator, a high-voltage main condenser of approximately 200 nF is charged up to 50 kV by a power supply, and electric charges in the condenser are discharged to an X-ray tube after triggering the cathode electrode. Flash X-rays are then produced. The X-ray tube is a demountable triode connected to a turbo molecular pump with a pressure of approximately 1 mPa. As electrons from the cathode electrode are roughly focused onto a rod nickel target of 3.0 mm in diameter by the electric field in the X-ray tube, a weakly ionized linear plasma consisting of nickel ions and electrons forms by target evaporation. At a charging voltage of 50 kV, the maximum tube voltage was almost equal to the charging voltage of the main condenser, and the peak current was about 17 kA. When the charging voltage was increased, the linear plasma formed, and the intensities of K-series characteristic X-rays increased. The K-series lines were quite sharp and intense, and hardly any bremsstrahlung rays were detected. The X-ray pulse widths were approximately 700 ns, and the time-integrated X-ray intensity had a value of approximately 30 μC/kg at 1.0 m from the X-ray source at a charging voltage of 50 kV.

The development of a portable X-ray generator with a cerium-target tube and its application to angiography are described. The portable X-ray generator consists of a main controller, a unit with a Cock–Croft circuit and an X-ray tube, and a personal computer. Negative high voltages are applied to the cathode electrode in the X-ray tube, and the tube voltage and current are regulated by the controller or the computer. The X-ray tube is a glass-enclosed double-focus diode with a cerium target and a 0.5 mm-thick beryllium window. The maximum tube voltage and current were 60 kV and 0.8 mA, respectively. The focal-spot sizes were 4 mm ×4 mm (large) and 1 mm ×1 mm (small), respectively. Angiography was performed with a computed radiography system using iodine-based microspheres. The tube voltage, the current, the distance between the imaging plate and the X-ray source, and the spot size were 60 kV, 0.4 mA, 1.5 m, and small, respectively. In this angiography, we observed coronary arteries and fine blood vessels of about 50 μm or less with high contrasts.

A fundamental study on quasi-monochromatic parallel radiography using a polycapillary plate and a copper-target X-ray tube is described. The X-ray generator consists of a negative high-voltage power supply, a filament (hot cathode) power supply, and an X-ray tube. The negative high-voltage is applied to the cathode electrode, and the anode electrode is connected to the ground. In this experiment, the tube voltage was regulated from12–25 kV, and the tube current was regulated within 3.0 mA by the filament temperature. The exposure time was controlled in order to obtain optimum X-ray intensity, and the maximum focal spot dimensions were approximately 2 mm ×1.5 mm. The polycapillary plate was J5022-21 (Hamamatsu Photonics Inc.), and the plate thickness was 1.0 mm. The outer, effective, and hole diameters were 87 mm, 77 mm, and 25 μm, respectively. Quasi-monochromatic X-rays were produced using a 10 μm-thick copper filter, and these rays were formed into parallel beams by the polycapillary, and the radiogram was taken using a computed radiography system utilizing imaging plates. In the measurement of image resolution, the resolution fell according to increases in the distance between the chart and imaging plate using a polycapillary. We could observe a 50 μm tungsten wire clearly, and fine blood vessels of approximately 100 μm were visible in angiography.

The development of an extremely soft x-ray generator with a tungsten-target tube and its applications including radiography are described. This generator consists of a high-voltage transformer, a filament power supply, and an x-ray tube. Negative high voltages are applied to the cathode electrode in the x-ray tube, and the tube voltage and current are regulated by the input voltage of the transformer and the filament voltage, respectively. The x-ray tube is a glass-enclosed double-focus diode with a tungsten target and a 0.2 mm-thick beryllium window. The maximum tube voltage and the electric power were 60 kV and 400 W, respectively. The focal-spot sizes were 4×4 (large) and 1×1 mm (small), respectively. Radiography was performed with a computed radiography system. In angiography using iodine-based microspheres, we observed fine blood vessels of about 50 μm or less with high contrasts. Using this generator, we designed an experimental setup for disinfection achieved with extremely soft x rays.

