JP6057932B2 - Plasma antenna discharge tube and plasma antenna apparatus - Google Patents

Description

  The present invention relates to a plasma antenna discharge tube and a plasma antenna device, and more particularly to a plasma antenna discharge tube that operates as a conductive antenna by supplying high-frequency power, and a plasma antenna device using the discharge tube. Is.

  In general, in an antenna used in the defense field, it is desired to realize a low scattering cross section, particularly when the antenna is not used. That is, when a single antenna is not used as an antenna, it is required that the single antenna does not scatter electromagnetic waves radiated from another antenna.

  In addition, in a case where a plurality of antennas arranged so as to be close to each other in order to support a plurality of frequencies are used by switching, it is required to suppress mutual interference between the antennas. That is, it is required that an unused antenna does not scatter electromagnetic waves radiated from the used antenna.

  Conventionally, there is a plasma antenna device as an antenna that can be made electrically transparent when the antenna is not used. In the plasma antenna device, for example, a dielectric tube in which an ionizing gas is sealed inside and a pair of electrode terminals are installed at both ends is used. By supplying power for generating plasma from the power source for plasma excitation to the electrode terminal via a pair of wires connected to each electrode terminal, the ionizing gas is brought into a plasma state. Since the ionizing gas in the plasma state has conductivity, the dielectric tube operates as an antenna by supplying high-frequency power.

  There exists patent document 1 as an example of the patent document which disclosed the discharge tube (dielectric tube) and plasma antenna apparatus which are applied to such a plasma antenna apparatus. The plasma antenna device includes a discharge tube that has a pair of electrode terminals at both ends and is bent so that both ends are close to each other. High-frequency power from a high-frequency power source is supplied to at least one of these.

JP 2010-148025 A (4 pages 48 to 5 lines, FIG. 1)

  In the plasma antenna device, in addition to reducing the scattering cross section, it is required to efficiently feed and radiate high frequency power to the discharge tube, that is, to improve the antenna gain.

  The present invention has been made as part of such development, and one object is to provide a discharge tube for a plasma antenna in which the antenna gain can be improved, and another object is to provide such a plasma. It is an object to provide a plasma antenna device to which an antenna discharge tube is applied.

A discharge tube for a plasma antenna according to the present invention includes a dielectric tube, an ionizing gas, a first electrode terminal, and a second electrode terminal. The dielectric tube has one end and the other end, and is bent so that the one end and the other end are adjacent to each other with a gap therebetween. The ionizing gas is enclosed in a dielectric tube. The first electrode terminal is disposed on each of one end and the other end of the dielectric tube. The second electrode terminal is disposed outside the dielectric tube so as to face each of the first electrode terminals, and is held at the ground potential of the high frequency power. The first electrode terminal has a discharge electrode disposed in one end portion and the other end portion of the dielectric tube, one end connected to the discharge electrode, and the other end led out of the dielectric tube. The second electrode terminal is disposed so as to cover one end portion and the other end portion of the dielectric tube in which the discharge electrodes are respectively disposed.
Another discharge tube for a plasma antenna according to the present invention includes a dielectric tube, an ionizing gas, a first electrode terminal, and a second electrode terminal. The dielectric tube has one end and the other end, and is bent so that the one end and the other end are adjacent to each other with a gap therebetween. The ionizing gas is enclosed in a dielectric tube. The first electrode terminal is disposed on each of one end and the other end of the dielectric tube. The second electrode terminal is disposed outside the dielectric tube so as to face each of the first electrode terminals, and is held at the ground potential of the high frequency power. The second electrode terminal is disposed so as to integrally surround one end and the other end of the dielectric tube in which the first electrode terminal is disposed.
Still another discharge tube for a plasma antenna according to the present invention includes a dielectric tube, an ionizing gas, a first electrode terminal, and a second electrode terminal. The dielectric tube has one end and the other end, and is bent so that the one end and the other end are adjacent to each other with a gap therebetween. The ionizing gas is enclosed in a dielectric tube. The first electrode terminal is disposed on each of one end and the other end of the dielectric tube. The second electrode terminal is disposed outside the dielectric tube so as to face each of the first electrode terminals, and is held at the ground potential of the high frequency power. The second electrode terminal is disposed so as to individually surround one end and the other end of the dielectric tube in which the first electrode terminal is disposed.

A plasma antenna device according to the present invention is a plasma antenna device having the above-described plasma antenna discharge tube , another plasma antenna discharge tube, or still another plasma antenna discharge tube, comprising: a plasma excitation power source; a high frequency power source; A conductive member and a high frequency power coupling portion are provided. The power source for plasma excitation turns the ionizing gas sealed in the dielectric tube into a plasma state. The high frequency power supply supplies high frequency power to the ionizing gas. The conductive member electrically connects the plasma excitation power source and the first electrode terminal. The high frequency power coupling unit couples the high frequency power supplied from the high frequency power source to the conductive member.

According to the plasma antenna discharge tube , the other plasma antenna discharge tube or the further other plasma antenna discharge tube according to the present invention, the antenna gain can be improved by arranging the second electrode terminal. it can.

  According to the plasma antenna device of the present invention, the antenna gain can be improved by arranging the second electrode terminal in the plasma antenna discharge tube.

