Effect of laser erosion on the copper and zinc concentrations in the surface layer of brass

A REMMA 102 scanning electron microscope equipped with semiconductor and wave spectrometers is applied to measure the copper and zinc concentrations in the surface layers of an M161 brass sample and the same sample subjected to a focused laser radiation. The results are compared with the results obtained with an MS3101 laser mass spectrometer having a laser-plasma ion source. The laser-assisted erosion of the surface layer in the brass is shown to significantly change the copper and zinc concentrations. It is found that, when the craters produced by laser pulses on the initial surface do not overlap, the copper and zinc contents in the laser-induced plasma correspond to their contents in the sample.     

Investigations of electron beam characteristics using an accelerator based on a magnetron gun with a secondary-emission cathode

The reliability and service life of accelerating installations are substantially determined by the lifetime of electron sources. The accelerator under consideration has a magnetron gun with a channel-free cold secondary-emission cathode in crossed fields as an electron source [1, 2]. In the present work, the data of the electron beam parameters obtained in the accelerator based on the magnetron gun with a secondary-emission cathode are given, and possible secondary uses are suggested. The text was submitted by the authors in English.     

Effect of laser erosion on the element concentration in the surface layer of a solid

SEM data (obtained under a RÉMMA 102 microscope configured with an energy-dispersive analyzer) demonstrating the effect of surface erosion due to focused laser radiation on the elemental composition of the surface (eroded) layer are presented.     

Floating boundary particle swarm optimization algorithm

A new modification to the particle swarm optimization (PSO) algorithm is proposed aiming to make the algorithm less sensitive to selection of the initial search domain. To achieve this goal, we release the boundaries of the search domain and enable each boundary to drift independently, guided by the number of collisions with particles involved in the optimization process. The gradual modification of the active search domain range enables us to prevent particles from revisiting less promising regions of the search domain and also to explore the areas located outside the initial search domain. With time, the search domain shrinks around a region holding a global extremum. This helps improve the quality of the final solution obtained. It also makes the algorithm less sensitive to initial choice of the search domain ranges. The effectiveness of the proposed Floating Boundary PSO (FBPSO) is demonstrated using a set of standard test functions. To control the performance of the algorithm, new parameters are introduced. Their optimal values are determined through numerical examples.     

Investigation of the foil destruction dynamics in an explosively formed fuse opening switch by proton radiography

The dynamics of mechanical destruction of a conductor in an explosively formed fuse opening switch on a finned obstacle under the action of detonation products is studied in the injection channel of the U-70 proton synchrotron. Protonograms are recorded with digital multiframe electron-optic cameras. The exposure time per frame, about 30 ns, is determined by the duration of a proton bunch. The time from the beginning of motion of the conductor to its destruction is about 3 ??s. It is shown that the switch with typical sizes of the obstacle (the thickness of the fin is 1.5 mm, and the width and depth of the groove are 1.5 and 4.5 mm, respectively) provides operation with satisfactory gasdynamic parameters.     

Autonomous magnetocumulative power supply

Helical magnetocumulative generators (MCGs) fed from explosive piezo generators (EPGs) are the most compact power supplies with an output energy of 1–10 kJ. EPGs are successfully coupled with MCGs in the operation mode and in structural parameters; these generators are easy to operate and do not require transformers or commutators. We report on the results of designing an autonomous small-size power supply based on EPGs and MCGs. Owing to bidirectional impact loading of the piezoceramic block of an EPG, the energy at the piezo generator output attains values of ～25 J and is transferred to the helical MCG with an initial inductance of ～1000 μH. The power supply is constructed in the form of a monoblock with a volume of ～2 dm³ or in the form of two separate devices connected by a high-voltage cable.     

High-current plasma opening switch fed by a magnetic explosion generator

A plasma opening switch fed by a helical magnetic explosion generator is developed. A plasma sheath with an axial length of ≈4 cm and an electron density of ～10¹⁷ cm^?3 is produced in the electrode gap of the switch by six coaxial gaseous-plasma injectors. A series of explosion experiments shows that the system developed allows one to study the switch at currents of about 2 MA.     

Ion-optical characteristics of a laser mass spectrometer with a coordinate-sensitive microelectronic detector

The ion-optical systems of a mass spectrometer with a laser ion source and coordinate-sensitive microelectronic detector are analyzed using the matrizant method. The dispersion properties of the mass spectrometer, as well as ion beam radial and axial focusings in its optimized ion-optical system, are determined, and first-and second-order angular and velocity aberrations of the image are corrected. The basic parameters and characteristics of a refined (according to calculation results) version of the laser mass spectrometer with a coordinate-sensitive microelectronic detector are presented.     

Generation of electron beams in a multicathode secondary-emission source

A study is made of the generation of electron beams in a system consisting of eight secondary-emission cathodes arranged at regular intervals in the azimuthal direction inside a coaxial cylindrical anode in crossed electric and magnetic fields. In this system with an azimuthally nonuniform electric field, secondary-emission multiplication of electrons is realized and beam generation is achieved. With a cathode voltage of ∼37 kV and a magnetic field of ∼3000 Oe, the total current of all the beams amounts to ∼35 A, the microperveance of each beam being ∼0.7 μA/V^3/2.