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Numerical studies of isotopic selective photoionization of ytterbium in a three-step ionization scheme

Chinese Physics B 2023年第5期32卷 395-404页

作者：卢肖勇王立德 Science and Technology on Particle Transport and Separation Laboratory CNNCTianjin 300180China

Selective photoionization of ytterbium isotope is studied numerically based on a three-step photoionization scheme,4f^(14)6s^(21)S_0(0 cm^(-1))→4f~(14)6s6p~3P_1(17992.008 cm^(-1))→(4f~(13)6s~26p)(7/2,3/2)_2(35196.98 cm^(-1))→auto-ionization state(52353 cm^(-1))→Yb^(+),by the density matrix theory with the consideration of atomic hyperfine structures and magnetic *** examine the physical model,the numerical isotopic abundance of ytterbium is compared with that from mass spectroscopy experiment,showing that they are in good agreement with each *** excitation process and ionization process of ytterbium,especially for odd isotopes,are discussed and analyzed in detail on this *** effects of frequency detuning,power densities,spectral bandwidths,polarization of two excitation lasers,and atomic Doppler broadening on the total ionization yield and isotopic abundance are investigated numerically and the optimal excitation conditions for~(176)Yb enrichment are identified semi-quantitatively.

关键词： ytterbium isotope hyperfine structure selective photoionization

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Theoretical investigations of population trapping phenomena in atomic four-color,three-step photoionization scheme

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Chinese Physics B 2024年第3期33卷 333-340页

作者：卢肖勇孙亚鹏 Science and Technology on Particle Transport and Separation Laboratory Tianjin 300180China Department of Engineering Physics Tsinghua UniversityBeijing 100084China

The four-color three-step selective photoionization process of atom is very important in laser isotope separation *** population trapping phenomena and their influences are studied theoretically in monochromatic and non-monochromatic laser fields based on the density matrix theory in this *** evolutions of the photoionization properties of the four-color,three-step process are *** population trapping effects occur intensely in monochromatic excitation,while it gradually turns weak as the laser bandwidth *** effects of bandwidth,Rabi frequency,time delay,and frequency detuning on the population trapping effect are investigated in monochromatic and non-monochromatic laser *** effects of laser process parameters and atomic parameters on the effective selective photoionization are also *** ionization probability and selectivity factors,as evaluation indexes,are difficult to improve synchronously by adjusting systematic ***,the existence of metastable state may play a negative role when its population is low enough.

关键词： population trapping metastable state selective photoionization laser bandwidth

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Numerical studies of atomic three-step photoionization processes with non-monochromatic laser fields

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Chinese Physics B 2022年第6期31卷 300-309页

作者： Xiao-Yong Lu Li-De Wang Yun-Fei Li Science and Technology on Particle Transport and Separation Laboratory Tianjin 300180China

The atomic selective multi-step photoionization process is a critical step in laser isotope *** this work,we study three-step photoionization processes with non-monochromatic laser fields theoretically based on the semi-classical ***,three bandwidth models,including the chaotic field model,de-correlation model,and phase diffusion model,are introduced into the density matrix *** numerical results are compared with each other *** phase diffusion model is selected for further simulations in terms of the correspondence degree to physical ***,numerical calculations are carried out to identify the influences of systematic parameters,including laser parameters(Rabi frequency,bandwidth,relative time delay,frequency detuning)and atomic Doppler broadening,on photoionization *** order to determine the optimal match among different systematic parameters,the ionization yield of resonant isotope,and selectivity factor are adopted as evaluation indexes to guide the design and optimization *** results in this work can provide a rewarding reference for laser isotope separation.

关键词： non-monochromatic laser field bandwidth model ionization yield selectivity factor

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Power Ratio Measurement of Dual Wavelength Dye Laser with Picometer-level Wavelength Difference

Power Ratio Measurement of Dual Wavelength Dye Laser with Pi...

