FR2962004A1 - DEVICE FOR GENERATING A PLASMA JET - Google Patents

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 nozzle the emission being provided with a mouth for generating a generated plasma jet, said discharge chamber and said emission nozzle having an adjustable length according to a predetermined output power of said plasma jet.

Description

Stolmâr Scheele & Partner - 1/22 - 24.06.2010 34879-CRS-P-FR Applicant: NCI - Swissnanocoat SA DEVICE FOR GENERATING A PLASMA JET 5 Technical Field [0001] 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 a longitudinal axis and an emission nozzle connected to said plasma jet; discharge chamber, said emission nozzle being provided with a

Mouthpiece for the emission of a generated plasma jet. State of the art [0002] The German patent application DE 195 32 412 A1 describes such a

Device for pretreating 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 allowing the creation of a swirling

25 of this 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 into the casing and an electric current is applied to the electrode. discharge and counter electrode. Thus, an electric shock is generated which results in the creation

35 of an electric arc suitable for generating a plasma jet Stolmâr Scheele & Partner - 2/22 - 24.06.2010 34879-CRS-P-FR 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 only a limited scope since the plasma jet generated has only limited output power. DISCLOSURE OF THE INVENTION [0005] The object of the present invention is to propose a new device for the generation of a plasma jet from a carrier gas having a reduced number of components and an enlarged 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 nozzle emission 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.

Stolmâr Scheele & Partner - 3/22 - 24.06.2010 34879-CRS-P-EN [0008] The device according to the invention preferably comprises a discharge electrode and an associated counter-electrode, adapted to generate an electric discharge enabling the generation of an electric discharge. 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 and easy adjustment of the predetermined output power of the plasma jet by adjusting the length of the discharge chamber and the emission nozzle and / or an adjustment of the diameter of the plasma. mouth 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 in such a way as to allow an acceleration of the carrier gas of a subsonic speed at a speed of at least one radial orifice to allow Stolmâr Scheele & Partner - 4/22 - 24.06.2010 34879-CRS-P-FR approximately supersonic.

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

plasma jet generation. 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 the generation of a plasma jet from a carrier gas according to the invention will emerge from the detailed description Stolmâr Scheele & Partner - 5/22 - 24.06.2010 34879-CRS-P-EN following of the various embodiments, given by way of example and illustrated by the accompanying drawings which show schematically: FIG. of one of a [0024] FIG. of one of a [0025] FIG. 1 a longitudinal sectional view of a downstream device for generating a plasma jet from carrier gas according to an embodiment of the invention; 2 a longitudinal sectional view of an upstream device for the generation of a plasma jet from carrier gas according to an embodiment of the invention; 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 an exemplary operation in a regime based on short pulses 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; Stolmâr Scheele & Partner - 6/22 - 24.06.2010 34879-CR5-P-EN [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 the illustration, the discharge electrode 16 Stolmâr Scheele & Partner - 7/22 - 24.06.2010 34879-CRS-P-EN is 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 for 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 emissive nozzle The generation of the plasma jet 11 is made from a carrier gas, such as air, injected into the discharge chamber 12, for example, through 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 a length adjustable in accordance with 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. [0041] 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 directly depends 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. 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.

Stolmâr Scheele & Partner - 8/22 - 24.06.2010 34879-CRS-P-EN [0042] According to one embodiment, the mouth 15 of the emission nozzle 14 is made to allow an acceleration of the jet plasma 11 of a subsonic velocity at an approximately supersonic velocity. 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. [0044] 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 injecting a carrier gas towards the surface inside 29 of the emission nozzle 14 producing 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 Stolmâr Scheele & Partner - 9/22 - 24.06.2010 34879-CRS-P -FR arrow 26. This swirling is necessary to the stabilization of 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 Stolmâr Scheele & Partner - 10/22 - 24.06.2010 34879-CRS-P-FR Fig. 2) of the 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.

Stolmâr Scheele & Partner - 11/22 - 24.06.2010 34879-CRS-P-EN The arrangement on the longitudinal axis 13 of the discharge chamber 12 of the additional electrode 89 increases the stability of the electric discharge and therefore of the electric arc 17 and, therefore, of 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. [0053] 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 Figures 1, 2, 6 and 8, wherein the mouth 15 of the emission nozzle 14 comprises at least one radial opening Stolmâr Scheele & Partner - 12/22 - 24.06. 2010 34879-CRS-P-EN 132 allowing the angular emission of the plasma jet 11 or a part of it. [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 a carrier gas intensifies the effect of the active gas treatment 159, since the free radicals of nitrogen have a much longer life span. that the free radicals of the oxygen contained in the air.

Stolmâr Scheele & Partner - 13/22 - 24.06.2010 34879-CRS-P-EN [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 Figs. 1 to 15 to surface 164. Object 165 is cone-shaped and positioned approximately on the axis of object 162. Object 165 is adapted to redirect plasma jet 11 toward the surface 164 of the object 162 to increase a corresponding angle of attack of the plasma jet 11. For increasing the angle of attack of the plasma jet 11, the outer surface of the object 165 may have an almost hyperbolic form. According to one embodiment, during operation of the device 10 the plasma jet 11 arrives on the object 165 which redistributes it in a regular manner on the surface to be treated 164 along 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 Stolmâr Scheele & Partner - 14/22 24.06.2010 34879-CRS-P-EN lateral to be treated 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 treat only the

side surface 185 of plate 184. In order to increase

the angle of attack of the plasma jet 11, the cross-section

prism 165 can have an almost hyperbolic shape.

