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A fine-focusing x-ray source has been constructed employing a field electron emitter prepared by growing carbon-nanofibers (CNFs) on a metal tip. The x-ray source is composed of a CNF field electron emitter, an electrostatic lens, two magnetic lenses, and a W-target for generating x-rays by electron impact. The CNFs provided field electrons with a current density of J∼5×109 A/m2, which was evaluated with the aid of Fowler–Nordheim theory. The electron beam extracted from the CNF emitter was accelerated to the energies of E=10–25 keV, and then focused by the lenses. By recording the x-ray images of test charts, the optimum resolution of the x-ray source was estimated to be approximately Dx=0.5 μm. [ABSTRACT FROM AUTHOR]

An x-ray irradiation system of field-emission type has been constructed using carbon-nanofibers (CNFs) grown on a palladium wire that is 50 μm in diameter. The electron current emitted from the CNFs was approximately 1 mA and was stable within 10% for a long time t>5000 h. The electrons passing through a slit in the gate electrode were accelerated to the desired energy, and were made to impinge on the metal target (Ti, Cu, Mo, and W) for generating x rays. The x-rays transmitted through Be-window were characterized using energy analyzers and a dosimeter. At an acceleration voltage of Va=50 kV, the energy spectra of the x-rays were exclusively composed of characteristic signals except for the Mo-target, and the dose rates of x-rays were D=2.5–14 Gy/min, depending on the target metals. This system also provides sharp x-ray images of both biological and nonbiological materials. [ABSTRACT FROM AUTHOR]

Presents a study which investigated the noise properties of Josephson harmonic mixers. Functionality of Josephson harmonic mixers; Circuit diagram for the simulation study of Josephson mixer noise; Electric current conversion coefficients for biased and unbiased mixing operations.