WO2011161251A1

WO2011161251A1 - Device for generating a plasma jet

Info

Publication number: WO2011161251A1
Application number: PCT/EP2011/060637
Authority: WO
Inventors: Serguei Mikhailov; Sergey Goloviatinski; Sheleh Yauheni
Original assignee: Nci - Swissnanocoat Sa
Priority date: 2010-06-24
Filing date: 2011-06-24
Publication date: 2011-12-29
Also published as: EP2586276A1; FR2962004A1; JP2013535080A; FR2962004B1

Abstract

The present invention relates to a device for generating a plasma jet from a carrier gas, comprising a discharge chamber having a longitudinal axis and an emission nozzle connected to said discharge chamber, said emission nozzle being provided with an outlet for emitting a generated plasma jet, said discharge chamber and said emission nozzle having a length that can be adjusted as a function of a preset output power of said plasma jet.

Description

DEVICE FOR GENERATING A PLASMA JET

Technical area

The present invention relates to a device for generating a plasma jet and, more particularly, a device for generating a plasma jet from a carrier gas, comprising a discharge chamber having an axis. longitudinal and an emission nozzle connected to said discharge chamber, said emission nozzle being provided with a mouthpiece for the emission of a plasma jet generated.

State of the art

The German patent application DE 195 32 412 A1 describes such a device for the pretreatment of the surface of parts to be manufactured. This device comprises upstream a housing with a longitudinal axis, along which a discharge electrode is housed. The housing comprises a radial orifice for the injection of a carrier gas for the creation of a swirling of the carrier gas along the longitudinal axis. Downstream of the device, an emission nozzle surrounded by a counter electrode defining a mouth for the emission of a plasma jet generated is provided. The emission nozzle is coupled to the housing.

During commissioning of the device of DE 195 32 412 A1, a carrier gas such as air is injected through the radial orifice in the housing and an electric current is applied to the discharge electrode and the counter electrode. Thus, an electric discharge is generated which results in the creation of an electric arc suitable for the generation of a plasma jet from the carrier gas. This generated plasma jet is emitted from the mouth of the emission nozzle on the surface of a part to be manufactured for the pretreatment of this surface.

The disadvantage of the device of DE 195 32 412 A1 is the number of components required for its manufacture. In addition, this device has a limited scope, because the plasma jet generated has limited output power.

Disclosure of the invention

The present invention aims to provide a new device for the generation of a plasma jet from a carrier gas having a reduced number of components and an expanded field of application.

This object is achieved by a device for generating a plasma jet from a carrier gas, comprising a discharge chamber having a longitudinal axis and an emission nozzle connected to said discharge chamber, said emission nozzle being provided with a mouthpiece for the emission of a generated plasma jet. Said discharge chamber and said emission nozzle have an adjustable length as a function of a predetermined output power of said plasma jet. In other embodiments, the device comprises a plurality of discharge chambers and a plurality of emission nozzles. This makes it possible to widen the zone of the treatment of the surface. It is also possible to use several carrier gases from several nozzles, i.e. each nozzle uses a different gas to allow the execution of the successive operations.

The present invention therefore makes it possible to widen the scope of a device for generating a plasma jet from a carrier gas by making it possible to increase or reduce the output power of a plasma jet generated by a suitable adjustment of the length of the discharge chamber and the emission nozzle of the device. The device according to the invention preferably comprises a discharge electrode and an associated counter electrode, adapted to generate an electric discharge for generating a plasma jet from a carrier gas. The counter electrode is preferably made by the emission nozzle and the electric discharge is able to create an electric arc necessary for the generation of a plasma jet between the discharge electrode and the mouth of the emission nozzle. Electrical pulses of short duration are applicable to the discharge electrode and the counter electrode. The pulses can have different polarities, constant or variable, in all frequency ranges.

Thus, by using the emission nozzle as a counter electrode, the number of components necessary for producing the device can advantageously be reduced.

According to one embodiment of the invention, the discharge electrode is arranged on the longitudinal axis of the discharge chamber and movably along this axis to allow adjustment of the length of the discharge chamber and the emission nozzle. The mouth of the emission nozzle preferably has an adjustable diameter depending on the predetermined output power of the plasma jet.

