Radiation effect and simulation of 850 nm vertical-cavity surface-emitting laser
Jiawei CHEN, Yudong LI, MALIYA·Heini , Qi GUO, and Xiyan LIU
Background Vertical cavity surface emitting lasers (VCSEL) have very high application value in space radiation environment. Purpose This study aims to explore the degradation rule and mechanism of 850 nm VCSEL in harsh radiation environment. Methods First of all, the MULASSIS tool was employed to calculate displacement damage dose (DDD) and design experimental scheme for 850 nm multimode VCSEL samples. Then, 3 MeV and 10 MeV proton irradiation experiments were conducted to obtain the degradation rule of parameters such as light output power and threshold current with the proton fluence, and to find that the degradation degree of light output power and threshold current were equal under the same DDD. Finally, the Silvaco software was used for modeling and simulation on an experimental basis to extract microscopic parameters such as trap density, donor and acceptor ionization density, mirror loss, radiation recombination rate and photon number. Results The simulation results are in good agreement with the experimental results, these results show that each parameter changes to different degrees with the increase of proton fluence. Conclusions The parameter degradation law and radiation damage mechanism of VCSEL can be deeply explored by simulation on the basis of the experimental law, and simulation results are of great significance for understanding the degradation mechanism of VCSEL.
  • Nov. 25, 2022
  • Vol. 45, Issue 11, 110202 (2022)
  • DOI:10.11889/j.0253-3219.2022.hjs.45.110202
Design of a TDC chip based on 0.18 μm SMIC technology
Yichao MA, Liangyi WANG, Haiyun TENG, and Junguo JIANG
Background The measurement of time-of-flight is one of the indispensable experimental contents in contemporary high-energy physics experiments and plays a vital role in exploring the essence of particle physics. Purpose This study aims to design a time to digital convertor (TDC) chip that meets the high-resolution time measurement requirements of time-of-flight detectors for high-speed flying particles in high-energy physics experiments. Methods First of all, a differential structure TDC was proposed and the main measurement part was realized by differential delay loop composed of time measurement core module, time measurement data transmission module, delay loop calibration module and clock generation module. Based on this structure, three parts of delay loop module, thermometer code generation module, and coarse count and fine count generation module were integrated into the core module of time measurement, and the 0.18 μm SMIC (Semiconductor Manufacturing International Corporation) process was adopted to achieve the TDC chip design. Results & Conclusions The designed TDC chip has a layout area of 1.35 mm×1.35 mm, a resolution of 17 ps, an accuracy of 8.5 ps (Root Mean Square, RMS), and a dynamic range of 0~210 μs. It can meet the current requirements for high-precision time measurement in high-energy physics.
  • Nov. 25, 2022
  • Vol. 45, Issue 11, 110402 (2022)
  • DOI:10.11889/j.0253-3219.2022.hjs.45.110402
Design of portable multi-function radiation detection system
Song YANG, Xiaoquan ZHANG, Changming DENG, Yanting ZHANG, Fei XU, Lingling GUAN, and Shaoqiang DUAN
Background In order to fast and conveniently measure X, γ and neutron radiation field simultaneously, portable multi-function radiation detector is highly demanded. Purpose This study aims to design a portable multi-function radiation detection system based on LaBr3(Ce) crystal, lithium aluminum silicate oxygen (LASO) neutron detector and high range Geiger-Muller (GM) counter. Methods After the optical signal output from the LaBr3 crystal was photoelectrically converted into electronic signal by the photomultiplier tube (PMT), the integrated digital multi-channel was used for data acquisition of electronic signal, and the subsequent data processing and calculation. The front signal processing circuits, such as amplification, discrimination and shaping, were designed for both the LASO neutron detector and the GM tube counter. Finally, the digital signal processed of the LaBr3 detector was transmitted to the ARM (Advanced RISC Machine) processor in the form of TTL (Transistor-Transistor Logic) serial port, and the pulse signal formed of the neutron detector and GM counter tube was connected to the external counting port of ARM processor. Energy spectrum was processed for nuclide identification and displayed by ARM processor whilst the low dose rate measurement base on the Gamma data collected by the LaBr3 detector, the neutron detector and the high range GM tube counter were counted at fixed time and converted from the count rate into the dose rate. Results & Conclusions The designed portable multi-function radiation detector realize simultaneous measurement of wide range (48 keV~3.0 MeV) γ, low-energy (48 keV~1.25 MeV) X-ray, (0.1~100 mSv∙h-1) neutron dose rates, and nuclide identification capability of LaBr3 spectrometer, and upload the data to PC through USB interface.
