Accurate knowledge of the charged particle bunch longitudinal (time) profile is important in the context of wakefield accelerators, Compton Light sources, x-ray SASE FELs and THz radiation sources. However, it is still a challenge to obtain this information for subpicosecond long bunches and microbunched beams with the required femtosecond (fs) resolution and nondestructively. Apart from determining the profile in a nondestructive manner, the ideal bunch diagnostic would enable extraction of all required information in a single shot, have a sufficiently high repetition rate to monitor each bunch, small footprint, good cost efficiency and reliability. In this paper we present the design of a longitudinal bunch profile monitor that can determine the charged particle bunch profile with femtosecond resolution, nondestructively and in a single shot via the spectral analysis of coherent Smith-Purcell radiation (cSPr). It is based on the simultaneous deployment of three gratings with different periodicities, each with its own set of detectors. The number of the frequency sampling points is equal to the number of the optical channels and the discrimination against background radiation is based on the different polarization properties of cSPr and background radiation. The rationales for the choices made to optimize the monitor operation will be presented and the criteria for determining the number of frequency sampling points will be discussed. The possible future developments of the monitor are also presented and discussed.

中文翻译：

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单次非破坏性监视器，用于飞秒分辨率的纵向亚皮秒束轮廓测量

在尾波加速器，康普顿光源，X射线SASE FEL和THz辐射源的背景下，准确了解带电粒子束的纵向（时间）轮廓非常重要。然而，对于亚皮秒长束和具有所需飞秒（fs）分辨率且无损检测的微束光束而言，获取此信息仍然是一个挑战。除了以非破坏性方式确定配置文件之外，理想的束诊断程序还可以一次提取所有所需信息，并具有足够高的重复率来监视每个束，占用空间小，具有良好的成本效益和可靠性。在本文中，我们介绍了纵向束轮廓仪的设计，该监视器可以确定飞秒分辨率的带电粒子束轮廓，通过相干Smith-Purcell辐射（cSPr）的光谱分析，无损且一次性完成。它基于同时部署三个周期不同的光栅，每个光栅都有自己的检测器。频率采样点的数量等于光通道的数量，对背景辐射的区分是基于cSPr和背景辐射的不同偏振特性。将介绍进行选择以优化监控器操作的基本原理，并讨论确定频率采样点数量的标准。还介绍并讨论了监视器的未来可能发展。它基于同时部署三个周期不同的光栅，每个光栅都有自己的检测器。频率采样点的数量等于光通道的数量，对背景辐射的区分是基于cSPr和背景辐射的不同偏振特性。将介绍进行选择以优化监控器操作的基本原理，并讨论确定频率采样点数量的标准。还介绍并讨论了监视器的未来可能发展。它基于同时部署三个周期不同的光栅，每个光栅都有自己的检测器。频率采样点的数量等于光通道的数量，对背景辐射的区分是基于cSPr和背景辐射的不同偏振特性。将介绍进行选择以优化监控器操作的基本原理，并讨论确定频率采样点数量的标准。还介绍并讨论了监视器的未来可能发展。频率采样点的数量等于光通道的数量，对背景辐射的区分是基于cSPr和背景辐射的不同偏振特性。将介绍进行选择以优化监控器操作的基本原理，并讨论确定频率采样点数量的标准。还介绍并讨论了监视器的未来可能发展。频率采样点的数量等于光通道的数量，对背景辐射的区分是基于cSPr和背景辐射的不同偏振特性。将介绍进行选择以优化监控器操作的基本原理，并讨论确定频率采样点数量的标准。还介绍并讨论了监视器的未来可能发展。