Weeding device

Abstract

The utility model relates to a weeding device which comprises a plasma generating system, the plasma generating system is configured to generate plasma from plasma generating gas, and the weeding device comprises a microwave generator, a gas supply device of the plasma generating gas and at least one waveguide. And the weeding device is configured to generate at least one plasma jet by ionizing the plasma generating gas using microwaves.

Description

TECHNICAL FIELD

[0001] The present utility model relates to the field of weeding, i.e. eliminating unwanted plants, also called adventitious plants or weeds. BACKGROUND

[0002] In the field of agriculture, it is important to eliminate unwanted plants, as these plants take some of the water necessary for the growth of the seeds planted and provide shelter for insects that are harmful to the plants one wishes to see grow.

[0003] It can be necessary to completely weed a field before planting or to partially weed a field after planting, between the rows planted, during their growth.

[0004] In urban areas or for public infrastructure (roads, highways, railways, airports, etc.), it is necessary to eliminate unwanted plants so as not to disturb traffic or cause deterioration of the infrastructure.

[0005] Chemical weeding can be performed using chemical weeding products such as glyphosate.

[0006] However, chemical weeding products have major drawbacks, such as persistent pollution of the soil, which can also pollute the subsoil and thus the water of the underground water table. In the long term, their intensive use makes the soil more and more resistant to their action. Furthermore, glyphosate is now recognized as potentially carcinogenic to humans and carcinogenic to animals.

[0007] Other non-chemical weeding methods are also possible, such as thermal weeding, electrical weeding, infrared radiation weeding, ultraviolet radiation weeding, microwave weeding or hot water weeding.

[0008] Thermal weeding (or "flaming weeding") is a weeding technique that relies solely on heat to freeze-dry and ultimately kill unwanted plants by thermal shock. This method consists in applying intense heat to the unwanted plants to kill them by rupturing their tissues so that they then dry out within a few days. Thermal weeding can be achieved using heating elements that generate heat using electricity or gas.

[0009] Thermal weeding in agriculture is achieved, for example, by means of gas-powered thermal radiators, which require the transport of one or more gas cylinders.

[0010] Electrical weeding consists in generating an electric arc that can reach the unwanted plants and damage them by the passage of an electric current through them.

[0011] Infrared radiation weeding and ultraviolet radiation weeding consist in subjecting the unwanted plants to infrared radiation and ultraviolet radiation, respectively. Infrared radiation weeding and ultraviolet radiation weeding can be combined.

[0012] Infrared radiation can heat the roots of unwanted plants, thereby interfering with their functioning. Ultraviolet radiation can damage unwanted plants, as the leaves of the unwanted plants heat up after the vegetation tissue of the unwanted plants absorbs the ultraviolet radiation.

[0013] Microwave weeding consists in emitting microwaves to the ground to damage the roots of unwanted plants.

[0014] Weeding by hot water consists in spraying liquid hot water or hot steam on the unwanted plants. Utility model content

[0015] One of the objects of the utility model is to propose an effective and easy-to-implement weeding method.

[0016] To this end, the utility model proposes a weeding method, which comprises generating plasma from a gas for generating plasma and exposing unwanted plants to the plasma to eliminate these unwanted plants.

[0017] The plasma can be produced very easily, for example, using ambient air as a gas for generating plasma, which avoids having to transport a reserve gas.

[0018] The use of plasma combines the effects of other weeding methods, namely thermal effects (heat), chemical effects (formation of active substances (for example, ozone)) and radiation effects (emission of UV light, emission of infrared light). Thus, the use of plasma makes it possible to effectively weed.

[0019] In particular embodiments, the weeding method comprises one or more of the following optional features, taken alone or according to all technically possible combinations:

[0020] - the gas for generating plasma is air;

[0021] - the gas for generating plasma is compressed;

[0022] - the generation of plasma comprises generating at least one plasma jet;

[0023] - each plasma jet is columnar or curtain-like;

[0024] - the weeding method comprises generating several plasma jets spaced apart from one another along a distribution direction;

[0025] - the plasma jets are uniformly spaced apart, with the spacing between the plasma jets in the distribution direction being constant;

[0026] - the weeding method comprises moving the plasma jets along a plantation row extending in a plantation direction, the distribution direction being perpendicular to the plantation direction, each plasma jet being positioned facing an inter-row of the plantation;

[0027] - the weeding method comprises generating at least one plasma jet by ionizing a plasma-generating gas by means of microwaves;

[0028] - generating at least one plasma jet comprises generating microwaves in an elongated waveguide between a first end designed to receive the microwaves and a closed second end, and circulating a plasma-generating gas in one or more passages transversely across the waveguide, a respective plasma jet being formed at the outlet of each passage;

