A precise analysis of the electron capture process through chirping wave frequency from a phase viewpoint

Abstract

The mechanism of electron capture and acceleration in a chirped plane-wave laser pulse is investigated from the point of view of phase evolution and phase velocity synchronization. An in depth analysis shows that the phase evolution process, under appropriate conditions, changes at one special point due to the chirping effect, which causes the electrons to be captured in the pulse and remain in the acceleration stage for a long time rather than oscillating between acceleration and deceleration. This point is a turning point of the phase evolution, and the changing process of the phase direction is named U-turn.