Terawatt-Attosecond Soft X-ray Pulse Generation in X-ray Free Electron Laser.

For real time observations of electron motion inside atoms, molecules and solids via pump-probe type of experiments, a few cycle infrared optical laser pulse is used initially as a pump to excite the electron dynamics and an attosecond pulse is used as a probe. To carry out these experiments, such shortest photon pulse needs to be develop. In free electron laser, a pulse of 270 attosecond full-width half maximum (FWHM) duration at 1 nm radiation wavelength based on our proposed single current spike scheme [1], is shown in simulations. According to the scheme, one current spike with good contrast ratio in an electron bunch is repeatedly used to amplify the seed radiation spike to a terawatt (TW) level of power. In our preliminary simulation for soft X-ray case, initial electron-beam energy spread is lower than 0.1%. However, for the realistic simulation, later stages electron-beam degradation due to the repeated use of a single spike should be taken into account. [ABSTRACT FROM AUTHOR]