It is a side view including a partial cross section showing a discharge tube for a plasma antenna according to Embodiment 1 of the present invention. FIG. 2 is a cross-sectional view taken along a cross-sectional line II-II shown in FIG. 1 in the same embodiment. In the same embodiment, it is a side view including a partial cross section showing a state in which the plasma antenna device is used. FIG. 4 is a cross-sectional view taken along a cross-sectional line IV-IV shown in FIG. 3 in the same embodiment. It is a partial side view including a partial cross section showing a discharge tube for a plasma antenna according to a comparative example. It is a partial side view including a partial cross section which shows the state in which the plasma antenna apparatus which concerns on a comparative example is used. In the embodiment, it is a partial side view including a partial cross section schematically showing a state in which high-frequency power propagates through a plasma antenna discharge tube. FIG. 5 is a partial side view including a partial cross section showing a first example of a variation of the second electrode terminal in the plasma antenna discharge tube in the embodiment. FIG. 6 is a partial side view including a partial cross section showing a second example of a variation of the second electrode terminal in the plasma antenna discharge tube in the embodiment. FIG. 11 is a cross-sectional view taken along a cross-sectional line corresponding to the cross-sectional line II-II shown in FIG. 1, showing a third example of variations of the second electrode terminal in the plasma antenna discharge tube in the embodiment. FIG. 10 is a side view including a partial cross section showing a fourth example of a variation of the second electrode terminal in the plasma antenna discharge tube in the embodiment. FIG. 12 is a cross sectional view taken along a cross sectional line XII-XII shown in FIG. 11 in the same embodiment. It is a side view including a partial cross section which shows the discharge tube for plasma antennas concerning Embodiment 2 of this invention. FIG. 14 is a cross sectional view taken along a cross sectional line XIV-XIV shown in FIG. 13 in the same embodiment. In the same embodiment, it is a side view including a partial cross section showing a state in which the plasma antenna device is used. FIG. 16 is a cross-sectional view taken along a cross-sectional line XVI-XVI shown in FIG. 15 in the same embodiment. It is a figure which shows the simulation for evaluating the propagation of the high frequency electric power in the discharge tube for plasma antennas concerning a comparative example, (a) is a figure for demonstrating a simulation model, (b) is a figure which shows a simulation result It is. In the same embodiment, it is a figure which shows the simulation for evaluating the propagation of the high frequency electric power in the discharge tube for plasma antennas, (a) is a figure for demonstrating a simulation model, (b) is a simulation result. FIG. It is a side view including a partial cross section which shows the discharge tube for plasma antennas concerning Embodiment 3 of this invention. FIG. 20 is a cross-sectional view taken along a cross-sectional line XX-XX shown in FIG. 19 in the same embodiment. In the same embodiment, it is a side view including a partial cross section showing a state in which the plasma antenna device is used. FIG. 22 is a cross-sectional view taken along a cross-sectional line XXII-XXII shown in FIG. 21 in the same embodiment. In the embodiment, it is a partial side view including a partial cross section schematically showing a state in which high-frequency power propagates through a plasma antenna discharge tube. FIG. 6 is a side view including a partial cross section showing a first modification of the plasma antenna discharge tube in the embodiment. In the embodiment, it is a side view including a partial cross section showing a second modification of the discharge tube for a plasma antenna. It is a perspective view which shows the plasma antenna apparatus which applied the discharge tube for plasma antennas based on Embodiment 4 of this invention. In the embodiment, it is a partial side view including a partial cross section showing a state in which the plasma antenna device is used.

Embodiment 1
Here, a first example of a plasma antenna discharge tube will be described.

  FIG. 1 and FIG. 2 show the plasma antenna discharge tube 1 in an unused state, and FIGS. 3 and 4 show the plasma antenna discharge tube 1 in a used state. First, the broken line shown inside the plasma antenna discharge tube 1 is the axis of the plasma antenna discharge tube 1 or the dielectric tube 2, and the direction along this direction is the plasma antenna discharge tube 1 or dielectric. The direction of the axis of the tube 2 is assumed. Further, the direction perpendicular to the axis (FIGS. 2 and 4) and the direction perpendicular to the plane (FIGS. 1 and 3) are perpendicular to the axis of the plasma antenna discharge tube 1 or the dielectric tube 2, respectively. The direction.

  As shown in FIGS. 1 and 2, the plasma antenna discharge tube 1 includes a dielectric tube 2 in which an ionizing gas 3 a is sealed, a pair of first electrode terminals 4 a and 4 b, and a second electrode terminal 7. And. The dielectric tube 2 is bent so that one end and the other end are adjacent to each other with a gap therebetween. Of the pair of first electrode terminals 4 a and 4 b, the first electrode terminal 4 a is disposed at one end of the dielectric tube 2, and the first electrode terminal 4 b is disposed at the other end of the dielectric tube 2. Has been. The second electrode terminal 7 is disposed outside the dielectric tube 2 so as to face the pair of first electrode terminals 4a and 4b.

  The configuration of each part will be described in detail. In the plasma antenna discharge tube 1, a discharge space is formed by a dielectric tube 2 made of an electrically insulating material. One end and the other end of the dielectric tube 2 are bent so as to be close to each other, and an ionizing gas 3a is sealed in the inside thereof. As a member (material) of the dielectric tube 2, for example, ceramics such as quartz, borosilicate glass and alumina, plastics such as acrylic resin and polycarbonate resin, composite materials such as glass fiber reinforced plastic, or a combination thereof, etc. A material having electrical insulation is used.

  In order to realize a low scattering cross section (low reflection cross section) when the antenna is not used, a glass fiber reinforced plastic whose relative dielectric constant is close to the vacuum relative dielectric constant (= 1). Is preferably used. Further, a protective film (not shown) may be applied to the inner wall of the dielectric tube 2 in order to suppress deterioration of the dielectric tube 2 by ultraviolet rays emitted from the ionizing gas in the plasma state.

  As the ionizing gas 3, an inert gas containing a rare gas as a main component is enclosed. The rare gas may contain at least one kind of rare gas among helium (He), neon (Ne), argon (Ar), xenon (Xe), and krypton (Kr). Further, in order to improve discharge efficiency, mercury (Hg) may be enclosed together with a rare gas. The pressure of the ionizing gas 3 may be a pressure range that can maintain a stable glow-like discharge, and the pressure of the ionizing gas 3 can be set to 10 Pa to 15 kPa. In order to use as a plasma antenna device, the range of 10 Pa to 1 kPa is preferable in order to suppress the loss of high frequency power in the ionized gas 3 b in the plasma state shown in FIGS. 3 and 4.

  A pair of first electrode terminals 4 a and 4 b are installed at one end and the other end of the dielectric tube 2. The first electrode terminals 4a and 4b are composed of discharge electrodes 5a and 5b and lead wires 6a and 6b. The discharge electrodes 5 a and 5 b are installed inside the dielectric tube 2. One end of each of the lead wires 6 a and 6 b is connected to the bottom of the discharge electrodes 5 a and 5 b, and the other end is led out of the dielectric tube 2.

