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Comment on “Even-order harmonic generation from nonlinear Thomson backscatter in a tightly focused Gaussian laser pulse” [Phys. Plasmas 29, 043102 (2022)]

Hong et al. [Phys. Plasmas 29, 043102 (2022)] researched the nonlinear Thomson backscatter in a highly focused Gaussian linear laser pulse. They studied the law of backward harmonic spectrum and electron motion trajectory and put forward the view that “the electron will be pushed to the −z-axis by the responsible force of the falling edge of the laser pulse when the interaction time is long enough.” In this Comment, we study the electron motion law under the precise laser pulse expression. We find and explain that the initial position of the electron is the reason why the electron is pushed to the −z-axis. Only when the initial position of the electron is in the −z half-axis, the electron will be pushed away at the end of the pulse.