Частотные характеристики полосковых модулей формирования квазихаотических сигналов на основе объемных нелинейно- оптических кристаллов

In this paper the experimental study of frequency dependences of scattering matrix coefficients of strip modules based on a coplanar strip line with partial dielectric filling in the form of bulk non-linear optical crystals of quartz, potassium titanium phosphate (KTP), zinc germanium diphosphide, lithium niobate has been performed. The appearance of the effect of forming quasi- chaotic oscillations in modules containing KTiOPO4, ZnGeP2, LiNbO3 bulk crystals when LFM signals are fed at fast switching of incident wave direction in the receiving and transmitting tract of the vector network analyzer is demonstrared. Parameters of comparative characterization of crystal materials are introduced. The complete phase of the modulus transmission coefficient is determined.  The analysis of its physical sense is made, followed by processing complete phase shift, which provides the possibility to develop the algorithm of estimating the frequency dependence of crystal’s relative permittivity. The studied modules may be used as formers of quasi- chaotic microwave signals. Arutyunyan A. A., Malyutin N. D., Malyutin G. A., Podzyvalov S. N., Yudin N. N. Frequency characteristics of strip modules of the quasi- chaotic signals formation based on bulk nonlinear optical crystals. Ural Radio Engineering Journal. 2023;7(3):227–249. (In Russ.) DOI: 10.15826/urej.2023.7.3.001В работе проведено экспериментальное исследование частотных зависимостей коэффициентов матрицы рассеяния полосковых модулей на основе копланарной полосковой линии с частичным диэлектрическим заполнением в виде объемных нелинейно-оптических кристаллов кварца SiO2, титанил-фосфата калия KTiOPO4 (KTP), дифосфида цинка германия ZnGeP2, ниобата лития LiNbO3. Показано возникновение эффекта формирования квазихаотических колебаний в модулях, содержащих объемные кристаллы KTiOPO4, ZnGeP2, LiNbO3 при подаче на вход ЛЧМ-сигналов с быстрым переключением направления падающей волны в тракте приема-передачи векторного анализатора цепей. Введены параметры для сравнительной характеристики материалов кристаллов. Определена полная (развернутая) фаза коэффициента передачи модулей. Проведены анализ ее физического смысла и обработка полной фазы, позволившая построить алгоритм оценки частотной зависимости относительной диэлектрической проницаемости кристаллов. Исследованные модули могут выполнять функцию формирователей квазихаотических сигналов СВЧ. Арутюнян А. А., Малютин Н. Д., Малютин Г. А., Подзывалов С. Н., Юдин Н. Н. Частотные характеристики полосковых модулей формирования квазихаотических сигналов на основе объемных нелинейно- оптических кристаллов. Ural Radio Engineering Journal. 2023;7(3):227– 249. DOI: 10.15826/urej.2023.7.3.001

GEOMETRIC MEANING OF THE INTERPOLATION CONDITIONS IN THE CLASS OF FUNCTIONS OF FINITE ORDER IN THE HALF-PLANE

The aim of this paper is to study the interpolation problem in the spaces of analytical functions of finite order ρ > 1 in the half-plane. The necessary and sufficient conditions for its solvability are found in terms of the measure defined by the nodes of interpolation

THE INTERPOLATION PROBLEM IN THE SPACES OF ANALYTICAL FUNCTIONS OF FINITE ORDER IN THE HALF-PLANE

The aim of this paper is to study the interpolation problem in the spaces of analytical functions of finite order ρ > 1 in the half-plane. The necessary and sufficient conditions for its solvability in terms of the canonical Nevanlinna product of nodes of interpolation are obtained. The solution of the interpolation problem is constructed in the form of the Jones interpolation series, which is a generalization of the Lagrange interpolation series

Studies on charge production from Cs2Te photocathodes in the PITZ L-band normal conducting radio frequency photo injector

This paper discusses the behavior of electron bunch charge produced in an L-band normal conducting radio frequency cavity (RF gun) from Cs2Te photocathodes illuminated with ps-long UV laser pulses when the laser transverse distribution consists of a flat-top core with Gaussian-like decaying halo. The produced charge shows a linear dependence at low laser pulse energies as expected in the quantum efficiency limited emission regime, while its dependence on laser pulse energy is observed to be much weaker for higher values, due to space charge limited emission. However, direct plug-in of experimental parameters into the space charge tracking code ASTRA yields lower output charge in the space charge limited regime compared to measured values. The rate of increase of the produced charge at high laser pulse energies close to the space charge limited emission regime seems to be proportional to the amount of halo present in the radial laser profile since the charge from the core has saturated already. By utilizing core + halo particle distributions based on measured radial laser profiles, ASTRA simulations and semi-analytical emission models reproduce the behavior of the measured charge for a wide range of RF gun and laser operational parameters within the measurement uncertainties.Comment: 15 pages, 16 figures, 2 table