[0029] - each passage is positioned at a distance from the second end of the waveguide substantially equal to λ / 4 + N λ / 2, where λ is the wavelength of the microwaves in the waveguide and N is a natural integer greater than or equal to zero;

[0030] - a plurality of waveguides are connected to respective outlet arms of a branching power divider, the waveguides receiving the microwaves by means of said branching power divider;

[0031] - at least one plasma jet is generated by electrical discharge, in particular by bare electrode discharge, by single dielectric barrier discharge, or by double dielectric barrier discharge;

[0032] - the weeding method comprises generating plasma by ionizing an air layer located above the ground;

[0033] - ionization is achieved by means of a power supply electrode located above the ground, a dielectric layer located below the power supply electrode, and by applying a voltage between the power supply electrode and the ground.

[0034] The utility model also relates to a weeding device, the weeding device includes the plasma generation system, the plasma generation system is configured to generate plasma from the plasma-generating gas.

[0035] In particular embodiments, the weeding device comprises one or more of the following optional features taken alone or in all technically possible combinations:

[0036] - the plasma-generating gas is air;

[0037] - the plasma-generating gas is compressed;

[0038] - the weeding device is configured to generate at least one plasma jet, for example each plasma jet being columnar or curtain-like;

[0039] - the weeding device is configured to generate a plurality of plasma jets spaced apart from each other along a distribution direction;

[0040] - the plasma jets are uniformly spaced apart, wherein the spacing between the plasma jets in the distribution direction is constant;

[0041] - the weeding device is configured to generate at least one plasma jet by ionizing a plasma-generating gas by means of microwaves;

[0042] - the weeding device is configured to generate at least one plasma jet from microwaves, the weeding device comprising: a microwave generator configured to generate microwaves in at least one elongated waveguide between a first end designed to receive the microwaves and a second, closed end, each waveguide having at least one passage transversely through the waveguide; and a supply device configured to supply a flow of plasma-generating gas to each passage to generate a respective plasma jet at the outlet of each passage as the microwave generator generates microwaves in the waveguide;

[0043] - each passage of each waveguide is positioned at a distance from the second end of the waveguide substantially equal to λ / 4 + N λ / 2, where λ is the wavelength of the microwaves in the waveguide and N is a natural integer greater than or equal to zero;

[0044] - the plurality of waveguides are connected to respective outlet branches of a branching power divider from which the waveguides receive the microwaves;

[0045] - the weeding device is configured to generate at least one plasma jet by means of a discharge, in particular by means of a bare electrode discharge, by means of a single dielectric barrier discharge or by means of a double dielectric barrier discharge;

[0046] - the weeding device is configured to generate plasma by ionizing an air layer located above the ground;

[0047] - the ionization is effected by means of a power supply electrode located above the ground, a dielectric layer located below the power supply electrode, and by means of applying a voltage between the power supply electrode and the ground. BRIEF DESCRIPTION OF DRAWINGS

[0048] The application and its advantages will be better understood by reading the following description, given only as a non-limiting example and in reference to the attached drawings in which:

[0049] Figure 1 is a schematic side view of a tractor equipped with a weeding device configured to generate plasma to implement a method of weeding by plasma.

[0050] Figure 2 is a schematic cross-section of a plasma generation system using microwaves to generate a plasma jet;

[0051] Figure 3 is Figure 2 a perspective view of a waveguide of the plasma generation system of

[0052] Figure 4 is a schematic plan view of a plasma generation system configured to simultaneously generate a plurality of plasma jets;

[0053] Figure 5 is a schematic plan view of a plasma generation system configured to simultaneously generate a plurality of plasma jets using microwaves;

[0054] Figure 6 is a schematic cross-section of a torch-like plasma generation system using microwaves to generate a plasma jet;

[0055] Figure 7 is a schematic cross-section of a plasma generation system using electrodes to generate a plasma jet;

[0056] Figure 8 is a schematic cross-section of a plasma generation system using electrodes to generate a plasma jet;

[0057] Figure 9 is a schematic cross-section of a plasma generation system using electrodes to generate a plasma jet;

[0058] Figure 10 is a schematic cross-section of a plasma generation system using electrodes to generate a plasma in an air layer located between the electrodes and the ground. DETAILED DESCRIPTION

[0059] As shown in Figure 1 , the vehicle 2 is equipped with a weeding device 4 configured to eliminate unwanted plants 6 growing on the ground 8 using a weeding method comprising generating a plasma from a plasma-generating gas and exposing the unwanted plants to the plasma to eliminate these unwanted plants.

[0060] A plasma is a gas that is ionized by an increase in energy, in particular under the action of an electric and / or electromagnetic field (for example an electromagnetic field generated by a laser or other electric generator (direct current, alternating current, radiofrequency, microwave, pulsed, etc.).

