A preparation device for an erosion-resistant platinum film heat flux sensor

Abstract

The present invention discloses a preparation device for an erosion-resistant platinum film heat flux sensor, comprising: a plasma generation cavity assembly for generating high-density plasma; a thin film deposition cavity connected to the output end of the plasma of the plasma generation cavity assembly; a deposition table disposed inside the thin film deposition cavity, the deposition table being used to place the platinum film heat flux sensor body such that there is an acute angle between the surface of the platinum film heat flux sensor body and the axis of the thin film deposition cavity; an inner channel for providing a raw material medium for chemical deposition reaction with the plasma; and a protective gas supply system for providing a protective gas environment to the plasma generation cavity assembly and the thin film deposition cavity. The present invention grows a silicon nitride thin film on the surface of a platinum film heat flux sensor with a flexible substrate by PECVD and actively interferes with its microscopic growth structure, thereby obtaining an erosion-resistant platinum film heat flux sensor applicable to a hypersonic shock tunnel.

Description

Technical Field

[0001] The present invention relates to the technical field of hypersonic shock tunnels, and specifically relates to a preparation device for a platinum film heat flux sensor resistant to erosion. Background Art

[0002] In existing platinum film heat flux sensors, since the Pt platinum film resistance temperature sensor uses glass or ceramic as the substrate material, when measuring the surface heat flux of a model with a complex surface in a hypersonic shock tunnel experiment, the measuring point spacing of the sensor is relatively large, and the measuring end face of the sensor does not coincide well with the model surface, which will have a certain impact on the flow field and thus affect the measurement accuracy. To solve the problem of measuring the surface heat flux of a model with a complex surface, if the sensor has a flexible substrate, such a problem can be well solved. It can not only make the installation of the sensor more convenient, the measuring end face and the model surface completely coincide, but also increase the density of measuring points and more clearly obtain the heat flux distribution on the model surface.

[0003] However, when the high-speed air flow generated by the hypersonic shock tunnel impacts the surface of the flexible substrate, it will also impact the surface of the substrate material, thereby affecting the service life of the platinum film heat flux sensor and increasing the complexity of the shock tunnel experiment measurement process.

[0004] In the existing technology, coating is performed on the surface of the platinum film heat flux sensor with a flexible substrate. Although this method can, to a certain extent, improve the service life of the platinum film heat flux sensor according to the material properties of the coating, in the hypersonic shock tunnel experiment process, the platinum film heat flux sensor prepared by the existing coating method cannot effectively improve the erosion resistance of the platinum film heat flux sensor. Summary of the Invention

[0005] The purpose of the present invention is to provide a preparation device for a platinum film heat flux sensor resistant to erosion, so as to solve the technical problems in the prior art that the service life of the platinum film heat flux sensor with a flexible substrate is reduced under shock wave impact and there is a lack of an effective preparation device.

[0006] To solve the above technical problems, the present invention specifically provides the following technical solutions:

[0007] A preparation device for a platinum film heat flux sensor resistant to erosion, comprising:

[0008] A plasma generation cavity assembly for generating high-density plasma;

[0009] A thin film deposition cavity, the thin film deposition cavity being connected to the plasma output end of the plasma generation cavity assembly;

[0010] A deposition stage is arranged inside the thin film deposition cavity. The deposition stage is used to place the platinum film heat flux sensor body, such that there is an acute angle between the surface of the platinum film heat flux sensor body and the axis of the thin film deposition cavity;

[0011] An inner channel is arranged at the connection between the thin film deposition cavity and the plasma generation cavity assembly. The inner channel is used to provide a raw material medium for chemical deposition reaction with the plasma and is transmitted along the axis of the thin film deposition cavity;

[0012] A protective gas supply system is built on the plasma generation cavity assembly and the thin film deposition cavity, and is used to provide a protective gas environment to the plasma generation cavity assembly and the thin film deposition cavity.

[0013] As a preferred embodiment of the present invention, the deposition stage includes a support frame arranged on the axis of the thin film deposition cavity, and a disc seat installed at the end of the support frame close to the inner channel. A clamping structure for fixing the platinum film heat flux sensor body is arranged on the disc seat;

[0014] Wherein, a gap flow channel is formed between the circumferential surface of the disc seat and the inner wall of the thin film deposition cavity, and the clamped platinum film heat flux sensor body forms a fluid guiding plane of the gap flow channel.

