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We observed that increasing the clusters size and laser pulse contrast can enhance the X-ray flux emitted by femtosecond-laser-driven-cluster plasma. By focusing a high contrast laser (10(-10)) on large argon clusters, high flux Kα-like X-rays (around 2.96 keV) is generated with a total flux of 2.5 × 10(11) photons/J in 4π and a conversion efficiency of 1.2 × 10-4. In the case of large Kr clusters, the best total flux for L-shell X-rays is 5.3 × 1011 photons/J with a conversion efficiency of 1.3 × 10-4 and, for the Kα X-ray (12.7 keV), it is 8 × 10(8) photons/J with a conversion efficiency of 1.6 × 10-6. Using this X-ray source, a single-shot high-performance X-ray imaging is demonstrated.

In this article, a method to reveal the presence of Mg content inside the different parts of leaves of Hedera helix is presented. In fact a sample of a Hedera helix's leaf, commonly characterized by a green and a white side, is analyzed under X-ray radiation. The presence of two zones with different colors in the Hedera helix's leaf has not been explained. In this connection, there are presently three hypotheses to explain the characteristic double-color appearance of the leaf. The first hypothesis suggests a different cytoplasmic inheritance of chloroplasts at the cell division, the second a different allelic composition, homozygote and heterozygote, between the two zones, and finally the third the action of a virus which changes the color properties in the Hedera's leaves. The resulting effect is a different content of "something" between the green and the white side. We utilized X-ray radiation, obtained from a plasma source with a Mg target, to image Hedera helix leaves and we found that the green side of the leaf is highlighted. We may suppose that the reason why the X-rays from a Mg plasma source, allow us to pick up the green side is probably due to the greater presence of the amount of Mg (from chlorophyll or other complexes and/or salts) in the two sides, green and white, of the leaf., ((c) 2008 Wiley-Liss, Inc.)

The generation of a plasma with an ultrahigh energy density of 1.2 GJ/cm3 (which corresponds to about 12 Gbar pressure) is investigated by irradiating thin stainless-steel foils with high-contrast femtosecond laser pulses with relativistic intensities of up to 1022 W/cm2. The plasma parameters are determined by X-ray spectroscopy. The results show that most of the laser energy is absorbed by the plasma at solid density, indicating that no pre-plasma is generated in the current experimental setup. [ABSTRACT FROM AUTHOR]

We experimentally investigated electron acceleration from submicron size argon clusters-gas target irradiated by a 100 fs, 10 TW laser pulses having a high-contrast. Electron beams are observed in the longitudinal and transverse directions to the laser propagation. The measured energy of the longitudinal electron reaches 600 MeV and the charge of the electron beam in the transverse direction is more than 3 nC. A two-dimensional particle-in-cell simulation of the interaction has been performed and it shows an enhancement of electron charge by using the cluster-gas target. [ABSTRACT FROM AUTHOR]