[0061] The plasma-generating gas is for example, but not limited to, air. The use of air as plasma-generating gas avoids the use of a stock of plasma-generating gas. The air necessary for generating the plasma can be taken from the environment and simply compressed by a compressor.

[0062] The ground 8 is for example a ground intended for cultivating plants. In variants, the ground 8 is a road, a railway, etc.

[0063] The vehicle 2 is for example a tractor intended for performing agricultural work, in particular in a field. In variants, the vehicle 2 is a road vehicle, a rail vehicle, etc.

[0064] The weeding device 4 comprises for example a shaft 10 (here two shafts 10) and a coupling device 12 for coupling the weeding device 4 to the vehicle 2 so that the weeding device is towed by the tractor 2.

[0065] In variants, the weeding device 4 is for example configured to be mounted on the vehicle 2 and in particular to be suspended from the vehicle 2. Such a weeding device 4 is for example mounted or suspended at the rear of the vehicle 2, at the front of the vehicle 2 or under the vehicle 2.

[0066] In another variant, the weeding device can be fixed to the vehicle (if the weeding device and the vehicle are integral in the design of the vehicle).

[0067] The weeding device 4 has at least one plasma-generating system 14 configured to generate a plasma for eliminating unwanted plants 6 growing on the ground 8.

[0068] In particular, the plasma-generating system 14 is configured to generate one or more plasma jets 16.

[0069] Preferably, the weeding device 4 is configured so that, when the weeding device 4 is fitted on the vehicle 2, said weeding device 4 is located above the ground 8 so that the plasma-generating system 14 generates one or more plasma jets 14 directed towards the ground 8 for eliminating unwanted plants 6 growing on the ground 8.

[0070] The weeding device 4 is configured to be equipped on the vehicle 2, for example towed by the vehicle 2 or mounted on the vehicle 2, so that the weeding device 4 can quickly and efficiently treat large surfaces, for example a field, a road or a railway.

[0071] The generation of one or more plasma jets 16 allows targeted elimination of unwanted plants, for example by eliminating unwanted plants located between rows of a plantation (also called "inter-row" alien plants).

[0072] Advantageously, the plasma generation system 14 is configured to use air as plasma generation gas, i.e. to generate plasma from air, in particular from the environment of the plasma generation system 14, and to be able to compress it, for example by means of a compressor.

[0073] The use of air as plasma generation gas, in particular for generating one or more plasma jets, makes it possible to take air from the environment and to avoid transporting a reserve gas. This advantageously simplifies the system, avoids the time spent on changing the reserve gas (for another gas) and reduces the risk of accidents. Furthermore, it is the cheapest of the gases.

[0074] As shown in Figure 2 and Figure 3 , the plasma generation system 14 is configured to use microwaves to ionize the gas to generate at least one plasma jet 16.

[0075] The plasma generation system 14 comprises at least one microwave generator 18 configured to generate microwaves and at least one waveguide 20 configured to guide the microwaves generated by the one or more microwave generators 18, each waveguide 20 having a channel 22 passing through the waveguide 20 and having an inlet 24 for receiving a flow of plasma generation gas and an outlet 26 at which the flow of plasma generation gas is converted into a plasma jet 16.

[0076] Each waveguide 20 is tubular. The waveguide 20 comprises a lateral wall 30 and the waveguide 20 has a first end 32 designed to receive the microwaves and a second end 34 which is closed. Each waveguide 20 is preferably rectilinear between its first end 32 and its second end 34. The lateral wall 30 is preferably metallic.

[0077] Each waveguide 20 extends longitudinally between its first end 32 and its second end 34, and preferably each channel 22 of the waveguide 20 extends transversely through the waveguide 20.

[0078] The inlet 24 and the outlet 26 of each channel 22 are defined, for example, by openings provided in the lateral wall 30 of the waveguide 20 and facing each other.

[0079] The inlet 24 and the outlet 26 are defined by openings provided in the lateral wall 30 of the waveguide 20 at the same point along the waveguide 20.

[0080] Preferably, the waveguide 20 has a rectangular cross-section ( Figure 3 ) so that the lateral wall 30 has two opposite first faces 30A and two opposite second faces 30B.

[0081] The inlet 24 is provided on one of the two opposite first faces 30A, while the outlet 26 is provided on the other of the two opposite first faces 30A and is positioned facing the inlet 24.

[0082] The second end 34 is closed, for example, by a bottom 35, which is preferably metallic. The bottom 35 is, for example, a plate, in particular a metal plate.

[0083] In a variant, as shown by the dotted line in Figure 3 , the waveguide 20 has, near its second end 34, for example, a bevel shape, the cross section of the waveguide 20 gradually decreasing towards its second end 34, which terminates in a point.

