Materials Literature
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Electron guns for RF sources typically use barium dispenser cathodes to produce electron emission. Barium diffuses to the emission surface whenever the cathode is hot to replace that lost by evaporation. The barium forms barium oxide to reduce the surface work function. Barium that evaporates from the surface is depos…
This study demonstrated designs of non polarizing AR coatings at high incidence angles for visible region. Results appear new design stacks of non-polarizing AR coatings with optimal specifications such as low reflectance for the performance of both S-and P-polarizations and limit the separation of the two planes of p…
Thin films of Se 85 Ge 15-x Bi x Chalcogenide glasses (where x -0, 5, 10, and 15 at. %) were prepared by thermal evaporation technique. All samples were amorphous as checked by x-ray diffraction. The samples of as-deposited Se 85 Ge 15 and Se 80 Ge 10 Bi 5 thin films, as illustrative examples, were investigated using…
Thin amorphous films of (Ge4Sb4Te6) have been widely employed in the technology. It has been prepared on glass substrates by a thermal evaporation technique. The target materials used for the films deposition were prepared by conventional solid state reaction in a vacuum sealed silica tube to avoid oxide formation. Th…
High quantum efficiency, long-life photocathodes are required for the next generation of accelerators, light sources, and ultra-fast electron microscopes. This requirement is being addressed by depositing high QE materials on Controlled Porosity Reservoir (CPR) cathodes. A production facility is now on line to produce…
We report on high-brightness, thermal-field emission cathodes using (210) and (110) oriented hafnium carbide. HfC(210) cathodes are shown to deliver very high angular intensities to >50 mA/sr and remain stable. Modeling and experimental data are shown which highlights the utility of these sources for SEM and other hig…
Radioactivity is a part of our environment. Natural radionuclides in soil generate a significant component of the background radiation exposure to the population. Radiation becomes a concern when these particles and energy come in contact with molecules inside the human body. This paper evaluates the radioactivity con…
Tungstate cathodes have been prepared by impregnating a mixture of the barium-strontium tungstate and zirconium hydride at 1840 °Cb. Emission characteristics and evaporation properties were tested. The result shows that the dc emission current density reaches 4.30A/cm2at 1000 °Cb, 7.54A/cm2at 1050 °Cb, 9.43A/cm2at 110…
This paper presents our on-going work on the development of an output system for a THz gyro-multiplier. The beam-wave interaction and frequency multiplication in the gyro-multiplier generate two high-order modes at two distinguished frequencies. To convert the high-order waveguide modes into quasi-Gaussian beams and s…
Binary rare-earth lanthanum hexaborides LaB6 and CeB6 have been successfully used in specialty electron guns, such as e-beam lithography systems, for over two decades. During this time, there were a few papers suggesting ternary compound crystal ReB6 may be a better emitter than binary crystals. We have started studyi…
A method of screen printing carbon nanotubes (CNTs) in a dielectric binder to produce low-cost, large area field emission electron sources is presented. Imaging under the scanning electron microscope (SEM) shows the nanotubes forming dense clusters on the substrate surface with protruding CNTs in random orientations.…
Geometrical and mathematical proportions play a fundamental role in art and architecture. Persian architecture has been always closely related to geometry. This is easily visible in decorations and patterns of surfaces. Persian architects made utmost effort to apply construction materials as economically as possible.…
We have presented a detailed investigation of hybrid photodiode based on the combination of Gr/Si heterojunction and nanoscale vacuum device based on graphene-SiO2-Si (GrOS) field effect structure. We elucidate on the underlying mechanism of impact-ionization process in a two-Dimensional Electron Gas (2DEG) confined i…
در چند دهه گذشته علاقمندی به پژوهش و استفاده از نانوفیبر سلولزی به طور چشمگیری افزایش یافته است. بنابراین اصلاح سطح نانوفیبر سلولزی به صورت شیمیایی می تواند با ایجاد ویژگی جدید و یا بهبود ویژگی های آنبا حفظ ویژگی های ذاتی نانوفیبر کاربردهای جدیدی را برای آن معرفی کند. در این پژوهش به منظور افزایش پایداری گرمایی ن…
Paduan aluminium banyak digunakan sebagai rumah pompa sentrifugal karena memiliki keunggulan yaitu ringan sehingga mudah dipindahkan dan dipasang, sifat mekanik yang baik dan memiliki lapisan passif sehingga tahan korosi [2]. Dari segi harga, paduan aluminium lebih efisien dibandingkan stainless steel. Untuk memilih p…
Abstract Objective: Mycobacterium tuberculosis (MTB) is an obligate aerobe bacterial pathogen. Here, the citrate synthase (CS) family, an important component of aerobic respiration, was investigated in MTB. Methods: MTB genome was analyzed in silico to reveal the members of CS family. The nucleotide and amino acid seq…
When constructing large-span metal domes different methods of installation are used, which depend on geometry schemes of the frames and their construction solution. The frames of such domes consist of a lot of structures. During assembling large number of structures with different spatial orientation are joined togeth…
The optical layout of an objective with relative aperture 1∶1 and two viewing fields, based on a six-lens arrangement that contains no aspheric lenses, is considered in this article. This is used in thermal viewers based on microbolometric photodetector arrays. The design parameters of the optical layout and the calcu…
Tujuan utama dari optimasi desain ini adalah untuk meningkatkan kualitas dari mesin bubut yang akan dibuat BMEPPO-BBPT. Dengan tetap menggunakan material Gray cast iron (FC25) serta menekan jumlah material yang di butuhkan dalam pembuatan bed bubut tersebut tetapi menghasilkan bentuk desain Slant Bed bubut CNC yang op…
Carbon fibre reinforced silicon carbide (C/SiC) brake materials are new highly competitive brake materials. They possess a series of outstanding advantages such as high strength, low density, good high temperature resistance, excellent friction properties, low wear rate and long life. Up to now, it has been equipped i…