  As a member (material) of the discharge electrodes 5a and 5b, for example, a material such as nickel (Ni), molybdenum (Mo), tungsten (W) or the like is used. As the shape of the discharge electrodes 5a and 5b, a shape such as a column, a cylinder, a bottomed opening (cup), a spiral, a coil, or the like produced by a known method such as plate bending, injection molding, member welding or caulking is used. be able to.

  Similarly to the illumination discharge tube, in order to increase the efficiency and life of the discharge tube, a structure in which the surface area of the entire discharge electrode is increased is preferable. Moreover, the discharge efficiency can be improved by applying an electron-emitting substance (not shown) to the surfaces of the discharge electrodes 5a and 5b.

  Further, for example, in the case of a discharge electrode having a shape of a cylinder or a bottomed opening (cup), the space inside the cylinder is set to a space of about 1 to 5 mm, or in the case of a discharge electrode made of a spiral or a coil. Then, by setting the interval between adjacent windings to about 1 to 5 mm, the hollow cathode effect can be used, and electrons can be generated efficiently.

  The lead wires 6 a and 6 b are electrically connected to predetermined wiring (not shown) outside the dielectric tube 2. Conductive material having a thermal expansion coefficient close to the value of the thermal expansion coefficient of the material constituting the dielectric tube 2 as a member (material) of the lead wires 6a and 6b in order to ensure the airtightness of the end of the dielectric tube 2 It is desirable to be made of the material. For example, when the dielectric tube 2 is made of hard glass, molybdenum (Mo), tungsten (W), or the like can be used. When the dielectric tube 2 is made of a composite material such as glass fiber reinforced plastic, a composite material having a thermal expansion coefficient close to the value of the thermal expansion coefficient of the lead wires 6a and 6b can be selected.

  The second electrode terminal 7 is formed in a flat plate shape. The second electrode terminal 7 is arranged outside the dielectric tube 2 so as to be substantially parallel to the dielectric tube 2 and the first electrode terminal 4 in a range facing the discharge electrodes 5a and 5b and the lead wires 6a and 6b. Is installed. The second electrode terminal 7 is held at a ground potential of high-frequency power by a predetermined wiring (not shown). The member (material) of the second electrode terminal 7 may be conductive, and materials such as copper (Cu) and aluminum (Al) can be applied. The plasma antenna discharge tube 1 according to the first example is configured as described above.

  Next, a state in which the above-described plasma antenna discharge tube 1 is used (a state in which the plasma antenna discharge tube 1 operates) will be described. A predetermined power is supplied to the pair of first electrode terminals 4a and 4b by turning on a plasma excitation power source (not shown). As a result, as shown in FIGS. 3 and 4, the ionizing gas 3a sealed in the dielectric tube 2 is turned into plasma, and the ionizing gas 3b in a plasma state is generated. The ionizing gas 3b in the plasma state acts as a conductor for high frequencies.

  In the plasma antenna discharge tube 1 described above, the antenna gain can be improved by providing the second electrode terminal 7. This will be described in relation to a plasma antenna discharge tube according to a comparative example.

  First, a discharge tube for a plasma antenna according to a comparative example is shown in FIG. Here, due to the symmetry of the dielectric tube 2, one end portion of the dielectric tube 2 and its vicinity are shown. As shown in FIG. 5, the plasma antenna discharge tube according to the comparative example is similar to the plasma antenna discharge tube according to the first example (FIG. 1) except that the second electrode terminal is not disposed. The dielectric tube 2 is provided, and the dielectric tube 2 is filled with an ionizing gas 3 a, and the first electrode terminal 4 is disposed at the end of the dielectric tube 2.

  In the first electrode terminal 4, a coaxial cable is used as the wiring 8. In the coaxial cable, an insulator 10 is provided so as to surround the center conductor 11, and an external conductor 9 is attached so as to cover the insulator 10.

  By turning on a plasma excitation power source (not shown), predetermined power is supplied to the first electrode terminal 4, and plasma ionizing gas 3 b is generated in the dielectric tube 2. This is shown in FIG. FIG. 6 schematically shows a state in which high-frequency power propagates across the connection portion between the first electrode terminal 4 and the wiring 8 together with the ionized gas 3b that has been converted to plasma.

  In the plasma antenna discharge tube according to the comparative example, the second electrode terminal is not provided. In this case, high-frequency power is propagated by the electric field 12 a (transverse magnetic mode) along the axis of the dielectric tube 2 inside the dielectric tube 2. On the other hand, in the wiring 8, high-frequency power is propagated by an electric field 12b (transverse electromagnetic mode) perpendicular to the axis of the central conductor 11.

  For this reason, in the connection part of the 1st electrode terminal 4 and the wiring 8, the direction of the electric field 12a and the electric field 12b will differ 90 degree | times, and the electric field 12a and the electric field 12b cannot couple | bond together, and 1st There is a problem that high-frequency power is reflected between the electrode terminal 4 and the wiring 8. That is, there is a problem that the antenna gain decreases when the first electrode terminal 4 is in a position where it operates as a high-frequency power feeding line.

  In contrast to the comparative example, in the plasma antenna discharge tube 1 according to the first example, the second electrode terminal held at the ground potential so as to face the first electrode terminal 4 outside the dielectric tube 2. 7 is arranged. Since the second electrode terminal 7 is arranged, as shown in FIG. 7, in the state where the plasma antenna discharge tube 1 is used, the ionized gas 4b in the plasma state is formed inside the dielectric tube 2. An electric field 12 perpendicular to the axis of the dielectric tube 2 is maintained between the first electrode terminal 7 and the second electrode terminal 7.

  Thereby, also in the dielectric tube 2, the high frequency electric power is propagated by the electric field 12 (transverse electromagnetic mode). For this reason, the propagation mode of the high frequency power becomes the same propagation mode between the first electrode terminal 4 and the wiring 8, and the electric field 12 is efficiently coupled at the connection portion between the first electrode terminal 4 and the wiring 8. be able to. As a result, it is possible to suppress the reflection of high-frequency power at the connection portion between the first electrode terminal 4 and the wiring 8, and the antenna gain can be improved.

