Upgrading the front end of the petawatt-class PEARL laser facility.

A new front-end laser system with optical synchronization of chirped femtosecond and pump pulses for the petawatt laser complex PEtawatt pARametric Laser (PEARL) has been developed. The new front-end system provides a broader femtosecond pulse spectrum, temporal shaping of the pump pulse, and a significant increase in the stability of the parametric amplification stages of the PEARL.

Pulsed magnetic field generation system for laser-plasma research.

An up to 15 T pulsed magnetic field generator in a volume of a few cubic centimeters has been developed for experiments with magnetized laser plasma. The magnetic field is created by a pair of coils placed in a sealed reservoir with liquid nitrogen, installed in a vacuum chamber with a laser target. The bearing body provides the mechanical strength of the system both in the case of co-directional and oppositely connected coils. The configuration of the housing allows laser radiation to be introduced into the working area between the coils in a wide range of directions and focusing angles, places targets away from the symmetry axis of the magnetic system, and irradiates several targets simultaneously.

Cytokinin membrane receptors participate in regulation of plastid genome expression in the skotomorphogenesis.

Analysis by real-time PCR of single and double insertion mutants of A. thaliana with inactivated cytokinin receptor genes showed that the level of transcripts of some of plastid genes during skotomorphogenesis depended on the state of functionally active receptor AHK3. The cytokinin-regulated plastid encoded genes involved the housekeeping genes (rpoB and accD) and the genes for photosynthetic proteins (ndhA, psbA, atpB, and psaA). However, the absence of hormone activation of plastid encoded genes engaged in the translation of plastid proteins, rRNA (rrn16), and tRNA (trnE), indirectly indicate the disruption of the synthesis of chloroplast proteins in the dark.

Problems in the application of a null lens for precise measurements of aspheric mirrors.

Problems in the application of a null lens for surface shape measurements of aspherical mirrors are discussed using the example of manufacturing an aspherical concave mirror for the beyond extreme ultraviolet nanolithographer. A method for allowing measurement of the surface shape of a sample under study and the aberration of a null lens simultaneously, and for evaluating measurement accuracy, is described. Using this method, we made a mirror with an aspheric surface of the 6th order (i.e., the maximum deviation from the best-fit sphere is 6.6 µm) with the parameters of the deviations from the designed surface PV=5.3 nm and RMS=0.8 nm. An approximation of the surface shape was carried out using Zernike polynomials {Z(n)(m)(r,φ),m+n≤36}. The physical limitations of this technique are analyzed. It is shown that for aspheric measurements to an Angstrom accuracy, one needs to have a null lens with errors of less than 1 nm. For accurate measurements, it is necessary to establish compliance with the coordinates on the sample and on the interferogram.

Application of point diffraction interferometry for measuring angular displacement to a sensitivity of 0.01 arcsec.

The use of point diffraction interferometry is reported for measuring minutes, on the order of 0.01 arcsec angular movements. The algorithm for determining the angular displacement by the dynamics of the interference pattern is described. We also demonstrate results for applying this method to the study of the linearity and hysteresis of the angular shift of the platform, controlled by piezo actuators, which are designed for angular adjustment of the mirror of a solar extreme-ultraviolet telescope.

Two-screen single-shot electron spectrometer for laser wakefield accelerated electron beams.

The laser wakefield acceleration electron beams can essentially deviate from the axis of the system, which distinguishes them greatly from beams of conventional accelerators. In case of energy measurements by means of a permanent-magnet electron spectrometer, the deviation angle can affect accuracy, especially for high energies. A two-screen single-shot electron spectrometer that correctly allows for variations of the angle of entry is considered. The spectrometer design enables enhancing accuracy of measuring narrow electron beams significantly as compared to a one-screen spectrometer with analogous magnetic field, size, and angular acceptance.

Variations of trends of indicators describing complex systems: change of scaling precursory to extreme events.

Socioeconomic and natural complex systems persistently generate extreme events also known as disasters, crises, or critical transitions. Here we analyze patterns of background activity preceding extreme events in four complex systems: economic recessions, surges in homicides in a megacity, magnetic storms, and strong earthquakes. We use as a starting point the indicators describing the system's behavior and identify changes in an indicator's trend. Those changes constitute our background events (BEs). We demonstrate a premonitory pattern common to all four systems considered: relatively large magnitude BEs become more frequent before extreme event. A premonitory change of scaling has been found in various models and observations. Here we demonstrate this change in scaling of uniformly defined BEs in four real complex systems, their enormous differences notwithstanding.