The present invention therefore allows a quick adjustment and. easy of the predetermined output power of the plasma jet by adjusting the length of the discharge chamber and the emission nozzle and / or a setting of the diameter of the nozzle of the emission nozzle.

Preferably, at least one radial orifice is provided allowing injection of the carrier gas into the discharge chamber in a direction approximately perpendicular to the longitudinal axis in order to create a swirling of the carrier gas along the longitudinal axis in the direction of the mouth of the emission nozzle. According to one embodiment, at least one radial orifice is made so as to allow an acceleration of the carrier gas from a subsonic velocity to an approximately supersonic velocity.

Thus, the generation of the plasma jet from the carrier gas can advantageously be improved.

According to one embodiment, the device comprises at least one axial orifice for injecting a reactive gas capable of being mixed with the carrier gas for the generation of the plasma jet. The axial orifice is preferably adapted to allow a swirling of the reactive gas along the longitudinal axis in the direction of the mouth of the emission nozzle.

The present invention therefore allows the creation of different plasma jets having different characteristics and fields of application.

Preferably, the carrier gas is air.

Thus, a carrier gas well available and inexpensive can be used.

According to one embodiment, the mouth of the emission nozzle is made to allow an acceleration of the plasma jet of a subsonic speed at an approximately supersonic speed.

The present invention thus allows rapid and efficient cooling of the plasma jet at the output of the device.

The mouth of the emission nozzle preferably comprises at least one radial opening for the angular emission of the plasma jet.

Thus, an additional widening of the fields of application of the plasma jet generated is advantageously possible.

Brief description of the drawings

The details of embodiment and the advantages of the device for generating a plasma jet from a carrier gas according to the invention will emerge from the detailed description following various embodiments, given by way of example and illustrated by the accompanying drawings which show schematically:

[0023] FIG. 1 a longitudinal sectional view of a downstream part of a device for generating a plasma jet from a carrier gas according to an embodiment of the invention;

[0024] FIG. 2 a longitudinal sectional view of an upstream part of a device for generating a plasma jet from a carrier gas according to an embodiment of the invention;

[0025] FIG. 3 a cross-sectional view of the upstream portion of the device of FIG. 2 according to another embodiment;

[0026] FIG. 4 a schematic view of a radial temperature distribution measured in the discharge chamber and in the emission nozzle according to FIG. 1 and 2;

FIG. A schematic view of a radial distribution of a pressure measured in the discharge chamber and in the emission nozzle according to FIG. 1 and 2;

[0028] FIG. 6 a longitudinal sectional view of an upstream portion of a device for generating a plasma jet from a carrier gas and a reactive gas according to another embodiment of the invention;

[0029] FIG. 7 a cross-sectional view of the upstream portion of the device of FIG. 6;

[0030] FIG. 8 a longitudinal sectional view of an upstream part of a device for generating a plasma jet from a carrier gas according to another embodiment, with an additional electrode in front of the electrode discharge;

[0031] FIG. 9 and 10 are diagrammatic views of exemplary short-pulse mode operation of the electric current applied to the device of the preceding figures;

[0032] FIG. 11 and 12 views in longitudinal section of preferable mouths of the emission nozzle according to the preceding figures; [0033] FIG. 13 a schematic view of the device of the preceding figures with radial orifices provided at the mouth of the emission nozzle;

[0034] FIG. A schematic view of a device comprising a plurality of discharge chambers and emission nozzles for treating the inner surface of tubes having a relatively large inner diameter;

[0035] FIG. A schematic sectional view of a device according to the preceding figures, adapted as an example to the treatment of an inner surface of a closed volume;

[0036] FIG. 16 and 17, a diagrammatic sectional view of an exemplary device for redirecting a plasma jet generated for internal surface treatment of objects in the form of a ring or a tube;

[0037] FIG. 18 a schematic sectional view of an exemplary device for redirecting a generated plasma jet for simultaneous processing of two side surfaces of a predetermined object. Mode (s) of realization of the invention

In the following detailed description of the accompanying drawings, the identical elements are designated by identical identification references. In general, these elements and their functionalities are described once for reasons of brevity and to avoid repetitions.

