EP0157407A2 - Verfahren und Vorrichtung zur Erzeugung einer Plasmaströmung mit einem geheizten und erweiterten Plasmastrahl - Google Patents

Verfahren und Vorrichtung zur Erzeugung einer Plasmaströmung mit einem geheizten und erweiterten Plasmastrahl Download PDF

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Publication number
EP0157407A2
EP0157407A2 EP85103923A EP85103923A EP0157407A2 EP 0157407 A2 EP0157407 A2 EP 0157407A2 EP 85103923 A EP85103923 A EP 85103923A EP 85103923 A EP85103923 A EP 85103923A EP 0157407 A2 EP0157407 A2 EP 0157407A2
Authority
EP
European Patent Office
Prior art keywords
plasma
induction coil
flow
flow channel
jet
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP85103923A
Other languages
English (en)
French (fr)
Other versions
EP0157407A3 (de
Inventor
Gerhard Frind
Henry Takeshi Nagamatsu
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
General Electric Co
Original Assignee
General Electric Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by General Electric Co filed Critical General Electric Co
Publication of EP0157407A2 publication Critical patent/EP0157407A2/de
Publication of EP0157407A3 publication Critical patent/EP0157407A3/de
Withdrawn legal-status Critical Current

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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H1/00—Generating plasma; Handling plasma
    • H05H1/24—Generating plasma
    • H05H1/46—Generating plasma using applied electromagnetic fields, e.g. high frequency or microwave energy
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H1/00—Generating plasma; Handling plasma
    • H05H1/24—Generating plasma
    • H05H1/26—Plasma torches
    • H05H1/32—Plasma torches using an arc
    • H05H1/34—Details, e.g. electrodes, nozzles
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H1/00—Generating plasma; Handling plasma
    • H05H1/24—Generating plasma
    • H05H1/26—Plasma torches
    • H05H1/30—Plasma torches using applied electromagnetic fields, e.g. high frequency or microwave energy
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H1/00—Generating plasma; Handling plasma
    • H05H1/24—Generating plasma
    • H05H1/26—Plasma torches
    • H05H1/32—Plasma torches using an arc
    • H05H1/34—Details, e.g. electrodes, nozzles
    • H05H1/3484—Convergent-divergent nozzles
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H1/00—Generating plasma; Handling plasma
    • H05H1/24—Generating plasma
    • H05H1/26—Plasma torches
    • H05H1/32—Plasma torches using an arc
    • H05H1/34—Details, e.g. electrodes, nozzles
    • H05H1/40—Details, e.g. electrodes, nozzles using applied magnetic fields, e.g. for focusing or rotating the arc

