Isolated ultrafast gamma-ray pulse generation device and method

Abstract

The present application relates to a kind of isolated ultrafast gamma-ray pulse generation device, it includes electron beam generation system, two-stage compression system and laser Compton scattering system, the electron beam generation system is used to generate electron beam, the two-stage compression system is used to two-stage compression to the electron beam, to obtain isolated ultra-short electron slice, the laser Compton scattering system is used to make the isolated ultra-short electron slice and Compton scattering laser occur inverse Compton scattering, to generate isolated ultrafast gamma-ray pulse.

Description

Technical Field

[0001] This invention relates to the field of high-energy radiation technology, and more specifically to an isolated ultrafast gamma-ray pulse generation device and method. Background Technology

[0002] Ultrafast X-ray / gamma-ray pulses have significant applications in ultrafast dynamics detection, atomic and molecular structure research, and extreme condition physics. One of the main methods for obtaining extremely short pulses is the X-ray free-electron laser, but further increasing photon energy to the MeV level and compressing pulse duration to attoseconds or even zetaseconds presents challenges such as complexity, high cost, and large-scale equipment requirements. Laser Compton scattering, with its advantages of tunable photon energy and controllable polarization, is an important pathway for generating high-quality, high-energy gamma rays. However, current methods typically rely on geometrically shortening the interaction time (e.g., near-90° interaction), and the realization of isolated pulses remains limited to the femtosecond level by the longitudinal structure of the electron beam. Summary of the Invention

[0003] The purpose of this invention is to provide an isolated ultrafast gamma-ray pulse generation device and method. Under the premise of feasibility, through multi-dimensional phase space fine manipulation and hierarchical compression mechanism, high-quality, isolated, ultrashort (attosecond or zetasecond) electron beam slices suitable for laser Compton scattering are realized, thereby generating isolated ultrafast (attosecond or zetasecond) gamma-ray pulses.

[0004] To achieve the above objectives, the present invention provides an isolated ultrafast gamma-ray pulse generation device, comprising an electron beam generation system, a two-stage compression system, and a laser Compton scattering system. The electron beam generation system generates an electron beam, the two-stage compression system compresses the electron beam in two stages to obtain an isolated ultrashort electron slice, and the laser Compton scattering system causes the isolated ultrashort electron slice and the Compton scattering laser to undergo inverse Compton scattering to generate an isolated ultrafast gamma-ray pulse.

[0005] Optionally, the electron beam is an electron beam with a preset energy and low charge.

[0006] Optionally, the two-stage compression system includes a first beam confinement device, a lateral deflection cavity, an acceleration section, a lateral matching section, a first compression section, a second beam confinement device, and a second compression section. The first beam confinement device is used to perform a first beam scraping on the electron beam. The lateral deflection cavity is used to introduce a first segment of lateral-to-longitudinal coupling into the electron beam after the first beam scraping, forming a zx tilt correlation. The acceleration section is used to accelerate the electron beam with zx tilt correlation. The lateral matching section is used to adjust the Twiss parameter of the electron beam. The first compression section is used to convert the zx tilt correlation of the electron beam into a longitudinal compression effect to achieve a first-stage compression. The second beam confinement device is used to perform a second beam scraping on the electron beam after the first-stage compression. The second compression section is used to perform a second-stage compression on the electron beam after the second beam scraping to obtain the isolated ultrashort electron slice.

[0007] Optionally, the first beam confinement device and the beam confinement device are at least one of an adjustable slit, a beam scraper, and a collimation and beam limiting assembly.

[0008] Optionally, the first compression segment is a dipolar iron.

[0009] Optionally, the second compression section includes a modulation section and a dispersion section, wherein the modulation section is used to modulate the energy of the electron beam, and the dispersion section is used to convert the energy modulation of the electron beam into density modulation to produce the isolated ultrashort electron slice.

[0010] Optionally, the modulation section includes a seed laser system and a undulator, wherein the seed laser system is used to generate a seed laser, the seed laser and the electron beam are synchronously injected into the undulator, and the seed laser modulates the energy of the electron beam in the undulator;

[0011] The dispersion segment is a Doglg composed of two dipolar irons with the same strength but opposite magnetic poles.