[0015] As a preferred embodiment of the present invention, the disc seat is installed on the support frame through a telescopic assembly. The telescopic assembly is used to drive the disc seat to displace along the axis of the thin film deposition cavity, so as to increase or decrease the gap flow channel.

[0016] As a preferred embodiment of the present invention, the inner channel includes a pipeline body and a medium discharge hole arranged on the inner wall of the pipeline;

[0017] Wherein, the medium discharge hole is used to form a swirl channel of fluid in the axial direction of the pipeline body, and the diameter of the swirl channel is smaller than the diameter of the pipeline body.

[0018] As a preferred embodiment of the present invention, the medium discharge hole includes a protective gas discharge hole and a raw material discharge hole. The raw material discharge hole is located above the protective gas discharge hole, and the raw material discharge hole is close to the connection between the thin film deposition cavity and the plasma generation cavity assembly;

[0019] Wherein, the raw material discharge hole is used to provide a raw material medium for chemical deposition reaction with the plasma, the protective gas discharge hole is used to provide a protective gas, and the radial injection length of the raw material medium in the thin film deposition cavity of the raw material discharge hole is greater than the radial injection length of the protective gas in the thin film deposition cavity of the protective gas discharge hole.

[0020] As a preferred embodiment of the present invention, the clamping structure includes a frustum base mounted on the disc base. A placement groove is provided on the waist surface of the frustum base along the waist surface, and a stop edge is provided at the bottom of the placement groove; a tapered guide head is provided at the top of the frustum base, and the tapered guide head is threadedly connected to the disc base through a threaded bolt passing through the axis of the frustum base;

[0021] Wherein, the bottom diameter of the tapered guide head is the same as the top diameter of the frustum base.

[0022] As a preferred embodiment of the present invention, the protective gas supply system includes an intake end mounted on the top of the plasma generation cavity assembly and an outlet end mounted on the bottom of the thin film deposition cavity, and the intake end is used to supply nitrogen and protective gas.

[0023] As a preferred embodiment of the present invention, the plasma generation cavity assembly includes:

[0024] A quartz tube body, which is hermetically connected to the thin film deposition cavity;

[0025] A helical wave generator, which is coupled into the quartz tube body and used to generate helical waves;

[0026] Helmholtz coils, which are used to construct a propagation magnetic field for the helical waves generated by the helical wave generator.

[0027] The present invention has the following beneficial effects compared with the prior art:

[0028] In the present invention, a silicon nitride thin film is grown on the surface of a platinum film heat flux sensor with a flexible substrate by PECVD, and active interference is carried out on its microscopic growth structure, so as to obtain a platinum film heat flux sensor resistant to erosion applicable to a hypersonic shock tunnel. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only exemplary, and for those of ordinary skill in the art, without creative efforts, other implementation drawings can also be obtained according to the provided drawings.

[0030] Figure 1 It is a schematic structural diagram of a device for preparing a platinum film heat flux sensor resistant to erosion provided by an embodiment of the present invention;

[0031] Figure 2 It is a schematic structural diagram of a clamping structure provided by an embodiment of the present invention.

[0032] The reference numerals in the figures are respectively represented as follows:

[0033] 1 - Plasma generation cavity assembly; 2 - Thin film deposition cavity; 3 - Deposition stage; 4 - Platinum film heat flux sensor body; 5 - Inner duct;

[0034] 101 - Quartz tube body; 102 - Helicon wave generator; 103 - Helmholtz coil;

[0035] 31 - Support frame; 32 - Disc seat; 33 - Clamping structure; 34 - Gap flow channel; 35 - Telescopic assembly;

[0036] 331 - Frustum seat; 332 - Placement groove; 333 - Edge stop; 334 - Cone guide head; 335 - Threaded bolt;

[0037] 51 - Pipe body; 52 - Medium discharge hole. Specific implementation mode

[0038] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0039] The platinum film heat flux sensor preparation device of the present invention is aimed at a flexible variable integrated platinum film heat flux sensor, and the existing preparation methods for platinum film heat flux sensors with flexible substrates include:

[0040] Manufacture a mask according to the designed size, fix a finished polyimide film with a thickness of 0.18 mm on a silicon wafer substrate, and use lithography technology to transfer the sensor pattern on the mask to the platinum layer on the polyimide film to form a sensitive element. Then, a polyimide film is plated in the area except for the temperature sensing component and the pin component through lithography technology to play a role of protection and heat insulation, avoiding the influence of temperature on other components except the sensitive part. Finally, the polyimide base layer and the silicon wafer are separated, and the size of each measuring point is 0.1×1 mm, which can be installed on a curved surface with a certain curvature.

