计算机模拟CT法测量束流发射度的弧度定标

Radian calibration of measuring beam emittance by computer simulated CT method

发射度是反映加速器束流品质的重要物理参数,束流发射度的精确测量在工业生产中日益重要。CT法测束流发射度是利用CT原理与参数可调的输运元件相结合的方法测束流发射度。该方法具有对实验器材要求不高,不需要预设初始束流发射度图像,测量精度高的优点。在以往的CT法测量束流发射度实验中,四极磁铁的控制电流是均匀选取的,均匀的电流值对应的投影角度是不均匀的,角度的不均匀造成发射度图像的重建精度不高。提出先计算出的均匀角度对应的电流值,再根据电流值调节四极磁铁的控制电流;并编写模拟程序,进行模拟计算。模拟计算结果表明:弧度定标确定四极磁铁的控制电流比直接选取均匀四极磁铁电流值的方法测得的发射度更精确,同时减少了测量次数。

Emittance is an important parameter which can reflect the quality of accelerator beam. Accurate measuring of beam emittance becomes more and more important in industrial production. CT method to measure beam emittance is a method that combines CT principle and parameters-adjustable transport elements. It can measure accurately, demands little of experimental equipment, and does not need to preset initial beam emittance image. In the past experiments of measuring beam emittance with CT method, quadrupole electromagnet current was not even, thus there being no better reestablishment accuracy of emittance image. To get even current, this thesis does simulation calculation. It shows that emittance can be more accurate by getting quadrupole electromagnet current through radian calibration, and at the same time the measurement times decrease.