电子轰击离子源(Electron Impact Ion Source,EI源)作为小型化磁质谱仪的核心部件之一,其性能指标直接影响质谱仪器的质量分辨率与灵敏度。本文对小型化EI源的结构和电压驱动方式进行了改进和优化,旨在提升EI源的综合性能。采用离子光...电子轰击离子源(Electron Impact Ion Source,EI源)作为小型化磁质谱仪的核心部件之一,其性能指标直接影响质谱仪器的质量分辨率与灵敏度。本文对小型化EI源的结构和电压驱动方式进行了改进和优化,旨在提升EI源的综合性能。采用离子光学模拟软件simion-8.0构建了小型化EI源的三维模型,重点研究几何参数、离子推斥极结构以及驱动EI源的电压参数对离子聚焦性能和离子传输效率的影响。通过模拟离子的运动轨迹,得到离子的运动参数,同时利用相空间法,分析EI源的离子聚焦效果和离子传输效率。理论模拟结果表明:当聚焦极与电离室距离S1为1.2mm,主狭缝与聚焦极距离S2与S1的比值为1.6,主狭缝缝宽S3为2mm,推斥极为圆弧结构,且聚焦透镜和主狭缝透镜通过扫描高压恒压跟踪驱动方式时,离子的位置聚焦半径小于0.08mm,离子传输效率可达到99%以上。研究表明:经过几何参数、推斥极结构优化和电压驱动方式改进后的EI源,可大幅提高离子传输效率,提升聚焦效果,并能在全质量范围内保持离子聚焦性能稳定,上述特性使其在小型化磁质谱仪开发中具有显著优势。展开更多
It is known that ion-focused regime(IFR)can effectively suppress expansion of a relativistic electron beam(REB).Using the particle-in-cell Monte Carlo collision(PIC-MCC)method,we numerically investigate the propagatio...It is known that ion-focused regime(IFR)can effectively suppress expansion of a relativistic electron beam(REB).Using the particle-in-cell Monte Carlo collision(PIC-MCC)method,we numerically investigate the propagation of an REB in neutral gas.The results demonstrate that the beam body is charge neutralization and a stable IFR can be established.As a result,the beam transverse dimensions and longitudinal velocities keep close to the initial parameters.We also calculate the charge and current neutralization factors of the REB.Combined with envelope equations,we obtain the variations of beam envelopes,which agree well with the PIC simulations.However,both the energy loss and instabilities of the REB may lead to a low transport efficiency during long-range propagation.It is proved that decreasing the initial pulse length of the REB can avoid the influence of electron avalanche.Using parts of REB pulses to build a long-distance IFR in advance can improve the beam quality of subsequent pulses.Further,a long-distance IFR may contribute to the implementation of long-range propagation of the REB in space environment.展开更多
文摘电子轰击离子源(Electron Impact Ion Source,EI源)作为小型化磁质谱仪的核心部件之一,其性能指标直接影响质谱仪器的质量分辨率与灵敏度。本文对小型化EI源的结构和电压驱动方式进行了改进和优化,旨在提升EI源的综合性能。采用离子光学模拟软件simion-8.0构建了小型化EI源的三维模型,重点研究几何参数、离子推斥极结构以及驱动EI源的电压参数对离子聚焦性能和离子传输效率的影响。通过模拟离子的运动轨迹,得到离子的运动参数,同时利用相空间法,分析EI源的离子聚焦效果和离子传输效率。理论模拟结果表明:当聚焦极与电离室距离S1为1.2mm,主狭缝与聚焦极距离S2与S1的比值为1.6,主狭缝缝宽S3为2mm,推斥极为圆弧结构,且聚焦透镜和主狭缝透镜通过扫描高压恒压跟踪驱动方式时,离子的位置聚焦半径小于0.08mm,离子传输效率可达到99%以上。研究表明:经过几何参数、推斥极结构优化和电压驱动方式改进后的EI源,可大幅提高离子传输效率,提升聚焦效果,并能在全质量范围内保持离子聚焦性能稳定,上述特性使其在小型化磁质谱仪开发中具有显著优势。
基金supported by the Joint Funds of the National Natural Science Foundation of China(Grant Nos.61372050 and U1730247)。
文摘It is known that ion-focused regime(IFR)can effectively suppress expansion of a relativistic electron beam(REB).Using the particle-in-cell Monte Carlo collision(PIC-MCC)method,we numerically investigate the propagation of an REB in neutral gas.The results demonstrate that the beam body is charge neutralization and a stable IFR can be established.As a result,the beam transverse dimensions and longitudinal velocities keep close to the initial parameters.We also calculate the charge and current neutralization factors of the REB.Combined with envelope equations,we obtain the variations of beam envelopes,which agree well with the PIC simulations.However,both the energy loss and instabilities of the REB may lead to a low transport efficiency during long-range propagation.It is proved that decreasing the initial pulse length of the REB can avoid the influence of electron avalanche.Using parts of REB pulses to build a long-distance IFR in advance can improve the beam quality of subsequent pulses.Further,a long-distance IFR may contribute to the implementation of long-range propagation of the REB in space environment.
