RS49706B - ONE-DIRECT ARCH PLASMA GENERATOR WITH INPUT VOLT AMP - Google Patents

Abstract

One-way arc plasma generator with input volt-apmer characteristic, with connection to the generator (5) of direct current with switch (501) as well as with connections at the opening (108) of the sleeve (107) and the opening (119) of the cooling water supply and drain housing and having a connection to the opening (122) of a portion (104) of the working gas housing, comprising a two-part housing (1) consisting of a supporting part (101) in which a cylindrical opening (114) with an interior is provided on the underside a coil in which a second, lower conical portion (2) of the housing with sealing 0 rings (202) and a lower cylindrical notch (201) is screwed in with its complementary coil, in which an anode (4) is provided with a conical opening (418) of the divergent channel shape. and the cylindrical opening (114) of the supporting part is continued by a vertical notch (113) whose inner side is formed by a cone (112) completed by a lower flat surface (111a) which passes into a cylindrical opening (102) in which an insulating sleeve (103) is mounted in the pressed assembly, in which the middle part (104) of the supporting part of the housing is again placed in the pressed assembly, in which again an insulating sleeve (106) with a pressed conductive sleeve (106) is mounted in the pressed assembly. 107) with an inner opening (108), and having the middle part (104) of the housing, in the place of the end of the conductive sleeve (107) as well as of the insulating sleeve (106) in the form of a cylindrical opening (110) which is further extended by a conical opening (109) ) and terminated by a cylindrical opening (111) with an inner coil, wherein a cathode (3) with a sealing 0 ring (301) is inserted in the cylindrical opening (110), to which is fitted a gas conduit (302) with a divergent conical opening (304) and the openings (303) of the tangential channels pressed, in the opening (111) with an inner coil twisted by a priatode segment (404) with a sealing 0 ring (405), made with a lower extension (407), a conical inner opening (406) shaped convergent g channels as well as a lateral through-hole (412) and a notch in extension (407) in which an insulating ring (410) is mounted with openings (411) of its tangential channels, while the middle anode segment (408) is pressed on the ring (410) with a tapered inner opening (413) of divergent channel shape and lateral through hole (414) as well as a pair of sealing 0 rings (409) pressed against an insulating ring (415) with openings (416) of tangential channels inserted in the anode extension (417) (4) .- The application contains 5 more patent claims.

Description

The field of technology at co. and the invention relates

The invention belongs to the field of electrical engineering, that is, to the field of plasma technology, especially its production, and relates to a one-way arc plasma generator with a rising volt-ampere characteristic.

According to the International Classification of Patents (IPC)5, the designation is:

H 05H 1/24; H 05H 1/26 and H 05H 1/32.

Technical problem

The invention solves the problem of the construction of a DC arc plasma generator, a simple and modern construction that will work with a noticeable rising volt-ampere characteristic, or

with voltage-current, which will produce direct plasma with high heat content (enthalpy) and high ionization, which will emerge from the generator at a relatively high speed in the form of a jet suitable for use in e.g. plasma chemistry, and mass losses inside the plasma generator will be minimal.

Technical status

It is known from the non-patent literature that for the generation of low-temperature plasma in the form of a jet, three types of generators are used today: radio frequency plasma sources, one-way arc generators, and three-phase alternating generators.

Direct current plasma generators, which are the subject of this invention, produce plasma by passing a direct current through the gas. There are two basic varieties of these. In the first variant, the electric arc is established between the cathode in the shape of a spike (electrode) and the anode with a cylindrical opening (nozzle), which are electrically isolated from each other. The working gas is introduced tangentially between the cathode and the anode, and when a direct current passes through it, it is heated, forming a plasma that emerges from the anode opening into the open space. The disadvantages of this solution are reflected in the so far commercially available solutions in the form of a short stream of output plasma at a low operating voltage (below 100V) that requires a high current (of the order of 1000 A) with a hyperbolically decreasing characteristic of the voltage-current curve.

