Electromagnetic wave modulation device and method and electromagnetic wave generator

Abstract

The invention discloses an electromagnetic wave modulation device and method and an electromagnetic wave generator, relates to the field of plasmas, and is used for intuitively, efficiently and dynamically adjusting the field intensity of electromagnetic waves in a large range. The electromagnetic wave modulation device comprises a plasma column, a plasma excitation source and a plasma regulator, electromagnetic waves vertically enter the plasma column, the electromagnetic waves are focused on the other face of the plasma column, field intensity amplification is achieved, and adjustment of field intensity distribution of the incident electromagnetic waves is achieved by adjusting the plasma frequency and / or the plasma collision frequency. The field intensity and the focusing position are included. According to the invention, the electromagnetic wave field intensity can be efficiently, intuitively and continuously adjusted in a large range, and the method has good flexibility and degree of freedom.

Description

Technical Field

[0001] The present invention relates to the field of plasma, and in particular to an electromagnetic wave modulation device, an electromagnetic wave modulation method, and an electromagnetic wave generator. Background Art

[0002] In scenarios such as radio communication, radio wave measurement, and target detection, antennas are used. As one of the key components in the system, the performance of the antenna determines the performance of the system to a certain extent.

[0003] In recent years, for the improvement of antenna performance, the concept of a plasma antenna has been proposed. A plasma antenna refers to an antenna that uses ionized gas as an electromagnetic energy conduction medium; the plasma antenna can dynamically reconstruct characteristics such as antenna bandwidth, frequency, gain, and directivity by controlling parameters such as the shape and intensity of the plasma. Compared with traditional antennas, the plasma antenna has higher efficiency, lighter weight, smaller volume, shorter size, and wider bandwidth.

[0004] However, current research on plasma antennas still mainly focuses on the gain or impedance of the antenna. For example, the device for enhancing the electromagnetic radiation of a miniaturized omnidirectional antenna by plasma modulation proposed in the Chinese patent document with the publication number CN106025546A proposes a miniaturized omnidirectional antenna structure with adjustable antenna gain. Improving the gain or impedance of the antenna to improve the performance of the antenna, especially for the amplification effect of the electromagnetic wave field strength, has a certain upper limit. After that, even if the antenna gain or impedance is further improved, the improvement effect on the electromagnetic wave field strength will no longer be significant. Moreover, improving the effect of electromagnetic wave emission by improving the antenna gain or impedance is not intuitive and belongs to an indirect improvement measure with poor controllability. Summary of the Invention

[0005] The object of the present invention is to provide an electromagnetic wave modulation device, method, and electromagnetic wave generator to achieve the modulation of the electromagnetic wave field strength by focusing the electromagnetic wave, and to achieve intuitive, efficient, and large-range dynamic adjustment of the electromagnetic wave field strength for all or part of the above-mentioned problems.

[0006] The technical solution adopted by the present invention is as follows:

[0007] An electromagnetic wave modulation device for adjusting the field strength distribution of incident electromagnetic waves; the method includes:

[0008] A plasma column;

[0009] A plasma excitation source for exciting the plasma in the plasma column;

[0010] A plasma regulator for regulating the plasma frequency and / or the plasma collision frequency.

[0011] In use, electromagnetic waves can be perpendicularly incident on the plasma column of the device according to their basic frequency and power. The electromagnetic waves are focused on the other side of the plasma column, thereby enhancing the electromagnetic wave field strength. And by adjusting at least one of the plasma frequency and the plasma collision frequency of the plasma through the plasma regulator, the local transmittance is adjusted to achieve amplification of the electromagnetic wave field strength. In addition, adjustment of the position of the maximum electromagnetic wave field strength can also be achieved. Of course, since the change in field strength is continuous, adjustment of the position of the maximum electromagnetic wave field strength also realizes modulation of the spatial distribution of the electromagnetic waves.

[0012] Further, the plasma excitation source excites the plasma in a discharge manner.

[0013] Further, the plasma regulator adjusts the plasma frequency and / or the plasma collision frequency by adjusting the excitation power of the plasma excitation source.

[0014] Further, the plasma regulator adjusts the plasma frequency within a predetermined first frequency range.