[0084] Preferably, the length taken by the waveguide 20 between the first end 32 and the second end 34 is equal to M λ, where λ is the wavelength of the microwaves in the waveguide, and M is a natural integer greater than or equal to 1.

[0085] Preferably, the inlet 24 and the outlet 26 of each channel 22 are provided at a distance D from the second end 34 of the waveguide 20 substantially equal to λ / 4 + N λ / 2, where λ is the wavelength of the microwaves in the waveguide, and N is a natural integer greater than or equal to zero.

[0086] These positions, located at such a distance from the closed second end 34 of the waveguide 20, are the positions where the microwave energy is the strongest.

[0087] In one example embodiment, a plurality of channels 22 is provided along the waveguide 20.

[0088] Advantageously, as shown in Figure 3 , the outlet 26 of each channel 22 has an elongated shape in the elongation direction E. This makes it possible to generate a plasma jet 16 having an elongated shape. The plasma jet 16 takes the form of a blade elongated along the elongation direction E, as shown by the dashed line in Figure 3 .

[0089] Preferably, in this case, the inlet 24 also has an elongated shape in the elongation direction E.

[0090] In particular, the inlet 24 has the same form and the same dimensions as the outlet 26. This allows the gas flow at the inlet 24 and at the outlet 26 of the channel 22 to have the same flow speed.

[0091] Preferably, the plasma generation system 14 is configured to supply each channel 20 with a compressed plasma generation gas, in particular with compressed air.

[0092] The plasma generation system 14 comprises a gas supply device 36 configured to supply compressed plasma generation gas.

[0093] The gas supply device 36 is for example a source of compressed gas or a compressor.

[0094] In particular, the gas supply device 36 is for example an air compressor configured to supply compressed air to each channel 22, preferably by taking air from the environment of the weeding device 4. In a variant, the gas supply device 36 comprises a reservoir of compressed plasma generation gas.

[0095] Optionally, as Figure 2 illustrated, the plasma generation system 14 comprises at least one delivery pipe 38 in each channel 22, each pipe extending in the channel 22 from the inlet 24 to the outlet 26.

[0096] Each delivery pipe 38 makes it possible to deliver a flow of plasma generation gas between the inlet 24 and the outlet 26, without the plasma generation gas being conveyed in the waveguide 20. The plasma generation gas is in particular confined in the region of the strongest microwave energy.

[0097] The plasma generation system 14 comprises for example a single delivery pipe 38 in at least one channel 22 or in each channel 22, the cross section of the delivery pipe 38 corresponding to the cross section of the inlet 24 and to the cross section of the outlet 26. In operation, the plasma jet 16 is generated at the outlet of the delivery pipe 38.

[0098] In a variant, the plasma generation system 14 comprises for example a plurality of delivery pipes 38 arranged side by side in at least one channel 22 or in each channel 22.

[0099] In operation, an elementary plasma jet is generated at the outlet of each delivery pipe 38, the elementary plasma jet being defined as the plasma jet 16.

[0100] The delivery pipes 38 are for example pipes with a circular cross section, the pipes being arranged side by side to together take the elongated shape of the inlet 24 and of the outlet 26 of the channel 22.

[0101] In operation, the microwave generator 18 generates microwaves which propagate in the waveguide 20 and the gas supply device supplies gas, in particular air, to each channel 22. On passing through the channel 22, the gas is ionized by the microwaves propagating in the waveguide 20, so as to generate a plasma jet 16 at the outlet 26 of each channel 22. The plasma jet 16 causes damage to unwanted plants located in the vicinity of the plasma jet 16.

[0102] Advantageously, as shown in Figure 4 The weeding device 4 comprises a plasma generation system 14, and the weeding device 4 is configured to simultaneously generate a plurality of plasma jets 16.

[0103] Preferably, the plasma jets 16 are distributed along a distribution direction DD while being spaced apart from each other, preferably uniformly spaced apart, i.e. the spacing between the plasma jets 16 is constant.

[0104] This arrangement of the plasma jets 16 makes it possible, for example, to simultaneously treat several spaces between (or “inter-row”) parallelly extending plantation rows, the weeding device 4 being arranged such that the distribution direction DD is perpendicular to the plantation rows, and such that each plasma jet 16 is located inter-row, the weeding device 4 being moved along the plantation rows.

[0105] In one example embodiment, the plurality of plasma jets 16 distributed along the distribution direction DD is generated by means of microwaves, preferably by means of a single microwave generator 18 generating the plurality of plasma jets 16 distributed along the distribution direction DD.

[0106] To this end, the plasma generation system 14 comprises, for example, at least one waveguide 20 provided with a plurality of channels 22 arranged along this same waveguide 20.