In the second variant, a solution with two electrodes with cylindrical openings is used, where in one electrode it is a blind opening and the electrodes are electrically separated at the mutual contact by a ring through which the gas is introduced tangentially. Through the formed arc, the working gas is now introduced, which is brought to the state of plasma, which emerges from the cylindrical opening of one of the electrodes. The disadvantages of this solution are reflected in the fact that a significantly higher gas flow is required, e.g. compared to the first described solution, in order to ensure stable operation. For this reason, the described solution is mainly used in special industrial plants. At the same time, this solution is not suitable for use as a plasma generator in the so-called spray step-by-step application of material to a surface.

Of the relevant solutions in relation to the subject of the invention, the patent file No. 5,519,183 as well as file No. 5,620,616 and No. 5,628,924 should be mentioned in the patent documentation. from the US patent fund. US Patent No. 5,243,169 describes the so-called solution. double-current type, where two plasma generators are used, placed at an angle of 90 degrees, which form a common output plasma beam.

US Patent No. 5,500,501 describes a construction in which the cathode and anode are two coaxially placed tubular electrodes.

US Patent No. 5,514,848 describes a solution that represents an attempt to influence the speed of plasma discharge by profiling the plasma exit channel.

Finally, in US Patent No. 5,406,046 shows a solution with three cathodes and an increased distance between the cathode and the anode with the insertion of several mutually electrically isolated segments.

Analyzing all the mentioned patent documents from the US patent fund, it is concluded that all the described solutions have shortcomings from which the proposed definition of the technical problem that is to be solved by the subject of this invention arises, as well as the shortcomings of the described solutions known from non-patent literature.

Presentation of the essence of the invention

The basic intentions in the construction of plasma generators today are to produce plasma with the highest possible heat content (enthalpy), with as little electrode erosion as possible. A high plasma enthalpy ensures a high plasma temperature, a high degree of plasma ionization and its high exit velocity. All these characteristics of the plasma jet are important for the application of plasma in plasma chemistry where it is used as a medium for the initiation of chemical processes and for application in plasma spray processes in which the plasma is used for melting and for accelerating the material particles introduced into the plasma.

For the above, as well as in order to eliminate the shortcomings observed in the previously described solutions, the solution according to the invention is characterized by a specific construction of the anode set. This includes three parts, each of which has a central opening in the form of a channel, and which are structurally properly connected to each other, ensuring ideal coaxiality with simple assembly. The first anode segment, the so-called near-cathode is closest to the cathode and by twisting its coil

in the corresponding screw hole, it pulls the cathode and the gas inlet together, performing the function of an auxiliary electrode for ignition. The central anode segment is placed between both ends and is electrically isolated from them. The third segment is the anode itself, electrically connected to the supporting part of the housing. Anodic segments are at that

electrically isolated from each other by means of insulating rings in which tangential openings are made for the introduction of secondary gas, which has the additional function of cooling the anode set.

With the specific geometry of the segments and their arrangement of the anode set, the rising volt-amperage characteristic of the plasma generator according to the invention was achieved. To this end, the common central opening of all segments of the anode set in the assembly, going from the cathode towards the anode outlet, has a Laval nozzle profile, which ensures the expansion of the working gas flowing through it, which reaches maximum speed.

The advantage of the solution according to the invention is primarily that it enables the operation of a plasma generator constructed in this way with a voltage of only a few hundred volts, whereby it is possible to significantly increase the power of the device compared to analog constructions of similar dimensions. During the operation of the device according to the invention, the formed plasma achieves its full development due to the long path of the electric arc from the cathode to the anode, which makes the plasma exit the generator at a higher speed than with a generator with a shorter arc. The reduction of heat losses caused by better blowing of the arc anode spot enables obtaining high-enthalpy plasma and at the same time significantly extends the service life of the anode. Finally, the rising volt-ampere characteristic allows for greatly simplified current control in the plasma generator circuit.