[0012] Optionally, the laser Compton scattering system includes a Compton scattering laser system and an interaction cavity. The Compton scattering laser system is used to generate Compton scattering laser. Both the Compton scattering laser and the isolated ultrashort electron slice are fed into the interaction cavity. The isolated ultrashort electron slice collides with the Compton scattering laser in the interaction cavity to generate the isolated ultrafast gamma-ray pulse.

[0013] Optionally, the laser Compton scattering system further includes a collimator for collimating and outputting the isolated ultrafast gamma-ray pulse.

[0014] Another aspect of the present invention provides a method for generating isolated ultrafast gamma-ray pulses, comprising:

[0015] An isolated ultrafast gamma-ray pulse generating device as described above is provided;

[0016] The electron beam generation system generates an electron beam and transmits the electron beam to the first beam confinement device;

[0017] The first beam confinement device performs the first beam scraping on the electron beam, and the electron beam after the first beam scraping is transmitted to the transverse deflection cavity.

[0018] The transverse deflection cavity introduces the first transverse and longitudinal coupling into the electron beam after the first beam scraping, forming zx tilt correlation, and the electron beam with zx tilt correlation is transmitted to the acceleration section.

[0019] The acceleration section accelerates the electron beam with zx tilt correlation, and the accelerated electron beam is then transmitted to the transverse matching section.

[0020] The transverse matching section adjusts the Twiss parameters of the electron beam, and the adjusted electron beam is then transmitted to the first compression section.

[0021] The first compression stage converts the zx tilt correlation of the electron beam into a longitudinal compression effect to achieve the first stage of compression. The compressed electron beam is then transmitted to the second beam confinement device.

[0022] The second beam confinement device performs a second beam scraping on the first-stage compressed electron beam, and the electron beam after the second beam scraping is transmitted to the modulation section.

[0023] The modulation section modulates the energy of the electron beam, and the energy-modulated electron beam is then transmitted to the dispersion section.

[0024] The dispersive section converts the energy modulation of the electron beam into density modulation to produce isolated ultrashort electron slices, which are then transmitted to the laser Compton scattering system.

[0025] The laser Compton scattering system causes inverse Compton scattering of isolated ultrashort electron slices and Compton scattering lasers to generate isolated ultrafast gamma-ray pulses. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of an isolated ultrafast gamma-ray pulse generating device according to an embodiment of the present invention;

[0027] Figure 2 This is a schematic diagram of a two-stage compression system according to an embodiment of the present invention;

[0028] Figure 3 This is a schematic diagram of the structure of the second compression section according to an embodiment of the present invention;

[0029] Figure 4 A schematic diagram of the modulation segment according to an embodiment of the present invention;

[0030] Figure 5 This is a schematic diagram of the structure of a laser Compton scattering system according to an embodiment of the present invention;

[0031] Figure 6 This is a flowchart of an isolated ultrafast gamma-ray pulse generation method according to an embodiment of the present invention. Detailed Implementation

[0032] The preferred embodiments of the present invention are given below with reference to the accompanying drawings and described in detail.

[0033] like Figure 1 As shown, this embodiment of the invention provides an isolated ultrafast gamma-ray pulse generation device, which includes an electron beam generation system 100, a two-stage compression system 200, and a laser Compton scattering system 300. The electron beam generation system 100 is used to generate an electron beam, the two-stage compression system 200 is used to compress the electron beam in two stages to obtain an isolated ultrashort electron slice, and the laser Compton scattering system 300 is used to cause the isolated ultrashort electron slice and the Compton scattering laser to undergo inverse Compton scattering to generate an isolated ultrafast gamma-ray pulse.

[0034] The electron beam is preferably an electron beam with a preset energy and low charge (less than 50 picocoulombs). A low-charge electron beam can reduce space charge effects and collective effects, improving the stability and controllability of ultrashort slice formation. The electron beam generation system 100 may include an electron gun, an injector, and an accelerator. The electron gun is used to output the initial electron beam, the injector is used to perform beam compression, timing synchronization, lateral focusing, and initial emittance shaping on the initial electron beam, and the accelerator is used to accelerate the electron beam after it has been shaped by the injector, while simultaneously suppressing beam divergence and controlling the total charge, ultimately outputting an electron beam with a preset energy and low charge (i.e., a high-energy, low-charge electron beam).

