光电子能量角度分布和空间电荷效应对变像管条纹相机的影响

基于飞秒条纹相机系统和飞秒电子衍射系统设计需求,通过蒙特卡罗方法模拟研究了在阴栅加速区光电子能量、角度分布和空间电荷效应对光电子时间弥散和能量弥散的影响。确定了紫外和软X射线波段入射光电阴极时,光电子六种初始能量分布的时间弥散精确值。分析了光电子发射电流密度、加速电场和时间弥散的关系。发现了电子脉冲在加速区轴向速度的线性啁啾、能量弥散变化和在自由区不相同。

Influence of photoelectron energy and angular distribution and space charge effect on streak cameras

Based on study of femtosecond streak camera system and femtosecond electron diffraction system, the influence of photoelectron energy, angular distribution and space charge effect on photoelectron time and energy spread in photocathode-mesh acceleration region is analyzed using Monte Carlo simulation. When the ultraviolet and soft X-ray incident photocathode, the time spread values of six types of photoelectron initial energy distribution is given. The relationship of electronic time spread between emission current density and accelerating field is analyzed. Electrons redistribute themselves inside the pulse, a linear velocity chirp develops on the electron pulse in acceleration region, the energy dispersion changes differently from that in free propagation region. The analysis and findings are useful for the study of ultrafast electronic propagation dynamics and the design of femtosecond streak camera, femtosecond electron diffraction and energy compensation components.