[0015] The present invention also provides an electromagnetic wave modulation method, which includes:

[0016] Vertically incident electromagnetic waves on a plasma column;

[0017] Excite the plasma in the plasma column and adjust the plasma frequency and / or the plasma collision frequency to adjust the field strength distribution of the incident electromagnetic waves.

[0018] Further, the plasma frequency and / or the plasma collision frequency are adjusted by adjusting the excitation power of the plasma.

[0019] Further, the plasma frequency is adjusted within a predetermined first frequency range.

[0020] The present invention also provides an electromagnetic wave generator, which includes:

[0021] An electromagnetic wave source;

[0022] A plasma column; the electromagnetic waves emitted by the electromagnetic wave source are perpendicularly incident on the plasma column;

[0023] A plasma excitation source for exciting the plasma in the plasma column;

[0024] A plasma regulator for regulating the plasma frequency and / or the plasma collision frequency and adjusting the field strength distribution of the incident electromagnetic waves.

[0025] Further, the plasma regulator adjusts the plasma frequency within a predetermined first frequency range.

[0026] Further, the electromagnetic wave generator further includes: a frequency regulator connected to the electromagnetic wave source for adjusting the frequency of the electromagnetic wave emitted by the electromagnetic wave source.

[0027] In summary, due to the adoption of the above technical solutions, the beneficial effects of the present invention are as follows:

[0028] The present invention utilizes plasma to focus electromagnetic waves to achieve amplification of the electromagnetic field strength. Moreover, by adjusting at least one of the plasma frequency and the plasma collision frequency, the adjustment of the electromagnetic field strength and position is realized, so that the field strength and distribution at the near field and the far field change, thereby changing the transmission or reflection state of the electromagnetic wave and realizing the modulation of the electromagnetic wave. By adjusting the plasma frequency or the plasma collision frequency, the present invention has the ability of fast switching, making the modulation of the electromagnetic wave easy to control and reconstruct, and having better flexibility and freedom for the modulation of the electromagnetic wave. Description of the Drawings

[0029] The present invention will be described by way of examples with reference to the accompanying drawings, where:

[0030] Figure 1 is the internal field and near-field distribution diagram when TM-polarized electromagnetic waves are incident on a plasma column.

[0031] Figure 2 is the internal field and near-field distribution diagram when TE-polarized electromagnetic waves are incident on a plasma column.

[0032] Figure 3 is the planar distribution diagram of the internal field and near-field of TM-polarized and TE-polarized electromagnetic waves along the incident direction in a plasma column.

[0033] Figure 4 is the test diagram of the modulation of the TM-polarized electromagnetic wave field strength by the change of the plasma collision frequency.

[0034] Figure 5 is the test diagram of the modulation of the TE-polarized electromagnetic wave field strength by the change of the plasma collision frequency.

[0035] Figure 6 is the test diagram of the modulation of the TM-polarized electromagnetic wave field strength by the change of the plasma frequency.

[0036] Figure 7 is the test diagram of the modulation of the TE-polarized electromagnetic wave field strength by the change of the plasma frequency.

[0037] Figure 8It is a test diagram of the influence of the change in the frequency of the incident electromagnetic wave on the focusing field strength distribution of the plasma column.

[0038] Figure 9 It is the field strength distribution diagram when TM polarized electromagnetic waves are incident on the plasma column. Specific implementation manners

[0039] All features disclosed in this specification, or all steps in the disclosed methods or processes, except for mutually exclusive features and / or steps, can be combined in any manner.

[0040] Any feature disclosed in this specification (including any additional claims, abstract) can be replaced by other equivalent or features with similar purposes unless specifically stated. That is, unless specifically stated, each feature is only an example of a series of equivalent or similar features.

[0041] Aiming at the problems of limited improvement effect and poor controllability in the adjustment process existing in the traditional plasma antenna mainly considering improving the antenna performance from the directions of antenna gain and impedance, the embodiments of the present application propose an electromagnetic wave modulation device, method and electromagnetic wave generator, aiming to intuitively, efficiently and widely perform on the intensity and / or position of the maximum field strength of the incident electromagnetic wave.

[0042] In some embodiments, the electromagnetic wave modulation device includes:

[0043] A plasma column;

[0044] A plasma excitation source for exciting the plasma in the plasma column;

[0045] A plasma regulator for adjusting the plasma frequency and / or the plasma collision frequency.