[0035] Before entering the two-stage compression system 200, the electron beam can also undergo beam matching and initial diagnosis to obtain initial parameters such as transverse beam spot size, emittance, energy dispersion and longitudinal length.

[0036] like Figure 2 As shown, the two-stage compression system 200 includes a first beam confinement device 210, a lateral deflection cavity 220, an acceleration section 230, a lateral matching section 240, a first compression section 250, a second beam confinement device 260, and a second compression section 270 arranged sequentially along the electron beam transmission direction.

[0037] The first beam confinement device 210 is used to perform non-conservative emittance destruction (beam scraping) on ​​the electron beam to selectively remove peripheral particles of the electron beam in the lateral position space and / or lateral angle space, thereby reducing the effective phase space volume participating in subsequent compression and scattering processes. The purpose of setting the first beam confinement device 210 is to reduce the six-dimensional phase space volume of the beam by controllingly sacrificing a portion of the electrons, thus facilitating the formation of isolated, high-contrast ultrashort electron slices. The first beam confinement device 210 can be at least one of an adjustable slit, a beam scraper, and a collimation and beam-limiting assembly. After passing through a slit with a width of 2a, the geometric emittance of the electron beam... The specific value can be determined using the following formula:

[0038]

[0039] in, It is the standard normal distribution function. The cumulative distribution function of the standard normal distribution. This is the emissivity correction factor caused by slit truncation. This is the ratio of the slit size to the electron beam size. The decrease in transverse emittance, which is the geometric emittance of the electron beam at the slit entrance, directly leads to a contraction in the six-dimensional phase space volume of the beam. times.

[0040] The lateral deflection cavity 220 is used to introduce the first segment of transverse-longitudinal coupling into the scraped electron beam, enabling the electron beam to form a predetermined tilt correlation (i.e., a zx tilted phase space structure) between the longitudinal coordinate z and the transverse coordinate x. The lateral deflection intensity of the lateral deflection cavity 220 is... Where V is voltage, E is electron energy, and e is electron charge. For the radio frequency wavelength, the length of the lateral deflection cavity is L. rf After being scraped, the electron beam enters the transverse deflection cavity 220. By adjusting the radio frequency phase and deflection voltage of the transverse deflection cavity 220, a first segment of transverse-longitudinal coupling is introduced into the electron beam, forming a spatial position zx tilt correlation of the beam. This provides input conditions for the subsequent first compression stage 250, enabling the first compression stage 250 to map the zx correlation to a longitudinal compression effect, rather than relying solely on the traditional longitudinal dispersion compression path. Preferably, matching magnetic elements (e.g., quadrupole iron groups) can be placed before and after the transverse deflection cavity 220 to adjust the transverse beta function, beam spot size, and phase space tilt to meet the matching requirements of the subsequent first-stage compression. After passing through the transverse deflection cavity 220, the beam at zx and Near-linear correlation formed in phase space In the symplectic system, the Twiss parameter ( The evolution of ) under the most ideal condition has a conserved quantity:

[0041]

[0042] in, It is the relativistic factor (Lorentz factor) of the particle. , , For horizontal Twiss parameters, is the linear coefficient between the particle's horizontal coordinate x and vertical coordinate. The lateral deflection angle of the particle The linear coefficient between the vertical coordinate z and the vertical coordinate z, W is a conserved quantity (constant).

[0043] Acceleration section 230 is used to accelerate an electron beam with zx tilt correlation to increase its energy. Since the electron beam generation system 100 produces a high-energy electron beam, longitudinal dispersion during acceleration is negligible. During acceleration, the conserved quantity W remains constant, while the relativistic factor increases with increasing electron beam energy. The increase, accompanied by a thermal damping effect, reduces W / γ, which is beneficial for improving the compression capacity of the subsequent second-stage compression process and improving the conditions for the formation of the final ultrashort slices.