Frequency Characteristics of Strip Modules of the Quasi-chaotic Signals Formation Based on Bulk Nonlinear Optical Crystals

Поступила: 28.04.2023. Принята в печать: 21.07.2023.Received: 28.04.2023. Accepted: 21.07.2023.В работе проведено экспериментальное исследование частотных зависимостей коэффициентов матрицы рассеяния полосковых модулей на основе копланарной полосковой линии с частичным диэлектрическим заполнением в виде объемных нелинейно-оптических кристаллов кварца SiO2, титанил-фосфата калия KTiOPO4 (KTP), дифосфида цинка германия ZnGeP2, ниобата лития LiNbO3. Показано возникновение эффекта формирования квазихаотических колебаний в модулях, содержащих объемные кристаллы KTiOPO4, ZnGeP2, LiNbO3 при подаче на вход ЛЧМ-сигналов с быстрым переключением направления падающей волны в тракте приема-передачи векторного анализатора цепей. Введены параметры для сравнительной характеристики материалов кристаллов. Определена полная (развернутая) фаза коэффициента передачи модулей. Проведены анализ ее физического смысла и обработка полной фазы, позволившая построить алгоритм оценки частотной зависимости относительной диэлектрической проницаемости кристаллов. Исследованные модули могут выполнять функцию формирователей квазихаотических сигналов СВЧ.In this paper the experimental study of frequency dependences of scattering matrix coefficients of strip modules based on a coplanar strip line with partial dielectric filling in the form of bulk non-linear optical crystals of quartz, potassium titanium phosphate (KTP), zinc germanium diphosphide, lithium niobate has been performed. The appearance of the effect of forming quasi-chaotic oscillations in modules containing KTiOPO4, ZnGeP2, LiNbO3 bulk crystals when LFM signals are fed at fast switching of incident wave direction in the receiving and transmitting tract of the vector network analyzer is demonstrared. Parameters of comparative characterization of crystal materials are introduced. The complete phase of the modulus transmission coefficient is determined. The analysis of its physical sense is made, followed by processing complete phase shift, which provides the possibility to develop the algorithm of estimating the frequency dependence of crystal’s relative permittivity. The studied modules may be used as formers of quasi-chaotic microwave signals.Публикация выполнена при финансовой поддержке Министерства науки и высшего образования Российской Федерации в рамках проекта № FEWM‑2023-0014.The study was made with the financial support of the Ministry of Science and Higher Education of the Russian Federation within the framework of project No. FEWM‑2023-0014

THE PECULIARITIES OF CEREBRAL BLOOD FLOW IN PATIENTS WITH CHRONIC HEPATITIS

Aim. To study extra- and intracranial hemodynamics in patients with chronic hepatitis of different activity.Material and methods. Ultrasonography of the cerebral blood flow was performed in 576 patients with chronic hepatitis.Results. Contralateral hemyspherical asymmetry (more than 30 %) of the maximum linear rate of blood flow in the medium cerebral arteries and decrease in resistance index (0,55±0,09) and pulsativity index (1,34±0,66) were found in 33,8 % of patients with chronic hepatitis of high activity. Collateral blood flow reduction through connecting arteries of Willis circle was revealed in 13,8 % of patients. The tortuosity of arteries and thickening of intima-media complex was found in patients with chronic hepatitis (mainly of high activity). It leads to decline of cerebral blood flow.Conclusion. Symptomatic and asymptomatic cerebral blood flow disturbances were observed in 23,2% and 38,8% of patients with active chronic hepatitis respectively

AN OPTION OF HIGH CHARGE OPERATION FOR THE EUROPEAN XFEL

Abstract The 1.3 GHz superconducting accelerator developed in the framework of TESLA and the European XFEL project holds the potential to accelerate high charge electron beams. This feature has been successfully demonstrated during the first run of the free electron laser at the TESLA Test Facility with lasing driven by electron bunches with a charge of up to 4 nC. Currently DESY and the European XFEL GmbH perform revision of the baseline parameters for the electron beam. In this report we discuss a potential option of operation of the European XFEL driven by high charge (1 nC to 3 nC) electron beams. We present the results of the production and characterization of high charge electron bunches. Experiments have been performed at PITZ and demonstrated good properties of the electron beam in terms of emittance. Simulations of the radiation properties of SASE FELs show that application of high charge electron beams will open up the possibility to generate radiation pulse energies up to the few hundred milli-Joule level

Characterization of Reactive Organometallic Species via MicroED

Here we apply microcrystal electron diffraction (MicroED) to the structural determination of transition-metal complexes. We find that the simultaneous use of 300 keV electrons, very low electron doses, and an ultrasensitive camera allows for the collection of data without cryogenic cooling of the stage. This technique reveals the first crystal structures of the classic zirconocene hydride, colloquially known as “Schwartz’s reagent”, a novel Pd(II) complex not amenable to solution-state NMR or X-ray crystallography, and five other paramagnetic and diamagnetic transition-metal complexes