Device for generating zeptosecond γ-ray pulses

Abstract

The present invention relates to a device for generating zeptosecond γ-ray pulses, comprising a zeptosecond electron beam slicing generation system, a cavity, a Compton scattering laser system, and a collimation device. The zeptosecond electron beam slicing generation system, the cavity, and the collimation device are arranged in sequence along a first axis. The zeptosecond electron beam slicing system is used to generate a zeptosecond electron beam with high-density slices. The cavity is used to provide an interaction cavity. The Compton scattering laser system is used to generate pulsed laser light. The pulsed laser light and the zeptosecond electron beam with high-density slices undergo Compton scattering in the interaction cavity to generate zeptosecond γ-ray pulses. The collimation device is used to collimate the zeptosecond γ-ray pulses.

Description

Technical Field

[0001] The present invention relates to the field of ultrafast pulse generation, and more particularly to an attosecond gamma-ray pulse generation device. Background Art

[0002] Ultrafast X / gamma-ray pulses have important applications in detecting the ultrafast dynamics of substances, studying the internal structures of atoms and molecules, and exploring physical phenomena under extreme conditions. Currently, the only way to generate attosecond-scale ultrashort pulses of hard X-rays is through X-ray free electron laser devices. However, from the perspective of free electron laser physics, it is extremely limited and costly to achieve higher photon energies (in the MeV range) and pulse durations of dozens of attoseconds or even attosecond scale solely by means of free electron lasers. Therefore, there is an urgent need in this field for an easily implementable attosecond gamma-ray pulse generation device. Summary of the Invention

[0003] The object of the present invention is to provide an attosecond gamma-ray pulse generation device to generate attosecond-scale gamma-ray pulses with adjustable energy.

[0004] Based on the above object, the present invention provides an attosecond gamma-ray pulse generation device, which includes an attosecond-scale electron beam slicing generation system, a cavity, a Compton scattering laser system, and a collimation device. The attosecond-scale electron beam slicing generation system, the cavity, and the collimation device are arranged in sequence along a first axis; the attosecond-scale electron beam slicing generation system is used to generate an attosecond-scale electron beam with a high-density slice, the cavity is used to provide an interaction cavity, the Compton scattering laser system is used to generate pulsed laser, and the pulsed laser and the attosecond-scale electron beam with a high-density slice undergo Compton scattering in the interaction cavity to generate an attosecond-scale gamma-ray pulse; the collimation device is used to collimate the attosecond-scale gamma-ray pulse.

[0005] Optionally, the attosecond-scale electron beam slicing generation system includes an injector, a first linear accelerator, and an undulator. The injector is used to generate an electron beam, the first linear accelerator is used to accelerate the electron beam to a preset energy, and the undulator is used to cause the electron beam reaching the preset energy to undergo transverse oscillation to generate an electron beam with a microbunched structure as the attosecond-scale electron beam with a high-density slice.

[0006] Optionally, the injector, the first linear accelerator, and the undulator are arranged in sequence along the first axis.

[0007] Optionally, the undulator operates in the self-amplified spontaneous emission mode, and the resonance radiation wavelength of the undulator is less than 1 nanometer.

[0008] Optionally, the amplitude of the bunching factor of the electron beam with a micro-bunching structure is greater than 0.4.

[0009] Optionally, the zeptosecond-scale electron beam slicing generation system includes a photocathode electron gun, a transverse emittance exchange system, a second linear accelerator, and a chromaticity-driven micro-bunching system. The photocathode electron gun is used to generate a circular electron beam with a uniform transverse emittance. The transverse emittance exchange system is used to convert the circular electron beam into a flattened beam with a larger transverse emittance in one direction and a smaller transverse emittance in the other direction. The second linear accelerator is used to accelerate the flattened beam to a preset energy. The chromaticity-driven micro-bunching system is used to introduce chromaticity to the flattened beam with the preset energy and convert the flattened beam into a circular beam with a relatively uniform emittance, so as to obtain the zeptosecond-scale electron beam with high-density slices.

[0010] Optionally, the transverse emittance exchange system includes a solenoid coil, an accelerating cavity, and an inclined quadrupole iron group. The cathode of the photocathode electron gun is immersed inside the solenoid coil. The solenoid coil is used to magnetize the electron beam generated by the photocathode electron gun. The accelerating cavity is used to accelerate the magnetized electron beam. The inclined quadrupole iron group is used to convert the accelerated magnetized electron beam into a flattened beam.

[0011] Optionally, the inclined quadrupole iron group includes a first focusing inclined quadrupole iron, a defocusing quadrupole iron, and a second focusing inclined quadrupole iron arranged in sequence.

[0012] Optionally, the ratio of the emittance in the y direction to the emittance in the x direction of the flattened beam is 5.