[0044] The lateral matching section 240 is used to adjust the Twiss parameters of the electron beam, so that the α function of the electron beam at the entrance of the first compression section 250 approaches 0 and the β function has a large value. This allows the angular divergence of the electron beam in the x-direction at the entrance of the first compression section 250 to reach a small value (the magnitude of the angular divergence is ultimately proportional to the longitudinal dimension of the final compressed beam), thereby creating conditions for the formation of ultrashort electron slices. The lateral matching section 240 may include a quadrupole and a drift section.

[0045] The first compression section 250 is used to convert the zx tilt correlation of the electron beam into a longitudinal compression effect, thereby achieving the first stage of compression. The first compression section 250 can be a dipole magnet (i.e., a bending magnet), which utilizes the existing zx tilt correlation of the electron beam and the geometric mapping relationship between the magnetic element to rotate the zx beam current phase space of the electron beam, achieving the first stage of compression. By rationally designing the input beam current parameters, the tilt intensity introduced by the transverse deflection cavity 220, the dipole magnet deflection parameters, and the matching optical parameters, the electron beam can be compressed to the theoretical or predicted minimum longitudinal dimension in the first compression section 250. :

[0046]

[0047] in, The value of the β function after passing through the first beam confinement device 210. Let x' be the standard deviation of the initial beam (the projection of the angle between the direction of electron motion in the beam and the z-axis onto the x-axis). It is half the slit width of the first beam confinement device 210.

[0048] The deflection angle θ of the dipole B The calculation formula is as follows:

[0049]

[0050]

[0051] in, Let x be the linear coefficient between the horizontal coordinate x and the vertical coordinate of the particle at the entrance of the diode. , and The Twiss parameters are at the outlet of the lateral deflection cavity 220. and These are the relativistic factors of the electron energies at the transverse deflection cavity inlet 220 and the first compression section inlet 250, respectively.

[0052] The second beam confinement device 260 is used to scrape the electron beam after the first stage compression, so that the dimensions of the beam in the x and y directions are controlled at a relatively high level, so as to ensure that the electron beam can obtain a relatively ideal linear energy chirp during the second stage compression process of the second compression section 270.

[0053] The second compression section 270 is used to perform a second stage of compression on the electron beam, further transforming the favorable phase space conditions after the first stage of compression into isolated ultrashort electron slices. For example... Figure 3 As shown, the second compression section 270 may include a modulation section 271 and a dispersion section 272 arranged sequentially along the electron beam transmission direction. The modulation section 271 is used to modulate the energy of the electron beam, and the dispersion section 272 is used to convert the energy modulation of the electron beam into density modulation to produce local high-density electron slices on the order of attoseconds or even zetaseconds, i.e., isolated ultrashort electron slices.

[0054] like Figure 4 As shown, the modulation section 271 includes a seed laser system 2711 and an undulator 2712. The seed laser system 2711 generates a seed laser, which is synchronously injected into the undulator 2712 along with the electron beam. The seed laser modulates the energy of the electron beam within the undulator 2712. The wavelength of the seed laser resonates with that of the undulator.

[0055]

[0056] Where λ is the resonant wavelength of the undulator, i.e., the wavelength of the seed laser. u This refers to the undulator period, i.e., the period of the electron beam's torsional motion, and K is the undulator magnetic field parameter. The wavelength of the seed laser typically needs to be larger than the longitudinal dimension of the electron beam's RMS. Six times that.

[0057] The dispersion section 272 can be a Doglg composed of two dipolar irons with the same strength but opposite magnetic poles, which can convert the energy modulation of the electron beam into density modulation.

[0058] The final longitudinal dimension of the isolated ultrashort electron slice obtained after the second-stage compression is: :

[0059]

[0060] in, denoted as the geometric emittance in the x-direction of the electron slice, and h as the slope of the longitudinal phase space (the relative deviation of the electron energy from the center), which measures the energy gradient generated by the interaction between the electron beam and the laser.

[0061] like Figure 5 As shown, the laser Compton scattering system 300 includes a Compton scattering laser system 310 and an interaction cavity 320. The Compton scattering laser system 310 is used to generate a Compton scattering laser. The Compton scattering laser and the isolated ultrashort electron slice are both fed into the interaction cavity 320. The isolated ultrashort electron slice collides with the Compton scattering laser in the interaction cavity 320 to generate an inverse Compton scattering gamma-ray pulse, i.e., an isolated ultrafast gamma-ray pulse.