  • Nov. 25, 2022
  • Vol. 45, Issue 11, 110403 (2022)
  • DOI:10.11889/j.0253-3219.2022.hjs.45.110403
Study on many-objective optimization method for reactor 3D shielding structure based on Genetic Algorithm
Huajian ZHANG, Zhenping CHEN, Chengwei LIU, Chao YANG, Bo TAN, Bin GAN, Fucai CHEN, and Tao YU
Background Radiation shielding design is an important part of reactor design, and the development of new nuclear power technology for various kinds of reactors has put forward new demands on radiation shielding optimization design methods. Purpose This study aims to overcome the shortcomings of the traditional multi-objective optimization methods for shielding structures in dealing with the optimization problem of 3D shielding structures, such as slow optimization speed, difficulty in convergence, and poor globalization. Methods Based on the non-dominated sorting genetic algorithm Ⅲ (NSGA-Ⅲ), the many-objective optimization method for 3D shielding structure design for nuclear reactor was proposed. The Monte Carlo N-Particle Transport Code (MCNP) was employed to analyze comparative performance of the NSGA-III optimization method on the basis of the 3D shielding structure model of nuclear reactors, and shield weight, volume and radiation dose rate in specific regions were taken as the optimization targets. Results & Conclusions The numerical simulation results show that the NSGA-III based optimization method for 3D shielding structure design can search for the Pareto-optimal front more efficiently and stably, providing a new idea for the optimization of radiation shielding design.
  • Nov. 25, 2022
  • Vol. 45, Issue 11, 110603 (2022)
  • DOI:10.11889/j.0253-3219.2022.hjs.45.110603
Development of extendable on-line test system for total ionizing dose effect of microprocessor
Faguo CHEN, Weiyue YU, Runcheng LIANG, Zhirui ZHENG, and Rong GUO
Background Compared with transistors and small-scale integrated circuits, the total ionizing dose (TID) effect and testing of multifunctional large scale integrated microprocessors are more complex. The difficulty of testing is to analyze the failure mode of microprocessor online from limited information under irradiation. Purpose This study aims to develop an extendable on-line test system for TID effect of microprocessor and carry out preliminary application. Methods The testing system was composed of control circuit, extendable signal acquisition circuit, tested sample interface, upper computer and software. Multiple parametric measurement or functional verification methods such as power consumption current, on-chip memory, communication, clock, analog-to-digital/digital-to-analog converter (ADC/DAC) and direct memory access of microprocessor were provided. Sixteen microprocessors with feature size 40 nm were irradiated with 60Co source and tested on-line. Results After the irradiation dose is accumulated to (377.44±20.34) Gy(Si), all samples are malfunctional with digital communication interruption, sudden drop in current consumption, abnormal ADC/DAC output and so on. Conclusion Based on all 12 kinds of parametric measurement or functional verification results, the TID effect of this type of microprocessor is probable to be a functional failure caused by some kernel instructions. The on-line test system of this study can provide more direct data information for the total dose failure mode analysis.
  • Nov. 25, 2022
  • Vol. 45, Issue 11, 110404 (2022)
  • DOI:10.11889/j.0253-3219.2022.hjs.45.110404
Optimal design of core flow distribution for 10 MW liquid fuel molten salt reactor
Siqin HU, Jian TIAN, Chong ZHOU, Yang ZOU, and Xiaohan YU
Background The flow distribution in core for the liquid fuel molten salt reactor (MSR) is an important part of the thermal hydraulic design, and the hydraulic structure of reactor core plays a decisive role on flow distribution. Purpose This study aims to find out a suitable hydraulic structure design to make the core flow distribution match with the power distribution, and flatten the core temperature distribution for a 10 MW MSR. Methods First of all, a one-twelfth core model of liquid fuel MSR was established. Then, ANSYS FLUENT16.0 software was employed to conduct three-dimensional numerical simulation of the flow field. The influence of hydraulic structure of reactor core was analysed by changing the structure of upper plenum, downcomer and lower plenum, and the corresponding flow distribution characteristics of the core are obtained. Finally, a suitable structure was proposed after step-by-step improvement. Results The simulation results show that increasing of the height of upper plenum can balance the flow distribution between central and peripheral channels, increasing of the width of the downcomer can reduce the vortex flow at the downcomer outlet and flattens the flow distribution at the same time. The cylindrical lower structure with shroud in lower plenum can restrain the vortex to a certain extent and make the flow distribution more gentle. Based on the analysis above, a reasonable hydraulic structure is proposed for the molten salt reactor. Conclusions The results of this study provide important reference for the further optimization design of liquid fuel molten salt reactor.
  • Nov. 25, 2022
  • Vol. 45, Issue 11, 110601 (2022)
  • DOI:10.11889/j.0253-3219.2022.hjs.45.110601
Research status and development trends of irradiation effects on memristor
Yuxiang WANG, Ge TANG, Yao XIAO, Xinyu ZHAO, Peng FENG, and Wei HU
As a strong candidate for the new type of non-volatile memories and artificial synaptic devices, memristor has a huge development prospect in aerospace, Mars exploration and other space science and application fields. Once large-scale application of memristor requires extremely stringent radiation resistance performance for the memristors. In order to improve the radiation resistance of memristors, it is necessary to explore the radiation effect mechanism and develop an effective radiation resistance technology. This paper summarizes the research status and trends of irradiation effects on memristors, describes the mechanism and analysis method of irradiation damage of memristor, and focuses on the irradiation effects of the memristors with transition metal oxide material system. Additionally, the possibility of scientific problems and key technologies are discussed, so as to provide some ideas for the radiation hardening and space application of memristor.
  • Nov. 25, 2022
  • Vol. 45, Issue 11, 110001 (2022)
  • DOI:10.11889/j.0253-3219.2022.hjs.45.110001