【摘要】 介绍了一台基于电偏转扫描方法的强流离子束发射度仪,讨论了发射度仪硬件的系统构成和设计要点,该发射度仪采用阶梯型电压对通过前缝的束流进行扫描来获得束流散角信息。并对测量计算软件和数据处理方法进行了介绍,采用了先扣除本底,再设置阈值的方法进行数据处理。处理后的数据利用程序可获得均方根和边界发射度、束斑大小、最大正负散角以及发射度相图。利用该发射度仪对ECR离子源引出的强流质子束的发射度进行了测量,并对测量数据进行了分析。对于引出电压为50 kV、脉冲重复频率为166 Hz、脉冲宽度为1 ms、平均束流强度为4 mA的质子脉冲束,其归一化均方根发射度为0.27πmm.mrad。更多还原

【Abstract】 A high-current ion beam emittance measurement unit Allison scanner was introduced.The scanner consists of two slits and a pair of electrical deflection plates driven by a ±1.2 kV bipolar power supply.When the scanner moves to a measurement position,the step-changed voltages are fed to the deflection plates.The divergence angle of the ions passing through the rear slit can be calculated from the voltages.The data of position,divergence angle and beam current are collected to the computer through an AD card.A program of measuring and data processing can handle the case of pulsed beam.In order to obtain correct emittance results,subtracting background and setting threshold value are important.The program can calculate the root-mean-square emittance,the beam size,the biggest positive and negative divergence angle and the boundary emittance.The root-mean-square emittance of a pulsed beam extracted from a 50 keV ECR proton source was measured,which took about 2.5 min.The average beam intensity was 4 mA with beam pulse of 1 ms at 166 Hz,and its normalized emittance was 0.27 πmm·mrad.更多还原