In the plasma flash x-ray generator, a high-voltage main condenser of approximately 200 nF is charged up to 50 kV by a power supply, and electric charges in the condenser are discharged to an x-ray tube after triggering the cathode electrode. Flash x rays are then produced. The x-ray tube is a demountable triode connected to a turbo molecular pump with a pressure of approximately 1 mPa. As electrons from the cathode electrode are roughly focused onto a rod nickel target of 3.0 mm in diameter by the electric field in the x-ray tube, a weakly ionized linear plasma consisting of nickel ions and electrons forms by target evaporation. At a charging voltage of 50 kV, the maximum tube voltage was almost equal to the charging voltage of the main condenser, and the peak current was about 17 kA. When the charging voltage was increased, the linear plasma formed, and the intensities of K-series characteristic x rays increased. The K-series lines were quite sharp and intense, and hardly any bremsstrahlung rays were detected. The x-ray pulse widths were approximately 700 ns, and the time-integrated x-ray intensity had a value of approximately 30 μC/kg at 1.0 m from the x-ray source at a charging voltage of 50 kV.

In the plasma flash x-ray generator, a 200 nF condenser is charged up to 50 kV by a power supply, and flash x rays are produced by the discharging. The x-ray tube is a demountable triode with a trigger electrode, and the turbomolecular pump evacuates air from the tube with a pressure of approximately 1 mPa. Target evaporation leads to the formation of weakly ionized linear plasma, consisting of copper ions and electrons, around the fine target, and intense characteristic x rays are produced. At a charging voltage of 50 kV, the maximum tube voltage was almost equal to the charging voltage of the main condenser, and the peak current was about 20 kA. When the charging voltage was increased, the linear plasma formed, and the K-series characteristic x-ray intensities increased. The K lines were quite sharp and intense, and hardly any bremsstrahlung rays were detected at all. The x-ray pulse widths were approximately 700 ns, and the time-integrated x-ray intensity had a value of approximately 30 μC/kg at 1.0 m from the x-ray source with a charging voltage of 50 kV.

X-ray absorption and magnetic circular dichroism measurements were carried out around the Sm M 4 , 5 and Co L 2 , 3 edges on SmCo 3 B 2 . The valence of Sm ions in SmCo 3 B 2 is trivalent. Co-3d electrons of SmCo 3 B 2 are more localized than those of pure Co metal and SmCo 5 . The component of the orbital magnetic moment of Co-3d electrons in SmCo 3 B 2 enhances in comparison with that of pure Co metal.

Electronic structures of YCo 4 B and YCo 3 B 2 are calculated in a self-consistent linear muffin-tin orbital method and the atomic sphere approximation. The effects of B atom in these compounds are discussed, by comparing the calculated local density-of-states curves with those of YCo 5 obtained previously. A good agreement between the calculated and observed values of the low-temperature specific heat coefficient for YCo 3 B 2 is obtained. Spin-polarized band calculations are also carried out and the local spin and orbital magnetic moments are evaluated at each Co atom site in YCo 4 B. It is found that the Co moment on 6i site is small, while the Co moment on 2c site is large. On the other hand, YCo 3 B 2 is found to be non-magnetic. These results are consistent with the observed ones and can be explained by the mixing model between 3d-states of Co and 2p-states of B.

Basic properties of 3d transition-metal pnictides and chalcogenides are presented. After describing the sintering method to prepare polycrystalline sample, the crystal structures of the NiAs-, MnP-, and Cu2Sb-type structures are shown. Phase diagram of typical MX-type compound is also shown.

Detailed descriptions of magnetic and related properties for respective compounds are presented. In Sects. 3.1–3.6, properties of the compounds containing Mn or Cr, which are most interesting from both fundamental and application view points, are described in detail together with phenomenological theory to explain magnetic properties. Application of MnAs as an magnetic refrigerant is also included in these sections. Properties of the M2X-type compounds are shown in the last Sect. 3.7, where many pages are used for the antiferromagnetic–ferrimagnetic transition Cr-modified Mn2Sb.

We survey basic magnetic data such as magnetic transition temperatures, magnetic moments and magnetic orders etc. for the compounds of MX- and M2X-types. Properties of the compounds that do not have magnetic ordering are also shown.

We show theoretical results of the Cu2Sb-type compounds obtained on the basis of the itinerant electron picture. Crystal structure and magnetic ordering are shown in Sect. 2.1, band structures of the Cu2Sb-type compounds calculated by the first principle method are shown, followed by comparison between experimental and theoretical results in magnetic ordering and optical spectra.