[0041] Since the Pt platinum film resistance temperature sensor uses glass or ceramic as the substrate material, when measuring the heat flux on the surface of a model with a complex shape in a hypersonic shock tunnel experiment, the spacing between the measurement points of the sensor is relatively large, and the measurement end face of the sensor does not coincide well with the model surface, which will have a certain impact on the flow field and thus affect the measurement accuracy. To solve the problem of measuring the heat flux on the surface of a complex-shaped model, if the sensor has a flexible substrate, such problems can be well solved. It can not only make the installation of the sensor more convenient, the measurement end face and the model surface completely coincide, but also increase the density of the measurement points and obtain the heat flux distribution on the model surface more clearly.

[0042] The selection of the substrate material is the basis for fabricating this flexible substrate heat flux sensor. It not only needs to have certain bending properties but also good heat insulation properties. According to this requirement, polyimide is selected as the substrate material. Polyimide is an aromatic heterocyclic polymer compound with an imide group chain link in its molecular structure, which can be divided into four categories: pyromellitic PI, soluble PI, polyamide-imide (PAI), and polyetherimide (PEI).

[0043] However, at the same time, when the high-speed airflow generated by the hypersonic shock tunnel impacts the surface of the flexible substrate, it will also impact the surface of the substrate material. And when the surface flatness of the substrate material is insufficient, it is very easy for the platinum film heat flux sensor to separate from the model surface to be detected or for the circuit inside the platinum heat flux sensor to be broken under the impact of the hypersonic shock.

[0044] Therefore, in the present invention, a silicon nitride thin film with a very thin thickness (in the micron range) and high thermal conductivity is deposited on the platinum film surface of the already developed platinum film heat flux sensor (referring to the intermediate product during the preparation process). Due to the high hardness of the silicon nitride material, the erosion resistance of the sensor during use is greatly improved, enabling the sensor to be used repeatedly for a long time, increasing the sensor life, and the frequency response of the sensor can still reach up to 100 kHz.

[0045] Therefore, as Figure 1 and Figure 2 shown, the present invention provides a preparation device for an erosion-resistant platinum film heat flux sensor, including:

[0046] A plasma generation cavity assembly 1 for generating high-density plasma;

[0047] A thin film deposition cavity 2, and the thin film deposition cavity 2 is connected to the plasma output end of the plasma generation cavity assembly 1;

[0048] A deposition stage 3 is arranged inside the thin film deposition cavity 2. The deposition stage 3 is used to place the platinum film heat flux sensor body 4, so that there is an acute angle between the surface of the platinum film heat flux sensor body 4 and the axis of the thin film deposition cavity 2;

[0049] The inner channel 5 is provided at the connection between the thin film deposition chamber 2 and the plasma generation chamber assembly 1. The inner channel 5 is used to provide a raw material medium for chemical deposition reaction with the plasma and is transmitted along the axis of the thin film deposition chamber 2.

[0050] The protective gas supply system is built on the plasma generation chamber assembly 1 and the thin film deposition chamber 2 and is used to provide a protective gas environment in the plasma generation chamber assembly 1 and the thin film deposition chamber 2.

[0051] The specific working principle of the present invention is to realize the formation of the silicon nitride thin film on the surface of the platinum film heat flux sensor based on the helicon wave plasma enhanced chemical vapor deposition of the plasma generation chamber assembly 1.

[0052] Among them, the plasma generation chamber assembly 1 is through the collision of electrons heated by helicon waves and N 2 (nitrogen gas), which ionizes the nitrogen gas, thereby generating a high-density plasma, and the axial magnetic field provides conditions for the propagation of the helicon wave.