[0062] To suppress the influence of the Compton scattering laser length on the final broadening of isolated gamma rays, the pulse width of the Compton scattering laser is... The following relationship must be satisfied:

[0063]

[0064] Because isolated ultrashort electron slices have attosecond or zetasecond time structures, the generated gamma-ray pulses can also have corresponding attosecond or zetasecond time widths. By adjusting the Compton scattering laser wavelength, the laser pulse energy, and the interaction angle, the output gamma-ray energy, bandwidth, and pulse quality can be adjusted.

[0065] The laser Compton scattering system 300 may also include a collimator 330 for collimating and outputting the generated isolated ultrafast gamma-ray pulses, for example, by screening small divergence propagation components to improve the directionality and application availability of the output gamma-ray pulses.

[0066] In some embodiments, the device may further include a gamma-ray detection and diagnostic unit for measuring pulse energy spectrum, angular distribution and temporal structure, and feeding the measurement results back to the electron beam and laser system to achieve closed-loop optimization.

[0067] The isolated ultrafast gamma-ray pulse generation device of this invention achieves high-quality, isolated, ultrashort (attosecond or zwitter second) electron beam slices suitable for laser Compton scattering through multidimensional phase space fine manipulation and hierarchical compression mechanism, thereby generating isolated ultrafast gamma-ray pulses.

[0068] like Figure 6 As shown, this embodiment of the invention also provides a method for generating isolated ultrafast gamma-ray pulses, which includes the following steps:

[0069] S10: Provide an isolated ultrafast gamma-ray pulse generating device as described in the above embodiments;

[0070] S20: The electron beam generation system generates an electron beam and transmits the electron beam to the first beam confinement device;

[0071] S30: The first beam confinement device performs the first beam scraping on the electron beam, and the electron beam after the first scraping is transmitted to the transverse deflection cavity;

[0072] S40: The transverse deflection cavity introduces the first transverse and longitudinal coupling into the electron beam after the first beam scraping, forming zx tilt correlation, and the electron beam with zx tilt correlation is transmitted to the acceleration section.

[0073] S50: The acceleration section accelerates the electron beam with zx tilt correlation, and the accelerated electron beam is then transmitted to the transverse matching section.

[0074] S60: The transverse matching section adjusts the Twiss parameters of the electron beam, and the adjusted electron beam is then transmitted to the first compression section;

[0075] S70: The first compression stage converts the zx tilt correlation of the electron beam into a longitudinal compression effect to achieve the first stage of compression. The compressed electron beam is then transmitted to the second beam confinement device.

[0076] S80: The second beam confinement device performs a second beam scraping on the first-stage compressed electron beam, and the electron beam after the second beam scraping is transmitted to the modulation section;

[0077] S90: The modulation section modulates the energy of the electron beam, and the energy-modulated electron beam is then transmitted to the dispersion section.

[0078] S100: The dispersive section converts the energy modulation of the electron beam into density modulation to produce isolated ultrashort electron slices, which are then transmitted to the laser Compton scattering system.

[0079] S110: The laser Compton scattering system causes inverse Compton scattering of isolated ultrashort electron slices and Compton scattering lasers to generate isolated ultrafast gamma-ray pulses.

[0080] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the invention. Various variations can be made to the above embodiments of the present invention. That is, all simple and equivalent changes and modifications made based on the claims and description of this invention fall within the protection scope of the claims of this patent. All aspects not described in detail in this invention are conventional technical content.

Claims

1. An isolated ultrafast gamma-ray pulse generating device, characterized in that, The system includes an electron beam generation system, a two-stage compression system, and a laser Compton scattering system. The electron beam generation system generates an electron beam, the two-stage compression system compresses the electron beam in two stages to obtain an isolated ultrashort electron slice, and the laser Compton scattering system causes the isolated ultrashort electron slice and the Compton scattering laser to undergo inverse Compton scattering to generate an isolated ultrafast gamma-ray pulse.

2. The isolated ultrafast gamma-ray pulse generating device according to claim 1, characterized in that, The electron beam is an electron beam with a preset energy and low charge.