Theoretical results on the basis of the itinerant electron picture for the NiAs- (MnP)-type compounds are shown. In Sects. 1.1 and 1.2, we show and discuss in detail the electronic band structures calculated by the first principle method for paramagnetic, ferromagnetic, or antiferromagnetic states of the 3d-pnictides and chalcogenides. In the following Sects. 1.3–1.7, we theoretically investigate various phenomena such as anomalous behavior of paramagnetic susceptibility, de-Haas-van Alfen effect, occurrence of double-helical magnetic ordering, and structural transformation from the NiAs- to the MnP-type structures on the basis of the calculated band structures.

In order to investigate the crystalline electric field at R (R=rare earth) site and the induced magnetic moment at Co site in RCo3B2 compounds, high field magnetization process up to 15 T and paramagnetic susceptibility have been measured at various temperatures. It is found by analysis of the experimental data that (1) the crystal field parameter A20 is very large (∼−2000Ka0−2) and (2) significant magnetic moment (0.15–0.93μB) is induced at the Co site, in RCo3B2 compounds.

Thermal expansions of the lattice parameters a and c of the system in the title have been measured by x-ray diffraction technique to investigate the nature of magnetic interactions as well as chemical bond in these systems. Our data reveals that a spontaneous magnetostriction caused by the Co–Co intrasublattice interaction in YCo4B (n=1) occurs in the c plane unlike YCo5 whose magnetostriction occurs only along the c axis. It is also found that the positive spontaneous magnetostriction of GdCo4B in the c plane can be divided into three contributions due to the Co–Co, Co–Gd, and Gd–Gd interactions in the crystal. Thermal expansion coefficients in the c plane in the paramagnetic temperature region strongly decrease with increasing n in the Gd system. This implies a significant covalent bonding in the R–B layer in the present compounds. These results are discussed on the basis of the results of energy band calculation together with the previous magnetic data.

In the plasma flash x-ray generator, a 200 nF condenser is charged up to 50 kV by a power supply, and flash x-rays are produced by the discharging. The x-ray tube is a demountable triode with a brass target containing 65% copper and 35% zinc by weight, and the turbomolecular pump evacuates air from the tube with a pressure of approximately 1 mPa. Target evaporation leads to the formation of weakly ionized linear plasma, consisting of metal ions and electrons, around the fine target, and intense characteristic x-rays are produced. At a charging voltage of 50 kV, the maximum tube voltage was almost equal to the charging voltage of the main condenser, and the peak current was about 15 kA. When the charging voltage was increased, the linear plasma formed, and the K-series characteristic x-ray intensities of zinc Kα, copper Kα, and copper Kβ lines increased substantially. However hardly any zinc Kβ lines were detected. The x-ray pulse widths were approximately 700 ns, and the time-integrated x-ray intensity was approximately 1.2 mGy at 1.0 m from the x-ray source with a charging voltage of 50 kV.

In the plasma flash x-ray generator, a 200 nF condenser is charged up to 50 kV by a power supply, and flash x-rays are produced by the discharging. The x-ray tube is a demountable triode with a trigger electrode, and the turbomolecular pump evacuates air from the tube with a pressure of approximately 1 mPa. Target evaporation leads to the formation of weakly ionized linear plasma, consisting of copper ions and electrons, around the fine target, and intense Kα lines are left using a 10-μm-thick nickel filter. At a charging voltage of 50 kV, the maximum tube voltage was almost equal to the charging voltage of the main condenser, and the peak current was about 16 kA. The K-series characteristic x-rays were clean and intense, and higher harmonic x-rays were observed. The x-ray pulse widths were approximately 300 ns, and the time-integrated x-ray intensity had a value of approximately 1.5 mGy per pulse at 1.0 m from the x-ray source with a charging voltage of 50 kV.

