CSNS/RCS次级准直器吸收体的冷却设计

作为CSNS/RCS横向束流准直系统的关键部件,次级准直器用于吸收经主准直器散射后不在预定轨道的束晕粒子,其工作原理决定了该设备要求满足强辐射环境下的稳定性、超高真空及高定位精度等要求。基于主准直器的设计及研制经验,对次级准直器结构方案及控制系统进行详细设计。针对关键部件吸收体,结合辐射防护分析结果,考虑水冷降温的方式,设计了控制程序,通过有限元分析软件ANSYS对其进行瞬态热分析,保证吸收体设计的可行性。     

Study on the effects of chromaticity and magnetic field tracking errors at CSNS/RCS

The Rapid Cycling Synchrotron (RCS) is a key component of the China Spallation Neutron Source (CSNS). For this type of high intensity proton synchrotron, the chromaticity, space charge effects, and magnetic field tracking errors between the quadrupoles and the dipoles can induce beta function distortion and tune shift, and induce resonances. In this paper, the combined effects of chromaticity, magnetic field tracking errors and space charge on beam dynamics at CSNS/RCS are studied systemically. 3-D simulations with different magnetic field tracking errors are performed by using the code ORBIT, and the simulation results are compared with the case without tracking errors.     

Design and simulation of a wire scanner for the CSNS linac

In this paper,we report the design and simulation of a wire scanner for the linac of the CSNS(China Spallation Neutron Source).The wire scanner is used to measure the transverse beam profile andthe emittance.The effect of beam energy change upon the mechanical design of the wire scanner must beconsidered.The simulation results of heat on the two specified wires,tungsten and carbon,by using the finite element method software,ANSYS,are presented.In addition,the effect of wire deformation on the beam profile measurement is qualitatively analyzed,and the signal level of the wire scanner is discussed.     

Measurements of the 107Ag neutron capture cross sections with pulse height weighting technique at the CSNS Back-n facility

Silver indium cadmium (Ag-In-Cd) control rod is widely used in pressurized water reactor nuclear power plants, and it is continuously consumed in a high neutron flux environment. The mass ratio of ¹⁰⁷Ag in the Ag-In-Cd control rod is 41.44%. To accurately calculate the consumption value of the control rod, a reliable neutron reaction cross section of the ¹⁰⁷Ag is required. Meanwhile, ¹⁰⁷Ag is also an important weak r nucleus. Thus, the cross sections for neutron induced interactions with ¹⁰⁷Ag are very important both in nuclear energy and nuclear astrophysics. The (n,γ) cross section of ¹⁰⁷Ag has been measured in the energy range of 1-60 eV using a back streaming white neutron beam line at China spallation neutron source. The resonance parameters are extracted by an R-matrix code. All the cross section of ¹⁰⁷Ag and resonance parameters are given in this paper as datasets. The datasets are openly available at http://www.doi.org/10.11922/sciencedb.j00113.00010.     

Design of the low energy beam transport line for the China spallation neutron source

The design of the China Spallation Neutron Source (CSNS) low-energy beam transport (LEBT) line, which locates between the ion source and the radio-frequency quadrupole (RFQ), has been completed with the TRACE3D code. The design aims at perfect matching, primary chopping, a small emittance growth and sufficient space for beam diagnostics. The line consists of three solenoids, three vacuum chambers, two steering magnets and a pre-chopper. The total length of LEBT is about 1.74m. This LEBT is designed to transfer 20mA of H-pulsed beam from the ion source to the RFQ. An induction cavity is adopted as the pre-chopper. The electrostatic octupole steerer is discussed as a candidate. A four-quadrant aperture for beam scraping and beam position monitoring is designed.     

Neutron capture cross section of 169Tm measured at the CSNS Back-n facility in the energy region from 30 to 300 keV

The capture cross sections of the ¹⁶⁹Tmbegin{document}$ (n, gamma) $end{document} reaction were measured at the back streaming white neutron beam line (Back-n) of the China Spallation Neutron Source (CSNS) using four C₆D₆ liquid scintillation detectors. The background subtraction, normalization, and correction were carefully considered in the data analysis to obtain accurate cross sections. For the resonance at 3.9 eV, the R-matrix code SAMMY was used to determine the resonance parameters with the internal normalization method. The average capture cross sections of ¹⁶⁹Tm for energy between 30 and 300 keV were extracted relative to the ¹⁹⁷Aubegin{document}$ (n, gamma) $end{document} reaction. The measured cross sections of the ¹⁶⁹Tmbegin{document}$ (n, gamma) $end{document} reaction were reported in logarithmically equidistant energy bins with 20 bins per energy decade with a total uncertainty of 5.4% – 7.0% in this study and described in terms of average resonance parameters using a Hauser-Feshbach calculation with fluctuations. The point-wise cross sections and the average resonance parameters showed fair agreement with the evaluated values of the ENDF/B-VIII.0 library in the energy region studied.     

Design and analysis of the tunnel connecting the beamcorridor and the spectrum hall of the CSNS

There is a tunnel connecting the beamcorridor and the target station in the spectrum hall in the CSNS project.The length of the tunnel is about 20 m.The shielding design of the tunnel is very significant for the persons working in the spectrum hall because the tunnel is not covered ed soil for shielding.In order to reduce the dose rate at the exit of the cable ducts,we use the ISIS construction,which is designed with four turnings,as a reference for the tunnel design.The thickness of the shielding is obtained by a simulationwith the Monte Carlo Code FLUKA.The result is compared with the data obtained with Moyer Mode and the reliability of the simulation is proved.This paper provides the basis for the design of the tunnel.     

中国散裂中子源快循环同步加速器主准直器的设计与研究

为满足强流加速器对准直器高散热性能、高抗辐射性能、超高真空、高定位精度、高稳定性和在线实时调整等特殊要求,在CSNS/RCS主准直器设计时针对结构方案和控制方案进行了详细设计和研究,针对关键部件：刮束器、真空盒、驱动装置和远程快速拆卸装置等设计难点进行了阐述,在设计中使用ANSYS完成了刮束器的热分析及支架强度和变形校核,用FLUKA程序对辐射屏蔽进行了分析和设计,确保主准直器设计的可靠性。     

中国散裂中子源磁铁系统和样机研制

中国散裂中子源(China Spallation Neutron Source, CSNS)快循环同步加速器(Rapid Cycling Synchrotron, RCS)磁铁由24块二极磁铁、48块四极磁铁、16块六极磁铁和若干斜四极磁铁以及校正磁铁组成, 其中二极磁铁和四极磁铁是带直流偏置的25Hz正弦交流励磁, 铁芯和线圈导体将产生不可忽视的涡流效应. 为了积累批量生产磁铁的制造经验, 探索磁铁后期处理和磁场测量方法, 已完成了中空水冷铝绞线试样线圈的研制, 启动了二极磁铁和四极磁铁样机的研制. 本文将对相关进展进行介绍.     

Control system for the CSNS ion source test stand

A penning plasma surface H-ion source test stand for the CSNS has just been constructed at the IHEP.In order to achieve a safe and reliable system,nearly all devices of the ion source are designed to have the capability of both local and remote operation function.The control system consists of PLCs and EPICS real-time software tools separately serving device control and monitoring,PLC integration and OPI support.This paper summarizes the hardware and software implementation satisfying the requirements of the ion source control system.