Surface modification of field emission cathodes made of artificial carbon-based material

While the field emission acts at the technical vacuum level conditions (10-5 Pa) and electrons emitted from cathode, the ion bombardment exists and continuously modifies the cathode surface. Using X-ray photoelectron spectroscopy (XPS) we studied the electronic structure of thin surface layer of artificial carbon-based materials (ACB) used as field emission cathodes (FEC). The research resulted in the spectra of the samples B-1300, B-1500, B-1900. After spectra processing features analysis shows the change in type of hybridization of the original material. This change is supported by three characteristic spectral features: asymmetry of the core levels spectrum lines change, the satellite structure transformation, Auger-line and modification. So the initial material had sp2 type of hybridization, the spectra show that in thin surface layer a new phase with sp3-hybridization exists and we can conclude formation of nanoclusters with diamond-phase in thin surface layer of cathode. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Research of luminophores afterglow under influence of pulsed X-ray radiation of nanosecond duration

The work describes an investigation of afterglow of various luminophores under influence of pulsed X-ray radiation of nanosecond duration. As a source of radiation a pulsed X-ray "Yasen 01" apparatus is applied. Maximum impulse current of an X-ray tube is 300 A. Maximum electron energy is 120 keV. Half-height pulse duration of an X-ray burst is about 30 ns. A pulse repetition rate is up to 4 kHz. Two types of X-ray luminophores based on gadolinium oxysulfide Gd 2 O 2 S:Tb and cesium iodide CsI:Tl have been investigated. The novelty of the work is use of a fast-acting solid-state semiconductor photomultiplier. It allows recording changes of luminophores luminosity in the nanosecond time range. The photomultiplier is characterized by having two discreet outputs for measuring quickly and slowly time-changing light flows. Presence of two signal outputs allows recording changes of luminophores luminosity both during fast nanosecond excitation and during long-time afterglow. Obtained data about the nature of afterglow of investigated luminophores makes it possible to select the best one for use in conjunction with a pulsed X-ray apparatus with a high pulse repetition rate. © Published under licence by IOP Publishing Ltd

Fabrication and characterization of 1, 5, 10 at.% Ce:Y2O3 nanopowders

Nanopowders (particle size of about 7-14 nm) of yttrium oxide doped with cerium ions with concentrations of 1, 5, 10 at.% have been synthesized by laser ablation of the target. For the first time in the world the cerium concentration of 10 at.% in the yttrium oxide lattice has been obtained. Their morphology, structure, and scintillation properties have been investigated. No significant cathodoluminescence of the activator in the Ce3+ state has been detected in the powders, and X-ray luminescence was completely absent. Presumably, the cerium ion is in the nonradiative state of Ce4+. © Published under licence by IOP Publishing Ltd.Russian Foundation for Basic Research, RFBR: 19-08-00117The reported study was funded by RFBR, project number 19-08-00117. The authors gratefully acknowledge E.V. Tihonov and Dr. A.I. Medvedev from Institute of Electrophysics UrB RAS for laser synthesis of nanopowders and XRD analysis, respectively

4-kW multi-phase battery powered power supply

A method was developed for building the powerful battery power supplies. Using the method, the battery power supply with a 4 kW max power and up to 93% efficiency was developed to supply the "Yasen" X-ray apparatus. Two 60 Acenterdoth series-connected starter lead-acid batteries were used as a primary power supply. A DC output voltage of the source is stable over the entire power range and equals to 310 V. The power supply is based on a 5-phase HF-inverter. There is no difficulty in designing such power supplies with different power outputs. It can be done by the increasing or the decreasing number of phases (of inverter channels). This approach is not limited by the increased number of the inverter channels. The maximum output power will be determined by the battery characteristics only. The power supply is mounted on a mobile trolley, to increase the mobility of the entire set of equipment. The unit dimensions are 410•320•440, the weight is about 40 kg. The unit is forced air-cooled. A power operating mode is short and periodic

XPS studies on surfaces of field-emission cathodes of artificial carbon materials

The electronic structure of the surface layer of artificial carbon-based materials operated as field emission cathodes was studied using x-ray photoelectron spectroscopy. Samples B-1300, B-1500, and B-1900 were investigated. An analysis of the spectra showed an alteration of the hybridization of atoms in the original material, which suggested the formation of diamond-like inclusions on the sample surface. © 2013 Springer Science+Business Media New York

Application of Carbon Materials for Creation of X-ray Sources Cathodes

This research is devoted to investigating the properties of X-ray tube models with massive carbon cathode: field emission cathode in DC-mode and pulsed explosive emission cathodes. Construction of device with field emission cathode is described. It is able to operate at non-ultrahigh vacuum conditions. Two types of ring explosive emission cathodes were examined: metal-ceramic with slits (of a comb-shaped kind) and carbon-ceramic. The installation which makes it possible to investigate demountable models of pulsed X-ray tubes was designed. Experiments show better performance of carbon pulse cathode. It generates greater dose rate, possesses shorter current pulse, longer lifetime. Developed devices can be used in medicine, flaw detection, scientific researches and security systems. © 2016 The Authors.The reported study was supported by RFBR, research project No. 14-08-31243 мол_a and has been supported b

COMPOSITION AND METHOD FOR SYNTHESIS OF SCINTHILLATION CERAMICS BASED ON NANOPOWDER

FIELD: chemistry. SUBSTANCE: group of inventions relates to the field of scintillation technology used to register ionizing radiation. Disclosed is the composition of scintillation ceramics based on yttrium alumina garnet doped with cerium ions (Ce3+:Y3Al5O12) made of a mixture of nanopowders of yttrium oxide doped with cerium ions (Ce:Y2O3), aluminum oxide (Al2O3), and yttrium oxide (Y2O3). Yttrium oxide is added to maintain stoichiometry, if necessary. The composition contains a sintering additive. Zirconium (Zr) is used as a sintering additive in the form of zirconium oxide ZrO2 with the content of 0.05-0.15 wt.%. EFFECT: increased speed of the ceramic scintillator without reducing the glow intensity. 2 cl, 2 dwg, 1 tbl.Группа изобретений относится к области сцинтилляционной техники, применяемой для регистрации ионизирующих излучений. Состав сцинтилляционной керамики на основе алюмоиттриевого граната, активированного ионами церия (Ce3+:Y3Al5O12), изготовленной из смеси нанопорошков оксида иттрия, допированного ионами церия (Ce:Y2O3), оксида алюминия (Al2O3) и оксида иттрия (Y2O3), при необходимости добавления последнего с целью сохранения стехиометрии, и содержащей спекающую добавку, при этом в качестве спекающей добавки содержит цирконий (Zr) в виде оксида циркония ZrO2 с содержанием 0,05-0,15 мас.%. Технический результат – повышение быстродействия керамического сцинтиллятора без снижения интенсивности свечения. 2 н.п. ф-лы, 1 табл., 2 ил