Design and implementation of feedback logic of FOFB for HEPS

Purpose As a fourth-generation light source,High Energy Photon Source(HEPS)has much more stringent requirements to the beam orbit stability in both horizontal and vertical directions than the previous sources due to the much smaller beam sizes.Methods A Fast Orbit FeedBack(FOFB)system,with the closed-loop bandwidth around 500 Hz,is needed to meet the critical requirements.The latency of the FOFB system is the key to achieve these requirements.Results Proper design and implementation of the feedback logic to have low latency is illustrated in the paper.Calculation accuracy is kept in the whole operation except for the last-minute data translation into 32-bit floating point number.

The accelerator control system of CSNS

The China Spallation Neutron Source is an accelerator-based user facility for neutron,proton,muon applications and so on.The designed proton beam power is 100 kW for the first phase.Overall,the scope of accelerator control system covers four parts,the global systems,the device layer local controls and remote controls,the high-level applications and services and the integration of conventional facilities.The principle guideline is to adopt as many as possible matured technologies and commercial products in the design and implementation.The control system is based on Experimental Physics and Industrial Control System.VME64x bus is chosen for timing system and fast protection system.PLCs and embedded industrial computers are used in the device layer slow controls.Control System Studio is adopted as the high-level applications.Blade server-based virtualization platform is deployed for the computer system.The accelerator control system was completed in September 2017 and then transited to routine operations.The design,implementation and operation of the accelerator control system are described in this paper.

The run management system for CSNS

Purpose In order to increase CSNS beam power from 100 to 500 kW,the linac injection energy needs to be increased from 80 to 300 MeV.The combined layout of superconducting spoke cavities and elliptical cavities will be adopted to accelerate H−beam to 300 MeV.In this paper,a compact single spoke cavity withΦ50-mm beam aperture was proposed,with the RF performance of the spoke cavity optimized to Ep/Eacc<5,Bp/Eacc<9,as well as the good multipacting behavior.Methods CST Microwave Studio was used to optimize the RF performance(Epeak/Eacc,Bpeak/Eacc,R/Q)with cavity geometry parameters.After electromagnetic design was finished,multipacting behavior was studied with CST Particle Studio module,and cavity shape modification was made to get a reasonable<SEY>value.Results The simulation got optimum results of Epeak/Eacc=4.97 and Bpeak/Eacc=8.42 mT/(MV/m),and the<SEY>max is 1.52 at Eacc=7.74 MV/m.Conclusion A 648 MHzβg=0.4 single spoke cavity with beam apertureΦ50 mm was proposed in the paper.This compact cavity may be a very promising option for CSNS linac upgrading.In addition to the optimization of the RF parameters,the multipacting behavior of the cavity is also studied,and cavity shape is optimized to reduce<SEY>value.