[0039] FIG. 1 illustrates by way of example the downstream side of a device 10 for the generation of a plasma jet 11, comprising a discharge chamber 12 having a longitudinal axis 13 and an emission nozzle 14 connected to the chamber of discharge 12. The emission nozzle 14 is provided with a mouth 15 for the emission of the plasma jet 11. The device 10 further comprises a discharge electrode 16 and a counter electrode produced by way of example by the nozzle 14. For illustration, the discharge electrode 16 is formed in the form of a pin arranged on the longitudinal axis 13 of the discharge chamber 12. The discharge electrode 16 and the associated counter electrode are preferably adapted to generate an electric discharge allowing the generation of the plasma jet 11 by the creation of an electric arc 17 between the discharge electrode 16 and the mouth 15 of the emission nozzle 14. The generation of the plasma jet 11 is made from a carrier gas, such as air , injected into the discharge chamber 12, for example, by orifices (for example 82 in Fig. 8) provided between the discharge electrode 16 and the emission nozzle 14, as illustrated by arrows 19.

According to one embodiment, the discharge chamber 12 and the emission nozzle 14 have an adjustable length as a function of a predetermined output power of the plasma jet 11. In other words, the regulation of this length allows the regulation of the length of the electric arc 17 and thus the regulation of the output power of the plasma jet 11 generated. For this purpose, the discharge electrode 16 is arranged according to an embodiment in a displaceable manner along the longitudinal axis 13 of the discharge chamber 12 so as to allow an indirect adjustment of the length of the discharge chamber 12 and the emission nozzle 14.

In more detail, the output power of the plasma jet 11 generated by applying a fixed electric current to the discharge electrode 16 and the associated counter-electrode depends on the voltage drop of the electric arc 17. This drop depends directly on the discharge length L of the electric arc 17, and therefore the length of the discharge chamber 12 and the emission nozzle 14, and the pressure of a carrier gas injected into the device 10 as illustrated in FIG. Fig. 2. Thus, the change in the length of the discharge chamber 12 and the nozzle 14 can adjust the power put in the plasma jet 11 with the setting of other parameters, including the pressure of the carrier gas. According to one embodiment, the mouth 15 of the emission nozzle 14 is formed so as to allow an acceleration of the plasma jet 11 of a subsonic speed at an approximately supersonic speed. In addition, it preferably comprises an opening diameter D1 adjustable according to the predetermined output power of the plasma jet 11. In more detail, the regulation of the diameter D1 of the mouth 15 makes it possible to increase the voltage drop. of the electric arc and consequently to increase the power placed in the plasma jet 11. In the case of a shrinkage of the diameter D1, an increase in the pressure inside the discharge chamber 12 and the nozzle 14 appears. Thus, the regulation of the diameter D1 of the mouth 15 makes it possible to intensify the hydrodynamic pressure of the plasma jet 11 at the mouth 15.

[0043] FIG. 2 illustrates by way of example an upstream side of the device 10 of FIG. 1. As shown in Fig. 2, the emission nozzle 14 comprises a closing wall 22 provided with an opening 24 capable of receiving the discharge electrode 16 and at least one radial orifice 25 having an opening diameter D2. This defines the speed of the flow of the carrier gas and within certain limits also that of the plasma jet 11. The discharge electrode 16 comprises, according to one embodiment, an axial orifice 27.

The axial orifice 27 is preferably adapted for the injection of a reactive gas, for example tetrafluormethane (CF4), as illustrated by an arrow 23. The at least one radial orifice 25 is preferably adapted for the injecting a carrier gas towards the inner surface 29 of the emission nozzle 14 forming the counter electrode, that is to say in a direction approximately perpendicular to the longitudinal axis 13, as illustrated by an arrow 21. This allows to create a circular swirling of the carrier gas along this longitudinal axis 13 in the direction of the mouth (15 in Fig. 1) of the emission nozzle 14, as illustrated by a arrow 26. This swirling is necessary to stabilize the electric arc 17 over its entire length (L in Fig. 1) and the plasma jet 11 (Fig. 1). The carrier gas is capable of being mixed with the reactive gas for the generation of the plasma jet 11.