  As the frequency band of the high frequency power, a frequency band in which the way of propagation of power behaves like a radio wave can be used. Specifically, a frequency of a medium wave (300-3000 kHz) or more used in AM broadcasting or the like. The above-described action can be obtained for high-frequency power. However, the operation described above can be obtained in a limited manner by applying the plasma antenna discharge tube 1 having the second electrode terminal even in the frequency band below that.

  The dimension of the dielectric tube 2 is determined from the frequency of the high frequency power. For example, when the dielectric tube 2 is used as a monopole antenna, the length in the axial direction of the dielectric tube 2 is set to a half of the wavelength of the high frequency power. The antenna gain can be improved by setting it to be an odd multiple of.

  The second electrode terminal 7 only needs to be sufficiently conductive with respect to the high-frequency power. For example, when the second electrode terminal 7 is made of copper (Cu), the second electrode terminal 7 The thickness may be set to be thicker than the thickness corresponding to the skin depth (about 100 μm when the frequency of the high-frequency power is 1 MHz).

  The distance (interval A) between the second electrode terminal 7 and the first electrode terminal 4 is determined by the wavelength of the high frequency power because the second electrode terminal 7 and the first electrode terminal 4 are electrically coupled. Is also set short. In addition, the interval (interval B) between the second electrode terminal 7 and the plasma state ionizable gas 3b is high because the second electrode terminal 7 and the plasma state ionizable gas 3b are electrically coupled. It is set shorter than the wavelength of power. When the distance A and the distance B are not more than three times the radius of the ionizing gas 3b in the plasma state, the electrical coupling between the second electrode terminal 7, the plasma state, and the ionizing gas 3b is strengthened. Is particularly preferable.

  Further, as shown in FIG. 8 or FIG. 9, the interval A and the interval B may be changed in the axial direction of the dielectric tube 2. In particular, when the ground electrode of the wiring 8 and the second electrode terminal 7 are connected, the distance from the axis of the end on the dielectric tube 2 side of the ground electrode (external conductor) of the wiring 8 and the second electrode terminal 7, the ground electrode of the wiring 8 and the second electrode terminal 7 can be connected without any step, and the loss of high-frequency power at the connecting portion can be suppressed. can do.

  The second electrode terminal 7 desirably faces at least the entire discharge electrode 5 and the lead wire 6 in the direction of the axis of the dielectric tube 2 in order to keep the high-frequency power propagation mode uniform. Even when the second electrode terminal 7 is partially opposed to the discharge electrode 5 or the lead wire 6, the above-described effect can be obtained, but in the range where the second electrode terminal 7 is not located, the high frequency Since the power propagation mode is disturbed, the above-described action is limited. Also. In addition to the first electrode terminal 4, the second electrode terminal 7 can be extended to a portion of the dielectric tube 2 that is not used as a radiator of the plasma antenna. By extending the second electrode terminal 7, it is possible to suppress the loss of high-frequency power between the plasma antenna and the radiator.

  In the plasma antenna discharge tube 1 described with reference to FIG. 1 and the like, the second electrode terminal is described as an example of a continuous plate-like second electrode terminal 7. The second electrode terminal may be a plurality of divided second electrode terminals as long as the second electrode terminal surface is maintained at the ground potential of the high frequency power. It may be a second electrode terminal in which an opening is formed in the electrode terminal surface. However, since the gap acts as a capacitor with respect to the high-frequency power, the second electrode terminal 7 preferably has a continuous structure without an opening.

  Furthermore, as shown in FIG. 10, the second electrode terminal may be a second electrode terminal 7 having a curved shape along the shape of the dielectric tube 2 (the shape of the discharge space). By making the shape of the second electrode terminal 7 along the discharge space, the electric field 12 formed between the ionizing gas 3b in the plasma state and the second electrode terminal 7 is changed to the cross section of the dielectric tube 2. The high-frequency power can be more effectively suppressed from being reflected, and the antenna gain can be further improved.

  Further, as shown in FIG. 11 and FIG. 12, the second electrode terminal is a second electrode disposed so as to surround two ends of the dielectric tube 2 where the first electrode terminal 4 is disposed. The electrode terminal 7 may be sufficient. That is, it may be the second electrode terminal 7 that covers the entire region facing the first electrode terminal 4.

  By such a second electrode terminal 7, all electric field components of the high-frequency power propagating inside the dielectric tube 2 can be combined with the second electrode terminal 7 without leakage, and the reflection of the high-frequency power is ensured. Can be suppressed. In addition, since the first electrode terminal 4 is electrically shielded from the surroundings by the second electrode terminal 7, there is an effect of reducing the influence of noise from the surroundings on the operation of the plasma antenna.

  In each of the plasma antenna discharge tubes described above, the structure around the dielectric tube 2 and the second electrode terminal 7 is not shown, but the periphery of the dielectric tube 2 and the second electrode terminal 7 is electrically insulated. It only needs to be surrounded by a sex material.

Examples of the electrically insulating material include a high vacuum of 0.1 mPa or less or a rare gas of 1 atm or more, an inert gas such as air or SF ₆ , ceramics such as quartz, borosilicate glass and alumina, acrylic resin, and polycarbonate resin. A composite material such as plastic, glass fiber reinforced plastic, or a combination thereof is used.

  In order to achieve a low reflection cross section when the plasma antenna is not used, use an inert gas or glass fiber reinforced plastic whose dielectric constant is close to the vacuum dielectric constant (= 1). It is preferable to do. Further, by using a plastic or a composite material, it is possible to improve resistance to external impact.

Embodiment 2
Here, a second example of the plasma antenna discharge tube will be described.

  As shown in FIGS. 13 and 14, in the plasma antenna discharge tube 1, a pair of second electrode terminals 7 a and 7 b are arranged. The 2nd electrode terminal 7a is arrange | positioned on the outer side of the one end part in the dielectric tube 2 so that the 1st electrode terminal 4a may be opposed. The second electrode terminal 7a is disposed so as to be coaxial with the dielectric tube 2 and the first electrode terminal 4a.