[0046] Plasma is composed of high-density ionized gas, including charged particles such as electrons and ions, and neutral particles. The plasma volume can be contained in a housing (tube) or suspended in free space. The components that can be used to form plasma in the tube include neon, xenon, argon, krypton, hydrogen, helium, mercury vapor, etc. The tube confines the plasma gas and prevents diffusion. It has been found through research that plasma exhibits dielectric or metal-like properties under different parameter conditions. For example, by adjusting methods such as the excitation source power and the concentration of ionized gas, the dielectric constant of the plasma can be dynamically controlled. The present application utilizes this feature to use plasma as a dynamic regulation facility for electromagnetic waves. By adjusting the dielectric constant of the plasma, the electromagnetic wave field strength and distribution in the near field and far field of the plasma can be changed, thereby changing the transmission or reflection state of the electromagnetic wave.

[0047] In some embodiments, the plasma column is obtained by the following method:

[0048] 1) Design the shape and size of the plasma, select a tube column with the same shape and size, and use equipment such as a vacuum pump to extract the air inside the tube column.

[0049] 2) Fill the tube column with a noble gas, usually argon. Based on the regulation requirements, adjust the argon concentration until the corresponding air pressure is reached.

[0050] 3) Use a plasma excitation source to excite the plasma. Generally, the plasma excitation source uses a discharge method to excite the plasma, and its discharge electrodes are located inside the tube column.

[0051] On this basis, a plasma regulator adjusts the plasma frequency and / or the plasma collision frequency to perform the regulation of the incident electromagnetic wave field strength distribution. In some embodiments, the plasma regulator adjusts the plasma frequency and / or the plasma collision frequency by adjusting the excitation power of the plasma excitation source.

[0052] In some embodiments, assume that the radius of the tube column is 25×10 -2 m, the incident plane electromagnetic wave propagates along the positive y-axis direction and is perpendicularly incident on the plasma column.

[0053] In this scenario, the internal field and near-field distributions of the TM-polarized electromagnetic wave incident on the plasma column are as Figure 1 shown, and the internal field and near-field distributions of the TE-polarized electromagnetic wave incident on the plasma column are as Figure 2 shown. Figure 1 and Figure 2 In, (a) is the focusing field distribution diagram of the plasma column in the x-y plane, and (b) is the three-dimensional distribution diagram of the plasma column focusing field. In this embodiment, the frequency f i of the electromagnetic wave = 2.1 GHz, the plasma frequency f p = 6.6 GHz, and the plasma collision frequency ν c = 690 GHz.

[0054] From Figure 1 , Figure 2 it can be seen that after the incident electromagnetic wave passes through the plasma column, it focuses the electromagnetic field on the other side of the plasma column along the incident direction, enhancing the electromagnetic wave field strength.

[0055] The planar distributions of the TM-polarized and TE-polarized electromagnetic waves along the incident direction in the internal field and near-field of the plasma column are as Figure 3As shown, where (a) is the TM-polarized electromagnetic wave and (b) is the TE-polarized electromagnetic wave. It can be seen that the plasma forms a narrow and high field strength convergence point at the plasma collision frequency of 690 GHz, and the near-field distributions of the TM wave and the TE wave are similar. After the TE wave converges, the maximum field strength is 77.9 times that of the incident field strength, and the position of the maximum field strength is at 1.51R, that is, 38.5×10 -2 m from the z-axis; the maximum field strength of the TM wave is 88.54 times that of the incident field strength, and the position of the maximum field strength is at 1.54R, that is, 37.8×10 -2 m from the z-axis.

[0056] It has been found through research that the convergence intensity of the electromagnetic field by the plasma column and the position of the maximum converged field strength are related to the plasma frequency, the plasma collision frequency, and the electrical size parameters of the plasma column. Based on this phenomenon, in the embodiments of the present application, the distribution of the electromagnetic wave field strength is adjusted by adjusting the plasma frequency and / or the plasma collision frequency.

[0057] The present application has verified the regulation effects of these two parameters on the electromagnetic wave field strength distribution respectively:

[0058] (1) Adjust the regulation influence of the plasma collision frequency on the electromagnetic wave field strength focusing effect.