[0045] FIG. 3 illustrates a view of the fence wall 22 on the upstream side of the device 10 of FIG. 2 according to another embodiment. As illustrated in FIG. 3, several radial orifices 25 for the injection of the carrier gas are provided. Thus, an increase in the total flow of the carrier gas in the discharge chamber (12 in Fig. 2) can be achieved while preserving the rate of propagation of the gas in the chamber.

Preferably, at least one of the radial orifices 25 is made to allow an acceleration of the carrier gas of a subsonic speed at an approximately supersonic speed. For example, one of the orifices 25 may have the shape of a Laval nozzle. Thus, a net cooling of the carrier gas can be obtained during its injection, allowing a cooling of the discharge electrode 16 and a reduction of its erosion.

[0047] FIG. 4 illustrates a radial distribution 40 of temperature T measured in dependence on the radius r in the discharge chamber 12 and the emission nozzle 14 according to FIGS. 1 and 2 during the generation of the plasma jet (11 in FIGS. ). As illustrated in FIG. 4, a main ohmic heating is performed along the longitudinal axis (13 in Figs 1 & 2) of the discharge chamber 12 of Fig. 1; 1 and 2.

[0048] FIG. 5 illustrates a radial distribution of a pressure P measured in dependence on the radius r in the discharge chamber 12 and the emission nozzle 14 according to FIGS. 1 and 2 during the generation of the plasma jet (11 in FIG. 2). As illustrated in FIG. 5, the pressure P is reduced in a zone of the discharge chamber 12 which is located near the longitudinal axis (13 in Figs 1 & 2) of the discharge chamber 12 of Fig. 1 & 2 without the knowledge of circular swirling (26 in FIG. 2) carrier gas along the longitudinal axis (13 in Fig. 1 & 2). Thus, by introducing or injecting the reactant gas through the axial orifice (27 in Fig. 2), the latter can easily be heated and the transformations necessary for subsequent chemical plasma reactions can take place.

[0049] FIG. 6 illustrates by way of example the upstream side of the device 10 according to FIG. 2, wherein a reactive gas is introduced or injected through the axial orifice 27 provided in the discharge electrode 16. This reactive gas is preferably injected with a clean turbulence illustrated by an arrow 61. Thus, two gas flows rotating, that is to say the flow of the reactive gas and the flow of the carrier gas along the longitudinal axis 13 of the discharge chamber 12 provide a hydrodynamic stabilization and allow mixing of gases over a great length, i.e. the length L of FIG. 1.

[0050] FIG. 7 schematically illustrates a migration of the starting point 72 of the electric arc (17 in Fig. 1, 2 & 6). As shown by an arrow 74, this starting point 72 migrates on the circumference of the discharge electrode 16 in the direction of clockwise due to the flow of the rotating gases, that is to say the reactive gas and swirling carrier gas as shown in FIG. 6. Thus, the erosion of the discharge electrode 16 can advantageously be reduced by considerably increasing its life time.

[0051] FIG. 8 shows the device 10 of FIG. 1 with a closing wall 81 defining for the illustration of the axial orifices 82 with the discharge electrode 16 for the injection of the carrier gas, as explained in FIG. 1. Axially opposed to the discharge electrode 16, and therefore in front of it, is arranged an additional electrode 89 having a direct electrical connection with the discharge chamber 12 and the emission nozzle (14 in FIG. ) according to an embodiment. The provision on the longitudinal axis 13 of the discharge chamber 12 of the additional electrode 89 increases the stability of the electric discharge and therefore the electric arc 17 and, therefore, its possible length. In addition, the additional electrode 89 allows the plasma jet 11 to exit the mouth 15 at different angles with respect to the longitudinal axis 13.

FIG. 9 and 10 illustrate electrical pulses 90, 100 of short durations applicable to the discharge electrode 16 and the counter electrode 14 of FIGS. 1, 2, 6 and 8 allowing a so-called "operation under short pulses" of the device 10 of these figures. The application of these electrical pulses allows an increase of the off-equilibrium plasma in comparison with the generation of the plasma during continuous operation, that is to say during the application of a direct current to the electrodes, and acceleration of chemical plasma reactions. As shown in Figs. 9 and 10, the pulses 90, 100 may have different polarities, constant or variable, in all frequency ranges.