  The second electrode terminal 7b is disposed outside the other end of the dielectric tube 2 so as to face the first electrode terminal 4b. The second electrode terminal 7b is disposed so as to be coaxial with the dielectric tube 2 and the first electrode terminal 4b. The pair of second electrode terminals 7a and 7b is held at the ground potential of the high frequency power.

  In addition, since it is the same as that of the structure of the discharge tube 1 for plasma antennas shown in FIG. 1 and FIG. And

  Next, a state where the above-described plasma antenna discharge tube 1 is used will be described. A predetermined power is supplied to the pair of first electrode terminals 4a and 4b by turning on a plasma excitation power source (not shown). As a result, as shown in FIGS. 15 and 16, the ionizing gas 3a sealed in the dielectric tube 2 is turned into plasma, and the ionizing gas 3b in a plasma state is generated. The ionizing gas 3b in the plasma state acts as a conductor for high frequencies.

  In the plasma antenna discharge tube 1 described above, the first electrode terminal 4a is electrically shielded by the second electrode terminal 7a, and the first electrode terminal 4b is electrically shielded by the second electrode terminal 7b. As a result, the first electrode terminal 4a and the first electrode terminal 4b are electrically shielded from each other.

  Thereby, the propagation mode of the high-frequency power propagating through the dielectric tube 2 propagates through the inside of the wiring 8 without being affected by interference between the first electrode terminal 4a and the first electrode terminal 4b. The same propagation mode as the high-frequency power propagation mode is maintained. As a result, it is possible to effectively suppress the reflection of high-frequency power at the connection portion between the first electrode terminal 4 and the wiring 8.

  The inventors have evaluated the manner in which high-frequency power propagates in the plasma antenna discharge tube described above by simulation based on the finite difference time domain method.

  First, a simulation model of a discharge tube for a plasma antenna according to a comparative example that does not have the second electrode terminal is shown in FIG. 17A, and the evaluation result is shown in FIG. FIG. 18A shows a simulation model of the plasma antenna discharge tube 1 described above, and FIG. 18B shows the evaluation result.

  As shown in FIGS. 17 (a) and 18 (a), as a simulation model, the vertical axis is the axial direction of the dielectric tube, and the horizontal axis is the direction (radial direction) orthogonal to the axis of the dielectric tube, A connection portion between the first electrode terminal 4 and the wiring 8 (coaxial cable) and a region (cross section) in the vicinity thereof were analyzed. In addition, in order to make the analysis result easy to see, the dimension in the horizontal axis direction is enlarged with respect to the dimension in the vertical axis direction.

The frequency of the high frequency power fed to the central conductor 11 of the coaxial cable as the wiring 8 electrically connected to the first electrode terminal 4 was set to 500 MHz. As plasma parameters, the electron density was 1 × 10 ¹² cm ⁻³ and the collision frequency was 1 GHz. Air 14 was provided around the plasma antenna discharge tube 1 and the wiring 8. In order to simplify the calculation in the simulation, the shapes of the dielectric tube 2 and the ionizing gas 3b in the plasma state are treated as a rectangular parallelepiped. However, these assumptions do not greatly affect the simulation result.

  The simulation result will be described. As shown in FIG. 17B, in the plasma antenna discharge tube according to the comparative example in which the second electrode terminal is not installed, the electric field is coupled at the connection portion between the first electrode terminal 4 and the wiring 8. The high frequency power is reflected between the first electrode terminal 4 and the wiring 8, and the strength of the electric field Er in the radial direction (left and right direction on the paper surface) of the dielectric tube 2 is weakened as shown by the circle CC. You can see that

  In FIG. 17B, it can be seen that an electric field exists in the area of the air 14. This is because the high-frequency power reflected by the first electrode terminal 4 passes through the dielectric tube 2. This is because it has propagated to the area of air 14.

  On the other hand, as shown in FIG. 18B, in the plasma antenna discharge tube described above, the electric field is coupled at the connection portion between the first electrode terminal 4 and the wiring 8 by installing the second electrode terminal 7. It can be seen that the reflection of the high frequency power between the first electrode terminal 4 and the wiring 8 is suppressed, and the strength of the electric field Er in the radial direction is not weakened as shown by the circle CE. . That is, it can be seen that the plasma antenna discharge tube described above can efficiently propagate high-frequency power fed to the wiring to the plasma antenna discharge tube.

  In the plasma antenna discharge tube described above, since the first electrode terminal 4 is electrically shielded from the surroundings by the second electrode terminal 7, there is an effect of reducing the influence of noise from the surroundings. As shown in FIG. 18B, this is because the high-frequency power propagating through the coaxial cable (wiring 8) and the dielectric tube 2 is reduced between the coaxial cable (wiring 8) and the second electrode terminal 7. This is consistent with not leaking outside.

Embodiment 3
Here, a third example of a plasma antenna discharge tube will be described.

  As shown in FIG. 19 and FIG. 20, in the plasma antenna discharge tube 1, dielectric cylinders 15 a and 15 b and third electrode terminals 16 a and 16 b are arranged inside the dielectric tube 2. The dielectric cylinder 15a is disposed inside one end of the dielectric tube 2 so as to surround the first electrode terminal 4a and be coaxial with the first electrode terminal 4a. The third electrode terminal 16a is disposed between the dielectric cylinder 15a and the first electrode terminal 4a so as to face the first electrode terminal 4a.

  The dielectric cylinder 15b surrounds the first electrode terminal 4b and is arranged inside the other end of the dielectric tube 2 so as to be coaxial with the first electrode terminal 4b. The third electrode terminal 16b is disposed between the dielectric cylinder 15b and the first electrode terminal 4b so as to face the first electrode terminal 4b.