Brief description of the draft images

The invention is described in detail on the example of the method of execution shown in the drawing in which: Figure 1 shows a longitudinal section of the DC arc plasma generator assembly.

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The one-way arc plasma generator with an ascending volt-ampere characteristic, according to Figure 1, includes a two-part housing 1 with a no-cutting part 101 as well as a lower conical part 2, which are cylindrical in shape, preferably made of electro-stretchable material, e.g. cast brass. The cutting part 101 is made with a cylindrical opening 102 in which an insulating sleeve 103, preferably made of plastic, is placed in the pressed assembly. Inside this insulating sleeve 103, the middle part 104 of the supporting part with its central opening 105 is placed in the pressed assembly, in which the middle insulating sleeve 106, also most advantageously made of plastic, is then placed in the pressed assembly. Finally, inside this sleeve 106, a metal conductive sleeve 107 with an internal opening 108 in the form of a channel for supplying water for cooling the generator is placed in a pressed assembly.

From the lower front side of both sleeves 106 and 107, in the extension of the inner opening 108, covering the middle part 104 of the supporting part of the housing, there is a cylindrical opening 110, continued with a conical opening 109, finished with a cylindrical opening 111 with an internal coil and a flat surface of the shell common to the end of the shell 103. This flat surface of the shell on the supporting part 101 is continued with an internal cone 112 that passes into a vertical cut 113 and is finished with an internal opening'114 with a coil in which the lower conical part 2 of the housing is twisted with its coil, allowing easy and quick access to the components of the generator la. The lower conical part 2 of the housing is made with a cylindrical cut 201 in which the anode 4 with its sealing ring 420 is placed, finished with an extension 417 and in which a coaxial conical divergent opening 418 of channel form is made.

At the same time, in the mentioned cylindrical opening 110, the cathode 3, the most favorable of tungsten, is inserted with its sealing ring 301, on which the gas inlet 302 with a divergent conical opening 304 as well as lateral tangential openings 303 for the introduction of gas is pressed. This gas inlet 302 is pressed by the cathode segment 404 with the sealing 0 ring 405, which is twisted with its complementary coil in the helical cylindrical opening 111 of the part 104 of the housing. The near-cathode segment 404 is made with a convergent conical inner opening 406 in the form of a channel with an extension 407 at its end in the form of a flange for receiving the middle anode segment 408 with its pair of sealing rings 409. At the same time, a shallow u-cut is made in the near-cathode segment 404 for receiving the insulating ring 410, in the central opening of which tangential channels with openings are made 411 for the introduction of working gas, while laterally in relation to the opening 406 in the segment, a passage opening 412 is also made for the passage of gas.

Fit under pressure, in the opening 114 with the coil of the twisted lower conical part 2 of the housing, on the insulating ring 410, the middle anode segment 408 is made with a coaxial conical opening 413 in the form of a divergent channel, as well as with a peripheral passage opening 414 for gas.

A lower insulating ring 415 with openings 416 in the central opening of the completed tangential gas inlet channels is pressed against the lower front side of the middle anode segment 408. This insulating ring 415 is inserted in a shallow notch made in the previously mentioned extension 417 of the anode 4 with an extension 419 made on the opposite side for resting on the lower side of the cut 201 of the lower conical part 2 of the housing.

A Laval nozzle with convergent and divergent conical openings 406, 413, 418 with precisely defined engagement angles was formed from the coaxially pressed together anode segments 404 and 408 as well as the anode 4 itself together with the insulating rings 410 and 415.

In order to ensure the smooth functioning of the plasma generator according to the invention, suitable openings and channels for the flow of cooling water were made. Although the radial channel 115 is connected to the previously mentioned inner opening 108 of the inner sleeve 107, which flows into the annular cast channel 116, which is connected via the vertical channels 117 to the space of the vertical cut 113 of the supporting part 101 of the housing. At the same time, this space is connected to the wall of the lower conical part 2 of the housing through water channels 203, the lower openings of which exit in its lower part.

