The interaction of short laser pulses with small rare gas clusters is investigated by using a microscopic, semi-classical model with an explicit treatment of the inner-atomic dynamics. Field and collisional ionisation as well as recombination are incorporated self-consistently so that the use of rates for these processes could be avoided. The laser absorption and ionisation mechanisms in cluste...

Recent research and development in laser machining and laser forming processes is reviewed. In the laser machining area, striation formation and prediction, and gas jet workpiece interactions are discussed. In the laser forming area, strain rate effects, and convex forming are presented.

We report on a novel resonantly-pumped, erbium (Er)-based, gas-cooled disk laser (GCDL) scalable to highaverage power (HAP). The GCDL uses edge-pumped composite laser disks known for their near perfect pump uniformity and compact configuration. Edge pumping enables a long path for pump absorption, which permits using low Er concentration and limits upconversion losses. Resonant operation reduce...

Beam-driven plasma wakefield acceleration using low-ionization-threshold gas such as Li is combined with laser-controlled electron injection via ionization of high-ionization-threshold gas such as He. The He electrons are released with low transverse momentum in the focus of the copropagating, nonrelativistic-intensity laser pulse directly inside the accelerating or focusing phase of the Li blo...

In this paper we present a prototype instrument for remote open-path detection of nitrous oxide. The sensor is based on a 4.53 μm quantum cascade laser and uses the chirped laser dispersion spectroscopy (CLaDS) technique for molecular concentration measurements. To the best of our knowledge this is the first demonstration of open-path laser-based trace-gas detection using a molecular dispersion...

Single photon counting techniques were used with an x-ray CCD camera to measure features of synchrotron-like x-ray spectra generated by betatron oscillations of electrons in a laser wakefield accelerator (LWFA) with different injection techniques. Measurements were made using the Hercules laser system at the University of Michigan. With a single stage gas cell, we demonstrate that pure helium g...

Bright betatron x-ray has been generated using an Ar clustering gas jet target irradiated with a 3 TW ultra-high contrast laser. The measured emission flux with photon energy > 2.4 keV reaches 2×10 8 photons/shot. It is ten-fold enhancement comparing to the emission flux produced by using gas target in the same laser parameters. Observation shows that much larger electron beam charge and diverg...

Large KrF amplifiers use electron beams to excite the laser gas. By necessity, the diode and laser cavity must be isolated by a mechanical barrier; an electron beam diode operates in vacuum, while the laser cavity may be filled with amagats of gas. Isolation is typically accomplished by a metal foil of low mass density which is mechanically supported by a structure having multiple open slots se...

In laser drilling, an assist gas is often used to remove material from the drilling point. In order to design assist gas nozzles to minimize spatter formation, measurements of spatter trajectories are required. We apply computer vision methods to measure the 3D trajectories of spatter particles in a laser cutting event using a stereo camera configuration. We also propose a novel method for cali...