Ph.G. Rutberg

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.

Plasma pyrolysis of toxic waste

The comparison of technical economic indexes of different waste treatment methods and plasma pyrolysis is presented in the paper. It testifies that plasma technologies are economically expedient for these purposes. Physical prerequisites allowing realizing plasma technologies are presented. Reliable and economical (70–120 Euro per ton of treated product) plasma generation is the basic condition of the technology realization. In this connection, various types of powerful generators of dense plasma (plasmatrons) in the range from 100 kW to 3 MW and temperature of plasma jets from 2000 to 10 000 K, and also physical processes taking place in electric-discharge chambers are examined. Differences between AC and DC electric arc plasma generators are analysed. Temperature in arcs of plasma generators varies from 6000 to 20 000 K, electron concentration is ne~(1014–1019 cm−3). Specific ware of electrodes in various types of plasma generators intended for long-time operation modes is (10−7–10−4) g C−1. Physicochemical processes in plasma reactors intended for waste treatment and pyrolysis are described. Different types of technological processes on plasma treatment and pyrolysis of waste are analysed. Estimation of present situation of physical investigations and technological developments in this area and predictions for nearest future are included. This article was scheduled to appear in issue 5 of Plasma Phys. Control. Fusion. To access this Special issue please follow this link: http://www.iop.org/EJ/toc/0741-3335/45/5

Multiphase stationary plasma generators working on oxidizing media

The subject of this paper is the design of two types of stationary multiphase ac plasma generators, developed for plasma chemical methods of waste destruction and processing (including syngas production). This paper presents plasma generators of average power (up to 50 kW) and high power (up to 500 kW) working on oxidizing media and describes the basic physical processes in the discharge chamber of a multiphase low-temperature (thermal) plasma generator. The presence of diffuse mode of arc burning at ne ~ 1014–1015 cm−3 and contracted mode ne ≥ 1016 cm−3 is detected. The external characteristics (dependence of working gas heat content, power in arcs and efficiency on flow rate) based on experimental data are presented. The influence of plasma forming gas variation on electric parameters is demonstrated. The powerful multiphase plasma generator works at atmospheric pressure on oxidizing media (air) in the power range 100–500 kW and the flow rates 10–70 g s−1 with thermal efficiency of 70–90% and electrode lifetime of more than a hundred hours. The thermal efficiency of an average power (up to 50 kW) plasma generator in the range of air flow rate of 2–25 g s−1 is 80–95%, while the electrode lifetime is hundreds of hours. The described multiphase plasma generators allow the working gas heat content to be controlled in a wide range at the outlet (for air—from 1.5 MJ kg−1 up to 12.5 MJ kg−1), which is important for the realization of plasma technologies, including syngas production.

The technology and execution of plasmachemical disinfection of hazardous medical waste

This report describes the technology used for plasma-chemical disinfection of hazardous medical waste (HMW), which employs high-temperature mineralization. This method uses low-temperature plasma produced in a plasma generator as an additional source of heat energy. The method not only neutralizes medical waste, but it also reduces by 50-400 times the volume of waste being buried. The waste-combustion process includes the following stages: two-stage combustion in the furnace at a temperature of 1000/spl deg/C-1200/spl deg/C and in the afterburning chamber at a temperature of 1200/spl deg/C-1300/spl deg/C, with dwell time of flue gases no less than 2 s; obligatory quenching (fast cooling) of flue gases; multistage cleaning of flue gases of fly ash, vapors of heavy metals, acid gases, and, if necessary, dioxins and furans; automated control of mode parameters, ejection into the atmosphere and control of all technological processes; low-consumption factors on energy and used reagents. The installation is designed for treatment of 150 kg/h of HMW and it employs a rotary kiln with parallel-current flow of burned waste and incandescent gases for plasma combustion of the waste. This allows the burning waste to be constantly mixed, which prevents fusion or baking into layers, and thus intensifies the processes of heat and mass exchange. Waste is supplied into the furnace periodically through the system of trays using pneumatic pushers. Two plasma generators are mounted on the loading end of the furnace, and one is mounted on the afterburning chamber. Slag is unloaded from the furnace by quenching it with water. After quenching, cooling, and discharging the slag, it is disposed of. The gas cleaning system consists of a Venturi scrubber, a packed-bed scrubber, a demister, and an absorber. This technological process solves several problems involved in collecting, packing, and disposing of HMW by automating the loading processes, organizing combustion regimes, and cleaning flue gases.

