High photon flux Kα Mo x-ray source driven by a multi-terawatt femtosecond laser at 100 Hz

We develop a pulsed hard x-ray K α source at 17.4 keV produced by the interaction of a multi-terawatt peak power in-frared femtosecond laser pulse with a thick molybdenum (Mo) target at a 100 Hz repetition rate. We measure the highest Mo K α photon production reported to date corresponding to a K α photon flux of 1×10 11 ph∕sr·s and an estimated peak brightness of ∼2.5×10 17 ph∕s·mm 2 ·mrad 2 0.1%bandwidth at ∼5 × 10 18 W∕cm 2 driving laser intensity.The Integrated Initiative of European Laser Research Infrastructure

22 W average power multiterawatt femtosecond laser chain enabling 1019 W/cm2 at 100 Hz

International audienceWe measure the wavefront distortions of a high peak power ultrashort (23 fs) laser system under high average power load. After 6 min-100 Hz operation of the laser at full average power (> 22 W after compression), the thermally induced wave-front distortions reach a steady state and the far-field profile of the laser beam no longer changes. By means of a deformable mirror located after the vacuum compressor, we apply a static pre-compensation to correct those aberrations allowing us to demonstrate a dramatic improvement of the far-field profile at 100 Hz with the reduction of the residual wavefront distortions below λ/16 before focusing. The applied technique provides 100 Hz operation of the femtosecond laser chain with stable pulse characteristics, corresponding to peak intensity above 10 19 W/cm 2 and average power of 19 W on target, which enables the study of relativistic optics at high repetition rate using a moderate f-number focusing optics (f/4.5)

High repetition rate (100 Hz), high peak power, high contrast femtosecond laser chain

High intensity femtosecond laser are now routinely used to produce energetic particles and photons via interaction with solid targets. However, the relatively low conversion efficiency of such processes requires the use of high repetition rate laser to increase the average power of the laser-induced secondary source. Furthermore, for high intensity laser-matter interaction, a high temporal contrast is of primary importance as the presence of a ns ASE pedestal (Amplified Spontaneous Emission) and/or various prepulses may significantly affect the governing interaction processes by creating a pre-plasma on the target surface. We present the characterization of a laser chain based on Ti:Sa technology and CPA technique, which presents unique laser characteristics : a high repetition rate (100 Hz), a high peak power (> 5 TW) and a high contrast ratio (ASE<10(-10)) obtained thanks to a specific design with 3 saturable absorbers inserted in the amplification chain. A deformable mirror placed before the focusing parabolic mirror should allow us to focus the beam almost at the limit of diffraction. In these conditions, peak intensity above 1019W. cm(-2) on target could be achieved at 100 Hz, allowing the study of relativistic optics at a high repetition rate