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

Abstract

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

Exploring phase contrast imaging with a laser-based Kα x-ray source up to relativistic laser intensity

“…The increase of laser intensity on target induces an enlargement of the x-ray source size (s ∝ I γ with γ = 0.32) as discussed previously 28,29,49 . Thanks to the high temporal intensity contrast ratio of the laser pulse (~10 10 ) and the good pointing stability (less than 1 µm displacement for a focused diameter of 6.2 µm at 1/e 2 ) of the laser source associated with a precise targetry positioning system 29 , this increase is limited to a factor ~3.5 (11 µm ≤ s ≤ 38 µm). Since the number of produced x-ray photons varies with laser intensity (Fig.…”

“…1b) and the x-ray spectrum (Fig. 1c) are acquired 29 with a 16 bits direct detection PIXIS-XB: 1024BR camera from Princeton Instruments, cooled down to −60 °C, with 1024 × 1024 pixels arrays and a pixel size of 13 × 13 µm 2 . The sample is then inserted.…”

“…1a). More details on the target surface can be found elsewhere 29 . The focal spot diameter is ~6 µm (FWHM) with the encircled energy at FWHM measured at ~34%, and the maximum energy of ~130 mJ is delivered on target.…”

“…Moreover, these sources provide collimated x-ray beams at low divergence limiting the field of view. In this context, an attractive solution is the K α x-ray table-top source driven by femtosecond laser systems 28,29 .…”

“…Finally, this source also has a pulse duration below one picosecond 32 , suitable to perform time-resolved applications. With the new advanced driving laser sources, brightness comparable to the 3 rd generation of synchrotrons has been demonstrated 29,30 . Previous studies have shown the capacity of this source for PCI using the method of in-line or propagation-based phase contrast imaging (PBI) 31,33,34 for biological samples 30,[35][36][37][38][39] , for shock wave characterization in the context of fusion plasma 40 , or for material characterization at submicron scale 41 .…”