Definitions

  • This invention relates to a method and apparatus for producing a plasma flow having a heated and broadened plasma jet. More particularly, it relates to'the use of an induction coil to heat the plasma jet exhausting from a plasma spray gun.
  • Plasma guns are frequently used to deposit a material, such as metal or ceramic, on an object to be coated or shaped, typically referred to as a target.
  • the material to be deposited is formed into powder particles, and the particles are injected into the plasma.
  • hot streaming gases from the plasma heat the powder particles to their melting point and accelerate them in preparation for deposit on the target.
  • the deposited material is of high, uniform density and high strength. In practice, however, such is not the case.
  • the deposits resulting from conventional plasma spray operations have higher density and strength in the area known as the "sweet spot", in the center of the deposit, than in the "fringe area" around the center of the deposit.
  • the temperature of the plasma decreases rapidly from the center of the plasma stream to its outer radius. Optimal heating and accleration of injected particles occurs within a relatively narrow radius from the center of the plasma stream. Furthermore, the overall temperature of the plasma stream decays rapidly as the plasma flows toward the target. The average temperature of a radial cross section of the plasma stream located near the target is significantly lower than the average temperature of a similar cross section located where the plasma stream exhausts from the plasma gun. Hence, the temperature of the plasma stream decays in both the axial and the radial directions.
  • a method for heating and broadening the plasma jet exhausting from a plasma gun comprises directing the plasma jet along the central axis of an induction coil and passing a high frequency alternating current through the coil, so that the outer layers of the plasma jet are heated more than the center of the jet, and so that the average temperature of the jet is increased.
  • a preferred method for producing a plasma flow having a hotter and broader jet than is conventionally provided comprises: establishing a plasma discharge in a gas flowing along the central axis of a first, upstream induction coil, by passing a high frequency alternating current through the coil; producing a plasma jet by directing the gas, .and at least a portion of the plasma discharge, through a throated passage; and heating the plasma jet emitted from the throated passage, by the method described above, using a second, downstream induction coil.
  • an apparatus for carrying out the present invention comprises a plasma gun having an inlet and an outlet, in which a plasma discharge may be established so that a plasma jet exhausts through the plasma gun outlet.
  • a heater housing having a flow channel defined therein is connected in flow communciation with the outlet of the plasma gun so that the plasma jet is directed through the flow channel.
  • the apparatus also includes a heater induction coil disposed around the outside of the flow channel and means for passing a high frequency alternating current through the coil in order to heat the plasma jet.
  • the plasma gun used in the above apparatus includes a housing having a flow channel with an inlet opening and an outlet opening, a throat region between the inlet and outlet ends of the channel, and another induction coil disposed around the inlet end of the flow channel.
  • An apparatus'for producing a plasma flow having a heated and broadened plasma jet includes the apparatus described above and further comprises means for introducing a high velocity flow of gas into the plasma gun and means for passing high frequency alternating currents through each of the induction coils.
  • a method for doing so comprises directing the plasma jet along the central axis of a downstream induction coil and passing a high frequency alternating current through the downstream induction coil, so as to both heat the outer layers of the plasma jet and increase the average temperature of the jet.
  • the magnitude and frequency of the high frequency alternating current flowing through the induction coil are chosen such that the current flow produces a power output of between about 20 kilowatts and 100 kilowatts.
  • the frequency of the current oscillation is preferably between about 500 kHz and 10 MHz.
  • plasma jet 14 exhausts from plasma spray gun 10 and flows along the central axis of a downstream induction coil 12 comprised of several induction coil winding turns.
  • induction coil 12 a high frequency magnetic field is produced, through which energy is coupled into plasma jet 14.
  • This energy transfer heats the outer layers of plasma jet 14 more than it heats the center thereof, thereby reducing the temperature decay of plasma jet 14 in the radial direction.
  • plasma jet 14 can be made to have a substantially flat radial temperature distribution.
  • Heating of plasma jet 14 in this manner results in a broader, larger diameter plasma jet stream, as illustrated in Figure 1 by plasma jet layer 16.
  • a larger diameter plasma jet stream particles injected into the stream can more easily be kept within the confines of the plasma stream.
  • the area within the stream where the plasma temperature is optimal has a larger radius.
  • Heating of plasma jet 14 by energy transfer from induction coil 12 also increases the average temperature of plasma jet 14, thereby reducing the effects on particle melting of temperature decay in the axial direction. As a result of these three effects, that is, reducing radial temperature decay, broadening the plasma jet, and increasing the average jet temperature, particles injected into the plasma stream are more uniformly heated and more completely melted before being deposited on a target.
  • Plasma gun 18 includes inlet 22 for receiving a high velocity flow of gas (not illustrated in Figure 2).
  • Plasma gun 18 also includes cathode 26 and anode 20 for producing an electrical arc and thereby initiating a plasma discharge in the gas, as shown in Figure 2 by arc discharge 28.
  • Plasma gun 18 also includes outlet 24 for exhausting at least a portion of the plasma discharge from plasma gun 18, as plasma jet 32.
  • Heater housing 34 having flow channel 30 defined therethrough is connected to plasma gun 18 so that flow channel 30 is in flow communication with outlet 24 of plasma gun 18, and so that plasma jet 32 is directed through flow channel 30.
  • Heater induction coil 36 is disposed around the outside of flow channel 30.
  • induction coil 36 is further disposed so that the longitudinal axis of the coil is located coaxially with the longitudinal axis of flow channel 30.
