Progress on the construction of the 100 MeV/100 kW electron linac for the NSC KIPT neutron source

IHEP, China is constructing a 100 MeV/100 kW electron Linac for NSC KIPT, Ukraine. This linac will be used as the driver of a neutron source based on a subcritical assembly. In 2012, the injector part of the accelerator was pre-installed as a testing facility in the experimental hall #2 of IHEP. The injector beam and key hardware testing results met the design goal. Recently, the injector testing facility was disassembled and all of the components for the whole accelerator have been shipped to Ukraine from China by the ocean shipping. The installation of the whole machine in KIPT will be started in June, 2013. The construction progress, the design and testing results of the injector beam and key hardware are presented.     

Preliminary study of residual orbit oscillation in BEPCⅡ

BEPCII has two rings each with an injection system. The injection system of each ring consists of two kicker magnets and a septum magnet. The injection layout of two rings is the same. Both two kickers would kick the beam in horizontal plane. The betatron phase advance in the horizontal plane between two kickers is designed exactly 180° in order to reduce the perturbation to the circulating beams during injection. In fact, the residual orbit oscillation will originate because of the existence of a variety of errors. The Librea Electron BPM processor is used to acquire the beam position data in turn-by-turn mode and to analyze the residual orbit oscillation. According to the measurement results, minimization of the residual orbit oscillation can be done by adjusting the peak field strength and trigger timing delay of two kickers. With very small residual orbit oscillation the two beams can keep collision condition during the injection.     

Design of BEPCⅡ bunch current monitor system

BEPCⅡ is an electron-positron collider designed to run under multi-bunches and high beam current condition. The accelerator consists of an electron ring, a positron ring and a linear injector. In order to achieve the target luminosity and implement the equal bunch charge injection, the Bunch Current Monitor (BCM) system is built on BEPCⅡ. The BCM system consists of three parts: the front-end circuit, the bunch current acquisition system and the bucket selection system. The control software of BCM is based on VxWorks and EPICS. With the help of BCM system, the bunch current in each bucket can be monitored in the Central Control Room. The BEPCⅡ timing system can also use the bunch current database to decide which bucket needs to refill to implement ``top-off' njection.     

单次通过型束流位置探测器的束流位置测量方法

针对当前单次通过型数字束流位置探测器（BPM）有效采样点数少、数据信噪比低、测量分辨率差的问题，提出了一种基于“束流单次通过”的数字BPM测量改进算法。该算法通过模拟信号的功分-延迟-合成，增加了有效采样数据，并通过采样数据的截取与数据拼接、数字滤波等数据处理方式，提高了采样数据的信噪比，并最终实现了BPM测量分辨率的提高。实验结果表明，该算法在不改变模数转换器（ADC）采样率的情况下，将单次通过型BPM的测量分辨率提高了约2倍。该测量方法为提高单次通过型BPM的测量分辨率提供了一种新的解决方案，已成功应用于北京正负电子对撞机（BEPCII）和高能同步辐射光源（HEPS）直线加速器项目中。