[0107] In this case, the separation between each plasma jet 16 and the subsequent plasma jet is about λ / 2, λ being the wavelength of the microwaves generated by the microwave generator in the waveguide.

[0108] Each waveguide 20 has, for example, one channel 22, two channels 22, three channels 22, four channels 22, or more channels 22.

[0109] In a variant or in an alternative complement, the plasma generation system 14 comprises a plurality of waveguides 20 receiving the microwaves generated by the same microwave generator 18.

[0110] Figure 5 The plasma generation system 14 of Figure 3 is similar to the plasma generation system in Figure 5 but The plasma generation system 14 of

[0111] The plasma generation system 14 comprises an inlet pipe 40 having a first end 42 designed to receive the microwaves generated by the microwave generator 18 and a second end 44, and a plurality of waveguides 20, the first end 32 of each waveguide 20 being connected to the second end 44 of the inlet pipe 40 to receive the microwaves propagating in the inlet pipe 40.

[0112] The first end 32 of each waveguide 20 is connected to the inlet pipe 40, for example by means of a power divider 46. The power divider 46 is a branching pipe comprising an inlet branch 48 connected to the second end 44 of the inlet pipe 40 and a plurality of outlet branches 50, each outlet branch 50 being connected to a waveguide pipe 28.

[0113] As shown in Figure 5 the plasma generation system 14 comprises two waveguides 20 and the power divider 46 comprises two outlet branches 50. The power divider 46 is in the form of a “T”.

[0114] Preferably, the waveguides 20 have the same cross section and the inlet pipe 40 and each branch of the power divider 46, i.e. the inlet branch 48 and each outlet branch 50, have the same cross section as the waveguides 20.

[0115] Each waveguide 20 comprises one or more channels 22 for the passage of a plasma generation gas through the waveguide 20 and for the generation of a plasma jet 16. Each channel 22 is connected to a gas supply device 36 (not shown in Figure 4 ) for supplying the channel 22 with a plasma generation gas.

[0116] Advantageously, each waveguide 20 comprises a plurality of channels 22 distributed along the waveguide 20.

[0117] In Figure 5 each waveguide 20 comprises three channels 22. The channel 22 closest to the second end 34 of the waveguide 20 is located at a distance λ / 4 from this second end 34, the subsequent channel 22 is located at a distance λ / 4 + λ / 2 from this second end 34 and the subsequent channel 22 is located at a distance λ / 4 + λ from this second end 34.

[0118] In possible variants, each waveguide 20 has a different number of channels 22, for example one channel 22, two channels 22, four channels 22, or more.

[0119] The plasma generation system 14 comprises a pair of waveguides 20, for example collinear in the distribution direction DD. This makes it possible to have a large number of channels 22 distributed along the distribution direction DD.

[0120] In operation, the microwave generator 18 generates microwaves which enter the waveguides 20 via the first end 42 of the inlet pipe 40 and propagate in each waveguide 20 by means of the power divider 46. The gas supply device 36 supplies gas, in particular air, to each channel 22. In each channel 22, the gas passing through the channel 22 is ionized by the microwaves and a plasma jet 16 is generated at the outlet 26 of the channel 22.

[0121] The plurality of channels 22 and / or the plurality of waveguides 20 are arranged along the waveguide 20 so that a plurality of zones can be processed in the same channel.

[0122] As an example, a configuration is given which is substantially "T" shaped and comprises two collinear waveguides 20. Other configurations are also possible, for example configurations which are substantially "L" shaped, comb-shaped or rake-shaped.

[0123] The microwaves used to generate the plasma have a frequency, for example, between 300 MHz and 300 GHz, in particular between 2.4 GHz and 2.5 GHz.

[0124] The microwaves used to generate the plasma therefore have a wavelength between 1 mm and 1 m, in particular between 17 cm and 18 cm.

[0125] When the waveguide 20 has a rectangular cross-section, the rectangular cross-section has, for example, a height between 5 mm and 75 mm, in particular between 42 mm and 44 mm, and / or a width between 10 mm and 150 mm, in particular between 84 mm and 88 mm.

[0126] In one example embodiment, the microwaves have a frequency between 2.4 GHz and 2.5 GHz and / or each waveguide 20 has a rectangular cross-section with a height of 43 mm and a width of 86 mm.

[0127] In this case, when a plurality of channels is arranged along the waveguide 20, the separation between one plasma jet 16 and the subsequent plasma jet is a multiple of half a wavelength in the waveguide (approximately 8.7 cm), which makes it possible to obtain values corresponding to the normal separation between rows of a plantation.

[0128] Other plasma generation systems 14 can be envisaged.

[0129] In one example, as shown in Figure 6 The plasma generation system 14 by microwaves is of the torch type.