Likewise, inside the housing 1, i.e. its supporting part 101, there is a molded circular channel 118 which is connected to the connection opening 119 with a coil. At the same time, several peripheral vertical channels 120 are connected to the channel 118, the free opening of which is finished at the edge of the inner cone 112 with a flat surface.

In the supporting part 101 of the housing 1 of the generator la, inside its middle part 104, there is also a vertical channel 121 with a connection opening 122 with an internal coil, for gas, the second free opening of which opens to the widened conical opening 109.

To supply direct current at the required voltage, a generator 5 with a switch 501 is installed. This generator 5 is connected with its (+) pole to the lead inside the connection opening 119 with the coil, for draining the cooling water. At the same time, the (-) pole of the generator 5 is connected to the conductive sleeve 107 with opening 8 for cooling water supply. In addition to this, the (+) pole of the generator 5 is connected via the switch 501 to the inlet inside the connection opening 122 for the supply of working gas.

The dc plasma generator with rising volt-ampere characteristic according to the invention works by first establishing the circulation of cooling water inside the housing 1 and its lower conical part 2. In this, the cooling water is supplied through the inner opening 108 of the channel shape where it cools the cathode 3. At the same time, this water is supplied through the radial channels 115, the cast-in channel 116, the vertical channels 117 and the channel 203.

in the lower part of the lower conical part 2 of the housing where it cools the anode 4

and then moving upward, cools the anode segments 408 and 404

as well as through these gas inlet 302 and insulating rings 410 and 415. Finally, the cooling middle part of the housing 104 is fed through vertical peripheral channels 120 into the circular channel 118 from where it is taken out of the plasma generator through the connecting opening 119.

After establishing a stable circulation of cooling water, working gas is introduced into the housing 1 of the generator through the connection opening 122, and the direct current generator 5 with the closed switch 501 is also switched on. 416 flows tangentially into the conical openings 304, 406, 413 and 418. When the direct current generator 5 is switched on and the working gas current is established, a plasma ignition occurs between the cathode 3 and the anode segment 404, whereby the cathode 3, via the metal conductive sleeve 107, is connected to

(-) pole while near-cathode anode segment 404, preferably made of copper, is connected via switch 501 to (+) pole of said direct current generator 5. After the plasma is ignited, the switch 501 is opened and the (+) voltage of the anode segment 404 is turned off, and the electric arc is further maintained between the cathode 3 and the anode 4 within the convergent and divergent channels of the openings 406, 413 and 418 of the anode set, while the secondary gas is introduced through the channels 412

and 414 through openings 411 and 416. In addition, the middle anode segment 408 remains electrically isolated at all times.

In order for the plasma generator to operate stably with the desired upward volt-ampere characteristic, it is necessary according to the invention to provide a ratio of the distance from the top of the cathode 3 to the beginning of the anode 4*that is, the beginning of its internal conical opening 418, measured along the conical internal openings 406 and 413 of the anode segments 404 and 408, to the exit of the conical opening 418, greater than 3, whereby the length of the middle anode segment 408, measured in the same direction, must not be less than twice the diameter of the same initial conical opening 418 of the anode 4.

Method of industrial or other application of the invention

The method of application of the invention follows in an obvious way from the preceding text of the description as well as the attached drawing, and it is not necessary to describe it separately. However, it is necessary to emphasize here that the plasma generator according to the invention, with its construction / which ensures the production of plasma with high enthalpy at high temperature, with a high degree of ionization and a high output speed, is suitable for use in plasma chemistry where the plasma jet is used as a medium for the initiation of chemical processes and for use in plasma spray processes in which p3m,zma is used to melt and accelerate particles of materials introduced into the plasma.

All structural and functional features mentioned in the description of the invention were checked by the inventor on the realized prototype.