A microfocus x-ray tube is useful in order to perform magnification digital radiography including phase-contrast effect. The 100-μm-focus x-ray generator consists of a main controller for regulating the tube voltage and current and a tube unit with a high-voltage circuit and a fixed anode x-ray tube. The maximum tube voltage, current, and electric power were 105 kV, 0.5 mA, and 50 W, respectively. Using a 3-mm-thick aluminum filter, the x-ray intensity was 26.0 μGy/s at 1.0 m from the source with a tube voltage of 60 kV and a current of 0.50 mA. Because the peak photon energy was approximately 38 keV using the filter with a tube voltage of 60 kV, the bremsstrahlung x-rays were absorbed effectively by iodine-based contrast media with an iodine K-edge of 33.2 keV. Magnification angiography including phase-contrast effect was performed by three-time magnification imaging with a computed radiography system using iodine-based microspheres 15 μm in diameter. In angiography of non-living animals, we observed fine blood vessels of approximately 100 μm with high contrasts.

The tungsten plasma flash x-ray generator is useful in order to perform high-speed enhanced K-edge angiography using cone beams because Kα rays from the tungsten target are absorbed effectively by gadolinium-based contrast media. In the flash x-ray generator, a 150 nF condenser is charged up to 80 kV by a power supply, and flash x-rays are produced by the discharging. The x-ray tube is a demountable diode, and the turbomolecular pump evacuates air from the tube with a pressure of approximately 1 mPa. Since the electric circuit of the high-voltage pulse generator employs a cable transmission line, the high-voltage pulse generator produces twice the potential of the condenser charging voltage. At a charging voltage of 80 kV, the estimated maximum tube voltage and current were approximately 160 kV and 40 kA, respectively. When the charging voltage was increased, the characteristic x-ray intensities of tungsten Kα lines increased. Using an ytterbium oxide filter, the Kα lines were clean, and hardly any Kβ lines and bremsstrahlung rays were detected. The x-ray pulse widths were approximately 60 ns, and the time-integrated x-ray intensity had a value of approximately 50 μGy at 1.0 m from the x-ray source with a charging voltage of 80 kV. Angiography was performed using a film-less computed radiography system and gadolinium-based contrast media. In angiography of non-living animals, we observed fine blood vessels of approximately 100 μm with high contrasts.

Energy-selective high-speed radiography utilizing a kilohertz-range stroboscopic x-ray generator and its application to high-speed angiography are described. This generator consists of the following major components: a main controller, a condenser unit with a Cockcroft-Walton circuit, and an x-ray tube unit in conjunction with a grid controller. The main condenser of about 500 nF in the unit is charged up to 120 kV by the circuit, and the electric charges in the condenser are discharged to the triode by the grid control circuit. Although the tube voltage decreased during the discharging for generating x-rays, the maximum value was equal to the initial charging voltage of the main condenser. The maximum tube current and the repetition rate were approximately 0.5 A and 50 kHz, respectively. The x-ray pulse width ranged from 0.01 to 1.0 ms, and the maximum shot number had a value of 32. At a charging voltage of 100 kV and a width of 1.0 ms, the x-ray intensity obtained using a 50-μm-thick tungsten filter was 9.88 μGy at 1.0 m, and the dimensions of the focal spot had values of approximately 1×1 mm. Angiography was performed using the filter at a charging voltage of 100 kV.

This generator consists of the following components: a constant high-voltage power supply, a filament power supply, a turbomolecular pump, and an x-ray tube. The x-ray tube is a demountable diode which is connected to the turbomolecular pump and consists of the following major devices: a molybdenum rod target, a tungsten hairpin cathode (filament), a focusing (Wehnelt) electrode, a polyethylene terephthalate x-ray window 0.25 mm in thickness, and a stainless-steel tube body. In the x-ray tube, the positive high voltage is applied to the anode (target) electrode, and the cathode is connected to the tube body (ground potential). In this experiment, the tube voltage applied was from 22 to 36 kV, and the tube current was regulated to within 100 μA by the filament temperature. The exposure time is controlled in order to obtain optimum x-ray intensity. The electron beams from the cathode are converged to the target by the focusing electrode, and clean Kα rays are produced through the focusing electrode using a 20-μm-thick zirconium filter. The x-ray intensity was 12.1 μGy/s at 1.0 m from the x-ray source with a tube voltage of 30 kV and a tube current of 100 μA, and monochromatic radiography was performed using a computed radiography system.