[0130] The plasma generation system 14 comprises, for example, a microwave generator 18 configured to generate microwaves and a waveguide 20 configured to guide the microwaves generated by the microwave generator 18, the waveguide 20 having a channel 22 which passes through the waveguide 20 and has an inlet 24 and an outlet 26 and a torch 51 which extends in the channel 22 while passing through the waveguide 20, a space being provided between the torch 51 and the internal wall 24A, 26A of each of the inlet 24 and the outlet 26.

[0131] A gas supply device 36 is connected to the torch-like piece 51 to supply a plasma-generating gas, for example air, to the torch-like piece 51, and the plasma-generating gas is preferably compressed.

[0132] The waveguide 20 comprises a first end 32 designed to receive the microwaves generated by the microwave generator 18 and a second end 34 closed by a short-circuit plug 52, also called "short-circuit piece".

[0133] Preferably, the short-circuit plug 52 is inserted into the waveguide 20 while being able to slide in the waveguide 20, so that the position of the plug 52 in the waveguide 20 is adjustable.

[0134] The inlet 24 of the channel 22 is provided with a starter plug 54, also called "starter", through which the torch-like piece 51 extends.

[0135] Preferably, the starter plug 54 is inserted into the inlet 24 of the channel 22 while being able to slide in the inlet 24 of the channel 22, so that the position of the starter plug 54 in the inlet 24 of the channel 22 is adjustable.

[0136] The torch-like piece 51 and the waveguide 20 are preferably metallic, and the plasma-generating system 14 comprises a voltage generator 56 configured to apply a voltage between the torch-like piece 51 and the waveguide 20.

[0137] In operation, the microwave generator 18 generates microwaves that propagate in the waveguide 20, and the gas supply device supplies a plasma-generating gas to the torch-like piece 51. The plasma-generating gas is ionized by the microwaves propagating in the waveguide 20, so as to generate a plasma jet 16 at the outlet of the torch-like piece 51.

[0138] Adjusting the position of the short-circuit plug 52 and / or adjusting the position of the starter plug 54 makes it possible to vary the propagation of the microwaves in the waveguide 20 to ensure the generation of a plasma jet 16 at the outlet of the torch-like piece 51.

[0139] The weeding device 4 comprises one or more plasma-generating systems 14 of this type.

[0140] In particular, a plurality of plasma-generating systems 14 can be arranged to generate plasma jets 16 distributed along the above-mentioned distribution direction DD.

[0141] In a variant or alternative complement, the plasma-generating system 14 is configured to generate at least one plasma jet by electrical discharge, in particular by bare electrode discharge, by single dielectric barrier discharge or by double dielectric barrier discharge.

[0142] In one example, the weeding device 4 comprises at least one discharge plasma generating system 14, in particular a system 14 for generating plasma by single dielectric barrier discharge, by double dielectric barrier discharge or by bare electrode discharge.

[0143] As shown in Figure 7 , the system 14 for generating plasma by bare electrode discharge comprises a tube 60 having a first end 62 connected to the gas supply device 36 for supplying the tube 60 with plasma generating gas, and a second end 64 at which the plasma is generated in operation, and an electrode 66, preferably filamentary, extending in the tube 60 and terminating in the vicinity of the second end 64, and a voltage generator 68 connected to the electrode 66 for applying a voltage to the electrode 66. The plasma generating gas conveyed in the tube 60 is in contact with the electrode 66.

[0144] In operation, the gas supply device 36 supplies the tube with plasma generating gas, and the voltage generator 68 applies a voltage to the electrode 66, which generates an electric field around the electrode 66, the plasma generating gas being ionized while passing through the electric field, so that a plasma jet 16 is generated at the outlet of the tube 60.

[0145] Other systems 14 for generating plasma by bare electrode discharge can be envisaged.

[0146] As shown in Figure 8 , the system 14 for generating plasma by single dielectric barrier discharge differs from the system 14 for generating plasma by bare electrode discharge of Figure 5 in that the electrode 66 constitutes a first electrode, the plasma generating system 14 comprises a second electrode 70 located outside the tube 60, here around the second end 64 of the tube 60, the voltage generator 68 being connected to both electrodes 66, 70 for generating a voltage between the two electrodes 66, 70.

[0147] The tube 60 is made of a dielectric material. The plasma generating gas conveyed in the tube 60 is in contact with the electrode 66, but not with the electrode 70.

[0148] In operation, the gas supply device 36 supplies the tube 60 with plasma generating gas, and the voltage generator 68 applies a voltage between the two electrodes 66, 70, which generates an electric field between the two electrodes 66, 70, the plasma generating gas being ionized while passing through the electric field, so that a plasma jet 16 is generated at the outlet of the tube 60.

