Electron acceleration by a chirped short intense laser pulse in vacuum

Electron acceleration by a chirped short intense laser pulse has been studied in a vacuum. A linear frequency chirp omega(t)=omega(0)(1-alpha t) has been considered, where omega(0) is the laser frequency at z=0 and alpha is frequency chirp parameter. Transverse electron momentum increases due to frequency chirp and the electron escapes from the laser pulse near the pulse peak. Longitudinal momentum also increases due to increase in longitudinal force. Retained electron energy is much higher with frequency chirp than that without frequency chirp. Retained energy peaks for a suitable value of alpha; the value of which decreases with laser intensity and initial electron energy.