Mega-ampere submicrosecond generator GIT-32

The GIT-32 current generator was developed for experiments with current carrying pulsed plasma. The main parts of the generator are capacitor bank, multichannel multigap spark switches, low inductive current driving lines, and central load part. The generator consists of four identical sections, connected in parallel to one load. The capacitor bank is assembled from 32 IEK-100-0.17 (0.17 microF, 40 nH, 100 kV) capacitors, connected in parallel. It stores approximately 18 kJ at 80 kV charging voltage. Each two capacitors are commuted to a load by a multigap spark switch with eight parallel channels. Switches operate in ambient air at atmospheric pressure. The GIT-32 generator was tested with 10, 15, and 20 nH inductive loads. At 10 nH load and 80 kV of charging voltage it provides 1 MA of current amplitude and 490 ns rise time with 0.8 Omega damping resistors in discharge circuit of each capacitor and 1.34 MA530 ns without resistors. The net generator inductance without a load was optimized to be as low as 12 nH, which results in extremely low self-impedance of the generator ( approximately 0.05 Omega). It ensures effective energy coupling with low impedance loads like Z pinch. The generator operates reliably without any adjustments in 40-80 kV range of charging voltage. Maximum jitter (relative to a triggering pulse) at 40 kV charging voltage is about 7 ns and lower at higher charging voltages. Operation and handling are very simple, because no oil and no purified gases are required for the generator. The GIT-32 generator has dimensions of 3200 x 3200 x 400 mm(3) and total weight of about 2500 kg, thus manifesting itself as a simple, robust, and cost effective apparatus.     

Structure and properties of a layered steel/vanadium alloy/steel composite prepared by high-pressure torsion

The microstructure and hardness of a layered steel 08Kh17T/V–10Ti–5Cr/steel 08Kh17T composite, which was prepared by torsion under a high hydrostatic pressure at temperatures of 20, 200, and 400°C, have been studied. Severe plastic deformation under used conditions is shown to provide good joining of layers, which is accompanied by their substantial hardening (from 2.0 to 3.5 times). During deformation at temperatures of 20 and 200°C, fragmentation of the vanadium alloy layer into thinner layers is observed; at 400°C, mainly a plane interface between the vanadium alloy and the steel layers is formed.     

A circuit implementation of a single-bit CMOS adder

In this article, a circuit implementation of a single-bit CMOS adder with enhanced performance is presented. The adder circuit consists of separate circuits operating in-parallel for obtaining the output sum and carry signals. The carry circuit signal is not used to form the sum signal. The sum signal circuit is a sequential connection of two XOR cells. The circuit operability is confirmed by the results of circuit simulation using Cadence Design Systems’ software.     

Shaping of discrete abrasive segments for plane face grinding

The shaping of discrete abrasive segments for plane face grinding is considered, along with the necessary tools. Measures significantly reducing the costs on switching to discrete plane face grinding are identified.     

Rail strengthening in prolonged operation

In rail operation (with traffic corresponding to passed tonnage of gross loads of 500 and 1000 million t), the surface layer of the steel is significantly strengthened. Electron-microscope data permit quantitative analysis of the contribution of different mechanisms to rail strengthening in prolonged operation, at different distances from the contact surface. The strengthening is multifactorial: it involves substructural strengthening associated with nanofragment formation; dispersional strengthening by carbide particles; the formation of atmospheres at dislocations; and polar stress due to interphase and intraphase boundaries. The significant increase in the surface strength of rail steel after prolonged operation (passed tonnage of gross loads of 1000 million t) is due to the presence of long-range internal stress fields and to the fragmentation of material with the formation of nanostructure.     

Initiation of high-energy material ignition by nanosecond high-current electron beam

Results of experiments on the initiation of ignition in high-energy materials with a broad range of physicochemical parameters by high-current electron beams of nanosecond duration are presented. It is shown that ignition of these materials can be initiated even at relatively low energy parameters of the electron beam, provided that the ignition temperature does not exceed 200°C.     

A holographic method of the quantitative measurement of photolithographic replicas of thick raised surface defects

To solve the problem of the evaluation of the characteristic sizes and patterns of surface microdefects of complex-shaped samples, a holographic method for the measurement of transparent replicas representing an inverse impression of the investigated surface is proposed. This measurement method is based on the digital registration of the interferograms of a polymeric replica in the modified off-axis Leith–Upatnieks holographic scheme and on the calculation of the phase-incursion difference from a series of reconstructed digital holograms.