[0059] Based on the previous embodiment of the plasma tube column, set the frequency f of the incident electromagnetic wave i = 2.1 GHz, the plasma frequency is f p = 6.6 GHz, and the electromagnetic wave is vertically incident on the plasma column. Figure 4 The figure shows the test diagram of the regulation of the TM-polarized electromagnetic wave field strength by the change of the plasma collision frequency. Among them, (a) is the three-dimensional diagram of the regulation of the electromagnetic wave intensity distribution in the y-axis direction by different plasma collision frequencies; (b) is the regulation diagram of the change of the plasma collision frequency on the maximum intensity of the electromagnetic wave field strength focusing; (c) is the regulation diagram of the change of the plasma collision frequency on the position of the maximum intensity of the electromagnetic wave.

[0060] Through experiments, in this embodiment, only when the plasma collision frequency reaches a certain value can a focusing effect be generated, that is, the plasma column enhances the electromagnetic wave field strength. For the TM-polarized electromagnetic wave, when the plasma collision frequency is greater than ν c = 540 GHz, the transmitted wave through the plasma column begins to have a focusing effect, that is, this frequency is used as the lower limit of the adjustment of the plasma collision frequency in this scenario.

[0061] From Figure 4 (b), it can be seen that as the plasma collision frequency increases, the maximum value of the focused field strength gradually decreases. The plasma collision frequency ν cWhen = 600 GHz, the maximum field strength is 198.3I0, and the collision frequency ν c When = 900 GHz, the maximum field strength is 30.6I0, which is reduced by 6.5 times.

[0062] And from Figure 4 (c), it can be seen that as the plasma collision frequency increases, the position of the maximum value of the focusing field strength moves away from the plasma column along the incident direction. When the plasma collision frequency changes from ν c = 600 GHz to ν c = 900 GHz, the focusing position changes from 1.43R from the center of the cylinder to 1.63R, and the change range is 0.2R. It can be seen that although the plasma collision frequency affects the position of the maximum field strength, the influence is small.

[0063] As Figure 5 shown is the test diagram of the regulation of the TE - polarized electromagnetic wave field strength by the change of the plasma collision frequency. Among them, (a) is the three - dimensional diagram of the regulation of the electromagnetic wave intensity distribution in the y - axis direction by different plasma collision frequencies; (b) is the regulation diagram of the maximum intensity of the electromagnetic wave field strength focused by the change of the plasma collision frequency; (c) is the regulation diagram of the position of the maximum intensity of the electromagnetic wave by the change of the plasma collision frequency.

[0064] For TE - polarized electromagnetic waves, the influence of the plasma collision frequency on the electromagnetic wave field strength distribution is similar to that on TM - polarized electromagnetic waves. For TE - polarized electromagnetic waves, when the plasma collision frequency is greater than ν c = 400 GHz, the transmitted wave passing through the plasma column begins to have a focusing effect, that is, this frequency is used as the lower limit of the adjustment of the plasma collision frequency in this scenario.

[0065] From Figure 5 (b), it can be seen that as the ion collision frequency increases, the maximum value of the focusing field strength gradually decreases. When the plasma collision frequency ν c = 550 GHz, the maximum field strength is 304.5I0, and when the collision frequency ν c = 900 GHz, the maximum field strength is 27.8I0, which is reduced by 11 times.

[0066] From Figure 5 (c), it can be seen that as the plasma collision frequency increases, the position of the maximum value of the focusing field strength moves away from the plasma column along the incident direction. When the plasma collision frequency changes from ν c = 550 GHz to ν c = 900 GHz, the focusing position changes from 1.18R from the center of the cylinder to 1.64R, and the change range is 0.46R. It can be seen that the influence of the plasma collision frequency on the position of the maximum field strength of TE - polarized electromagnetic waves is also small, but it is larger than the influence on TM - polarized electromagnetic waves.

[0067] From the embodiments of the regulation effect of adjusting the plasma collision frequency on the electromagnetic wave field strength focusing effect, it can be seen that for the adjustment of the plasma collision frequency, it will simultaneously affect the maximum field strength of the electromagnetic wave, that is, the position of the maximum field strength. Therefore, in scenarios where there is a demand for the electromagnetic wave field strength or the position of the maximum electromagnetic wave field strength, the plasma collision frequency can be adjusted to the corresponding value in the actual scenario through a plasma regulator.

