CN108598846B - System for generating Cerenkov radiation - Google Patents
System for generating Cerenkov radiation Download PDFInfo
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- CN108598846B CN108598846B CN201810367574.0A CN201810367574A CN108598846B CN 108598846 B CN108598846 B CN 108598846B CN 201810367574 A CN201810367574 A CN 201810367574A CN 108598846 B CN108598846 B CN 108598846B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S1/00—Masers, i.e. devices using stimulated emission of electromagnetic radiation in the microwave range
- H01S1/02—Masers, i.e. devices using stimulated emission of electromagnetic radiation in the microwave range solid
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Abstract
The invention discloses a system for generating Cerenkov radiation, which comprises: a metal sheet having an array of sub-wavelength through holes periodically arranged in a first predetermined direction and a sheet-like electron beam for exciting radiation; the laminar electron beams move in parallel above the through hole array, and the cerenkov radiation is generated in vacuum by changing an included angle between the movement direction of the laminar electron beams and the first preset direction. The system can realize Cherenkov radiation in vacuum, and can control the direction of the Cherenkov radiation.
Description
Technical Field
The invention relates to the technical field of electromagnetism, in particular to a system for generating Cerenkov radiation.
Background
A phenomenon of electromagnetic radiation, known as Cherenkov radiation, occurs when the velocity of motion of charged particles exceeds the speed of light in the surrounding medium. Cherenkov radiation plays an important role in the fields of high-energy particle physics, cosmic ray physics, electromagnetic radiation sources and the like, and becomes a global hot research topic since the discovery date.
It is known from the narrow theory of relativity that the velocity of any charged particle cannot exceed the speed of light in vacuum, and therefore, conventional Cherenkov radiation can only be generated in a medium, i.e., in vacuum. Conventional Cherenkov radiation typically requires high energy (i.e., high velocity) point particles, which requires the use of costly and bulky particle accelerators. Wherein, the Cherenkov radiation without threshold value refers to Cherenkov radiation without energy threshold value, i.e. charged particles of any energy can excite Cherenkov radiation. The thresholdless Cherenkov radiation can utilize low-energy charged particles, so that the cost can be greatly reduced, and meanwhile, the method has important significance for developing a miniaturized and integratable light source and particle diagnosis technology.
Existing methods for generating thresholdless Cherenkov radiation typically rely on artificial metamaterials, i.e., charged particles are used to generate thresholdless Cherenkov radiation in artificial metamaterials. However, the artificial metamaterial has dispersion characteristics, so that the Cherenkov radiation without threshold value can be realized only in a specific frequency band.
Disclosure of Invention
To solve the above problems, the present invention provides a system for generating cerenkov radiation, which can realize Cherenkov radiation in vacuum.
In order to achieve the purpose, the invention provides the following technical scheme:
a system for generating cerenkov radiation, the system comprising: a metal sheet having an array of sub-wavelength through holes periodically arranged in a first predetermined direction and a sheet-like electron beam for exciting radiation;
the laminar electron beams move in parallel above the through hole array, and the cerenkov radiation is generated in vacuum by changing an included angle between the movement direction of the laminar electron beams and the first preset direction.
Preferably, in the above system, the through hole is a rectangular parallelepiped through hole.
Preferably, in the above system, the length of the rectangular through hole is: the width of cuboid through-hole is 10: 1.
preferably, in the above system, the length of the rectangular through hole is: the height of the cuboid through hole is 1: 1.
Preferably, in the above system, the height of the rectangular through hole is: the thickness of the metal sheet is 1: 1.
Preferably, in the above system, the width of the rectangular through hole is smaller than the wavelength of the electromagnetic wave radiated from the rectangular through hole.
Preferably, in the above system, the parallel movement of the laminar electron beam above the array of through holes, and the generating of the cerenkov radiation in the vacuum by changing an included angle between a moving direction of the laminar electron beam and the first preset direction includes:
the sheet-like electron beams move in parallel above the through hole array, and the through hole array sequentially excites an electromagnetic resonance mode;
the electromagnetic resonance mode propagates as a radiation source in the first predetermined direction at a phase velocity, wherein the phase velocity is expressed as
veRepresenting the moving speed of free electrons in the sheet-like electron beam, and α representing the included angle between the moving direction of the sheet-like electron beam and the first preset direction;
when the included angle α between the movement direction of the laminar electron beam and the first preset direction is larger and larger, the phase speed is larger and larger than the movement speed of free electrons in the laminar electron beam until the movement speed exceeds the light speed in vacuum, when the phase speed is larger than the light speed in vacuum, the system generates the Cerenkov radiation in vacuum, and when the included angle α between the movement direction of the laminar electron beam and the first preset direction is close to 90 degrees, the phase speed is close to infinity and larger than the light speed in vacuum, and the system generates the Cerenkov radiation without a threshold value in vacuum.
