采用五阶修正的聚焦激光光场方程模拟研究了由Singh提出的在电子和激光脉冲作用尾部阶段施加外场的加速方案,将Singh方案中采用的外加磁场改成了外加电场,并且考虑了光束的纵向电场和光束衍射效应.模拟结果显示,电子可以从加速相位阶段被外场导入下一个加速相位阶段而不进入减速相位阶段,因此电子能获得比不加外场方案更高的净能增益. A modified fifth-order focused laser field equation was used to simulate the acceleration scheme proposed by Singh for applying external fields at the tail of electron and laser pulses. The applied magnetic field in Singh scheme was changed to an applied electric field, Longitudinal electric field and beam diffraction effect.The simulation results show that the electrons can be introduced from the accelerating phase to the next phase of accelerating without entering the phase of decelerating phase so that the electron can obtain a higher net energy gain than that without the external scheme.