submitted time 2024-04-24
Abstract： [Background] The RF linac dedicated to boron neutron capture therapy clinic facility(BNCT02) in our institute is mainly composed of an ion source, a low energy beam transmission line, a radio frequency quadrupole accelerator and three high energy beam transmission lines. [Purpose] This study aims to ensure the safe operation of the BNCT02 accelerator. [Methods] A machine protection system (MPS) was designed based on Yokogawa PLC and Experimental Physics and Industrial Control System (EPICS) software toolkit. In order to improve reliability and safety, the system adopts a redundant design, consisting of two completely independent subsystems with consistent main input and output signals. [Results & Conclusions] The test results show that the response time of the BNCT02 accelerator MPS is less than 1.6ms, and it has the characteristics of high stability and reliability, which meets the operational requirements of the BNCT02 accelerator.
Subjects: Nuclear Science and Technology >> Particle Accelerator submitted time 2023-11-07
Abstract： EPICS, a software tool extensively used in large-scale scientific experiments such as particle accelerators. Depending on the scale of the facility, the number of EPICS PV can range from tens of thousands to millions. The ability to swiftly retrieve information related to EPICS PV can notably enhance the operational efficiency and maintenance of particle accelerators. To address this requirement, we designed and developed the EPICS PV information platform. This platform provides a unified user interface that supports the querying of PV lists, real-time statuses, historical data, put logs, IOC statuses, and IOC network information. It integrates these data points to offer a comprehensive view. The user interface of the platform leverages Web technology, with the server-side developed in the Node.js environment. This is complemented by software modules from the EPICS community. In addition, programs for network information collection and other cyclical executions are developed using the Python language. At present, the EPICS PV information platform has been successfully implemented in the CSNS accelerator, where it has significantly contributed to its effective operation and maintenance.
Subjects: Geosciences >> Space Physics submitted time 2017-01-22
Abstract： Multi-point synchronous magnetic field measurements can give more accurate space current density compared with the traditional single-point measurement, since multi-point measurement can eliminate the temporal change in the magnetic field. Based on the current density inversion method for multi-point magnetic field measurements, through simulation, several factors affecting space current density inversion are analyzed, such as the number of satellites, satellite formation configuration, satellite positioning precision, satellite attitude determination error, magnetic field measurement accuracy, external magnetic field intensity, external current density and so on. It is shown that 5-point measurements are better than 4-point measurements, and error in attitude determination and external magnetic field intensity are the main factors causing the error in current density inverted, while satellite formation configuration is also an important factor. According to the simulation, the maximum error in current density is less than 24% near the equator when the attitude determination error is 0.001癮nd the scale of the satellite formation is about 100km.
Peer Review Status:
Awaiting Review
Subjects: Geosciences >> Space Physics submitted time 2016-05-13
Abstract： Formation initialization for elliptic reference orbit is studied in this paper, and three formation initialization strategies for planner formation configuration are derived. Firstly, two impulsive initialization strategy is derived using the state transition matrix. Secondly, three and four in-track impulsive initialization strategies are studied using the Gauss perturbation equations with the principle of minimal fuel consumption. Finally, numerical simulations of three initialization strategies are carried out, and the sequence quadratic programming and genetic algorithm are proposed to optimize the numerical results. Simulation results show that three in-track impulsive initialization strategy requires about 41% less velocity increment compared with two impulsive initialization strategy, and four in-track impulsive initialization strategy requires almost equal velocity increment compared with three in-track impulsive initialization strategy.
Peer Review Status:Awaiting Review
Subjects: Geosciences >> Space Physics submitted time 2016-05-04
Abstract： To cope with the orbit transfer problem with multiple constraints and sensitive initial values around the libration point L1 of the Sun-Earth system (SEL1 point), a transfer trajectory design method based on hierarchical differential corrections and initial value polynomial is proposed. At first, constraints are analyzed in the process of designing the transfer trajectory around the libration point. According to different terminal constraints, the hierarchical differential correction method is proposed by considering orbit altitude, orbit inclination, right ascension of ascending node and track angle simultaneously. Then, by analyzing relation between constraint variables and control variables,the initial value expression is got to solve the initial value problem of differential corrections. Finally, transfer trajectory from the earth parking orbit whose altitude is 200 km to Halo orbit around SEL1 point is designed under the condition of multi-constraints. The simulation results indicate the hierarchical differential correction method can deal with the problem with multiple constraints and initial value polynomial can provide appropriate initial conditions for differential corrections so as to guarantee convergence of the algorithm. In conclusion, this method has good practicality.
Peer Review Status:Awaiting Review
Subjects: Geosciences >> Space Physics submitted time 2016-05-04
Abstract： In order to choose the best detection efficiency of different formations, quantitative evaluation of different formations shall be employed. In this paper, the existing evaluation parameters of four-point cooperative detection are analyzed and summarized and then based on the definition of volumetric tensor, the five-point formation is divided into five tetrahedrons and one main tetrahedron plus a fifth point to evaluate the detection efficiency. Finally, orbit data of five-spacecraft in one orbit period is used to simulate and analyze the two methods, and result shows that the method works well in evaluating five-point formation.
Peer Review Status:Awaiting Review
Subjects: Geosciences >> Space Physics submitted time 2016-04-22
Abstract：针对地月系L2点不同任务需求下的低耗能转移轨道设计问题,基于不变流形理论与混合优化技术,深入研究了不同月球借力约束与不同幅值Halo轨道的入轨点(简称HOI点)对转移轨道飞行时间与燃料消耗的影响,给出了HOI点选择策略。首先结合任务要求并考虑月球引力影响,在月球借力点施加不同约束条件,通过微分修正算法调整Halo轨道的稳定流形,设计月球到Halo轨道的转移轨道。采用遗传算法与微分修正算法相结合的混合优化策略,在同时考虑地球停泊轨道高度、倾角、升交点赤经与航迹角等多约束条件下,对燃料最优的地月转移轨道进行研究。最后,分析月球借力高度、借力方位角和不同HOI点对平动点转移轨道飞行时间与燃耗变化量的影响,对于考虑月球借力的地月平动点转移轨道设计与应用具有重要的参考价值。
Peer Review Status:Awaiting Review
Subjects: Geosciences >> Space Physics submitted time 2016-04-22
Abstract： Cube-Sat is the research focus in the field of micro satellite in recent years. In this paper,mission that with a cube-sat in the Sun synchronous orbit ( SSO) is taken as an example,then the orbit evolution of SSO cube-sat is studied considering both the influence of atmosphere drag and that of J_2 coefficient (the Earth' s oblateness perturbations to the second-order zonal coefficient). Orbit altitude , solar activity index and atmosphere models are researched respectively to show their impacts on the evolution of orbit,and numerical simulations are carried out. The work above indicates some conclusions as follows : perturbation force that produced by air drag plays an important role to decide the lifetime of SSO cube-sat , and there is a nonlinear relationship between the orbit altitude and the magnitude of orbital decay which is induced by atmosphere drag. Orbital decay based on high solar activity is obviously different from that based on low solar activity, and the relationship between F10.7 and the magnitude of orbital change is not linear. Considering various air drag models separately, the orbit evolutions are not equal,but their order of magnitude are almost the same. The analysis above is helpful to both the orbital choosing of SSO CubeSat and its orbit control.
Peer Review Status:Awaiting Review
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