[0053] The N (nitrogen) active particles generated in the plasma generation chamber assembly 1 diffuse into the lower thin film deposition chamber 2. The raw material medium provided by the inner channel 5 is silane (silicon tetrahydride SiH 4 ). Since silane is easily dissociated, it enters the thin film deposition chamber 2 by spraying. The high-density plasma (N (nitrogen) active particles) generated by the plasma generation chamber assembly 1 bombards the silane, and finally the silicon nitride generated during the bombardment effect is deposited on the surface of the platinum film heat flux sensor body 4.

[0054] Although the existing silicon nitride is generally the same in principle in chemical vapor deposition technology, it is random at the microscopic level of deposition on the surface of the substrate (platinum film heat flux sensor body). When applied in a hypersonic shock tunnel, since the shock waves generated by it are highly directional to a large extent, that is, when the surface flatness is insufficient, it is easy for the platinum film heat flux sensor and the surface of the model to be detected to become detached under the hypersonic shock wave. In order to perform directional vapor deposition on the vapor-deposited silicon nitride thin film and make the formed silicon nitride thin film on the platinum film heat flux sensor have shock wave adaptability to reduce the influence of the force generated between the surface of the platinum film heat flux sensor and the shock wave, that is, the "scouring" effect of the shock wave on the surface of the platinum film heat flux sensor.

[0055] Therefore, during the directional deposition of the silicon nitride thin film in the present invention, a channel is formed in the thin film deposition cavity 2 through the inner channel 5, and silicon nitride generated during the construction of the axial final bombardment effect is deposited on the surface of the platinum film heat flux sensor body 4. At the same time, the platinum film heat flux sensor body 4 arranged on the surface of the deposition table 3 is set at a certain angle with the axis of this channel, so that the deposition of silicon nitride entering the deposition table 3 flows along the surface of the platinum film heat flux sensor 4, thereby controlling the microscopic structure state of the silicon nitride deposition on the surface of the platinum film heat flux sensor.

[0056] In the specific implementation process, the deposition table 3 includes a support frame 31 arranged on the axis of the thin film deposition cavity 2, and a disc seat 32 installed at the end of the support frame 31 close to the inner channel 5. A clamping structure 33 for fixing the platinum film heat flux sensor body 4 is arranged on the disc seat 32; wherein, a gap flow channel 34 is formed between the circumferential surface of the disc seat 32 and the inner wall of the thin film deposition cavity 2, and the platinum film heat flux sensor body 4 clamped by the clamping structure 33 forms a fluid guiding plane of the gap flow channel 34.

[0057] In the above working principle, the substantial role of the protective gas supply system can be to provide a gas phase deposition atmosphere for the protective gas, and at the same time, it can also be used to construct the medium flow field in the thin film deposition cavity 2. Of course, the main purpose of constructing the medium flow field is to interfere with the growth state and structure of the silicon nitride thin film on the surface of the platinum film heat flux sensor body 4. That is, it flows along the surface of the platinum film heat flux sensor body 4 towards the gap flow channel 34.

[0058] Furthermore, in the present invention, it is also intended to set the gap flow channel 34 at the center of the disc seat 32 and make corresponding changes to the clamping structure 33.

[0059] When using the above deposition table 3 in the actual generation of silicon nitride thin films by PECVD, it involves the preparation of a platinum film heat flux sensor body (intermediate product) with a flexible substrate. The specific method is as follows:

[0060] Step 1: Fix a finished polyimide film with a thickness of 0.18 mm on a glass substrate, and use photolithography technology to transfer the sensor pattern on the mask sheet onto the platinum layer on the polyimide film to form a sensitive element.

[0061] Step 2: Coating is used to cover a layer of polyimide film with an area larger than that of the sensitive element on the surface of the sensitive element in all areas (excluding the pin part), that is, the boundary of the newly coated layer of polyimide film is larger than the boundary of the sensitive element. After curing, an intermediate product is obtained.

[0062] Its purpose is to make the obtained sensitive element easy to be clamped on the deposition table, that is, the clamping structure 33 is used to clamp the edge of the sensitive element, and the main detection surface is used for deposition.