[0054] FIG. 11 and 12 illustrate two different embodiments of the mouth 15 of the emission nozzle 14 of the device 10 according to FIGS. 1, 2, 6 and 8. More particularly, the mouth 15 can be made in such a way as to allow an acceleration of the generated plasma jet 11 from a subsonic velocity to an approximately supersonic velocity. For this, the mouth may for example have a shape close to a Laval nozzle, thus ensuring a net and rapid cooling of the plasma jet 11 when it leaves the emission nozzle 14 and, if necessary, a clear shift in temperature increased by the aforementioned chemical plasma reactions.

[0055] FIG. 13 shows an arrangement 130 illustrating the device 10 according to FIGS. 1, 2, 6 and 8, in which the mouth 15 of the emission nozzle 14 comprises at least one radial opening 132 allowing the angular emission of the plasma jet 11 or a part thereof.

[0056] FIG. 14 shows an arrangement 140 comprising for illustration a plurality of discharge chambers 12 and associated emission nozzles 14, which generate different plasma jets 11. A treatment of an inner surface 133 (Fig. 13) of an extended object 135, such as a tube or a ring, can then be made by moving the different plasma jets generated 11 with respect to the surface 133, as illustrated by an arrow 149. Thus, a treatment zone of the inner surface 133 of the Expanded objects 135 may be enlarged, allowing, for example, successive executions of the following technological operations: a cleaning of the surface 133, its activation, or a deposition of the plasma transported by the plasma jet 11 on the surface 133 in order to create a layer functional or decorative.

[0057] FIG. 15 shows an arrangement 150 illustrating a treatment of an inner surface 153 of a closed volume 154 of a housing 155 with the device 10 according to Figures 1, 2, 6 and 8 having radial openings 132 in the mouth 15 of the emission nozzle 14 according to FIG. 13. To understand the operation of the arrangement 150, it should be known that free radicals and other particles exiting the plasma jet 11 keep their energy for a certain time. This allows after the introduction of the plasma jet 11 into the closed volume 154 using the device 10, for example an activation of the inner surface 153. For this, it is sufficient to give the active gas 159 generated by the plasma jet 11 sufficient time to interact with the inner surface 153. In addition, the use of nitrogen instead of air as the carrier gas intensifies the effect of the active gas treatment 159, since the free active radicals of the Nitrogen have a much longer life than the free radicals of oxygen in the air. [0058] FIG. 16 shows an arrangement 160 comprising an object 162, such as a tube or a ring, having an inner surface to be treated 164 and an object 165 for the redirection of the plasma jet 11 emitted by the device 10 as described above in FIG. Referring to Figures 1 to 15 to surface 164.

The object 165 is made in the form of a cone and positioned approximately on the axis of the object 162. The object 165 is adapted to redirect the plasma jet 11 towards the surface 164 of the object 162 in order to increase a corresponding angle of attack of the plasma jet 11. For the increase of the angle of attack of the plasma jet 11, the outer surface of the object 165 may have an almost hyperbolic shape.

According to one embodiment, during operation of the device 10 the plasma jet 11 arrives on the object 165 which redistributes it regularly on the surface to be treated

164 according to its circumference. For treatment p. e. long tubes, the device 10 and the object 165 move or together or with respect to each other, as illustrated by an arrow 169.

[0060] FIG. 17 shows an arrangement 170 which is a variant of the arrangement 160 of FIG. 16 and in which the electrical connection of the object 165 for the redirection of the plasma jet 11 and that of the emission nozzle 14, that is to say the counter electrode, is a ground connection. Preferably, the object 165 and the discharge electrode 16 are disposed on the longitudinal axis 13 of the emission nozzle 14. Thus, the electric arc 17 can stretch from the discharge electrode 16 to the to the object 165 by moving the particle generation zone of the plasma jet 11 to the surface to be treated 164 by increasing its efficiency.

