On the interpretation of the inverted kinetics equation and space-time calculations of the effectiveness of the VVER-1000 reactor scram system

In the present paper, an attempt is made to analyze the accuracy of calculating the effectiveness of the VVER-1000 reactor scram system by means of the inverted solution of the kinetics equation (ISKE). In the numerical studies in the intellectual ShIPR software system, the actuation of the reactor scram system with the possible jamming of one of the two most effective rods is simulated. First, the connection of functionals calculated in the space-time computation in different approximations with the kinetics equation is considered on the theoretical level. The formulas are presented in a manner facilitating their coding. Then, the results of processing of several such functions by the ISKE are presented. For estimating the effectiveness of the VVER-1000 reactor scram system, it is proposed to use the measured currents of ionization chambers (IC) jointly with calculated readings of IC imitators. In addition, the integral of the delayed neutron (DN) generation rate multiplied by the adjoint DN source over the volume of the reactor, calculated for the instant of time when insertion of safety rods ends, is used. This integral is necessary for taking into account the spatial reactivity effects. Reasonable agreement was attained for the considered example between the effectiveness of the scram system evaluated by this method and the values obtained by steady-state calculations as the difference of the reciprocal effective multiplication factors with withdrawn and inserted control rods. This agreement was attained with the use of eight-group DN parameters.     

Calculation of reactivities using ionization chamber currents with different sets of kinetic parameters for reduced scram system efficiency in the VVER-1000 of the third unit of the Kalinin nuclear power plant at the stage of physical start-up

The effectiveness of the VVER-1000 reactor scram system is analyzed using ionization chamber currents with different sets of kinetic parameters with allowance for the isotopic composition in the calculation of these parameters. The most “correct, aesthetically acceptable” results are obtained using the eight-group constants of the ROSFOND (BNAB-RF) library. The difference between the maximum and minimum values of the scram system effectiveness calculated with different sets of kinetic parameters slightly exceeds 2β. The problems of introducing corrections due to spatial effects are not considered in this study.     

A mobile test facility based on a magnetic cumulative generator to study the stability of the power plants under impact of lightning currents

The report presents the results of the development and field testing of a mobile test facility based on a helical magnetic cumulative generator (MCGTF). The system is designed for full-scale modeling of lightning currents to study the safety of power plants of any type, including nuclear power plants. Advanced technologies of high-energy physics for solving both engineering and applied problems underlie this pilot project. The energy from the magnetic cumulative generator (MCG) is transferred to a high-impedance load with high efficiency of more than 50% using pulse transformer coupling. Modeling of the dynamics of the MEG that operates in a circuit with lumped parameters allows one to apply the law of inductance output during operation of the MCG, thus providing the required front of the current pulse in the load without using any switches. The results of field testing of the MCGTF are presented for both the ground loop and the model load. The ground loop generates a load resistance of 2–4 Ω. In the tests, the ohmic resistance of the model load is 10 Ω. It is shown that the current pulse parameters recorded in the resistive-inductive load are close to the calculated values.     

Statistical verification of neutron-physics programs for calculations in support of nuclear safety

An algorithm for statistical verification of the XT26 code contained in the SAPHIRE-2006 code system is described. The results of conservative estimation of the calculation error in the K_eff calculations for different types of benchmark experiments are presented. The results of the statistical analysis of deviations from the experimental values are compared with the corresponding parameters obtained from the set of calculations performed using other codes.     

Specific resistance of highly alloyed semiconductors measured by the inductance method

The study examines the theory of inductance method for measuring specific resistance of semiconductors, using a superimposed spiral-shape transducer. The results of calculations are analyzed in dependence on the parameters of the system transducer-sample, and presented in the form of graphs.     

Vacuum system of heavy ion cyclotron complex DC-60

The vacuum system of the heavy ion cyclotron complex DC-60 created at the Flerov Laboratory of Nuclear Reactions of the Joint Institute for Nuclear Research for the interdisciplinary research complex (Astana, Kazakhstan) is described. The results of numerical simulation of transmission efficiency of accelerated ions in the course of recharging on residual gas, which determines the basic parameters of the designed vacuum system, are presented. As a result of successful implementation of the cyclotron complex DC-60 project, heavy ion beams were accelerated. The obtained parameters of the vacuum system agree completely with calculations, which were the basis of the project.     

Simulation of Magnetic Levitation Systems Based on Superconducting Rings

A comprehensive model of the HTSC ring magnet is developed. Magnetic and transport characteristics of commercialHTSCtapes are used in calculations, features of their layered structure are taken into account. The magnetic system parameters in external magnetic fields of various configurations are calculated. Magnetic fields, currents, magnetization, and levitation force are calculated for various geometrical parameters of magnetized rings.     