  • flow channel 30 is cylindrically shaped, and induction coil 36 is helically wound around the outside of flow channel 30.
  • the apparatus further includes conventional means (not illustrated in Figure 2) electrically connected to induction coil 36 for passing a high frequency alternating current therethrough, in order to heat the outer layers of plasma jet 32 more than the center thereof, and to increase the average temperature of plasma jet 32.
  • FIG. 2 is a side elevation, cross-sectional view schematically illustrating a plasma flow nozzle in accordance with another embodiment of the present invention.
  • the nozzle comprises housing 40 having main flow channel 42 defined therein, with inlet opening 44 located at one end of flow channel 42 and disposed in flow communication therewith, and outlet opening 48 located at the opposite end of flow channel 42 and also disposed in flow communication therewith.
  • throat region 46 having reduced cross-sectional flow area, is disposed in flow channel 42 and located between inlet opening 44 and outlet opening 48, for accelerating gas passing through throat region 46 and forming a jet stream downstream thereof.
  • First or upstream induction coil 50 is located at the inlet end of flow channel 42, and second or downstream induction coil 52 is located at the outlet end of flow channel 42.
  • First induction coil 50 and.second induction coil 52 are each disposed around the outside of flow channel 42.
  • first and second induction coils 50 and 52 are further disposed so that their longitudinal axes are each located coaxially with respect to the longitudinal axis of flow channel 42.
  • flow channel 42 is cylindrically shaped, and first and second induction coils 50 and 52 are each helically wound around the outside of flow channel 42.
  • first and second induction coils 50 and 52 may be electrically connected, so that they form a single electrical circuit.
  • a method for producing a plasma flow having a heated and broadened plasma jet comprises directing a gas flow, in which a plasma is to be established, at a high velocity along the central axis of a first, upstream induction coil, and passing a high frequency alternating current through the first induction coil so as to heat the gas and initiate a plasma discharge therein.
  • the method includes forming a plasma jet from the gas flow and at least a portion of the plasma discharge.
  • One method for forming the plasma jet is to direct the gas flow and a portion of the plasma discharge through a throated passage having reduced cross-sectional flow area, in order to accelerate the gas flow through the throated passage and to produce a plasma jet.
  • the method further includes directing the resulting plasma jet along the central axis of a second, downstream induction coil.
  • a high frequency alternating current is passed through the second induction coil, so as to heat the outer layers of the plasma jet more than the center thereof, and to increase the average temperature of the plasma jet.
  • the high frequency alternating current flowing through the first induction coil produces a power output of between about 20 kilowatts and 100 kilowatts
  • the high frequency current flowing through the second induction coil similarly produces a power output of between about 20 kilowatts and 100 kilowatts.
  • the current flowing through the coil preferably comprises current oscillating at a frequency of between about 500 kHz and 10 MHz.
  • the velocity of the gas flow along the central axis of the first induction coil is between about 5 meters per second and 50 meters per second.
  • the plasma flow nozzle of Figure 3 is especially suitable for carrying out this embodiment of the invention.
  • An apparatus for producing a plasma flow having a heated and broadened plasma jet includes the plasma flow nozzle shown therein, and further comprises conventional means (not illustrated in Figure 3.) for introducing a high velocity flow of gas into flow channel 42, connected in flow communication with inlet opening 44.
  • the apparatus also comprises conventional means (also not illustrated in Figure 3) electrically connected to first induction coil 50, for passing a high frequency alternating current therethrough, in order to heat gas flowing along the central axis of coil 50, and to initiate plasma discharge 56 in the gas flowing through flow channel 42.
  • the apparatus further includes conventional means (similarly not illustrated in Figure 3) electrically connected to second induction coil 52, for passing a high frequency alternating current therethrough, in order to heat the outer layers of jet stream 58, formed from gas passing through throat region 56, more than the center of jet stream 58 is heated, and to increase the average temperature of jet stream 58.
  • a plasma flow produced in accordance with this embodiment of the invention has, in addition to the desirable features described above, the advantage of being characterized by a broad and long plasma discharge, with a nearly flat radial temperature distribution. Furthermore, the flow velocity of the gas in which the plasma is.established may be quite low, so that the residence time of particles injected into the plasma may be quite long. Also, the plasma density can be made quite high, thereby facilitating heat transfer from the plasma to the injected particles, and further improving particle melting and acceleration and finished characteristics of the target.
  • the foregoing describes a method for heating and broadening the plasma jet exhausting from a plasma spray gun, by using a downstream induction coil to heat and broaden the plasma jet.
  • the present invention also provides a method for producing a plasma flow with less temperature decay in both the radial and the axial directions.
  • the present invention further provides a plasma flow nozzle having an induction coil to heat a gas stream flowing therethrough, and an apparatus for producing a plasma flow having a heated and broadened plasma jet.
  • Housings 34 and 40 may even comprise metal, if provisions are made so that absorption of radio frequency energy, produced by the induction coils, in each of housings 34 and 40 is minimized.
  • cathode 26 and anode 20 of Figure 2 have been shown as comprising metal, other electrically conductive materials may be used. Accordingly, it is intended by the appended claims to cover all such modifications and changes as fall within the true spirit and scope of the invention.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Electromagnetism (AREA)
  • Plasma Technology (AREA)
  • Discharge Heating (AREA)
EP85103923A 1984-04-04 1985-04-01 Verfahren und Vorrichtung zur Erzeugung einer Plasmaströmung mit einem geheizten und erweiterten Plasmastrahl Withdrawn EP0157407A3 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US59679284A 1984-04-04 1984-04-04
US596792 1984-04-04