[0061] FIG. 18 shows an arrangement 180 which is a variant of the arrangement 170 of FIG. 17, in which the object 165 for the redirection of the plasma jet 11 is made in the form of a prism and the object 162 having the inner surface to be treated 164 is made by two boards 182, 184 having two faces 183, 185. In this arrangement 180, it is possible to direct the plasma jet 11 on one side of the prism 165 to treat only the surface of one of the boards

182, 184. For example, the plasma jet 11 can be directed on a side 189 of the prism 165 and thus only treat the side surface 185 of the board 184. In order to increase the angle of attack of the plasma jet 11 , the cross section of the prism 165 may have an almost hyperbolic shape. Also note that during a treatment of the lateral surfaces

183, 185, the boards 182, 184 and the prism 165 can be moved relative to one another in two respective planes, as illustrated by arrows 187, 188.

As an indication, various embodiments of the device for generating a plasma jet according to the invention are given below.

Example 1:

This example uses the device 10 made according to FIG. 1.

Settings :

• continuous current power source

• applied electric current 1 A

• air carrier gas

• flow rate of the carrier gas 50 1 / min

• atmospheric outside pressure

• Discharge electrode diameter 3, 2 mm

• diameter of the discharge chamber 7 mm

• diameter of the mouth of the nozzle 2, 2 mm

• length of a first nozzle used 60 mm

• length of a second nozzle used 110 mm

Result: The power consumed by the plasma during

The use of the first nozzle is 1500 W, with the second nozzle 2300 W. Thus, the elongation of the nozzle increases the power consumed by the plasma.

Example 2: This example uses the device 10 made according to FIG. 1 Settings:

• continuous current power source

• applied electric current 1 A

• air carrier gas

• flow rate of the carrier gas 50 1 / min

• atmospheric outside pressure

• Discharge electrode diameter 3, 2 mm

• diameter of the discharge chamber 7 mm

• diameter of the mouth of a first nozzle used 2, 2 mm

• diameter of the mouth of a second nozzle used 2.0 mm

• length of the first and second nozzles used 60 mm

Result: The power consumed by the plasma when using the first nozzle is 1500 W, with the second nozzle of 1700 W. Thus, the decrease in the diameter of the mouth of the nozzle increases the power consumed by the plasma . The pressure measured in the first nozzle is about 4.5 bar and in the second nozzle about 5 bar. Example 3

This example uses the device 10 made according to FIGS. 2 and 6.

Settings :

• 24 kHz ac power source

• applied electric current 1.5 A

• nitrogen carrier gas

• flow rate of the carrier gas 25 1 / min

• CF4 reactive gas

• flow rate of the reagent gas 0.2 1 / min

• atmospheric outside pressure

4 mm discharge electrode diameter • diameter of the axial orifice in the discharge electrode 1.5 mm

• diameter of the discharge chamber 7 mm

• diameter of the orifice of the nozzle used 2.2 mm

• nozzle length used 60 mm

• quantity of radial ports for carrier gas injection 2

Result: This configuration makes it possible to obtain a succession of etchings of a photoresist layer.

Example 4:

This example uses the device 10 in the operating mode according to FIGS. 9 and 10.

Settings :

• current source with short pulses

• electrical current pulses 2.0 A

• variable pulse frequency, 50 to 2000 Hz

• pulse duration variable, 5 to 95%

• continuous electric current applied 0.1 A

• air carrier gas

• flow rate of the carrier gas 40 1 / min

• atmospheric outside pressure Result: This configuration with operation in short pulse mode makes it possible to obtain an increase in the speed and the activation level of a surface to be treated compared to the use of the continuous electric current likely to cause a identical energy consumption.

Example 5

This example uses the device 10 made according to FIG. 12. Settings:

• DC power source

• applied electric current 1.5 A

• air carrier gas

• flow rate of the carrier gas 80 1 / min

• atmospheric outside pressure • outside diameter of the nozzle used 4 mm

• quantity of radial holes in the mouth of the nozzle used 8

• diameter of each of these holes 1.2 mm

· Internal diameter of the tubes to be treated variable, 30 to

50 mm

• relative speed of variable scanning, 50 to 500 mm / s

Result: This configuration makes it possible to obtain a succession of cleaning and activation (s) of the inner surface of the tubes to be treated.

