Effect of Mode Transformation in THz Clinotron

Extension of the theory of a clinotron is developed by use of the scattering matrix of an oversized T-junction on the ends of a slow wave system. The matrix contains elements corresponding to the transformation of slow grating modes into fast ones and vice versa. Those fast waves with low ohmic losses provide strong resonant properties of a clinotron even in the case of strong attenuation of the surface mode. Results of the theoretical simulation are compared with experimental ones and obtained dependencies explain strong resonances in sub-THz clinotrons.     

Correlation of acoustic,physicochemical, and mechanical properties of coatings obtained using electron-beam welding deposition of chromium carbide on low-carbon steel

Multifunctional coatings have been developed using the method of nonvacuum electron-beam welding deposition of chromium carbide powder on low-carbon steel. The correlation dependences of the ultrasonic velocity, the thickness of coatings, the content of chromium in the coatings, and the loss of mass under exposure to corrosive media on the mechanical properties are constructed using the bend tests. It was shown that the observed correlation relations are mainly determined by two factors, i.e., the presence of a substitute doping agent of chromium in a solid solution and the character of a dislocation structure, which forms inside of the grain.     

Interrelation of equivalent values for linear energy transfer of heavy charged particles and the energy of focused laser radiation

The estimations of equivalent values for linear energy transfer of heavy charged particles based on the results of experimental investigations of sensitivity of LSICs to local radiation effects with the use of the procedure of local laser irradiation are presented. The possibility of recalculation of the energy of laser radiation into equivalent values of linear energy transfer with the use of the measurements of the ionization reaction in the supply circuit of LSIC is substantiated. Uncertainties caused by the characteristics of the interaction of optical radiation with semiconductor structures are eliminated in the suggested procedure.     

Liquidus Temperatures of Cryolite Melts With Low Cryolite Ratio

The effect of calcium fluoride on liquidus temperatures of the cryolite melts with a low cryolite ratio (CR) was studied. The systems KF-NaF-AlF₃ and KF-LiF-AlF₃ with CRs of 1.3, 1.5, and 1.7 have been investigated. The liquidus curves of systems containing CaF₂ are different and depend on the K/(K + Na) and K/(K + Li) ratios. In potassium cryolite with CRs of 1.3 and 1.5, the calcium fluoride solubility is low and increases with NaF (LiF) concentration.     

Surface plasmon enhanced energy transfer between donor and acceptor CdTe nanocrystal quantum dot monolayers

Surface plasmon enhanced Fo?rster resonant energy transfer (FRET) between CdTe nanocrystal quantum dots (QDs) has been observed in a multilayer acceptor QD-gold nanoparticle-donor QD sandwich structure. Compared to a donor-acceptor QD bilayer structure without gold nanoparticles, the FRET rate is enhanced by a factor of 80 and the Fo?rster radius increases by 103%. Furthermore, a strong impact of the donor QD properties on the surface plasmon mediated FRET is reported.     

Calibration of pulse pressure sensors using the laser near-surface air breakdown

A method for calibrating pulse pressure sensors by a spherical shock wave, generated by the laser near-surface air breakdown, is proposed. The method is based on comparing the breakdown shock wave amplitude, measured by the calibrated sensor, and the calculated amplitude for identical breakdown conditions. The amplitude of the shock wave is calculated by the Sadowski formula with coefficients modified with reference to the laser blast.     

Experimental studies of the adequacy of laser simulations of dose rate effects in integrated circuits and semiconductor devices

Comparative experimental studies of the responses of typical representatives of integrated circuits (ICs) and semiconductor devices (SDs) with various designs to high-energy pulsed ionizing radiations from simulation facilities and laser simulators have been carried out. The differences between the hardness values under exposure to radiations from simulation facilities and laser simulators have been found to be no larger than the dosimetry errors when the power supply ionization current calibration procedure is used. The shapes of power supply ionization currents and output voltages in the ICs are almost identical qualitatively. The levels and patterns of the functional IC failures are completely identical for both types of radiation sources. As a result, we have proven that a joint application of simulation facilities and laser simulators provides a rational combination of the reliability and efficiency of testing ICs and SDs for hardness to dose rate.     

Water dynamics in bulk and dispersed in silica CaCl2 hydrates studied by neutron scattering methods

Quasi-elastic and inelastic neutron scattering techniques have been used to study the dynamics of water in CaCl₂ · nH₂O (n = 1/3,2,4,6,9) hydrates dispersed in silica, in comparison with the bulk hydrates. Inelastic scattering shows that the water molecules in dispersed hydrates are in an amorphous state. Quasi-elastic scattering indicates a higher mobility of water in the hydrates dispersed in silica, compared to bulk hydrates. The self-diffusivity of water in the dispersed hydrates increases with water concentration, while remaining below the one of pure water. The neutron and pulsed-field gradient NMR diffusivities are similar, which indicates that the hydrates form a thin and continuous layer on the pore walls of silica.     

Effect of Layer-by-Layer Electric-Spark Alloying on the Properties of an Electrolytic Coating of the System Ni – B

The effect of layer-by-layer electric-spark alloying on the tribological parameters of a composite electrolytic coating of the system Ni – B is studied. It is shown that layer-by-layer electric-spark alloying with intermetallic TiAl and a composite AlN – ZrB₂ halves coating wear and prevents transfer of coating material to the counterbody. The reason for this is formation of a graded structure for the surface layer including zircon ZrSiO₄ and intermetallic TiAl. The latter is responsible for formation of β-tialite during tribological oxidation acting as a solid lubricant.