[0068] (2) Regulation effect of adjusting the plasma frequency on the electromagnetic wave field strength focusing effect.

[0069] Based on the previous plasma column embodiment, set the frequency f of the incident electromagnetic wave i = 2.1 GHz, the plasma collision frequency is ν c = 550 GHz, the electromagnetic wave is incident perpendicularly to the plasma column. Figure 6 The figure shows the test diagram of the regulation of the TM-polarized electromagnetic wave field strength by the change of the plasma frequency. Among them, (a) is the three-dimensional diagram of the regulation of the electromagnetic wave intensity distribution in the y-axis direction by different plasma frequencies; (b) is the regulation diagram of the maximum intensity of the electromagnetic wave field strength focused by the change of the plasma frequency; (c) is the regulation diagram of the position of the maximum intensity of the electromagnetic wave by the change of the plasma frequency.

[0070] As Figure 6 (b) shows that as the plasma frequency increases, the maximum value of the focused field strength gradually increases, from f p = 1 GHz, the maximum field strength value is 1.15 times that of the incident field strength, to 106.4 times at f p = 6 GHz.

[0071] As Figure 6 (c) shows that as the plasma frequency increases, the position of the maximum value of the focused field strength approaches the plasma column along the negative z-axis direction. When the plasma frequency changes from f p = 1 GHz to f p = 6 GHz, the focused position decreases from 1.78R from the center of the cylinder to 1.52R, and the change range is 0.26R. Then, although the plasma frequency affects the position of the maximum field strength, the influence is small.

[0072] In addition, it is found through experiments that when the plasma frequency f p > 6.7 GHz, the focusing effect of the plasma will gradually decrease, and the incident electromagnetic wave begins to oscillate inside the plasma column, and the plasma column gradually loses the focusing effect. Therefore, f p = 6.7 GHz can be used as the upper limit of the plasma frequency adjustment for TM-polarized electromagnetic waves in this scenario.

[0073] AsFigure 7 The figure shows the test diagram of the regulation of the TE - polarized electromagnetic wave field strength by the change of the plasma frequency. Among them, (a) is the three - dimensional diagram of the regulation of the electromagnetic wave intensity distribution in the y - axis direction by different plasma frequencies; (b) is the regulation diagram of the maximum intensity of the electromagnetic wave field strength focusing with the change of the plasma frequency; (c) is the regulation diagram of the position of the maximum intensity of the electromagnetic wave with the change of the plasma frequency.

[0074] For TE - polarized electromagnetic waves, the influence of the plasma collision rate on the electromagnetic wave field strength distribution is similar to that on TM - polarized electromagnetic waves.

[0075] As Figure 7 shown in (b), with the increase of the plasma frequency, the maximum value of the focused field strength gradually increases. When the plasma frequency increases from f p = 1GHz to f p = 6.5GHz, the maximum value of the electromagnetic wave field strength gradually increases from 1.14I0 to 244.4I0, an increase of 214.4 times, which is greater than the increase value of the TM - polarized electromagnetic wave field strength.

[0076] As Figure 7 shown in (c), with the increase of the plasma frequency, the position of the maximum value of the focused field strength approaches the plasma column along the negative z - axis direction. When the plasma frequency changes from f p = 1GHz to f p = 6.5GHz, the focusing position decreases from 1.83R away from the center of the cylinder to 1.28R, with a change range of 0.55R, and the influence trend is greater than that on TM - polarized electromagnetic waves.

[0077] In addition, for TE - polarized electromagnetic waves, when the plasma frequency f p >7.8GHz, the incident electromagnetic wave gradually enters the plasma column and generates oscillations, that is, the focusing effect of the plasma gradually decreases. Therefore, f p = 7.8GHz can be used as the upper limit of the plasma frequency regulation for TM - polarized electromagnetic waves in this scenario.

[0078] From the embodiments of the regulation influence of adjusting the plasma frequency on the electromagnetic wave field strength focusing effect, it can be seen that for the regulation of the plasma frequency, it will also simultaneously affect the maximum field strength of the electromagnetic wave, that is, the position of the maximum field strength. Therefore, in scenarios where there is a demand for the electromagnetic wave field strength or the position of the maximum electromagnetic wave field strength, the plasma frequency can be adjusted to the corresponding value in the actual scenario through the plasma regulator.