  In addition, since it is the same as that of the structure of the discharge tube 1 for plasma antennas shown in FIG. 1 and FIG. And

  The dielectric cylinders 15a and 15b and the third electrode terminals 16a and 16b will be specifically described. As the members (materials) of the dielectric cylinders 15a and 15b, the same material as that of the dielectric tube 2 can be used. For example, ceramics such as quartz, borosilicate glass and alumina, plastics such as acrylic resin and polycarbonate resin, A material having an electrical insulation property such as a composite material such as glass fiber reinforced plastic or a combination thereof is used. By using the same material as that of the dielectric tube 2 as the material of the dielectric cylinders 15a and 15b, the dielectric tube can be easily manufactured by a known method such as bonding or integral molding.

  The members (materials) of the dielectric cylinders 15a and 15b and the members (materials) of the dielectric tube 2 may be different. Since the dielectric cylinders 15a and 15b are arranged close to the discharge electrodes 5a and 5b, the dielectric cylinders 15a and 15b are heated by the discharge electrodes 5a and 5b during the discharge. Therefore, the dielectric cylinders 15a and 15b are preferably made of a heat resistant material such as quartz or borosilicate glass. By applying a material having heat resistance as the material of the dielectric cylinders 15a and 15b, heat transmitted to the dielectric tube 2 can be reduced, and the member of the dielectric tube 2 has heat resistance. No material can be applied.

  As the member (material) of the third electrode terminals 16a and 16b, the same material as the material of the discharge electrodes 5a and 5b can be used. For example, nickel (Ni), molybdenum (Mo), tungsten (W), etc. Materials can be used. The third electrode terminals 16a and 16b can be produced as cylindrical electrodes by a known method such as bending of a plate material, injection molding, welding or caulking of a member. Further, the third electrode terminals 16a and 16b are directly formed on the surfaces (regions) of the dielectric cylinders 15a and 15b facing the first electrode terminals 4a and 4b by a method such as vapor deposition, sputtering, and plating. May be.

  If a seam generated by machining or the like exists on the surfaces of the third electrode terminals 16a and 16b, the high-frequency power propagation mode may be disturbed. For this reason, it is preferable to use what was directly formed on the dielectric cylinders 15a and 15b by methods, such as vapor deposition, sputtering, and plating, as the 3rd electrode terminals 16a and 16b.

  Since the third electrode terminals 16a and 16b are arranged so as to face the discharge electrodes 5a and 5b, the surface of the third electrode terminals 16a and 16b or the discharge electrodes 5a and 5b can be used during the discharge. Members sputtered or evaporated from the surface may adhere to the surfaces of the discharge electrodes 5a and 5b or the surfaces of the third electrode terminals 16a and 16b. By using the same material as the material of the discharge electrodes 5a and 5b as the member (material) of the third electrode terminals 16a and 16b, the third electrode terminals 16a and 16b or the discharge electrode 5a can be used even if the discharge is performed for a long time. The surface composition of 5b can be kept constant.

  Next, a state where the above-described plasma antenna discharge tube 1 is used will be described. A predetermined power is supplied to the pair of first electrode terminals 4a and 4b by turning on a plasma excitation power source (not shown). Thereby, as shown in FIGS. 21 and 22, the ionizing gas 3a enclosed in the dielectric tube 2 is turned into plasma, and the ionizing gas 3b in a plasma state is generated. The ionizing gas 3b in the plasma state acts as a conductor for high frequencies.

  Next, the operation of the dielectric cylinders 15a and 15b and the third electrode terminals 16a and 16b will be described. FIG. 23 is a diagram schematically illustrating a state in which high-frequency power is propagated from the wiring 8 to the dielectric tube 2 with the connecting portion between the first electrode terminal 4 and the wiring 8 in the plasma antenna discharge tube 1 described above. It is. In FIG. 23, due to the symmetry of the dielectric tube 2, one end portion of the dielectric tube 2 and the vicinity thereof are shown. A coaxial cable is shown as the wiring 8.

  In the plasma antenna discharge tube 1 described above, since the ionizing gas 3b in the plasma state has conductivity, the third electrode terminal 16 and the first electrode terminal 4 are maintained at approximately the same potential. On the other hand, since there is no electron supply source (metal or metal oxide) necessary for maintaining plasma between the dielectric cylinder 15 and the inner wall of the dielectric tube 2, the ionizing gas 3 is turned into plasma. In this space, only the non-plasma ionizable gas 3a exists in this space. Therefore, the electric field 12 is stably generated between the second electrode terminal 7 and the third electrode terminal 16 regardless of the characteristics of the ionized gas 3b in the plasma state existing around the first electrode terminal 4. Can be formed. Thereby, reflection of the high frequency electric power in the connection part of the 1st electrode terminal 4 and the wiring 8 can be suppressed stably.

  The third electrode terminal 16 and the first electrode terminal 4 are formed by physical means such as a conductive film in order to suppress high-frequency power from being input into the dielectric tube 2 when the antenna is not used. It is preferable that they are not electrically connected. However, even if the third electrode terminal 16 and the first electrode terminal 4 are electrically connected by physical means, the above-described effects are not lost.

  The distance between the third electrode terminal 16 and the first electrode terminal 4 is such that the third electrode terminal 16 and the first electrode terminal 4 are kept at the same electric potential via the ionizing gas 3b in the plasma state. Set short to sag. In particular, if the distance between the third electrode terminal 16 and the first electrode terminal 4 is about 1 to 5 mm, the discharge efficiency can be improved by the hollow cathode effect, which is preferable. On the other hand, in order to avoid the direct contact between the third electrode terminal 16 and the first electrode terminal 4 due to external vibrations or shocks, the distance between the third electrode terminal 16 and the first electrode terminal 4 is determined. Is preferably set to at least 1 mm or more.

  It is desirable that the third electrode terminal 16 is at least opposed to the entire discharge electrodes 5a and 5b in the direction of the axis of the dielectric tube 2. The third electrode terminal 16 can obtain the above-described operation even when it is partially opposed to the discharge electrodes 5a and 5b. However, in the range where the third electrode terminal 16 does not exist, a high-frequency power propagation mode is obtained. The action is limited.

  Further, by providing the third electrode terminal 16 extending in the direction of the axis of the dielectric tube 2 from both ends of the dielectric tube 2 of the discharge electrode 5, a member sputtered from the surface of the discharge electrode 5 or evaporation It can suppress that the member which adhered has adhered to the inner wall of the dielectric tube 2, and can prevent that the high frequency characteristic of the dielectric tube 2 changes.