In the plasma flash x-ray generator, a 200 nF condenser is charged up to 50 kV by a power supply, and flash x rays are produced by the discharging. The x-ray tube is a demountable triode with a trigger electrode, and the turbomolecular pump evacuates air from the tube with a pressure of approximately 1 mPa. Target evaporation leads to the formation of weakly ionized linear plasma, consisting of molybdenum ions and electrons, around the fine target, and intense characteristic x rays are produced. At a charging voltage of 50 kV, the maximum tube voltage was almost equal to the charging voltage of the main condenser, and the peak current was about 16 kA. When the charging voltage was increased, the linear plasma formed, and the K-series characteristic x-ray intensities increased. The K lines were quite sharp and intense. The x-ray pulse widths were approximately 600 ns, and the time-integrated x-ray intensity had a value of approximately 65 μC/kg at 1.0 m from the x-ray source with a charging voltage of 50 kV.

In the flash x-ray generator, a 150 nF condenser is charged up to 80 kV by a power supply, and flash x rays are produced by the discharging. The x-ray tube is a demountable diode, and the turbomolecular pump evacuates air from the tube with a pressure of approximately 1 mPa. Since the electric circuit of the high-voltage pulse generator employs a cable transmission line, the high-voltage pulse generator produces twice the potential of the condenser charging voltage. At a charging voltage of 80 kV, the estimated maximum tube voltage and current were approximately 160 kV and 40 kA, respectively. When the charging voltage was increased, the K-series characteristic x-ray intensities of molybdenum increased. The K lines were clean and intense, and hardly any bremsstrahlung rays were detected at all. The x-ray pulse widths were approximately 100 ns, and the time-integrated x-ray intensity had a value of approximately 15 μC/kg at 1.0 m from the x-ray source with a charging voltage of 80 kV.

The high-voltage condensers in a polarity-inversion two-stage Marx surge generator are charged from Š 50 to Š 70 kV by a power supply, and the electric charges in the condensers are discharged to an x-ray tube after closing gap switches in the surge generator with a trigger device. The x-ray tube is a demountable diode, and the turbomolecular pump evacuates air from the tube with a pressure of approximately 1 mPa. Tungsten characteristic x rays can be produced, since the tube utilizes a disk cathode and a rod target, and bremsstrahlung rays are not emitted in the opposite direction to that of electron acceleration. At a charging voltage of Š 70 kV, the instantaneous tube voltage and current were 140 kV and 1.0 kA, respectively. The x-ray pulse widths were approximately 90 ns, and the estimated number of K photons was approximately 5 210 8 photons/cm per pulse at 0.5 m from the source of 3.0 mm in diameter. Keywords: angiography, gadolinium-based contrast media, characteristic x rays, quasi-monochromatic x rays, tungsten K lines

The cerium target plasma flash x-ray generator is useful in order to perform high-speed enhanced K-edge angiography using cone beams because K-series characteristic x rays from the cerium target are absorbed effectively by iodine-based contrast mediums. In the flash x-ray generator, a 150 nF condenser is charged up to 80 kV by a power supply, and flash x rays are produced by the discharging. The x-ray tube is a demountable diode, and the turbomolecular pump evacuates air from the tube with a pressure of approximately 1 mPa. Since the electric circuit of the high-voltage pulse generator employs a cable transmission line, the high-voltage pulse generator produces twice the potential of the condenser charging voltage. At a charging voltage of 80 kV, the estimated maximum tube voltage and current were approximately 160 kV and 40 kA, respectively. When the charging voltage was increased, the K-series characteristic x-ray intensities of cerium increased. The K lines were clean and intense, and hardly any bremsstrahlung rays were detected at all. The x-ray pulse widths were approximately 100 ns, and the time-integrated x-ray intensity had a value of approximately 10 μC/kg at 1.0 m from the x-ray source with a charging voltage of 80 kV. In the angiography, we employed a film-less computed radiography (CR) system and iodine-based microspheres.

High-voltage condensers in a polarity-inversion two-stage Marx surge generator are charged from -50 to -70 kV using a power supply, and the electric charges in the condensers are discharged to an x-ray tube after closing the gap switches in the surge generator using a trigger device. The x-ray tube is a demountable diode, and the turbomolecular pump evacuates air from the tube with a pressure of approximately 1 mPa. Clean copper Kα lines are produced using a 10-μm-thick nickel filter, since the tube utilizes a disk cathode and a rod target, and bremsstrahlung rays are not emitted in the opposite direction to that of electron acceleration. The peak tube voltage increased with increasing charging voltage. At a charging voltage of -70 kV, the peak tube voltage and current were 140 kV and 0.8 kA, respectively. The pulse widths were approximately 30 ns, and the maximum dimension of the x-ray source was 3.0 mm in diameter. The number of generator-produced Kα photons was approximately 2.5x106 photons/cm2 at 0.5 m per pulse.

