V. A. Kolikov

High-speed penetration into sand

Abstract The series of experiments aimed at the exploring high-speed impact of bullet on non-solid target were carried out at IPE RAS. The electro-discharge launcher (EDL) employed in these experiments can reach the projectile velocities of 4 km/s. The following topics were considered: the phenomena related to the high-speed penetration into non-solid targets, the parameters that influence the penetration depth and the projectile design suitable for the deepest penetration into sand. Experimental equipment allows the measurement of the penetration depth of bullet, its path inside the sand and the shock waves caused by the high-speed bullet impact. Experiments had shown the absence of significant deviation from a straight-line trajectory for the any tested bullet shapes at the impact velocity of 1.5–3.0 km/s. The most interesting result is the existence of a critical velocity for this type of interaction. The full bullet wear due to the friction with sand occurs at this velocity. The critical velocity value depends on bullet material and dimensions. Experiments show that exceeding the critical velocity leads to reduce in penetration depth. The influence of bullet material, shape and velocity on its penetration depth into sand was measured. These data allow a determination of the main characteristics of projectile for deep penetration into sand.

Electric Discharges and the Prolonged Microbial Resistance of Water

One of alternative methods of water disinfection is its treatment by pulsed electric discharges (PEDs). In this case, during the discharges, bacteria are destroyed by UV radiation with a significant share of energy in waves of 200-400 nm and by shock waves, which are formed at the initial stage of the discharge-column widening. This paper describes the electrophysical properties of PED in water, presents the results of an investigation of the physical, chemical, bactericidal, and fungicidal properties of treated water, and explains the prolonged microbial resistance of water (PMRW) - the phenomenon when bacteria continue to be destroyed for a long time (several months) after treatment by PED. The results of investigations make it possible to conclude that the PMRW is caused by the cooperative bactericidal action on microorganisms of both oxide nanoparticles of electrodes metal and positive ions emitted by the nanoparticles.

Prolonged microbial resistance of water treated by a pulsed electrical discharge

The main characteristics of pulsed discharges in water are studied, such as the discharge current, voltage drop across the discharge gap, temperature of the discharge column, and plasma conductivity, as well as compression waves and ultraviolet radiation, which are induced by the discharge. The physicochemical properties of water treated by pulsed discharges are considered in the context of the effect produced on microorganisms. The mechanism underlying the prolonged microbial resistance of water—its capability of retaining a high activity against virtually all known pathogenic microorganisms and human-opportunistic fungi for many months after the discharge treatment—is explained.

Multipulse discharge in the chamber of electric discharge launcher

The investigation results of an electric discharge launchers (EDL) chamber operation at hydrogen initial pressure 20-40 MPa, discharge current 0.5-1.0 MA, current rise rate (0.5-1.0)/spl times/10/sup 10/ A/s and input energy up to 2.2 MJ are presented. The coaxial electrode system consists of cylindrical anode and conic cathode. The discharge is initiated by copper wire in the interelectrode gap of 0.8-2.5 mm. The conditions of multipulse discharge current appearance, at the pulses number 5-15 (in comparison with usual multipulse regime 2-3 pulses), amplitude 0.5-1.0 MA and single pulse duration 50-200 /spl mu/s, are determined. The speeds of arc movement (1.5-3.0 km/s) and arc channel expansion (0.2-0.4 km/s), were measured by means of high-speed camera. The efficiency of energy transfer from the power supply (capacitor storage) to the arc was about 85% and from the arc to gas-90%. Electrodes erosion was found to be 30-40% less compared with usual multipulse regime. Besides the anode and cathode, total erosion was 30-40 mg/C at passed charge up to 800 C. The results estimation of different mechanisms contribution to heat transfer from the arc to surrounding hydrogen are discussed. It was shown that both repeated dissipation of arc plasma internal energy after arc extinction and the shock waves, appearing at the breakdowns of interelectrode gap, increase the efficiency of gas heating. It was proposed that decreasing of electrodes erosion at the multipulse regime is connected both with the growth of electrode spots movement speed and with the decreasing of current amplitude from 1.5-2.0 MA (usual multipulse regime) to 1.0 MA.

Influence of the cathode and anode jets on the properties of a high-current electric arc

AbstractA study is made of the effects related to the formation of electrode jets in discharges in hydrogen and air at a current of 105–106 A, a current growth rate of 1010 A/s, an initial pressure of 0.1–4.0 MPa, and a discharge gap length of 5–40 mm. After secondary breakdown, jets are observed in a semitransparent discharge channel expanding with a velocity of (4–7)×102 m/s. The formation of shock waves in the interaction of the jets with the ambient gas and the opposite electrode is observed by the shadowgraphy method. Seventy microseconds after the beginning of the discharge, the pressure of the metal vapor plasma near the end of the tungsten cathode amounts to 177 MPa. The brightness temperature in this case is T=59×103 K, the average ion charge number is

Experimental Study of Hydrogen Heating in Powerful Electric Discharge Launcher

\overline m = 3.1

Powerful pulse generator of dense plasma with high concentration of metal vapour

, and the metal vapor density is n=5.3×1019 cm−3. After 90 µs, the average ion charge number and the metal vapor density near the anode end are