  In addition to the dielectric cylinder 16, a dielectric cylinder made of an electrically insulating material may be further disposed between the dielectric cylinder 15 and the dielectric tube 2. By disposing another dielectric cylinder in this space, the ionized gas 3b in the plasma state diffuses into the space between the dielectric cylinder 15 and the dielectric tube 2, and the electric field 12 in the space is disturbed. Can be prevented.

  In addition, as the dielectric tube 15 of the plasma antenna discharge tube described above, a bottomed opening (cup shape) is formed, and the bottom portion is exposed to the outside of the dielectric tube 2 (see FIG. 19) as an example. As shown in FIG. 24, even if the entire dielectric cylinder 15 including the bottom portion is disposed inside the dielectric tube 2, the above-described effects can be obtained. Also, with this arrangement structure, heating of the lead wire 6 due to discharge can be suppressed, and the end portion of the dielectric tube 2 can be prevented from being broken by the thermal expansion of the lead wire.

  Next, as a modification, a plasma antenna discharge tube including a plurality of dielectric cylinders and a plurality of third electrode terminals will be described. As shown in FIG. 25, in addition to the dielectric cylinders 15a and 15b, dielectric cylinders 15c and 15d are arranged inside the dielectric tube 2 of the plasma antenna discharge tube 1, and the third electrode terminals 16a and 16b are arranged. In addition, third electrode terminals 16c and 16d are arranged.

  The dielectric cylinder 15 c is disposed between the dielectric cylinder 15 a and the dielectric tube 2, and the dielectric cylinder 15 d is disposed between the dielectric cylinder 15 b and the dielectric tube 2. The third electrode terminal 16c is disposed between the dielectric cylinder 15c and the dielectric cylinder 15a, and the third electrode terminal 16d is disposed between the dielectric cylinder 15d and the dielectric cylinder 15b.

  In the plasma antenna discharge tube 1 according to the modification, even if the shape and high frequency characteristics of the third electrode terminals 16a and 16b are changed by the electrode material sputtered from the first electrode terminal 4a or the evaporated electrode material, The electric field 12 can be stably formed between the second electrode terminals 7a and 7b and the third electrode terminals 16c and 16d, and high-frequency power is generated at the connection between the first electrode terminal 4 and the wiring 8. Can be stably suppressed.

Embodiment 4
Here, an example of a plasma antenna device to which the plasma antenna discharge tube is applied will be described.

  As shown in FIGS. 26 and 27, the plasma antenna device 50 includes a plasma antenna discharge tube 1, a ground conductor 17, a high-frequency power source 18, a plasma excitation power source 19, a high-frequency filter 20, and a high-frequency power coupling unit 21. .

  For example, the plasma antenna discharge tube 1 shown in FIG. 19 is applied as the plasma antenna discharge tube 1. The plasma antenna discharge tube 1 is inserted into an opening provided in the ground conductor 17 and disposed on the ground conductor 17 so that the dielectric tube 2 protrudes from one of the ground conductors 17. The second electrode terminal 7 is in contact with the edge of the opening provided in the ground conductor 17.

  The first electrode terminals 4 a and 4 b are electrically connected to the high frequency filter 20 through a pair of wirings 22. The high frequency power supply 18 is connected to the wiring 22 through the high frequency power coupling unit 21. The high frequency power supply 18 is electrically connected to the ground conductor 17 so that the ground potential of the high frequency power supply 18 is the same as the potential of the ground conductor 17. The plasma excitation power source 19 is electrically connected to the high frequency filter 20 via a pair of wirings 23.

  In addition, a plurality of capacitances (not shown) are arranged between the pair of wirings 22 at intervals shorter than the high-frequency wavelength λ. The capacitances of all the capacitances are set so as to be substantially short-circuited at a high frequency and to be almost open at the frequency of the plasma excitation power source 19.

  Next, the operation principle of the above-described plasma antenna device 50 will be described. First, when the plasma excitation power source 19 is turned on, direct current or low frequency power for exciting the ionizing gas 3 into a plasma state is supplied to the first electrode terminal 4 via the high frequency filter 20. At this time, as shown in FIG. 27, the ionizing gas 3 in the dielectric tube 2 is turned into plasma, and the ionizing gas 3b in a plasma state is generated. By generating the ionized gas 3b in a plasma state, the plasma antenna discharge tube 1 acts as a conductor at a high frequency.

  Note that a frequency band lower than the frequency of the high frequency power can be used as the frequency band of the low frequency power. In particular, a frequency of 100 kHz or less is preferable because the property as a radio wave of low frequency power is lost, and the low frequency power can be suppressed from being radiated from the plasma antenna device together with the high frequency power.

  When the high-frequency power source 18 is ON, high-frequency power for transmission / reception is supplied to the first electrode terminals 4 a and 4 b via the high-frequency power coupling unit 21 and the wiring 22. At this time, since the pair of wirings 22 are connected by a capacitance (not shown) installed between the wirings, the pair of wirings 22 operate as a single line with respect to a high frequency. Further, since the high frequency power propagating through the wiring 22 is blocked by the high frequency filter 20, the high frequency power is not supplied to the wiring 23 and the plasma excitation power source 19.

  Since the high-frequency power supplied to the first electrode terminals 4a and 4b propagates to the ionizing gas 3b in the plasma state without being reflected as described in the first to third embodiments, the plasma antenna discharge The tube is equivalent to a single conductor at high frequency, and operates as a monopole antenna on the ground conductor 17.

  On the other hand, when the plasma excitation power source 19 is OFF, the dielectric tube 2 and the ionizing gas 3a act as a dielectric for high frequencies. In addition, since the first electrode terminals 4a and 4b, the second electrode terminals 7a and 7b, and the third electrode terminals 16a and 16b are hidden behind the ground conductor 17, the front side of the ground conductor 17 is almost free. Acts as a space.

