<title>Ultrashort x-ray pulse generation using laser-driven accelerators</title>

Abstract

The generation of ultra-short x-ray pulses from femtosecond electron bunches, produced with laser driven plasma based accelerators, is discussed. The proposed accelerator relies on standard laser wakefield excitation by a high power ultra- short laser drive pulse in a plasma. Femtosecond duration electron bunches are produced through laser triggered injection using the colliding laser pulse scheme. Numerical simulations of test particles, with prescribed plasma and laser fields, indicate that for a 5 TW laser drive pulse, the wakefield acceleration scheme has the capability to produce relativistic (10s of MeV's) electron bunches over an acceleration length equal to the diffraction distance of the laser beam. The colliding pulse offers the possibility to produce femtosecond long electron bunches with peak currents on the order of a kilo Ampere, fractional energy spread of order a few percent and normalized transverse emittance less than 1 mm-mrad using 1 TW injection pulses. An example of the performance of this electron beam source for the generation of femtosecond X-rays using Bremsstrahlung and laser scattering will be discussed.