[0149] Other systems 14 for generating plasma by single dielectric barrier discharge can be envisaged.

[0150] AsFigure 9 The system 14 for generating plasma by double dielectric barrier discharge as shown differs from the system 14 for generating plasma by bare electrode discharge in that the first electrode 66 is separated from the gas stream by a dielectric material. The first electrode 66 is here covered by a dielectric material 71. Figure 6

[0151] The plasma-generating gas conveyed in the tube 60 does not come into contact with the first electrode 66 and the second electrode 70.

[0152] In operation, the gas supply device 36 supplies plasma-generating gas to the tube 60, and the voltage generator 68 applies a voltage between the two electrodes 66, 70, which generates an electric field between the two electrodes 66, 70, the plasma-generating gas being ionized while passing through the electric field, so that a plasma jet 16 is generated at the outlet of the tube 60.

[0153] Other systems 14 for generating plasma by double dielectric barrier discharge can be envisaged.

[0154] The weeding device 4 comprises one or more discharge plasma-generating systems 14.

[0155] In particular, a plurality of discharge plasma-generating systems 14 can be arranged to generate plasma jets 16 distributed along the above-mentioned distribution direction DD.

[0156] In one example, the weeding device 4 comprises a system 14 for generating plasma by double dielectric barrier discharge, which uses unwanted plants as one of the dielectric barriers to generate plasma in the air layer located between the electrode and the ground 8.

[0157] As shown, such a plasma-generating system 14 comprises a power supply electrode 72, for example configured to be arranged above the ground, a dielectric layer 74 arranged below the power supply electrode 72, and a voltage generator 76 configured to apply a voltage between the ground and the power supply electrode 72 to ionize the air layer located between the ground and the power supply electrode 72. Figure 10

[0158] In operation, the voltage generator 76 applies a voltage between the ground and the power supply electrode 72 to ionize the air layer located between the ground and the power supply electrode 72. The power supply electrode 72 is separated from the ground by the dielectric layer 74 and by the unwanted plants, which define a further dielectric layer.

[0159] Such a plasma-generating system 14 makes it possible to effectively weed large areas of ground.

[0160] ​​The above-described weeding device 4 and plasma generating system 14 make it possible to implement a weeding method comprising generating plasma from a plasma generating gas and exposing unwanted plants to the plasma to eliminate these unwanted plants.

[0161] Preferably, the plasma generating gas used to generate plasma is compressed. Advantageously, the plasma generating gas is not just air, in particular compressed air.

[0162] Generating plasma comprises, for example, generating at least one plasma jet, for example, each plasma jet 16 being columnar or curtain-like.

[0163] The weeding method advantageously comprises generating a plurality of plasma jets 16 spaced apart from each other along a distribution direction DD, the plasma jets 16 being preferably uniformly spaced apart, with a constant spacing between the plasma jets in the distribution direction DD.

[0164] In this case, the weeding method preferably comprises moving the plasma jets 16 along a plantation row extending in a plantation direction, the distribution direction DD being perpendicular to the plantation direction, each plasma jet 16 being positioned to face an inter-row of the plantation.

[0165] The weeding method comprises, for example, generating at least one plasma jet 16 by ionizing the plasma generating gas by means of microwaves.

[0166] Generating at least one plasma jet comprises generating microwaves in at least one elongated waveguide 20 between a first end 32 designed to receive the microwaves and a closed second end 34, and, for each waveguide 20, making a plasma generating gas flow circulate in at least one passage 22 crossing the waveguide 20 transversely, a plasma jet 16 being formed at the outlet of each passage 22.

[0167] Each passage 22 is positioned at a distance from the second end of the waveguide tube substantially equal to λ / 4 + N λ / 2, where λ is the wavelength of the microwaves in the waveguide and N is a natural integer greater than or equal to zero.

[0168] The weeding method comprises, for example, supplying the plurality of waveguides 20 with microwaves from a microwave generator 18, the first ends 32 of the waveguides 20 being connected to respective outlet branches of a branch power divider 46, the waveguides 20 receiving the microwaves through the branch power divider 46.

[0169] In a variant or as an optional complement, as Figure 7 to Figure 9As shown, according to the weeding method, at least one plasma jet 16 is generated by means of a discharge, in particular by means of a bare electrode discharge, by means of a single dielectric barrier discharge, or by means of a double dielectric barrier discharge.

[0170] In a variant or as an optional supplement, as Figure 10 As shown, the weeding method comprises generating a plasma by ionizing an air layer located above the ground. The ionization is achieved, for example, by means of a power supply electrode 72 located above the ground, a dielectric layer 74 located below the power supply electrode 72, and by applying a voltage between the power supply electrode 72 and the ground.