Publications (2)

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EP0157407A2 true EP0157407A2 (de) 1985-10-09
EP0157407A3 EP0157407A3 (de) 1986-12-03

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EP85103923A Withdrawn EP0157407A3 (de) 1984-04-04 1985-04-01 Verfahren und Vorrichtung zur Erzeugung einer Plasmaströmung mit einem geheizten und erweiterten Plasmastrahl

Country Status (3)

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EP (1) EP0157407A3 (de)
JP (1) JPS60249300A (de)
NO (1) NO851357L (de)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0500491A1 (de) * 1991-02-21 1992-08-26 Sulzer Metco AG Plasmaspritzgerät zum Versprühen von pulverförmigem oder gasförmigem Material
EP0673186A1 (de) * 1994-03-17 1995-09-20 Fuji Electric Co., Ltd. Verfahren und Vorrichtung zur Erzeugung eines induzierten Plasmas
WO1996012390A1 (en) * 1994-10-14 1996-04-25 The University Of British Columbia Plasma torch electrode structure
DE10140298A1 (de) * 2001-08-16 2003-03-13 Mtu Aero Engines Gmbh Verfahren zum Plasmaschweißen
US6808755B2 (en) 1999-10-20 2004-10-26 Toyota Jidosha Kabushiki Kaisha Thermal spraying method and apparatus for improved adhesion strength
EP1734360A1 (de) * 2004-03-25 2006-12-20 Japan Advanced Institute of Science and Technology Plasmaerzeugungsgerät
CN102271452A (zh) * 2010-06-03 2011-12-07 成都阳流科技发展有限公司 一种热等离子体弧焰发生器
WO2017083464A1 (en) 2015-11-12 2017-05-18 Cornell University Alternating current electrospray manufacturing and products thereof
CN108534549A (zh) * 2018-05-24 2018-09-14 刘冠诚 一种提高产品纯度的等离子金属冶炼还原装置

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2783813B2 (ja) * 1988-09-20 1998-08-06 ゼネラル・エレクトリック・カンパニイ 繊維強化金属マトリックス材料の製造方法及び複合構造体

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1338946A (fr) * 1962-08-21 1963-10-04 Soc De Traitements Electrolytiques Et Electrothermiques Chalumeau à plasma haute fréquence
US3332870A (en) * 1962-10-08 1967-07-25 Mhd Res Inc Method and apparatus for effecting chemical reactions by means of an electric arc
US3401302A (en) * 1965-11-01 1968-09-10 Humphreys Corp Induction plasma generator including cooling means, gas flow means, and operating means therefor
GB1260021A (en) * 1969-10-27 1972-01-12 British Titan Ltd Heating device
DE3130908A1 (de) * 1981-08-05 1983-03-10 Horst Dipl.-Ing. 5100 Aachen Müller "plasma-reaktor"