Claims (6)

1. Single-phase arc plasma generator with an upward volt-ampere characteristic, with a connection to the generator (5) of direct current with a switch (501) as well as with connections on the opening (108) of the sleeve (107) and the opening (119) of the housing of the supply and drainage of cooling water and with the connection on the opening (122) of the part (104) of the working gas housing, indicated by the fact that it includes a two-part housing (l) consisting of a supporting part (101) in which a cylindrical opening (114) with an inner coil is made on the lower side, in which the second, lower conical part (2) of the housing with sealing rings (202) and a lower cylindrical cut (201) with an inner coil is twisted with its complementary coil, and an anode (4) with a conical opening (418) shaped of a divergent channel, and a cylindrical opening (114) of the supporting part is continued with a vertical cut (113), the inner side of which is continued with a cone (112) finished with a lower flat surface (lila) that passes into a cylindrical opening (102) in which an insulating sleeve (103) is placed in the pressed assembly, in which the middle part (104) of the supporting part of the housing is placed in the pressed assembly, in which again in pressed assembly in its opening (105) placed an insulating sleeve (106) with a pressed conductive sleeve (107) with an inner opening (108), and the middle part (104) of the housing, at the end of the conductive sleeve (107) as well as the insulating sleeve (106) is made in the form of a cylindrical opening (110) which is continued downwards by a conical opening (109) and finished with a cylindrical opening (111) with an inner with a coil, where a cathode (3) with a sealing ring (301) is inserted in the cylindrical opening (110), on which a gas inlet (302) with a divergent conical opening (304) and openings (303) of tangential channels is pressed against the opening (lll) with an inner coil twisted near the cathode segment (404) with a sealing ring (405), made with a lower extension (407), a conical inner opening (406) in the form of a convergent channel, as well as a lateral passage opening (412) and a cut in the extension (407) in which the insulating ring (410) with the openings (411) of its tangential channels is placed, while the middle anode segment (408) with a conical inner opening is pressed onto the ring (410) (413) in the form of a divergent channel and lateral through the through hole (414) as well as a pair of sealing rings (409) pressed against the insulating ring (415) with ot vorima (416) of the tangential channels, inserted in the extension cut (417) of the anode (4). 2. One-way arc plasma generator, according to claim 1, characterized by the fact that in the wall of the lower part (2) of the housing there are passage channels (203) for water, while in the supporting part (101) of the housing with pressed insulating Sauras (103,106), and in the middle part (104) of the housing with a conductive sleeve (107), a circular channel is formed (118) with a connection opening (119) and vertical peripheral channels (120) for water, as well as a circular channel (116) with radial channels (115) as well as with vertical channels (117) for water, and that a vertical channel (121) with a connection opening (122) for working gas is derived. 3. One-way arc plasma generator, according to claims 1 and 2, characterized by the fact that the central conductive sleeve (107) is connected to the (-) pole of the generator (5) of direct current, while the connection openings (119) and (122) are designed for connection to the (+) pole of the same generator (5), where the connection opening (122) is connected via the switch (501). 4. Unidirectional arc plasma generator, according to claim 1, characterized by the fact that the convergent conical opening (406) as well as the divergent conical openings (413) and (418) together with the openings in the isolation rings (410) and (415) of the anode set, are placed strictly coaxially forming a convergent-divergent Laval nozzle. 5. One-way arc plasma generator, according to claims 1 and 4, indicated by the fact that the structurally determined ratio of the distance from the top of the cathode (3) to the beginning of the anode (4), i.e. to the beginning of its opening (418) of the divergent channel, measured along the conical openings (406,413) of the divergent-convergent channels of the anode segments (408,404) to the output, is greater than 3. 6. Unidirectional arc plasma generator, according to claim 114, characterized in that the structurally determined length of the middle anode segment (408) is equal to or greater than twice the diameter of the initial opening (418) of the divergent anode channel (4).