[0171] The plasma can be produced very easily, for example, using ambient air as the gas for generating the plasma, which avoids having to transport a reserve gas.

[0172] The use of the plasma combines the effects of other weeding methods, namely the thermal effect (heat), the chemical effect (formation of active substances such as ozone), and the radiation effect (emission of UV light, emission of infrared light). Thus, the use of the plasma makes it possible to effectively weed.

[0173] A plurality of plasma jets can be generated simultaneously, for example, by means of microwaves and / or by means of a discharge, in order to achieve inter-row weeding in a plantation.

Claims

1. A weeding device comprising a plasma generating system (14) configured to generate a plasma from a plasma generating gas, characterized in that, The weeding device comprises: a microwave generator (18), a gas supply device (36) for a plasma-generating gas, at least one waveguide (20), and the weeding device is configured to generate at least one plasma jet (16) by ionizing the plasma-generating gas using microwaves.

2. The weeding device according to claim 1, characterized in that The gas supply device for a plasma-generating gas is an air compressor.

3. The weeding device according to claim 1, characterized in that The gas supply device for a plasma-generating gas comprises a reservoir of compressed plasma-generating gas.

4. The weeding device according to any one of claims 1 to 3, characterized in that, The weeding device is configured to generate a plurality of uniformly spaced plasma jets (16), wherein the spacing between the plasma jets is constant according to a distribution direction (DD).

5. The weeding device according to any one of claims 1 to 3, characterized in that, The microwave generator (18) is configured to generate microwaves in the at least one waveguide (20), the at least one waveguide comprising: a lateral wall (30) having two opposite first faces (30A) and two opposite second faces (30B), a first end (32) intended for receiving the microwaves generated by the microwave generator (18), a second end (34) closed by a bottom (35), at least one channel (22) transversely intersecting the at least one waveguide (20), the channel being supplied with a plasma-generating gas flow originating from the gas supply device (36) for a plasma-generating gas, and the channel comprising an inlet (24) formed in one of the two opposite first faces (30A) and an outlet (26) formed in the other of the two opposite first faces (30A), the outlet being positioned opposite the inlet (24), a delivery tube located in the at least one channel (22), and the cross section of the delivery tube corresponding to the cross section of the inlet (24) and the cross section of the outlet (26) of the channel (22).

6. The weeding device according to claim 5, wherein The bottom (35) is a short-circuit plug (52) that can be moved in the waveguide (20) in a sliding manner, so that the position of the plug (52) in the waveguide (20) is adjustable.

7. The weeding device according to claim 5, wherein The inlet (24) of the channel (22) is provided with a starter plug (54) that can be moved in the inlet (24) in a sliding manner, so that the position of the starter plug (54) is adjustable.

8. The weeding device according to claim 5, wherein a length of the waveguide (20) between the first end (32) and the second end (34) is equal to M λ, where λ is a wavelength of the microwaves in the waveguide, and M is a natural integer equal to or greater than 1.

9. The weeding device according to claim 8, characterized in that From 1 to 4 channels (22) are provided along the at least one waveguide (20).

10. The weeding device according to claim 9, characterized in that The entrance (24) and the exit (26) of each channel (22) of each waveguide (20) are formed at a distance D equal to λ / 4 + N λ / 2 from the second end (34) of the waveguide, where λ is the wavelength of the microwaves in the waveguide and N is a natural integer equal to or greater than zero.

11. The weeding device according to claim 5, wherein Several waveguides (20) are connected to a respective outlet branch of a branching power distributor (46), the waveguides (20) receiving the microwaves through the branching power distributor.

12. The weeding device of claim 11, wherein, The power distributor has a "T" shape, an "L" shape, a comb shape, or a rake shape configuration.

13. The weeding device of claim 12, wherein, The microwave plasma-generating system (14) comprises: an inlet tube (40) receiving microwaves generated by the microwave generator (18), two waveguides (20), a power distributor (46) of T-shape having an inlet branch (48) and two outlet branches (50), the inlet tube (40) is connected to the power distributor (46) through the inlet branch (48) of the power distributor (46), and the two waveguides (20) are connected to the two outlet branches (50) of the power distributor (46), respectively.

14. The weeding device of claim 5, wherein The weeding device is configured to generate at least one plasma jet by means of a discharge, in particular the weeding device is configured to generate at least one plasma jet by means of a bare electrode discharge, by means of a single dielectric barrier discharge or by means of a double dielectric barrier discharge.

15. The weeding device according to any one of claims 1 to 3, characterized in that, The weeding device is configured for generating plasma by ionizing an air layer located above the ground.

16. The weeding device of claim 15, wherein The ionization is achieved using a power supply electrode (72) located above the ground, a dielectric layer (74) located below the power supply electrode, and by applying a voltage between the power supply electrode and the ground.

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