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2023 Applied Optics and Photonics China: Laser technology and Applications;and Optoelectronic Devices and Integration, AOPC 2023

作者： Guo, Yancheng Yang, Qiunan Zhang, Yuanyuan Science and Technology on Particle Transport and Separation Laboratory Tianjin300180 China

ISBN: (纸本)9781510672246

Dual wavelength lasers have wide applications in optical communication equipment, lidar, and other fields. The measurement and control of dual wavelength laser power ratio affect the application value of dual wavelength lasers in these fields directly. The dual wavelength dye laser used in the experiment has a wavelength difference of only several picometers. Based on this demand, our paper innovatively proposes a measurement method that using a scanning FP interferometer to characterize the power ratio. The linear correlation between spectral response and incident light power was verified through the establishment of theoretical models and experimental verification. On this basis, the optimization of optical layout design and the design of automatic recognition software can be carried out separately to achieve online monitoring of power ratio. Finally, the device was used for long-term experimental assessment, and the results showed that the comprehensive error of dual wavelength power ratio measurement based on scanning FP interferometer was less than ±3%, which met the experimental requirements. © 2023 SPIE.

关键词： Optical radar

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A digital representation algorithm for long distance transmission laser spot energy intensity distribution

A digital representation algorithm for long distance transmi...

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2023 Applied Optics and Photonics China: Laser technology and Applications;and Optoelectronic Devices and Integration, AOPC 2023

作者： Su, Ning Dai, Xiaoke Sun, Liang Science and Technology on Particle Transport and Separation Laboratory Tianjin300180 China

ISBN: (纸本)9781510672246

An algorithm is designed to realize the digital representation of long distance transmission laser spot energy intensity distribution, due to the current situation that the energy intensity of long distance transmission laser spots cannot be accurately represented in the laser system. A definite number is obtained by image processing and program calculation of a laser spot. The simulated laser spots are calculated and contrasted to verify the universality and applicability of the algorithm. The calculation results show that the spots size have negative impact on the representation results. Using this algorithm, the adjustment criterion of the long distance transmission laser spots in the laser system can be set more conveniently. © 2023 SPIE.

关键词： Image processing

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Discretization Analysis of Fluid Mechanical Flow Field Grid 7

Discretization Analysis of Fluid Mechanical Flow Field Grid

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7th International Conference on Design Engineering and science, ICDES 2022

作者： Sheng, Yu Science and Technology on Particle Transport and Separation Laboratory Tianjin300180 China

The design basis of the performance of special industrial fluid machinery is to obtain the distribution of air flow parameters through the solution of flow field. In the numerical solution of flow field, the discretization of computational domain grid is the key factor affecting the calculation results. In this paper, the two-dimensional axisymmetric flow field analysis model were adopted. By establishing the software interface and automatic execution script file, the grid discreteness analysis process was established. The Richardson extrapolation method was used to infer the accurate solution of the flow field, and the grid independence and convergence analysis and the grid spacing analysis of the first layer of the wall were carried out. The results showed that the numerical results gradually approached the exact solution with the increase of the total number of grids, but the correlation between the numerical results and the total number of grids decreased in this process;By changing the normal spacing of the first layer of grid on each wall and making mathematical statistical analysis, the sensitive area of grid spacing could be determined. The method established in this paper could significantly improve the overall efficiency of the fluid mechanical mesh discreteness analysis and flow field analysis, and recommended the configuration of the optimal mesh discretization mode for the subsequent simulation calculation, which was conducive to further improve the calculation accuracy and efficiency of the flow field. © Published under licence by IOP Publishing Ltd.

关键词： Computational efficiency

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Grain growth kinetics and densification mechanism of(TiZrHfVNbTa)C high-entropy ceramic under pressureless sintering

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Journal of Materials science & technology 2022年第15期110卷 57-64页

作者： Wen Zhang Lei Chen Chenguang Xu Xuming Lv Yujin Wang Jiahu Ouyang Yu Zhou School of Materials Science and Engineering Institute for Advanced CeramicsHarbin Institute of TechnologyHarbin 150001China National Key Laboratory of Science and Technology on Advanced Composites in Special Environment Harbin Institute of TechnologyHarbin 150001China Science and Technology on Particle Transport and Separation Laboratory Tianjin 300180China

The grain growth kinetics and densification mechanism of(TiZrHfVNbTa)C high-entropy carbide ceramic are investigated in this work.A single phase carbide with a rock-salt structure is formed until 2300°C,below which an apparent aggregation of V,Zr and Hf *** is associated with the slow diffusion rate of V element as well as the relatively poor solubility of VC in HfC(as well as ZrC).The grain growth mechanism gradually changes from surface diffusion to volume diffusion and then grain boundary diffusion with increasing sintering *** is attributed to the variation of activation energy of grain *** densification mechanism is principally dominated by the mass transport through lattice diffusion with the activation energy of 839±53 k J/*** the design of two-step sintering,it is verified that the solid solution formation can effectively promote the densification process.

