[en] A method is claimed of isotope-selectively exciting gaseous or vaporous uranium hexafluoride molecules by means of a monochromatic iodine laser beam. The beam frequency is tuned to an absorption band of the molecules to be excited. The iodine laser beam is scattered in liquid and/or solid nitrogen and the beam produced by triply stimulated Raman-scattering is brought into interaction with the uranium hexafluoride molecules

No abstract available

[en] A method is reported allowing the decoupling of laser amplifiers by means of a fast rotating mirror (ν approximately > 200 Hz). The generation of short pulses from continuous laser radiation needed for the solution of the trigger problem rotating mirror - laser oscillator is also considered. In this context, attention is drawn to two secondary applications: the measurement of the beam divergence of continuous laser radiation from the pulse width and pulse shaping. (orig.)

[en] Experimental investigations on the conditions to achieve transient gain in neon-like Ti and nickel-like molybdenum XUV laser pumped by a 10-HZ sub-Joule femtosecond laser are presented. The 4d-4p (J = 0-1) λ 18.9 nm and 4f-4d (J = 1-11) λ = 22.6 nm lines in Ni-like Mo as well as the 3p-3s (J = 0-1) λ = 32.6 nm line in neon-like titanium have been observed. The Ni-like laser lines show a threshold behavior with respect to the pump irradiance as they appear only above 10¹⁵ W/cm². Simulation for the fs-laser pumped Ni-like Mo XUV laser are also presented

[en] Hot electrons generated upon interaction of p-polarized 130 fs laser pulses with copper and penetrating into the target material are characterized with respect to their energy distribution and directionality. ''Experimental'' data are obtained by comparing the rear-side x-ray emission from layered targets with Monte Carlo electron-photon transport simulations. Theoretical electron energy distributions are derived by means of a one and a half--dimensional particle-in-cell code. Both sets of data consist of a two-temperature distribution of electrons propagating in a direction almost perpendicular to the target surface. The ''experimental'' data contain a considerably higher population of the lower temperature electrons. The discrepancy is explained by the intensity distribution of the laser spot. The results are used to design an experiment for demonstrating photopumping of cobalt with copper Kα radiation. A 10 μm copper foil is backed with 1 mm of polyethylene (PE) followed by 10 μm of cobalt, the rear-side Kα emission of which is measured. The PE layer prevents fast electrons from reaching the cobalt. Comparing the cobalt Kα emission with that of nickel, which is not photopumped by copper Kα shows enhancement by almost a factor of 2

No abstract available

[en] The characteristic properties of the iodine laser (gaseous laser substance, photolytic pump mechanism, variable stimulated emission cross-section) made it possible in a relatively short time to generate ns pulses in the kJ range. The Asterix II and III iodine laser systems at IPP are working successfully, and the question arises what prospects are afforded for further iodine laser development. What are the problems that have to be clarified in order to build 10 or 100 kJ systems for laser fusion experiments. According to our experience these can be classified as follows: 1) Short pulse generation and contrast ratio, 2) pulse shaping in a high-gain laser and amplification in the coherent time range, 3) non-linear properties at high intensities, 4) scalable pumping schemes and chemical processes. (orig./WL)

[en] When fs laser pulses interact with solid surfaces at intensities Iλ² > 10¹⁸ W/cm² microm², collimated relativistic electron beams are generated. These electrons can be used for producing intense X-radiation (bremsstrahlung or K_α) for pumping an innershell X-ray laser. The basic concept of such a laser involves the propagation of the electron beam in a material which converts electron energy into appropriate pump photons. Using the ATLAS titanium-sapphire laser at Max-Planck-Institut fuer Quantenoptik, the authors investigate the generation of hot electrons and of characteristic radiation in copper. The laser (200 mJ/130 fs) is focused by means of an off-axis parabola to a diameter of about 10 microm. By varying the position of the focus, they measure the copper K_α - yield as a function of intensity in a range of 10¹⁵ to 2 x 10¹⁸ W/cm² while keeping the laser pulse energy constant. Surprisingly, the highest emission is obtained at an intensity of about 10¹⁷ W/cm². However, this result is readily explained by the weak scaling of the hot-electron temperature with intensity. An efficiency of 2 x 10^-4 for the conversion of laser energy into copper K_α is measured. Simulations of the interaction of the hot electrons with the cold target material and the conversion into X-rays are carried out by means of the TIGER/ITS code, a time-independent, coupled electron/photon Monte Carlo transport code. The code calculates the propagation of individual electrons and the generation of photons in cold material. Comparison of the code predictions with the data shows an efficiency of 15% for the generation of electrons with energies in the 100 keV range. A second experiment involves the demonstration of photopumping of an innershell transition in cobalt by the copper radiation. Comparing the emission with the one of nickel, which is not photopumped by copper K_α photons, an enhancement of more than a factor of two was obtained. An essential part of this experiment is the use of a 1 mm carbon sheet to block the electrons from the material to be photopumped

No abstract available

[en] The application of X-ray fluorescence to the analysis of ceramic raw materials is presented. The samples preparation procedure, the calibration method and the quantitative determination of various elements are described in detail. (B.Cz.)