[0063] Furthermore, in the present invention, the disc base 32 is installed on the support frame 31 through the telescopic assembly 35. The telescopic assembly 35 is used to drive the disc base 32 to axially displace along the thin film deposition cavity 2, so as to increase or decrease the gap flow channel 34. Its purpose is to change the size of the fluid guiding plane to obtain the growth efficiency of the silicon nitride thin film under ideal conditions.

[0064] Furthermore, in order to obtain the production state of the silicon nitride thin film under ideal conditions, the inner channel 5 of the present invention includes a pipe body 51 and a medium discharge hole 52 provided on the inner wall of the pipe; wherein, the medium discharge hole 52 is used to form a swirling channel of the fluid in the axial direction of the pipe body 51, and the diameter of the swirling channel is smaller than the diameter of the pipe body 51.

[0065] In the prior art, silane is discharged into the thin film deposition cavity, and under the bombardment effect of the plasma, the silicon nitride thin film grows freely on the surface of the substrate. Silane and the protective gas are discharged into the thin film deposition cavity through the same pipe orifice. In order to interfere with the growth state of the silicon nitride thin film in the present invention, the medium discharge hole 52 includes a protective gas discharge hole and a raw material discharge hole. The raw material discharge hole is located above the protective gas discharge hole, and the raw material discharge hole is close to the connection between the thin film deposition cavity 2 and the plasma generation cavity assembly 1;

[0066] Among them, the raw material discharge hole is used to provide the raw material medium for the chemical deposition reaction with the plasma, the protective gas discharge hole is used to provide the protective gas, and the radial injection length of the raw material medium in the thin film deposition cavity 2 of the raw material discharge hole is greater than the radial injection length of the protective gas in the thin film deposition cavity 2 of the protective gas discharge hole.

[0067] Its purpose is to evacuate the plasma generation cavity assembly 1 and the thin film deposition cavity 2 and provide a protective gas environment through the protective gas supply system. During the subsequent deposition reaction, the raw material medium (silane) is confined in the axial direction of the thin film deposition cavity 2 by the protective gas, that is, a swirling channel is formed, so that sufficient contact with the high-density plasma generated by the plasma generation cavity assembly 1 can be obtained, and the effective bombardment of the plasma is increased.

[0068] Furthermore, the present invention provides a clamping structure 33 including a frustum base 331 installed on the disc base 32. A placement groove 332 is provided on the waist surface of the frustum base 331, and a retaining edge is provided at the bottom of the placement groove 332; a tapered guide head 334 is provided at the top of the frustum base 331, and the tapered guide head 334 is threadedly connected to the disc base 32 through a threaded bolt passing through the axis of the frustum base 331.

[0069] Among them, the bottom diameter of the conical guide head 334 is the same as the top diameter of the frustum base 331.

[0070] The protective gas supply system includes an air inlet end installed at the top of the plasma generation cavity assembly 1 and an air outlet end installed at the bottom of the thin film deposition cavity 2. The air inlet end is used to supply nitrogen and protective gas. Of course, in the present invention, an air extraction device can be connected to the air outlet end to perform a vacuum pumping operation on the inside of the plasma generation cavity assembly 1.

[0071] Furthermore, the plasma generation cavity assembly in the present invention can be any one of the existing plasma generation structures. To better illustrate the working principle of the present invention, a plasma generation cavity assembly 1 is provided, which includes:

[0072] A quartz tube body 101, which is hermetically connected to the thin film deposition cavity 2;

[0073] A helical wave generator 102, which is coupled into the quartz tube body 101 and used to generate helical waves;

[0074] A Helmholtz coil 103, which is used to construct a propagation magnetic field for the helical waves generated by the helical wave generator 102.

[0075] The above embodiments are only exemplary embodiments of the present application and are not used to limit the present application. The protection scope of the present application is defined by the claims. Those skilled in the art can make various modifications or equivalent replacements within the essence and protection scope of the present application, and such modifications or equivalent replacements should also be regarded as falling within the protection scope of the present application.