Energy-selective high-speed radiography utilizing a kilohertz-range stroboscopic x-ray generator and its application to high-speed angiography are described. This generator consists of the following major components: a main controller, a condenser unit with a Cockcroft-Walton circuit, and an x-ray tube unit in conjunction with a grid controller. The main condenser of about 500 nF in the unit is charged up to 100 kV by the circuit, and the electric charges in the condenser are discharged to the triode by the grid control circuit. Although the tube voltage decreased during the discharging for generating x rays, the maximum value was equal to the initial charging voltage of the main condenser. The maximum tube current and the repetition rate were approximately 0.5 A and 32 kHz, respectively. The x-ray pulse width ranged from 0.01 to 1.0 ms, and the maximum shot number had a value of 32. At a charging voltage of 80 kV and a width of 1.0 ms, the x-ray intensities obtained without filtering, using an aluminum filter, and using a barium sulfate filter were 14.8, 5.48 and 5.05 μGy per pulse, respectively, at 1.0 m, and the dimensions of the focal spot had values of 3.5×3.5 mm. Angiography was performed using both the aluminum and the barium sulfate filters at a charging voltage of 60 kV.

In the plasma flash x-ray generator, a 200 nF condenser is charged up to 50 kV by a power supply, and flash x rays are produced by the discharging. The x-ray tube is a demountable triode with a double target consisting of a copper and a molybdenum rods, and the turbomolecular pump evacuates air from the tube with a pressure of approximately 1 mPa. Target evaporation leads to the formation of weakly ionized linear plasma, consisting of metal ions and electrons, around the fine target, and intense characteristic x rays are produced. At a charging voltage of 50 kV, the maximum tube voltage was almost equal to the charging voltage of the main condenser, and the peak current was about 11 kA. When the charging voltage was increased, the linear plasma formed, and the molybdenum K-series characteristic x-ray intensities increased substantially. Although the intensities of copper Kα lines increased with increases in the charging voltage, hardly any clean Kα lines were detected. The x-ray pulse widths were approximately 1.2 μs, and the time-integrated x-ray intensity was approximately 30 μC/kg at 1.0 m from the x-ray source with a charging voltage of 50 kV.

The fundamental experiments for measuring soft x-ray characteristics from the vacuum capillary are described. These experiments are primarily performed in order to generate intense soft x rays. The generator consists of a high-voltage power supply, a polarity-inversion ignitron pulse generator, a turbomolecular pump, and a radiation tube with a capillary. A high-voltage condenser of 200 nF in the pulse generator is charged up to 20 kV by the power supply, and the electric charges in the condenser are discharged to the capillary in the tube after closing the ignitron. During the discharge, weakly ionized plasma forms on the inner and outer sides of a capillary. In the present work, the pump evacuates air from the tube with a pressure of about 1 mPa, and a demountable capillary was developed in order to measure x-ray spectra according to changes in the capillary length. In this capillary, the anode (target) and cathode elements can be changed corresponding to the objectives. The capillary diameter is 2.0 mm, and the length is adjusted from 1 to 50 mm. When a capillary with aluminum anode and cathode electrodes was employed, both the cathode voltage and the discharge current almost displayed damped oscillations. The peak values of the voltage and current increased when the charging voltage was increased, and their maximum values were -11.5 kV and 4.7 kA, respectively. The x-ray durations observed by a 1.6 μm aluminum filter were less than 30 μs. In the spectrum measurement, we observed orderly multi-line spectra. The line photon energies seldom varied according to changes in the condenser charging voltage and to changes in the electrode element. The line number decreased with corresponding decreases in the capillary length.