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1338946A (fr) * 1962-08-21 1963-10-04 Soc De Traitements Electrolytiques Et Electrothermiques Chalumeau à plasma haute fréquence
US3332870A (en) * 1962-10-08 1967-07-25 Mhd Res Inc Method and apparatus for effecting chemical reactions by means of an electric arc
US3401302A (en) * 1965-11-01 1968-09-10 Humphreys Corp Induction plasma generator including cooling means, gas flow means, and operating means therefor
GB1260021A (en) * 1969-10-27 1972-01-12 British Titan Ltd Heating device
DE3130908A1 (de) * 1981-08-05 1983-03-10 Horst Dipl.-Ing. 5100 Aachen Müller "plasma-reaktor"

Cited By (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4105408C1 (de) * 1991-02-21 1992-09-17 Plasma-Technik Ag, Wohlen, Ch
EP0500491A1 (de) * 1991-02-21 1992-08-26 Sulzer Metco AG Plasmaspritzgerät zum Versprühen von pulverförmigem oder gasförmigem Material
EP0977470A3 (de) * 1994-03-17 2003-11-19 Fuji Electric Co., Ltd. Verfahren und Vorrichtung zur Erzeugung eines induzierten Plasmas
EP0673186A1 (de) * 1994-03-17 1995-09-20 Fuji Electric Co., Ltd. Verfahren und Vorrichtung zur Erzeugung eines induzierten Plasmas
US5680014A (en) * 1994-03-17 1997-10-21 Fuji Electric Co., Ltd. Method and apparatus for generating induced plasma
EP0977470A2 (de) * 1994-03-17 2000-02-02 Fuji Electric Co., Ltd. Verfahren und Vorrichtung zur Erzeugung eines induzierten Plasmas
WO1996012390A1 (en) * 1994-10-14 1996-04-25 The University Of British Columbia Plasma torch electrode structure
US6913207B2 (en) 1999-10-20 2005-07-05 Toyota Jidosha Kabushiki Kaisha Thermal spraying method and apparatus for improved adhesion strength
US6808755B2 (en) 1999-10-20 2004-10-26 Toyota Jidosha Kabushiki Kaisha Thermal spraying method and apparatus for improved adhesion strength
DE10140298B4 (de) * 2001-08-16 2005-02-24 Mtu Aero Engines Gmbh Verfahren zum Plasmaschweißen
DE10140298A1 (de) * 2001-08-16 2003-03-13 Mtu Aero Engines Gmbh Verfahren zum Plasmaschweißen
EP1734360A1 (de) * 2004-03-25 2006-12-20 Japan Advanced Institute of Science and Technology Plasmaerzeugungsgerät
EP1734360A4 (de) * 2004-03-25 2011-05-11 Japan Adv Inst Science & Tech Plasmaerzeugungsgerät
CN102271452A (zh) * 2010-06-03 2011-12-07 成都阳流科技发展有限公司 一种热等离子体弧焰发生器
WO2017083464A1 (en) 2015-11-12 2017-05-18 Cornell University Alternating current electrospray manufacturing and products thereof
EP3374088A4 (de) * 2015-11-12 2019-07-03 Cornell University Herstellung eines wechselstromelektrosprays und produkte daraus
EP3374087A4 (de) * 2015-11-12 2019-11-06 Cornell University Luftkontrollierte elektrosprayherstellung und produkte daraus
US11224884B2 (en) 2015-11-12 2022-01-18 Cornell University Alternating current electrospray manufacturing and products thereof
US11383252B2 (en) 2015-11-12 2022-07-12 Cornell University Air controlled electrospray manufacturing and products thereof
US11911784B2 (en) 2015-11-12 2024-02-27 Cornell University Alternating current electrospray manufacturing and products thereof
CN108534549A (zh) * 2018-05-24 2018-09-14 刘冠诚 一种提高产品纯度的等离子金属冶炼还原装置

Also Published As

Publication number Publication date
NO851357L (no) 1985-10-07
EP0157407A3 (de) 1986-12-03
JPS60249300A (ja) 1985-12-09

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