3. The isolated ultrafast gamma-ray pulse generating device according to claim 1, characterized in that, The two-stage compression system includes a first beam confinement device, a lateral deflection cavity, an acceleration section, a lateral matching section, a first compression section, a second beam confinement device, and a second compression section. The first beam confinement device is used to perform a first beam scraping on the electron beam. The lateral deflection cavity is used to introduce a first segment of lateral-to-longitudinal coupling into the electron beam after the first beam scraping, forming a zx tilt correlation. The acceleration section is used to accelerate the electron beam with zx tilt correlation. The lateral matching section is used to adjust the Twiss parameter of the electron beam. The first compression section is used to convert the zx tilt correlation of the electron beam into a longitudinal compression effect to achieve a first-stage compression. The second beam confinement device is used to perform a second beam scraping on the electron beam after the first-stage compression. The second compression section is used to perform a second-stage compression on the electron beam after the second beam scraping to obtain the isolated ultrashort electron slice.

4. The isolated ultrafast gamma-ray pulse generating device according to claim 3, characterized in that, The first beam confinement device and the beam confinement device are at least one of an adjustable slit, a beam scraper, and a collimation and beam limiting assembly.

5. The isolated ultrafast gamma-ray pulse generating device according to claim 3, characterized in that, The first compression section is a dipolar iron.

6. The isolated ultrafast gamma-ray pulse generating device according to claim 3, characterized in that, The second compression section includes a modulation section and a dispersion section. The modulation section is used to modulate the energy of the electron beam, and the dispersion section is used to convert the energy modulation of the electron beam into density modulation to produce the isolated ultrashort electron slice.

7. The isolated ultrafast gamma-ray pulse generating device according to claim 6, characterized in that, The modulation section includes a seed laser system and a undulator. The seed laser system is used to generate a seed laser. The seed laser and the electron beam are synchronously injected into the undulator. The seed laser modulates the energy of the electron beam in the undulator. The dispersion segment is a Doglg composed of two dipolar irons with the same strength but opposite magnetic poles.

8. The isolated ultrafast gamma-ray pulse generating device according to claim 1, characterized in that, The laser Compton scattering system includes a Compton scattering laser system and an interaction cavity. The Compton scattering laser system is used to generate Compton scattering laser. Both the Compton scattering laser and the isolated ultrashort electron slice are fed into the interaction cavity. The isolated ultrashort electron slice collides with the Compton scattering laser in the interaction cavity to generate the isolated ultrafast gamma-ray pulse.

9. The isolated ultrafast gamma-ray pulse generating device according to claim 8, characterized in that, The laser Compton scattering system also includes a collimator for collimating and outputting the isolated ultrafast gamma-ray pulse.

10. A method for generating isolated ultrafast gamma-ray pulses, characterized in that, include: A device for generating isolated ultrafast gamma-ray pulses as described in claim 6 is provided; The electron beam generation system generates an electron beam and transmits the electron beam to the first beam confinement device; The first beam confinement device performs the first beam scraping on the electron beam, and the electron beam after the first beam scraping is transmitted to the transverse deflection cavity. The transverse deflection cavity introduces the first transverse and longitudinal coupling into the electron beam after the first beam scraping, forming zx tilt correlation, and the electron beam with zx tilt correlation is transmitted to the acceleration section. The acceleration section accelerates the electron beam with zx tilt correlation, and the accelerated electron beam is then transmitted to the transverse matching section. The transverse matching section adjusts the Twiss parameters of the electron beam, and the adjusted electron beam is then transmitted to the first compression section. The first compression stage converts the zx tilt correlation of the electron beam into a longitudinal compression effect to achieve the first stage of compression. The compressed electron beam is then transmitted to the second beam confinement device. The second beam confinement device performs a second beam scraping on the first-stage compressed electron beam, and the electron beam after the second beam scraping is transmitted to the modulation section. The modulation section modulates the energy of the electron beam, and the energy-modulated electron beam is then transmitted to the dispersion section. The dispersive section converts the energy modulation of the electron beam into density modulation to produce isolated ultrashort electron slices, which are then transmitted to the laser Compton scattering system. The laser Compton scattering system causes inverse Compton scattering of isolated ultrashort electron slices and Compton scattering lasers to generate isolated ultrafast gamma-ray pulses.

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