in the present study, an ultrafine grained (ufg) 304l stainless steel with the average grain size of 300 nm was produced by a combination of cold rolling and annealing. weldability of the ufg sample was studied by nd: yag laser welding under different welding conditions. taguchi experimental design was used to optimize the effect of frequency, welding time, laser current and laser pulse duratio...

Ultrafast dynamics in atomic, molecular and condensed-matter systems are increasingly being studied using optical-pump, X-ray probe techniques where subpicosecond laser pulses excite the system and X-rays detect changes in absorption spectra and local atomic structure(1-3). New opportunities are appearing as a result of improved synchrotron capabilities and the advent of X-ray free-electron las...

All-optical ideas provide a potential to dramatically cut off the size and cost of x-ray light sources to the university-laboratory scale, with the combination of the laser-plasma accelerator and the laser undulator. However, the large longitudinal energy spread of the electron beam from laser-plasma accelerator may hinder the way to high brightness of these all-optical light sources. In this p...

As an important x-ray source, enhancement of x-ray emissions from laser-produced plasmas is significant for various applications. Due to less expanding kinetic loss, gold foam with low initial density can have an enhanced x-ray conversion efficiency compared with solid-density gold. However, low-Z impurities within gold foam targets will diminish the enhancement remarkably, and should be tightl...

Laser pump-X-ray probe experiments require control over the X-ray pulse pattern and timing. Here, the first use of pseudo-single-bunch mode at the Advanced Light Source in picosecond time-resolved X-ray absorption experiments on solutions and solids is reported. In this mode the X-ray repetition rate is fully adjustable from single shot to 500 kHz, allowing it to be matched to typical laser exc...

The advent of X-ray lasers allowed the realization of compact coherent soft X-ray sources, thus opening the way to a wide range of applications. Here we report the observation of unexpected concentric rings in the far-field beam profile at the output of a two-stage plasma-based X-ray laser, which can be considered as the first manifestation of a mirage phenomenon in X-rays. We have developed a ...