The high-voltage condensers in a polarity-inversion two-stage Marx surge generator are charged from -50 to -70 kV by a power supply, and the electric charges in the condensers are discharged to an x-ray tube after closing gap switches in the surge generator with a trigger device. The x-ray tube is a demountable diode, and the turbo molecular pump evacuates air from the tube with a pressure of approximately 1 mPa. Clean molybdenum Kalpha lines are produced using a 20 microm-thick zirconium filter, since the tube utilizes a disk cathode and a rod target, and bremsstrahlung rays are not emitted in the opposite direction to that of electron acceleration. At a charging voltage of -70 kV, the instantaneous tube voltage and current were 120 kV and 1.0 kA, respectively. The x-ray pulse widths were approximately 70 ns, and the generator produced instantaneous number of Kalpha photons was approximately 3 x 10(7) photons/cm2 per pulse at 0.5 m from the source of 3.0 mm in diameter.

The cerium target x-ray generator is useful in order to perform enhanced K-edge angiography using a cone beam because K-series characteristic x rays from the cerium target are absorbed effectively by iodine-based contrast mediums. The x-ray generator consists of a main controller, a unit with a Cockcroft-Walton circuit and a fixed anode x-ray tube, and a personal computer. The tube is a glass-enclosed diode with a cerium target and a 0.5-mm-thick beryllium window. The maximum tube voltage and current were 65 kV and 0.4 mA, respectively, and the focal-spot sizes were 1.0 x 1.3 mm. Cerium Kalpha lines were left using a barium sulfate filter, and the x-ray intensity was 0.48 microC/kg at 1.0 m from the source with a tube voltage of 60 kV, a current of 0.40 mA, and an exposure time of 1.0 s. Angiography was performed with a computed radiography system using iodine-based microspheres. In coronary angiography of nonliving animals, we observed fine blood vessels of approximately 100 microm with high contrasts.

The high-voltage condensers in a polarity-inversion two-stage Marx surge generator are charged from -50 to -70 kV by a power supply, and the electric charges in the condensers are discharged to an x-ray tube after closing gap switches in the surge generator with a trigger device. The x-ray tube is a demountable diode, and the turbomolecular pump evacuates air from the tube with a pressure of approximately 1 mPa. Clean silver Kα lines are produced using a 30 μm-thick palladium filter, since the tube utilizes a disk cathode and a rod target, and bremsstrahlung rays are not emitted in the opposite direction to that of electron acceleration. At a charging voltage of -70 kV, the instantaneous tube voltage and current were 90 kV and 0.8 kA, respectively. The x-ray pulse widths were approximately 80 ns, and the instantaneous number of generator-produced Kα photons was approximately 40 M photons/cm 2 per pulse at 0.3 m from the source of 3.0 mm in diameter.

The development of an extremely soft x-ray generator with a tungsten-target tube and its applications to radiography and disinfection are described. This generator consists of a high-voltage power supply, a filament power supply, and an x-ray tube. Negative high voltages are applied to the cathode electrode in the x-ray tube, and the tube voltage and current are regulated by the input of a transformer and the filament voltage, respectively. The x-ray tube is a glass-enclosed double-focus diode with a tungsten target and a 0.2 mm-thick beryllium window. The maximum tube voltage and electric power were 60 kV and 400 W, respectively. The focal-spot sizes were 4×4 (large) and 1×1 mm (small), respectively. Extremely soft radiography was performed with a computed radiography system, and we observed fine blood vessels of about 100 μm with high contrasts. Using this generator, we performed the disinfection achieved with extremely soft x rays.

The cerium-target x-ray tube is useful in order to perform cone beam K-edge angiography because K-series characteristic x rays from the cerium target are absorbed effectively by iodine-based contrast mediums. The x-ray generator consists of a main controller and a unit with a high-voltage circuit and a fixed anode x-ray tube. The tube is a glass-enclosed diode with a cerium target and a 0.5 mm-thick beryllium window. The maximum tube voltage and current were 65 kV and 0.4 mA, respectively, and the focal-spot sizes were 1.3×0.9 mm. Cerium K-series characteristic x rays were left using a 3.0 mm-thick aluminum filter, and the x-ray intensity was 0.59 μC/kg at 1.0 m from the source with a tube voltage of 60 kV, a current of 0.40 mA, and an exposure time of 1.0 s. Angiography was performed with a computed radiography system using iodine-based microspheres 15 μm in diameter. In angiography of non-living animals, we observed fine blood vessels of approximately 100 μm with high contrasts.