As can be seen from the above description, the present invention provides a system for generating cerenkov radiation, the system comprising: a metal sheet having an array of sub-wavelength through holes periodically arranged in a first predetermined direction and a sheet-like electron beam for exciting radiation; the laminar electron beams move in parallel above the through hole array, and the cerenkov radiation is generated in vacuum by changing an included angle between the movement direction of the laminar electron beams and the first preset direction.
The system can realize Cherenkov radiation in vacuum, and can control the direction of the Cherenkov radiation.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a system for generating cerenkov radiation according to an embodiment of the present invention;
fig. 2 is a top view of a rectangular through hole array according to an embodiment of the present invention;
fig. 3 is a schematic diagram of a simulated radiation spectrum according to an embodiment of the present invention;
fig. 4 is a schematic diagram of a distribution of fields with three frequencies obtained by simulation in fig. 3 according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
Referring to fig. 1, fig. 1 is a schematic structural diagram of a system for generating cerenkov radiation according to an embodiment of the present invention.
The system for generating Cerenkov radiation comprises: a metal foil 11 with an array of sub-wavelength through holes 12 arranged periodically in a first predetermined direction and a laminar electron beam 13 for exciting radiation.
Wherein the laminar electron beam 13 moves in parallel above the through hole array 12, and the cerenkov radiation is generated in vacuum by changing an included angle between the moving direction of the laminar electron beam 13 and the first preset direction.
Optionally, the through hole includes, but is not limited to, a rectangular parallelepiped through hole.
Optionally, the cuboid through hole is long: the width of cuboid through-hole is 10: 1.
specifically, the rectangular through hole is a rectangular through hole with a large length-width ratio.
Optionally, the cuboid through hole is long: the height of the cuboid through hole is 1: 1.
Optionally, the height of the cuboid through hole is: the thickness of the metal sheet is 1: 1.
Specifically, the height of the cuboid through hole is the same as the thickness of the metal sheet.
Optionally, the width of the rectangular through hole is far smaller than the wavelength of the electromagnetic wave radiated by the rectangular through hole.
Specifically, the width of the rectangular through hole is smaller than one tenth of the wavelength of the electromagnetic wave radiated by the rectangular through hole.
Based on the system for generating Cerenkov radiation, the specific principle is as follows:
as shown in fig. 2, wherein z direction represents the movement direction of the laminar electron beam, z' represents the first preset direction, y represents a direction parallel to the length of the rectangular parallelepiped through hole, and α represents an angle between the movement direction of the laminar electron beam and the first preset direction.
The sheet-like electron beams move in parallel above the through hole array, and the through hole array sequentially excites an electromagnetic resonance mode.
The electromagnetic resonance mode propagates as a radiation source in the first predetermined direction at a phase velocity, wherein the phase velocity is expressed as
veRepresenting the moving speed of free electrons in the laminar electron beam, and α representing the included angle between the moving direction of the laminar electron beam and the first preset direction.
When the included angle α between the movement direction of the laminar electron beam and the first preset direction is larger and larger, the phase speed is larger and larger than the movement speed of free electrons in the laminar electron beam until the movement speed exceeds the light speed in vacuum, when the phase speed is larger than the light speed in vacuum, the system generates the Cerenkov radiation in vacuum, and when the included angle α between the movement direction of the laminar electron beam and the first preset direction is close to 90 degrees, the phase speed is close to infinity and larger than the light speed in vacuum, and the system generates the Cerenkov radiation without a threshold value in vacuum.
In addition, the radiation direction of the Cherenkov radiation generated in the vacuum satisfies the following radiation angle formula:
where θ represents the angle between the Cherenkov radiation direction and said first predetermined direction, and c represents the speed of light in vacuum.
It can be seen that by changing the angle α between the direction of movement of the laminar electron beam and the first predetermined direction, the direction of radiation of the Cherenkov radiation, i.e. the magnitude of θ, can be changed.
When the thickness of the metal sheet 11 is 0.5mm, the length of the rectangular through hole is 0.5mm, the width of the rectangular through hole is 0.05mm, the height of the rectangular through hole is 0.5mm, the distance between two adjacent rectangular through holes in the first preset direction is 0.5mm, α is 85 degrees and the electron energy is 5 kilo-electron volts, referring to fig. 3, fig. 3 is a schematic diagram of a radiation spectrum obtained by simulation provided by an embodiment of the present invention, wherein the Frequency is represented by the abscissa frequeness, and the electric field intensity is represented by the ordinate fieldinetentiality, as shown in fig. 3, it can be seen that the fields of the three radiation frequencies are mainly radiated into the vacuum, and the radiation direction is 59 degrees, so as to satisfy the radiation angle formula of chenkov radiation.