Robust active noise control in the loadmaster area of a military transport aircraft

The active noise control (ANC) method is based on the superposition of a disturbance noise field with a second anti-noise field using loudspeakers and error microphones. This method can be used to reduce the noise level inside the cabin of a propeller aircraft. However, during the design process of the ANC system, extensive measurements of transfer functions are necessary to optimize the loudspeaker and microphone positions. Sometimes, the transducer positions have to be tailored according to the optimization results to achieve a sufficient noise reduction. The purpose of this paper is to introduce a controller design method for such narrow band ANC systems. The method can be seen as an extension of common transducer placement optimization procedures. In the presented method, individual weighting parameters for the loudspeakers and microphones are used. With this procedure, the tailoring of the transducer positions is replaced by adjustment of controller parameters. Moreover, the ANC system will be robust because of the fact that the uncertainties are considered during the optimization of the controller parameters. The paper describes the necessary theoretic background for the method and demonstrates the efficiency in an acoustical mock-up of a military transport aircraft.     

A study on the performance of a gyromonotron

A method is presented which allows to calculate the large signal beam efficiency of a gyromonotron working at the s-th harmonic of the cyclotron frequency. The results of this calculation using efficiency optimized parameters are given for different TE_mn distributions and also for a magnetic taper. It is shown that beam efficiencies, which are higher than twice the value at constant electric and magnetic fields are theoretically possible. Also the influence of the beam voltage is considered. For a given beam voltage and a given electric field distribution in the resonator power calculations are performed and it is shown what powerlevels are available for different resonator modes and for different cyclotron harmonics.     

Characteristics of the magnetic analysis system for a compact MPR-type spectrometer

The magnetic proton recoil(MPR)spectrometer is a novel diagnostic instrument with high perfor-mance for measurements of neutron spectra in inertial confinement fusion(ICF)experiments and high power fusion devices.A compact MPR-type spectrometer dedicated to the research of pulsed deuterium-tritium(DT)neutron spectroscopy of special experimental conditions is currently under design.Analyses of the main parameters and performance of the magnetic analysis system through 3-D particle transport calculations and MonteCarlo simulations and calibration of the system performance as a test using CR-39 solid track detector and α particle from 239pu and 226Ra radioactive sources are presented in this paper.The results indicate that the magnetic analysis system will achieve a detection efficiency level of 10-5-10-4 at an energy resolution of 1.5%-2.1%,and fulfills the design goals of the spectrometer.     

A contribution to the assessment of the influence of collisions on the measurements with Langmuir probes in the thick sheath working regime

In the present work we investigate theoretically and experimentally the influence of elastic collisions in a probe sheath on a cylindrical Langmuir probe. The analysed probe working regime covers conditions under which the following probe characteristic parameters are comparable: the probe radius, the Debye length and both the ion and electron mean free paths.The preliminary investigations under almost collisionless conditions show good agreement between theoretical and experimental values of the ion saturation currents and of the floating potentials only when the ion currents for the studied working regime of the cylindrical Langmuir probe are calculated according to the theory of Chen (Plasma Phys.7 (1965)47). These collisionless currents form the basis for the calculation of the collision-corrected probe characteristics according to the presented procedure by Talbot and Chou (Rarefied Gas Dynamics, Academic Press, New York, 1966, p. 1723).The applied theoretical analysis covers the influence of the collisions on the electron and ion current of the single probe characteristic and on the estimation of the space potential. The results of the calculations are presented in graphical overviews for the series of cases of practical importance. The other working regimes can be covered using the calculating procedure presented.For comparison of the calculated collision-corrected characteristics with those from an experiment we used the positive column plasma of the He glow discharge where the electron density is known and the space potential can be experimentally estimated from the lowest excitation potential of He. The comparison was carried out for the ion and electron currents, the floating potential and the zero-cross of the probe characteristic second derivative.The estimation of the secondary electron current contribution to the total probe current shows that it limits the applicability of the collision-corrected probe characteristic to the plasma diagnostic in the transition to the collision-determined working regime.     

Oscillator strengths for thallium calculated using a semiempirical relativistic one-electron central-field model potential

The results of calculations for oscillator strengths, radiative transition probabilities and excited state lifetimes are presented and compared with those of other calculations and measurements. The agreement with measured oscillator strengths is generally quite good. The importance of core polarization effects for the diffuse series is demonstrated. The significance of the results for measurements of parity-nonconserving effects due to weak neutral currents is discussed.     

Optical surface profile measurement using phase retrieval by tuning the illumination wavelength

In this paper, we present a method for measuring the surface profile of an object by using diffraction intensity patterns recorded at different illumination wavelengths. The main advantages of this technique are: simple optical set-up, high immunity to noise and environmental disturbance, since no reference beam (like in holography) or additional moving parts are needed. Two iterative calculations are synchronously performed using two sequences of diffraction intensity patterns, producing fast convergence to the expected result. The effects of different parameters on the accuracy and efficiency of the method are investigated. Simulation and experimental results are presented.     