Example 6:

This example uses the device 10 made according to FIG. 13. Settings:

· Dc power source plasma jet electric current 1.5 A carrier gas air plasma carrier gas flow 50 1 / min atmospheric outside pressure · outside diameter of the nozzle used 20 mm quantity of nozzles used 12 inner diameter of the tubes to be treated 1420 mm distance between the nozzles used over the length of the tube to be treated 20 mm

· Rotation speed 6 t / min

relative linear speed of scanning 1.44 m / min

Result: This configuration makes it possible to obtain a succession of fine cleanings and activation (s) of the inner surface of the tubes to be treated.

Example 7:

This example uses the device 10 made according to FIG. 13. Settings:

• continuous current power source

• electric current applied by plasma jet 1.5 A quantity of nozzles used 3

atmospheric outside pressure first gas carrier air

flow rate of the first carrier gas 50 1 / min second carrier gas N2 (92%) / H2 (8%) flow rate of the second carrier gas 20 1 / min third carrier gas + reagent N2 + HMDSO vapor flow of the third carrier gas 20 1 / min relative linear speed of scanning 12 m / min

Result: This configuration allows to obtain a succession of technological operations in one cycle: a fine cleaning and an activation of a surface to be treated, as well as a reduction of oxides and a deposition of a thin layer of SiOx on this surface.

Example 8:

This example uses the device 10 made according to FIG. 14. Settings:

AC power source AC current applied 1.5 A

· Air carrier gas

flow rate of carrier gas 40 1 / min atmospheric outside pressure duration of pulses 0.6 s

volume closed to treat bottle, 0.5 1 · quantity of pulses per bottle 3

pause time before air blowing 2 min Result: This configuration makes it possible to obtain activation of the inner surface of the bottle by the plasma and the corresponding active gas which remains in the bottle for 2 min. The energy of the surface can be increased from 35 to 38 mN / m before the plasma treatment up to 56 to 72 mN / m.

Although the present invention has been described in the context of a particular application, it is susceptible of modifications or adaptations without departing from its scope.

Claims

Resells! Cations

Apparatus for generating a plasma jet from a carrier gas, comprising a discharge chamber having a longitudinal axis and an emission nozzle connected to said discharge chamber, said emission nozzle being provided with a mouthpiece for emitting a generated plasma jet, said discharge chamber and said emission nozzle having an adjustable length based on a predetermined output power of said plasma jet.

Apparatus according to claim 1, comprising a discharge electrode and an associated counter electrode adapted to generate an electric discharge for generating said plasma jet from said carrier gas.

3. Device according to claim 2, wherein said counter electrode is made by said emission nozzle, said electric discharge being able to create an electric arc necessary for the generation of said plasma jet between the discharge electrode and said mouth of said emission nozzle.

An apparatus according to any one of the preceding claims, wherein said discharge electrode is arranged along the longitudinal axis of said discharge chamber and movably along said axis to allow adjustment of said length of said chamber. discharge device and said emission nozzle.

Apparatus according to any one of the preceding claims, wherein said mouth of said emission nozzle has an adjustable diameter as a function of said predetermined output power of said plasma jet. Apparatus according to any one of the preceding claims, wherein at least one radial port is provided for injecting said carrier gas into said discharge chamber in a direction approximately perpendicular to said longitudinal axis to create a swirling of the carrier gas along said longitudinal axis in the direction of said mouth of said emission nozzle.

Apparatus according to any one of the preceding claims, wherein said at least one radial orifice is constructed to allow an acceleration of said carrier gas from a subsonic velocity to an approximately supersonic velocity.

Device according to any one of the preceding claims, comprising at least one axial orifice for injecting a reactive gas that can be mixed with said carrier gas for the generation of said plasma jet.

An apparatus according to claim 8, wherein said axial orifice is adapted to allow a swirling of said reactant gas along said longitudinal axis in the direction of said mouth of said emission nozzle.

Apparatus according to any one of the preceding claims, wherein said carrier gas is air.

Apparatus according to any one of the preceding claims, wherein said mouth of said emission nozzle is constructed to allow acceleration of said plasma jet from a subsonic velocity to an approximately supersonic velocity. Apparatus according to any one of the preceding claims, wherein said mouth of said emission nozzle comprises at least one radial opening for the angular emission of said plasma jet.

Device according to any one of the preceding claims, characterized in that it comprises a plurality of discharge chambers and emission nozzles.