  Thereby, in a state where the plasma antenna device is not used, the scattering cross section can be reduced. Further, in the state where the plasma antenna device is used, it is possible to suppress the reflection of the high frequency power at the connection portion between the first electrode terminals 4a and 4b and the wiring 22, and as a result, the antenna has a high antenna gain. A plasma antenna device can be obtained.

  The above-described plasma antenna device 50 is a monopole antenna having the ground conductor 17, but can be operated as a plasma antenna device without the ground conductor 17.

  In addition, the dielectric tube 2 of the plasma antenna discharge tube 1 described in each embodiment may be bent so that one end and the other end are adjacent to each other with a gap therebetween. The shape may be any structure suitable for operation as a plasma antenna device, such as a loop structure, a helical structure, or a folded dipole structure.

  The distance between one end and the other end of the dielectric tube is determined from the operating principle of the plasma antenna device and the frequency of the high frequency power. In the case where high frequency power with the same output is fed to each of the pair of first electrode terminals 4a and 4b, the interval needs to be set to be shorter than the wavelength of the high frequency power. What is necessary is just to set to an interval shorter than 1/10.

  On the other hand, when high-frequency power having different outputs is supplied to the pair of first electrode terminals 4a and 4b, or only one of the pair of first electrode terminals 4a and 4b is supplied with high-frequency power. When power is supplied, the interval needs to be set to an interval determined from the principle of operation of the plasma antenna device. For example, in the case of a loop antenna device, the interval is set to about one half of the wavelength of the high frequency power. do it.

  The embodiment disclosed this time is an example, and the present invention is not limited to this. The present invention is defined by the terms of the claims, rather than the scope described above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The present invention is effectively used for a plasma antenna device.

  DESCRIPTION OF SYMBOLS 1 Plasma antenna discharge tube, 2 Dielectric tube, 3a Ionizing gas, 3b Ionizing gas in plasma state 4, 4a, 4b First electrode terminal 5, 5, 5a, 5b Discharge electrode, 6, 6a, 6b Lead Wire, 7 second electrode terminal, 8 wiring, 9 outer conductor, 10 insulator, 11 center conductor, 12, 12a, 12b electric field, 13 magnetic field, 14 air, 15, 15a, 15b, 15c, 15d dielectric cylinder, 16, 16a, 16b, 16c, 16d Third electrode terminal, 17 Ground conductor, 18 High frequency power source, 19 Plasma excitation power source, 20 High frequency filter, 21 High frequency power coupling unit, 22, 23 Wiring.

Claims (11)

A dielectric tube which has one end and the other end, and is bent so that the one end and the other end are adjacent to each other with a gap therebetween;
An ionizing gas sealed in the dielectric tube;
A first electrode terminal disposed on each of the one end and the other end of the dielectric tube;
A second electrode terminal disposed outside the dielectric tube so as to face each of the first electrode terminals, and held at a ground potential of high-frequency power ;
The first electrode terminal is
A discharge electrode disposed in each of the inside of the one end and the inside of the other end of the dielectric tube;
A lead terminal having one end connected to the discharge electrode and the other end led out of the dielectric tube;
Including
The discharge electrode for a plasma antenna, wherein the second electrode terminal is disposed so as to cover the one end portion and the other end portion of the dielectric tube in which the discharge electrodes are respectively disposed .   The plasma antenna according to claim 1, wherein the second electrode terminal is disposed so as to integrally surround the one end portion and the other end portion of the dielectric tube in which the first electrode terminal is disposed. Discharge tube.   2. The plasma antenna according to claim 1, wherein the second electrode terminal is disposed so as to individually surround the one end and the other end of the dielectric tube in which the first electrode terminal is disposed. Discharge tube.   The discharge tube for a plasma antenna according to any one of claims 1 to 3, wherein the second electrode terminal includes a portion formed in a plate shape.   The discharge tube for a plasma antenna according to any one of claims 1 to 3, wherein the second electrode terminal includes a portion formed in a shape along the surface of the dielectric tube. A dielectric cylinder disposed on each of the inside of the one end and the inside of the other end of the dielectric tube so as to surround the first electrode terminal;
6. The device according to claim 1, further comprising a third electrode terminal disposed between the dielectric cylinder and the first electrode terminal so as to face the first electrode terminal. A discharge tube for a plasma antenna as described in 1. The dielectric cylinder is provided with a bottom,
The plasma antenna discharge tube according to claim 6, wherein the bottom is disposed inside the dielectric tube. A dielectric tube which has one end and the other end, and is bent so that the one end and the other end are adjacent to each other with a gap therebetween;
An ionizing gas sealed in the dielectric tube;
A first electrode terminal disposed on each of the one end and the other end of the dielectric tube;
A second electrode terminal disposed outside the dielectric tube so as to face each of the first electrode terminals, and held at a ground potential of high-frequency power;
With
The discharge electrode for a plasma antenna, wherein the second electrode terminal is disposed so as to integrally surround the one end portion and the other end portion of the dielectric tube in which the first electrode terminal is disposed. A dielectric tube which has one end and the other end, and is bent so that the one end and the other end are adjacent to each other with a gap therebetween;
An ionizing gas sealed in the dielectric tube;
A first electrode terminal disposed on each of the one end and the other end of the dielectric tube;
A second electrode terminal disposed outside the dielectric tube so as to face each of the first electrode terminals, and held at a ground potential of high-frequency power;
With
The discharge electrode for a plasma antenna, wherein the second electrode terminal is disposed so as to individually surround the one end and the other end of the dielectric tube in which the first electrode terminal is disposed. A plasma antenna apparatus comprising the discharge tube for a plasma antenna according to any one of claims 1 to 9 ,
A power source for plasma excitation for bringing the ionizing gas sealed in the dielectric tube into a plasma state;
A high frequency power supply for supplying high frequency power to the ionizing gas;
A conductive member that electrically connects the plasma excitation power source and the first electrode terminal;
A plasma antenna device, comprising: a high-frequency power coupling unit configured to couple the high-frequency power supplied from the high-frequency power source to the conductive member. The plasma antenna device according to claim 10 , further comprising: a ground conductor having an opening, the dielectric tube being inserted into the opening, and held at a ground potential of the high-frequency power.

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