THERMAL PLASMA TORCHES AND TECHNOLOGIES

By JOSHUA CLARK

ELECTRIC ARC GENERATORS OF THERMAL PLASMA: REVIEW TRENDS IN THERMAL PLASMA TECHNOLOGY INTEGRATED ANALYSIS OF INDUCTION PLASMA SYSTEMS PLASMA METALLURGY: CURRENT STATE, PROBLEMS AND PROSPECTS ATMOSPHERE PLASMA SPRAYING: THEORY, MODELLING, DIAGNOSTICS, COMPUTER- AIDED DESIGN AND SOME APPLICATIONS METALLIC AND CERAMIC MATERIALS: PRESENT AND FUTURE EXTREME TECHNOLOGIES IN BUILDING MATERIAL PRODUCTION ACHIEVEMENTS OF PLASMA TOMOGRAPHY NEW VORTEX METHOD OF PLASMA INSULATION AND THE RANQUE EFFECT PHYSICAL PHENOMENA IN A HOLLOW CATHODE AND INTERACTION OF POWDER WITH THE VACUUM ARC EXPERIMENTAL INVESTIGATION OF ELECTRIC, ENERGETIC AND OPTICAL CHARACTER- ISTICS OF THE INDUCTION TRANSFORMER-TYPE DISCHARGE MATHEMATICAL MODELLING OF TRANSFORMER DISCHARGE INTEGRATED METHOD OF RESEARCH OF PROCESSES IN THERMAL PLASMA GENERATORS MODELLING OF ELECTRIC ARC PLASMA ON THE PROBLEM OF TURBULENT ARC MODELLING ENERGY CHARACTERISTICS OF ELECTRIC ARC HEATERS FOR TETRAFLUOROMETHANE NUMERICAL INVESTIGATION OF THE CHARACTERISTICS OF A STEADY CURVED ARC IN EXTERNAL FIELDS PROPERTIES OF WATER-STABILIZED PLASMA TORCHES MODELING OF A D C ARC PLASMA TORCH WITH A HYDROGEN-ARGON MIXTURE AS THE WORKING GAS THE MODIFIED BALANCE METHOD OF CALCULATING CHARACTERISTICS OF NEAR- ANODE PROCESSES APPLICATION OF HEAT DIFFUSION THEORY TO COLD ELECTRODE EROSION FOR NONSTA- TIONARY ARC SPOTS EMISSION CURRENT DENSITY AND ELECTRONIC WORK FUNCTION OF METAL TO PLASMA EROSION OF MULTI-ARC CATHODES INFLUENCE OF THREE-PHASE ELECTRIC ARCS, BURNING ON OXIDE MELTS, ON QUALITY OF ELECTRIC POWER MODELLING OF FLOW STABILIZATION BY THE SWIRL OF A PERIPHERAL FLOW AS APPLIED TO PLASMA REACTORS LOW-DENSITY PLASMA JETS: PRODUCTION AND INVESTIGATION EFFECT OF ARC CURRENT MODULATION ON THERMAL PLASMA FLOW IN PLASMA TORCHES THE MAIN ELECTRICAL AND PHYSICAL PROCESSES IN A DISCHARGE CHAMBER OF A LINEAR PLASMA TORCH ARE REVIEWED THE CLASSIFICATION OF LINEAR PLASMA TORCHES IS PROPOSED THE DIAGRAMS OF THE PLASMA TORCHES FOR TECHNOLOGICAL PROCESSES AND PLASMA CHEMICAL REACTORS AS WELL AS THEIR PROBLEMS ARE DISCUSSED ! ! "#$ !$$$" $" " %&! $ "$'( THE DYNAMICS OF ELECTRIC ARC PLASMA INCLUDES A COMPLEX PHYSICAL PHENOMENON, OCCURRING IN THE DISCHARGE CHAMBER OF THE PLASMA TORCH, WHICH CAN BE REGARDED AS BOTH THERMAL AND AN ELECTRIC AND PHYSICAL DEVICE THE ELECTRIC ARC IS INFLUENCED BY DIFFERENT FACTORS: THE GAS FLOW, INNER AND OUTER MAGNETIC FIELDS, CONSTRUCTION ELEMENTS OF THE CHAMBER WHICH CONFINE THE ARC, THE ELEMENTS BEING OFTEN UNDER ELECTRIC VOLTAGE, DIFFERING FROM THAT OF THE ARC THUS, THERE IS A STRONG NEED FOR DEEP UNDERSTANDING OF A WIDE SPECTRUM OF THE PROCESSES TAKING PLACE IN THE DISCHARGE CHAMBER IN ORDER TO DEVELOP HIGHLY EFFECTIVE PLASMA TORCHES 1 1 DYNAMICS OF THE GAS FLOW IN THE CYLIDRICAL CHANNEL AND STRUCTURE OF THE ARC COLUMN [2] FIGURE 1 PRESENTS THE PRINCIPAL SCHEME OF A LINEAR PLASMA TORCH WITH A LONG DISCHARGE CHAMBER AND THE QUALITATIVE DISTRIBUTION PICTURE OF ITS ENERGETIC CHARACTERISTICS ALONG THE Z AXIS, I E THE SPECIFIC ENERGY GENERATION OF ARC EI AND THE FULL SPECIFIC HEAT FLUX PER UNIT LENGTH OF THE CHAMBER WALL Q THE ARC BURNS BETWEEN TWO ELECTRODES, PLACED AT THE ENDS OF THE DISCHARGE CHAMBER GAS G IS INTRODUCED INTO THE CHAMBER USUALLY WITH THE CIRCUMFERENTIAL COMPONENT OF VELOCITY W A CYLINDRICAL CHAMBER MAY BE ASSEMBLED FROM INDIVIDUAL SECTIONS (DISKS) OR IT CAN BE SOLID ONE CAN OBSERVE THREE TYPICAL ZONES IN THE STRUCTURE OF THE FLOW AND THE DISCHARGE IN THE FIRST ZONE, I E INITIAL AREA, THE ARC 2 IS STABILISED ALONG THE CHANNEL AXIS, THE GAS IS HEATED INTENSIVELY ALONG THIS AXIS, BUT INSIDE THE BOUNDARY OF HEAT LAYER 3 WITH LOW CONDUCTIVITY THE THICKNESS OF THIS LAYER INCREASES IN THE DIRECTION DOWN THE FLOW THIS LAYER POSSESSES HIGH HYDRODYNAMIC STABILITY AND IT PREVENTS HEAT TRANSFER BETWEEN THE COLD MEDIUM 4 AND THE ZONE WITH THE HIGHEST TEMPERATURE AND ELECTRICAL CONDUCTIVITY THIS FACT EXPLAINS A RELATIVELY LOW ELECTRIC FIELD STRENGTH IN THE INITIAL AREA OF THE CHANNEL AT THE END OF THE INITIAL AREA THE TANGENTIAL VELOCITY FIELD STARTS REARRANGING AND THIS LEADS TO A DECREASE OF ARC STABILITY ALONG THE CHAMBER AXIS TURBULENT BOUNDARY LAYER