Claims

1. A preparation device for an erosion-resistant platinum film heat flux sensor, characterized in that, it includes: a plasma generation cavity assembly (1) for generating high-density plasma; a thin film deposition cavity (2), and the thin film deposition cavity (2) is connected to the plasma output end of the plasma generation cavity assembly (1); a deposition stage (3) arranged inside the thin film deposition cavity (2), and the deposition stage (3) is used to place the platinum film heat flux sensor body (4), so that there is an acute angle between the surface of the platinum film heat flux sensor body (4) and the axis of the thin film deposition cavity (2); a connotation channel (5) arranged at the connection between the thin film deposition cavity (2) and the plasma generation cavity assembly (1), and the connotation channel (5) is used to provide a raw material medium for chemical deposition reaction with the plasma and transmit it along the axis of the thin film deposition cavity (2); a protective gas supply system built on the plasma generation cavity assembly (1) and the thin film deposition cavity (2) for providing a protective gas environment to the plasma generation cavity assembly (1) and the thin film deposition cavity (2).

2. The preparation device for an erosion-resistant platinum film heat flux sensor according to claim 1, characterized in that, the deposition stage (3) includes a support frame (31) arranged on the axis of the thin film deposition cavity (2), and a disc seat (32) installed at the end of the support frame (31) close to the connotation channel (5), and a clamping structure (33) for fixing the platinum film heat flux sensor body (4) is arranged on the disc seat (32); wherein, a gap flow channel (34) is formed between the circumferential surface of the disc seat (32) and the inner wall of the thin film deposition cavity (2), and the platinum film heat flux sensor body (4) clamped by the clamping structure (33) forms a fluid guiding plane of the gap flow channel (34).

3. The preparation device for an erosion-resistant platinum film heat flux sensor according to claim 2, characterized in that, the disc seat (32) is installed on the support frame (31) through a telescopic component (35), and the telescopic component (35) is used to drive the disc seat (32) to displace along the axis of the thin film deposition cavity (2) to increase or decrease the gap flow channel (34).

4. The preparation device for an erosion-resistant platinum film heat flux sensor according to claim 3, characterized in that, the connotation channel (5) includes a pipeline main body (51) and a medium discharge hole (52) arranged on the inner wall of the pipeline; wherein, the medium discharge hole (52) is used to form a swirl channel of fluid in the axis of the pipeline main body (51), and the diameter of the swirl channel is smaller than the diameter of the pipeline main body (51).

5. The preparation device for an erosion-resistant platinum film heat flux sensor according to claim 4, characterized in that, the medium discharge hole (52) includes a protective gas discharge hole and a raw material discharge hole, the raw material discharge hole is located above the protective gas discharge hole, and the raw material discharge hole is close to the connection between the thin film deposition cavity (2) and the plasma generation cavity assembly (1). Among them, the raw material discharge hole is used to provide a raw material medium for chemical deposition reaction with the plasma, the protective gas discharge hole is used to provide a protective gas, and the radial injection length of the raw material medium of the raw material discharge hole in the thin film deposition cavity (2) is greater than the radial injection length of the protective gas of the protective gas discharge hole in the thin film deposition cavity (2).

6. A preparation device for an erosion-resistant platinum film heat flux sensor according to claim 3, characterized in that the clamping structure (33) includes a frustum seat (331) installed on the disc seat (32), a placement groove (332) is provided on the waist surface of the frustum seat (331) along the waist surface, and a retaining edge (333) is provided at the bottom of the placement groove (332); a tapered guide head (334) is provided at the top of the frustum seat (331), and the tapered guide head (334) is threadedly connected to the disc seat (32) through a threaded bolt (335) passing through the axis of the frustum seat (331); wherein, the bottom diameter of the tapered guide head (334) is the same as the top diameter of the frustum seat (331).

7. A preparation device for an erosion-resistant platinum film heat flux sensor according to claim 1, characterized in that the protective gas supply system includes an air inlet end installed at the top of the plasma generation cavity assembly (1) and an air outlet end installed at the bottom of the thin film deposition cavity (2), and the air inlet end is used to provide nitrogen and a protective gas.

8. A preparation device for an erosion-resistant platinum film heat flux sensor according to claim 2, characterized in that the plasma generation cavity assembly (1) includes: a quartz tube body (101), sealingly connected to the thin film deposition cavity (2); a helical wave generator (102), coupled into the quartz tube body (101) for generating helical waves; a Helmholtz coil (103), used to construct a propagation magnetic field for the helical waves generated by the helical wave generator (102).

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