[0079] Combined with the embodiments of the regulation effect of adjusting the plasma collision frequency and the plasma frequency on the electromagnetic wave field strength focusing effect as analyzed above, it can be found that for the adjustment of the plasma frequency, when ensuring that the plasma has the maximum field strength focusing effect, there is an adjustment upper limit, and it can also be determined accordingly that when ensuring that the plasma loses the focusing effect, there will also be an adjustment upper limit. Therefore, in order to ensure that the plasma has the focusing effect, the plasma regulator adjusts the plasma frequency within a predetermined first frequency range. Based on the above phenomenon, for similar reasons, in order to ensure that the plasma has the best field strength focusing effect, the plasma regulator adjusts the plasma frequency within a predetermined first frequency range. This first frequency range at least has an adjustment upper limit. If there is a minimum requirement for the field strength amplification factor or a maximum requirement for the maximum field strength position (distance from the plasma column), the adjustment lower limit can also be designed; the threshold varies based on different plasma electrical size parameters, different incident electromagnetic wave frequencies, different plasma collision frequencies, and different polarization forms.

[0080] Similarly, for the adjustment of the plasma collision frequency, when ensuring that the plasma has the focusing effect, there is an adjustment lower limit. If there is a maximum requirement for the field strength amplification factor or a minimum requirement for the maximum field strength position, the adjustment upper limit can also be designed; the threshold varies based on different plasma electrical size parameters, different incident electromagnetic wave frequencies, different plasma collision frequencies, and different polarization forms. Therefore, for the plasma collision frequency, it can be designed to be adjusted within a second frequency range. This second frequency range at least includes the adjustment lower limit, and the adjustment upper limit can be designed according to needs, or the adjustment upper limit can also not be designed.

[0081] The embodiment of the present application also proposes an electromagnetic wave modulation method, which includes:

[0082] Vertically incident the electromagnetic wave on the plasma column;

[0083] Excite the plasma in the plasma column and adjust the plasma frequency and / or the plasma collision frequency to adjust the field strength distribution of the incident electromagnetic wave.

[0084] In some embodiments, the plasma frequency and / or the plasma collision frequency are adjusted by adjusting the excitation power of the plasma.

[0085] In some embodiments, the plasma frequency is adjusted within a predetermined first frequency range.

[0086] In other embodiments, the plasma expansion frequency is adjusted within a predetermined second frequency range.

[0087] For the electromagnetic wave modulation method proposed by the embodiment of the present application, the relevant features can refer to the relevant features in the electromagnetic wave modulation device described above.

[0088] An embodiment of the present application also provides an electromagnetic wave generator, which includes:

[0089] An electromagnetic wave source;

[0090] A plasma column; the electromagnetic wave emitted by the electromagnetic wave source is perpendicularly incident on the plasma column;

[0091] A plasma excitation source for exciting the plasma in the plasma column;

[0092] A plasma regulator for adjusting the plasma frequency and / or the plasma collision frequency to adjust the field strength distribution of the incident electromagnetic wave.

[0093] In some embodiments, the plasma regulator adjusts the plasma frequency within a predetermined first frequency range.

[0094] In some other embodiments, the plasma regulator adjusts the plasma collision frequency within a predetermined second frequency range.

[0095] In addition, in some embodiments, the electromagnetic wave generator further includes a frequency regulator, which is connected to the electromagnetic wave source and is used to adjust the frequency of the electromagnetic wave emitted by the electromagnetic wave source.

[0096] As Figure 8 shown in the test diagram of the influence of the incident electromagnetic wave frequency change on the focusing field strength distribution of the plasma column, where (a) is the incident TM-polarized electromagnetic wave and (b) is the incident TE-polarized electromagnetic wave. In this embodiment, the plasma frequency f p = 5.6 GHz, and the plasma collision frequency ν c = 410 GHz.