Some plasma environmental technologies developed in Russia

This paper deals with a number of studies, carried out in Russia, on investigation of plasma technologies for environment protection. Physical processes in low temperature plasma generators (AC plasmatrons), which are the basic units of these systems are described. Plasma technologies on treatment of medical waste and liquid Cl–F carbons are given. The results of pulse discharges of low energy for bactericidal water purification are presented.

Investigation of parameters of the three phase high-voltage alternating current plasma generator with power up to 100 kW working on steam

The paper presents the results of experimental investigation of parameters of the three-phase high voltage alternating current plasma generator with power up to 100 kW operating on steam with gas protection of the electrodes. Researches were carried out over a range of arc current from 25 to 50 A and range of steam consumption of 3–5 g/s. Current-voltage and volt consumable characteristics, operation oscillograms and dependence of power versus the flow rate of steam and protective gas are presented.

Production of synthesis gas by conversion of methane in a steam-carbon dioxide plasma

Experimental setup and results of methane conversion in a steam-carbon dioxide plasma are briefly described. Mass-flow rate of CH4 was varied from 2.5 to 3.7 g/s while mass-flow rates of H2O of ∼3 g/s and CO2 of ∼3 g/s were maintained constant. The energy consumption was 29–42 MJ per 1 kg of CH4. The H2/CO ratio in the produced synthesis gas was 2.2–2.4. The conversion rate of CH4 was 90.8–99.8%. The content of H2 and CO in the synthesis gas was ∼95%.

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

Abstract The results of experiments on the heating of hydrogen and nitrogen of high initial pressure (20 – 40 MPA) by high-current discharge with discharge current amplitude up to 1,5 MA, initiated by wire explosion, are represented in the paper. Owing to high erosion of anode and cathode due to the discharge, equal to 200 – 300 C, passing through them, the average magnitude of metal vapours concentration in the discharge chamber is 10cm20 cm−3, that can be compared to working gas concentration. On the basis of the experimental results and metal plasma conductance calculations data the estimations of the temperature of the discharge channel are given.Using data of the experiments with arcs in hydrogen, nitrogen and helium with current discharge amplitude equal to 20 – 200 kA the conclusion about the defining influence of metal vapours on the properties of the arc itself and on the heat exchange between the arc and the environmental gas is drawn. For example, the increase of arcs turbulence level with the decrease of distance between electrodes is connected with metal streams introduction from electrodes to the near-electrodes areas. The increase of gas heating efficiency with the increase of initiating wire mass is stipulated by metal vapours radiation absorption in the cold zone.

Study of electric arcs in an air-steam mixture in AC plasma torches

A review of existing plasma torches designed for steam plasma is presented in this paper. Together, they cover the following ranges of key technical parameters: efficiency from 51 to 95%, enthalpy of the plasma from 12 to 84 MJ/kg, and the fraction of the steam in the plasma forming gas from 17 to 100%. The advantages of alternating current to produce plasma is grounded. The problems of creating of a steam plasma torch are described. The description of the experiments carried out on the AC plasma torch, during which the total flow of the plasma forming steam-air mixture and the effective value of the current remained constant ∼ 6.7 g/s and ∼ 28.4 A, respectively, and the steam content ranged from 54 to 85%, is given. With an increasing proportion of steam, the voltage increased from 1.03 to 1.59 kV, while the estimated temperature of the arc decreased from 11600 to 10200 K, which is caused by intensification of heat transfer. In all modes, there was a high efficiency of 94.3–95.3% with a significant change in the specific energy input from 8.3 to 12.4 MJ per 1 kg of plasma-forming gas.

Attainment of the Pease-Braginskii current in an ultra-high-pressure discharge

Results are presented from experimental studies of the contraction of the channels of discharges in hydrogen and helium at current amplitudes of 0.5–1.6 MA and initial gas pressures of 5–35 MPa. The observed decrease in the brightness temperature of the discharge channel with increasing deposited energy is caused by the heating of the ambient gas. The channel contraction observed near the maximum of the discharge current is due to the attainment of the Pease-Braginskii critical current. Previously, it was shown that megampere discharges operate in a fully metallic plasma of the eroded electrodes. The theoretical value of the Pease-Braginskii current for discharges in vacuum is ∼100–200 kA. The observed increase in the critical current to ∼1 MA is attributed to the absorption of channel radiation in the dense ambient gas.