We report on an experimental study on the interaction of a high-contrast 40 fs duration 2 TW laser pulse with an argon-cluster target. A high-charge, homogeneous, large divergence electron beam with moderate kinetic energy (~2 MeV) is observed in the forward direction. The results show that an electron beam with a charge as high as 12 nC can be obtained using a table-top laser system. It was demonstrated that the accelerated electron beam is suitable for a variety of applications such as micro-radiography of thin samples in a wide field of view. It can also be applied for in vitro dosimetry studies.

It is shown that various spectroscopic methods based on measurements of X-ray spectra radiated from cluster targets can be used for estimation of the destruction degree of clusters by laser prepulses. These methods allow insight to be gained regarding the important issue of preservation of the dense cluster core at the moment of the arrival of the main laser pulse. In addition, they can be used for quantitative estimation of the size of the undestroyed parts of the clusters and also for measuring the temperature and density of the preplasmas produced by the laser prepulses.

In this paper, we describe the experimental validation of the technique of correction of wavefront aberration in the middle of the laser amplifying chain. This technique allows the correction of the aberrations from the first part of the laser system, and the pre-compensation of the aberrations built in the second part. This approach will allow an effective aberration management in the laser chain, to protect the optical surfaces and optimize performances, and is the only possible approach for multi-petawatt laser system from the technical and economical point of view. This approach is now possible after the introduction of new deformable mirrors with lower static aberrations and higher dynamic than the standard devices.

Los Alamos National Laboratory short pulse experiments have shown using various target cleaning techniques such that heavy ion beams of different charge states can be produced. Furthermore, by controlling the thickness of light ions on the rear of the target, monoenergetic ion pulses can be generated. The spectral shape of the accelerated particles can be controlled to yield a range of distributions, from Maxwellian to ones possessing a monoenergetic peak at high energy. The key lies in understanding and utilizing target surface chemistry. Careful monitoring and control of the surface properties and induction of reactions at different temperatures allows well defined source layers to be formed, which in turn lead to the desired energy spectra in the acceleration process. Theoretical considerations provide understanding of the process of monoenergetic ion production. In addition, numerical modeling has identified a new acceleration mechanism, the laser break-out afterburner that could potentially boost particle energies by up to two orders of magnitude for the same laser parameters. This mechanism may enable application of laser-accelerated ion beams to venues such as compact accelerators, tumor therapy, and ion fast ignition.

We describe here the present status of the Advanced Laser Light Source (ALLS) facility, a state-of-the-art multi-beam Ti:sapphire laser system presently under construction in Canada. ALLS is a national user facility to be commissioned in 2005 at the INRS campus near Montreal. The 25 fs ALLS multi-beam laser system has three components, each with different repetition rate and output energy. These multiple laser beams will be used to generate a “rainbow” of femtosecond pulses from the far infrared to hard X-rays, which can be combined to perform unique experiments, such as dynamic molecular imaging. In this paper, we describe two examples of experiments that are planned by our group with the ALLS facility. The first is the highly efficient generation of high-order harmonics using ablation medium. We demonstrate the generation of up to the 53rd harmonics (λ = 15 nm) of a Ti:sapphire laser pulse (150 fs, 10 mJ), using pre-pulse (210 ps, 24 mJ) produced boron ablation as the nonlinear medium. The second example is the demonstration of in-line phase-contrast imaging with an ultrafast (300 fs) laser-based hard X-ray source (Mo K-α line). Images of biological samples have shown great enhancement of contrast due to this technique, distinguishing details that are barely observable or even undetectable in absorption images.

It is shown that the effective hot electron temperature, Thot, associated with the energetic electrons produced during the interaction of an ultra-intense laser with thin solid targets is dependent on the thickness of the target. We report the first direct experimental observations of electron energy spectra obtained from laser-solid interactions that indicates the reflexing of electrons in thin targets results in higher electron temperatures than those obtained in thick target interactions. This can occur for targets whose thickness, xt, is less than about half the range of an electron at the energy associated with the initial effective electron temperature, provided the laser pulse length is at least cτp > 2xt. A simple theoretical model that demonstrates the physical mechanism behind this enhanced heating is presented and the results of computer simulations are used to verify the model.

In this paper, we suggest the creation of a nanoparticles and nanotubes by using the interaction of a femtosecond laser with a solid target in a vacuum. A simple model is used to predict the optimal target and the laser parameters for the production of efficient nanoparticles. At the Soreq laboratory, experiments are performed with aluminium and carbon targets using a femtosecond laser. The irradiated targets are composed of either a thin layer of aluminium or of carbon, deposited on a transparent heat-insulating glass substrate. The nanoparticle debris is collected on a silicone wafer for X-ray diffraction (XRD), for scanning electron microscopy (SEM), and for atomic force microscopy (AFM). For transmission electron microscopy (TEM), the debris is caught on a copper grid covered on one side with a carbon membrane. Our experiments confirm the creation of crystal nanoparticles for aluminium and nanotubes for carbon experiments.