关键词： High-entropy carbide ceramic Pressureless sintering Grain growth kinetics Densification mechanism

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Research on Collaborative Optimization Model of Complex System Reliability and System Availability

Research on Collaborative Optimization Model of Complex Syst...

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2024 International Conference on Information technology, Communication Ecosystem and Management, ITCEM 2024

作者： Bi, Shuyang Research Institute of Physical and Chemical Engineering of Nuclear Industry China National Key Laboratory of Particle Transport and Separation Technology Tianjin China

ISBN: (纸本)9798331542696

In this paper, the collaborative optimization model of complex system reliability and system availability is studied, aiming at solving the reliability and availability problems of key infrastructure such as cloud computing platform and intelligent transportation system in a highly information society. Firstly, this paper analyzes the reliability and availability characteristics of complex systems, and constructs a collaborative optimization model to achieve the optimal trade-off between system failure probability and system availability. The model selects the system's failure probability, mean time to failure (MTTF), and mean time to repair (MTTR) as key indicators, integrating a weight coefficient to balance the importance of reliability and availability. Subsequently, this paper designs an optimization method based on Genetic Algorithm (GA), which involves encoding and initialization, fitness function calculation, selection, crossover, mutation operations, and the setting of termination conditions, to solve the model. Case studies demonstrate that through GA optimization, the system's failure probability and availability have been significantly improved, validating the effectiveness and practicality of the model. © 2024 IEEE.

关键词： Mean time between failures

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Degradation Performance Analysis and Reliability Quantitative Evaluation technology of Electronic Equipment

Degradation Performance Analysis and Reliability Quantitativ...

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2024 International Conference on Computing, Robotics and System sciences, ICRSS 2024

作者： Bi, Shuyang Research Institute of Physical and Chemical Engineering of Nuclear Industry Tianjin China National Key Laboratory of Particle Transport and Separation Technology Tianjin China

ISBN: (纸本)9798331511296

With the increase of use time, electronic equipment will inevitably experience performance degradation, which will affect the user experience and system function. In this paper, based on the knowledge of materials science, statistics, data science and system engineering, a quantitative reliability evaluation technology based on degraded data is established. By analyzing the internal mechanism of performance degradation of electronic equipment, this paper develops a Wiener process model based on degradation trajectory to quantitatively evaluate the reliability of electronic equipment. The model assumes that the equipment performance degradation is a random process, and the model parameters are estimated by means of maximum likelihood estimation. In this paper, the reliability of electronic equipment is comprehensively evaluated by using such indicators as mean time between failures (MTTF), failure rate function and residual life expectation (ERL). Taking a sensor widely used in industrial control field as an example, this paper collects its performance degradation data, estimates model parameters, and calculates MTTF and ERL, which provides scientific basis for equipment maintenance, repair and replacement decision. The results show that the MTTF of the sensor is 8.5 years, and the ERL of the sensor that has been used for 4 years is 4.2 years. This study not only promotes the development of the theory and method of reliability evaluation of electronic equipment, but also provides technical support for manufacturers and users, and promotes the sustainable development of electronic products industry. © 2024 IEEE.

关键词： Mean time between failures

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Research on the Influence of Rub-impact Buffer Stroke on the Dynamic Response of Two-section Rotor 6

Research on the Influence of Rub-impact Buffer Stroke on the...

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6th International Conference on Mechanical, Electrical and Material Application, MEMA 2023

作者： Wu, Tingwei Li, Shitu Science and Technology on Particle Transport and Separation Laboratory Tianjin300180 China Institute of Physical and Chemical Engineering of Nuclear Industry Tianjin300350 China

The two-section rotor needs to go through multiple critical speeds in the process of speed increase. When the rotor approaches the critical speed, its amplitude increases rapidly, easily causing collision damage. The auxiliary over-critical device cushions and protects the rotor through rubbing, which makes it pass the critical speed under the safe amplitude. In this paper, the influence of buffer stroke, the key structural parameter of the auxiliary over-critical device, on the dynamic response of the two-section rotor at the first-order bending critical speed is analyzed, the influence of its buffer stroke on the over-critical dynamic response of the rotor is calculated and analyzed, and the impact and friction force on the rotor is calculated. The design principles and results of the buffer stroke parameters of the auxiliary supercritical device are proposed. © Published under licence by IOP Publishing Ltd.

关键词： Dynamic response

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