Note also that during a treatment of the side 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. Parameters: - DC power source - Applied electrical current 1 A - Air carrier gas - Carrier gas flow rate 50 1 / min - Atmospheric outside pressure - Discharge electrode diameter 3.2 mm - Chamber diameter 7 mm discharge - diameter of nozzle mouth 2.2 mm - length of first nozzle used 60 mm - length of second nozzle used 110 mm

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

Example 2: 20 Stolmes Scheele & Partner - 15/22 - 24.06.2010 34879-CRS-P-FR This example uses the device 10 made according to FIG. 1. Parameters: - DC power source - Applied electrical current 1 A - Air carrier gas - Carrier gas flow rate 50 1 / min - Atmospheric outside pressure - Discharge electrode diameter 3.2 mm - Chamber diameter 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.

Parameters: - 24 kHz alternating current power source - 1.5 A applied electric current - nitrogen carrier gas - 25 μg carrier gas flow / min - CF4 reactive gas - 0.2 1 / min reactive gas flow - external pressure electrode - discharge electrode diameter 4 mm Stolmâr Scheele & Partner - 16/22 - 24.06.2010 34879-CRS-P-EN - diameter of the axial orifice in the discharge electrode 1.5 mm - diameter of the discharge chamber 7 mm - diameter of nozzle mouth used 2.2 mm - length of nozzle used 60 mm - quantity of radial ports for gas injection

carrier 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.

Parameters: - short pulse current source - pulse current 2.0 A - variable pulse frequency, 50 to 2000 Hz - variable pulse duration, 5 to 95% - applied direct current 0.1 A - air carrier gas - carrier gas flow rate 40 1 / min - atmospheric external pressure Result: This configuration with operation in short pulse mode makes it possible to obtain an increase in the speed and activation level of a surface to be treated compared the use of the continuous electric current likely to cause an identical energy consumption.

Example 5

This example uses the device 10 made according to FIG. 12. Parameters: - DC power source - applied electric current 1.5 A - carrier gas air - carrier gas flow rate 80 1 / min - atmospheric outside pressure Stoimâr Scheele & Partner - 17/22 - 24.06.2010 34879- CRS-P-FR - 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 at 50 mm - variable speed of variable sweep, 50 to 500 mm / s Result: This configuration makes it possible to obtain a succession of cleanings 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. Parameters: - DC power source - Plasma jet electric current 1.5 A - Air carrier gas - Plasma jet carrier gas flow 50 1 / min - Atmospheric outside pressure - Outside diameter of the nozzle used 20 mm - quantity of nozzles used 12 - internal 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 - speed of rotation 6 rpm - 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. Parameters: - DC power source - Plasma jet electric current 1.5 A 20 25 Stolmâr Scheele & Partner - 18/22 24.06.2010 34879-CRS-P-EN - quantity of nozzles used 3 - atmospheric external pressure - first carrier gas air - flow rate of the first carrier gas 50 1 / min - second carrier gas N2 (92%) / H2 (8%) - flow of the second carrier gas 20 1 / min - third carrier gas + reagent N2 + HMDSO steam - third carrier gas flow 20 1 / min - relative linear scan speed 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. Parameters: - alternating current power source - applied electric current 1.5 A - carrier gas air - carrier gas flow 40 1 / min - atmospheric outside pressure - pulse duration 0.6 s - closed volume to be treated 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 stay in the bottle for 2 30 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

of a particular application, it is likely to

modifications or adaptations without departing from its scope.

Claims (9)

REVENDICATIONS1. Device for generating a plasma jet to CLAIMS1. 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. 2. Device 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 Apparatus according to claim 2, wherein said counter electrode is made by said emission nozzle, said electric discharge being capable of creating 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 and said emission nozzle. 5. Device according to any one of the preceding claims, wherein said mouth of said emission nozzle comprises an adjustable diameter according to said predetermined output power of said plasma jet.Stolmâr Scheele & Partner - 20/22 - 24.06. 2010 34879-CRS-P-EN 6. Device according to any one of the preceding claims, wherein at least one radial orifice is provided for an injection of said carrier gas into said discharge chamber in a direction approximately perpendicular to said longitudinal axis to create a swirling of the carrier gas the along said longitudinal axis in the direction of said mouth of said emission nozzle. 7. Device according to any one of the preceding claims, wherein said at least one radial orifice is formed so as to allow an acceleration of said carrier gas of a subsonic speed at an approximately supersonic speed. 8. Device according to any one of the preceding claims, comprising at least one axial orifice for injecting a reactive gas capable of being kneaded with said carrier gas for the generation of said plasma jet. 9. Device according to claim 8, wherein said axial orifice is adapted to allow a swirling of said reactive 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. A device according to any one of the preceding claims, wherein said mouth of said emission nozzle is constructed to allow an acceleration of said plasma jet from a subsonic velocity to an approximately supersonic velocity. 12.Dispositif according to any one of the preceding claims, wherein said mouth of said emission nozzle comprisesStolmâr Scheele & Partner - 21/22 - 24.06.2010 34879-CRS-P-FR at least one radial opening allowing the emission angularly of said plasma jet. 13.Device according to any one of the preceding claims, characterized in that it comprises a plurality of discharge chambers and emission nozzles.