[0097] It can be seen from Figure 8 that as the incident electromagnetic wave frequency increases, for both TM polarization and TE polarization, the focusing position of the plasma transmission field strength moves along the positive y-axis direction, that is, away from the plasma column, the focusing intensity weakens and multiple peaks appear, and the focusing peak far from the cylindrical surface becomes wider. Therefore, by using the frequency regulator to adjust the electromagnetic wave frequency, the field strength of the electromagnetic wave emitted by the electromagnetic wave generator can be adjusted, and the corresponding focusing peak width can be adjusted.

[0098] Figure 9 shows the field strength distribution diagram of the plasma column in three-dimensional space ( i = 9 GHz) for the TM-polarized electromagnetic wave and the field strength distribution diagram along the y-axis ( Figure 9 (a)) Figure 9(b)). Along the positive z-axis direction on the surface of the plasma column, there are 4 wave peaks. They are respectively at the position of 1.04R with an electric field strength of 158.9I0; at the position of 1.46R with an electric field strength of 151.1I0; at the position of 2.44R with an electric field strength of 147I0; and at the position of 6.45R with an electric field strength of 147.4I0. From the surface of the plasma column to the position 10R away from the center of the plasma column, the minimum value of the electric field strength is greater than 130I0, and the half-widths of each peak gradually increase. The width of the right peak can be regarded as the longest focusing length of the transmitted wave of the plasma column. Similar phenomena exist for TE-polarized electromagnetic waves as for TM-polarized electromagnetic waves, and this application does not give a separate example for this. Therefore, by adjusting the frequency of the incident electromagnetic wave, the electric field strength distribution of the electromagnetic wave emitted after plasma focusing can also be adjusted, including the peak value of the electric field strength, the position of the peak value of the electric field strength, and the width of the focusing peak. That is, for an electromagnetic wave generator, in addition to adjusting the plasma frequency and / or the plasma collision frequency through a plasma regulator to adjust the electric field strength distribution of the incident electromagnetic wave (from the electromagnetic wave source) for emission, the electric field strength distribution of the electromagnetic wave can also be adjusted by adjusting the frequency of the incident electromagnetic wave.

[0099] The present invention is not limited to the foregoing specific embodiments. The present invention extends to any new feature or any new combination disclosed in this specification, and to any step of any new method or process disclosed or any new combination.

Claims

1. An electromagnetic wave modulation device for adjusting the field intensity distribution of an incident electromagnetic wave; characterized in that: include: Plasma column; A plasma excitation source, used to excite plasma in the plasma column; A plasma regulator is used to adjust the plasma frequency and / or the plasma collision frequency.

2. The electromagnetic wave modulation device according to claim 1, characterized in that: The plasma excitation source excites the plasma in a discharge manner.

3. The electromagnetic wave modulation device according to claim 1, characterized in that: The plasma regulator adjusts the plasma frequency and / or the plasma collision frequency by adjusting the excitation power of the plasma excitation source.

4. The electromagnetic wave modulation device according to claim 1, characterized in that: The plasma regulator regulates the plasma frequency within a predetermined first frequency range.

5. An electromagnetic wave modulation method, characterized in that: include: The electromagnetic wave is incident vertically on the plasma column; The plasma in the plasma column is excited, and the plasma frequency and / or the plasma collision frequency are adjusted to adjust the field intensity distribution of the incident electromagnetic wave.

6. The electromagnetic wave modulation method according to claim 5, characterized in that: The plasma frequency and / or the plasma collision frequency is adjusted by adjusting the excitation power of the plasma.

7. The electromagnetic wave modulation method according to claim 5, characterized in that: The plasma frequency is adjusted within a predetermined first frequency range.

8. An electromagnetic wave generator, characterized in that: include: Electromagnetic wave sources; Plasma column; the electromagnetic wave emitted by the electromagnetic wave source is vertically incident on the plasma column; A plasma excitation source, used to excite plasma in the plasma column; The plasma regulator is used to adjust the plasma frequency and / or the plasma collision frequency to adjust the field intensity distribution of the incident electromagnetic wave.

9. The electromagnetic wave generator as claimed in claim 8, characterized in that The plasma regulator regulates the plasma frequency within a predetermined first frequency range.

10. The electromagnetic wave generator according to claim 8, characterized in that: Also includes: A frequency regulator is connected to the electromagnetic wave source and is used to adjust the frequency of the electromagnetic wave emitted by the electromagnetic wave source.

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