As can be seen from the above description, the present invention provides a system for generating cerenkov radiation, the system comprising: a metal sheet having an array of sub-wavelength through holes periodically arranged in a first predetermined direction and a sheet-like electron beam for exciting radiation; the laminar electron beams move in parallel above the through hole array, and the cerenkov radiation is generated in vacuum by changing an included angle between the movement direction of the laminar electron beams and the first preset direction.
The system can generate Cherenkov radiation in vacuum, and can control the direction of the Cherenkov radiation.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (6)
1. A system for generating cerenkov radiation, said system comprising: a metal sheet having an array of sub-wavelength through holes periodically arranged in a first predetermined direction and a sheet-like electron beam for exciting radiation;
the laminar electron beams move in parallel above the through hole array, and the cerenkov radiation is generated in vacuum by changing an included angle between the movement direction of the laminar electron beams and the first preset direction;
wherein the laminar electron beam moves in parallel above the array of through holes, and the generating of the cerenkov radiation in vacuum by changing an included angle between the movement direction of the laminar electron beam and the first preset direction comprises:
the sheet-like electron beams move in parallel above the through hole array, and the through hole array sequentially excites an electromagnetic resonance mode;
the electromagnetic resonance mode propagates as a radiation source with a phase velocity along the first predetermined direction, wherein the phase velocityDegree is expressed as
veRepresenting the moving speed of free electrons in the sheet-like electron beam, and α representing the included angle between the moving direction of the sheet-like electron beam and the first preset direction;
when the included angle α between the movement direction of the laminar electron beam and the first preset direction is larger and larger, the phase speed is larger and larger than the movement speed of free electrons in the laminar electron beam until the movement speed exceeds the light speed in vacuum, when the phase speed is larger than the light speed in vacuum, the system generates the Cerenkov radiation in vacuum, and when the included angle α between the movement direction of the laminar electron beam and the first preset direction is close to 90 degrees, the phase speed is close to infinity and larger than the light speed in vacuum, and the system generates the Cerenkov radiation without a threshold value in vacuum.
2. The system of claim 1, wherein the via is a rectangular parallelepiped via.
3. The system of claim 2, wherein the cuboid via has a length of: the width of cuboid through-hole is 10: 1.
4. the system of claim 2, wherein the cuboid via has a length of: the height of the cuboid through hole is 1: 1.
5. The system of claim 2, wherein the height of the cuboid via is: the thickness of the metal sheet is 1: 1.
6. The system of claim 2, wherein the width of the rectangular through-hole is less than one tenth of the wavelength of the electromagnetic wave radiated by the rectangular through-hole.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102593692A (en) * | 2011-12-21 | 2012-07-18 | 电子科技大学 | Cerenkov radiation source of surface plasma waves |
| CN102623873A (en) * | 2012-04-13 | 2012-08-01 | 电子科技大学 | Implement method for producing high power radiation based on double negative materials |
| JP2017054699A (en) * | 2015-09-09 | 2017-03-16 | 学校法人早稲田大学 | Electromagnetic wave generation device and method therefor |
| CN106770619A (en) * | 2016-12-28 | 2017-05-31 | 电子科技大学 | A kind of surface plasma excimer produces the device of Cerenkov radiation |
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- 2018-04-23 CN CN201810367574.0A patent/CN108598846B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102593692A (en) * | 2011-12-21 | 2012-07-18 | 电子科技大学 | Cerenkov radiation source of surface plasma waves |
| CN102623873A (en) * | 2012-04-13 | 2012-08-01 | 电子科技大学 | Implement method for producing high power radiation based on double negative materials |
| JP2017054699A (en) * | 2015-09-09 | 2017-03-16 | 学校法人早稲田大学 | Electromagnetic wave generation device and method therefor |
| CN106770619A (en) * | 2016-12-28 | 2017-05-31 | 电子科技大学 | A kind of surface plasma excimer produces the device of Cerenkov radiation |
Non-Patent Citations (2)
| Title |
|---|
| "Surface Polariton Cherenkov Light Radiation Source";Shenggang Liu et al.;《Physics Review Letters》;20121012;153902 * |
| "Diffraction radiation of a sub-wavelength hole array with dielectric medium loading";Ping Zhang et al.;《J. Phys. D: Appl. Phys.》;20120323;145303 * |
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