用传输线和时域有限差分法计算电缆X射线响应

 介绍了时域传输线和时域有限差分两种计算电缆X射线瞬态响应的方法,并利用电缆芯线总电荷以及介质层的电荷分布,结合实验结果,分别给出了时域传输线模型中的电流源和时域有限差分模型中电流密度的计算方法。作为例子,在60 keV单能X射线垂直于电缆轴向辐照的条件下,采用两种方法计算了电缆两端接匹配负载时负载上的电流响应;采用传输线方法计算了不同能量X射线辐照电缆时的芯线负载电流响应。计算结果表明,两种方法计算的电缆X射线瞬态响应是一致的;电缆介质层中存在静电场;X射线能量不同时,电缆芯线负载电流存在最大值。计算中,电缆与X射线的作用采用蒙特卡罗方法计算。     

Simulation of beam extraction from C235 cyclotron for proton therapy

The extraction of an accelerated beam from C235 cyclotron (IBA, Belgium) for proton therapy is simulated. The results of optimizing the parameters of the extraction system to increase the beam extraction efficiency are presented. Our theoretical results agree well with the experimental data. A new configuration of electrostatic deflector is proposed based on the numerical results; using this configuration essentially increases the efficiency of the cyclotron extraction system.     

回旋速调管放大器注-波互作用分析

给出了自洽非线性大信号理论分析方法,在理论分析和高频计算的基础上,建立了回旋速调管放大器注-波互作用计算模型,对其进行数值计算。研究多种参量对放大器输出功率、增益、效率等的影响,通过优化得到了中心频率34 GHz的四腔回旋速调管放大器设计方案。粒子模拟表明：在工作电压65 kV,注电流8 A,电子注横向与纵向速度比为1.5时,输出功率230 kW,带宽230 MHz,电子效率45%,饱和增益33 dB。     

Performance Investigation of Photonic Crystal-Based Microring Resonator for Optical Signal Processing

Abstract

A detailed theoretical analysis is presented to characterize wave propagation at 1,550 nm inside a glass (SiO₂) microring resonator implemented using photonic crystal technology. A photonic crystal reflection is used at each microring resonator corner to enhance the bending efficiency. The characteristics of both photonic crystal beam splitter and microring resonator bending losses are analyzed and investigated using both effective refractive index and finite difference time domain methods. Analytical expressions are also derived to describe the field enhancement inside the microring resonator, the transfer function of the microring resonator, and the main parameters characterizing the resonator such as resonator band width and quality factor. The analysis is also extended to characterize a drop filter implemented using photonic crystal-based microring resonator. The results indicate clearly that the effective refractive index method can give accurate results if one starts the calculations with finite difference time domain-estimated beam splitter parameters. Further, bending efficiency as high as 99% can be obtained using a ten-post layer photonic crystal mirror at each microring resonator corner.     

High-Efficiency Electron Source with a Hollow Cathode in Technologies of Thin Film Deposition and Surface Treatment under Forevacuum Pressures

It is shown that low-energy beams with a high efficiency in a wide range of beam currents can be obtained in electron sources with a hollow cathode in the forevacuum pressure range. By varying the geometrical parameters of the electrode system and electromagnetic optics of the electron source, we succeeded in reaching the efficiency at a level of 0.9 for an accelerating potential of 1 kV and beam currents from 100 to 300 mA. The parameters affecting most strongly the efficiency and stability of operation of the electron source with a hollow cathode have been determined.     

Analytical technique for calculation of mirror surface parameters in “HEX-DARR” resonator for lasers with a ring active medium

Within the geometrical optics approximation, we consider a class of mirrors (with surfaces formed by rotating second-order curves) which enables an extension of the range of possible beam conversions in optical systems. The formulas used in the calculations are quite simple. Based on this approach, we worked out and presented a complete analytical algorithm for calculation of the mirror surface parameters in a “HEX-DARR” resonator. To check the algorithm, a numerical calculation of an optical system is carried out for a specific set of initial data. The results obtained confirm the accuracy of the equations derived and the efficiency of the algorithm.     

A simple feedback control for a chaotic oscillator with limited power supply

We proposed a simple feedback control method to suppress chaotic behavior in oscillators with limited power supply. The small-amplitude controlling signal is applied directly to the power supply system, so as to alter the characteristic curve of the driving motor. Numerical results are presented showing the method efficiency for a wide range of control parameters. Moreover, we have found that, for some parameters, this kind of control may introduce coexisting periodic attractors with complex basins of attraction and, therefore, serious problems with predictability of the final state the system will asymptote to.