RFQ出口的束流纵向发射度对于强流直线加速器，尤其是超导直线加速器至关重要。本项目依托中科院近物所低能量强流重离子研究装置(LEAF)，建立一套纵向发射度测量方法，通过模拟和实验手段系统研究基于外聚束方式的重离子RFQ的出口束流纵向发射度及影响束流纵向发射度的因素。本项目研究将原理性验证重离子RFQ外聚束方式对减小束流纵向发射度的贡献；尤其针对毫安级强流重离子束，探索出一套获得高加速效率和小纵向发射度的优化方案，为国内外新一代强流高功率重离子直线加速器的方案设计提供重要参考数据。

Longitudinal emittance at the exit of RFQ is vital for the high-intensity LINACs, especially for the super-conducting LINACs. By establishing a longitudinal emittance measurement method based on LEAF (Low Energy high-intensity heavy-ion Accelerator Facility) at IMP, this project is to systematically study the beam longitudinal emittance both theoretically and experimentally at the exit of the RFQ which is based on external bunching, and to investigate the factors that affect the longitudinal emittance of the beam. The contribution of external bunching to reducing the longitudinal emittance will be verified in principle. With this study, we are aiming to find an optimized scheme to achieve high acceleration efficiency and small longitudinal emittance, especially in terms of intense heavy-ion beams with intensities of up to milliampere level. This study will provide important reference to the design of new-generation high-power high-intensity heavy-ion LINACs in the world.