[0013] Optionally, the chromaticity-driven micro-bunching system includes a dipole magnet, a few-cycle laser system, a modulation section, and a compression section. The dipole magnet is used to introduce chromaticity to the electron beam. The few-cycle laser system is used to generate a few-cycle laser. The electron beam with introduced chromaticity interacts with the few-cycle laser in the modulation section to generate energy modulation. The energy modulation is converted into density modulation in the compression section, so as to obtain the zeptosecond-scale electron beam with high-density slices.

[0014] The generation device of the zeptosecond γ-ray pulse of the present invention obtains an extremely short-duration γ-ray pulse, that is, a zeptosecond-scale γ-ray pulse, by using the micro-bunching structure generated in the free electron laser process or the high-density electron slices generated by the multi-dimensional phase space manipulation method to perform Compton scattering with a pulsed laser. Moreover, the ultrafast zeptosecond γ-ray pulse generated by this method is absolutely synchronous with the Compton scattering laser system, which is the key to the pump-probe technology. This technology can generate ultrafast high-energy (a few MeV to hundreds of MeV) γ-ray pulses in the attosecond and zeptosecond scales, and has important applications in aspects such as detecting nuclear dynamics processes and exploring physical phenomena under extreme conditions. Description of the Drawings

[0015] Figure 1 Schematic structural diagram of a zeptosecond γ-ray pulse generation device according to an embodiment of the present invention;

[0016] Figure 2 Schematic structural diagram of a kind of zeptosecond electron beam slicing system of the zeptosecond γ-ray pulse generation device according to an embodiment of the present invention;

[0017] Figure 3 Schematic structural diagram of another zeptosecond electron beam slicing system of the zeptosecond γ-ray pulse generation device according to an embodiment of the present invention;

[0018] Figure 4 For Figure 3 Schematic structural diagram of a transverse emittance exchange system of the zeptosecond electron beam slicing system;

[0019] Figure 5 For Figure 3 Schematic structural diagram of a role-dispersion-driven microbunching system of the zeptosecond electron beam slicing system. Detailed implementation manners

[0020] The following combines the accompanying drawings to give a preferred embodiment of the present invention and describes it in detail.

[0021] As Figure 1 shown, an embodiment of the present invention provides a zeptosecond γ-ray pulse generation device, which includes a zeptosecond electron beam slicing generation system 100, a cavity 200, a Compton scattering laser system 300 and a collimation device 400. The zeptosecond electron beam slicing generation system 100, the cavity 200 and the collimation device 400 are arranged in sequence along a first axis. The zeptosecond electron beam slicing system 100 is used to generate a zeptosecond electron beam with high-density slices. The cavity 200 is used to provide an interaction cavity. The Compton scattering laser system 300 is used to generate pulsed laser light and input the pulsed laser light into the interaction cavity. The pulsed laser light and the zeptosecond electron beam with high-density slices undergo Compton scattering in the interaction cavity to generate zeptosecond γ-ray pulses (for example, a single-peak γ-ray pulse of about 750 zeptoseconds); the collimation device 400 is used to filter out the small-divergence-angle γ-ray pulses that propagate collimated.

[0022] The generation principle of the zeptosecond γ-ray pulse in the embodiment of the present invention is as follows: The radiation pulse width generated by the laser Compton scattering of a relativistic (high-energy) electron beam mainly depends on the length of the electron beam. When the relativistic factor of the electrons is large enough, the width of the generated γ-ray pulse is almost equal to the length of the electron beam; since the electron beam generated by the zeptosecond electron beam slicing system 100 is of zeptosecond order, after it undergoes Compton scattering with the pulsed laser light, the generated γ-ray pulse is also of zeptosecond order.

[0023] In the interaction cavity, an attosecond-scale electron beam with a high-density slice and a laser can undergo Compton scattering at multiple angles (i.e., the emission angle of gamma rays) to adjust the energy of the generated scattered photons. The incident angle of the laser can be adjusted by a mirror, and the mirror is arranged in the interaction cavity. The energy of the scattered photons can also be adjusted by adjusting the wavelength of the pulsed laser generated by the Compton scattering laser system 300.

[0024] In the scope of linear Compton scattering, the energy E of the scattered photons can be expressed as:

[0025] 。

[0026] Among them, is the energy of the laser photons (h is Planck's constant, c is the speed of light, is the wavelength of the incident laser), is the angle between the electron and the photon interaction, which is π here, θ is the emission angle of the gamma rays relative to the electron motion trajectory, 。

[0027] As Figure 2 shown, in some embodiments, the attosecond-scale electron beam slice generation system 100 may include an injector 110, a first linear accelerator 120, and a wiggler 130. The injector 110, the first linear accelerator 120, and the wiggler 130 are arranged in sequence along a first axis. The injector 110 is used to generate an electron beam, the first linear accelerator 120 is used to accelerate the electron beam to a preset energy, and the wiggler 130 is used to make the electron beam with the preset energy undergo transverse oscillation to generate an electron beam with a microbunched structure (i.e., an attosecond-scale electron beam with a high-density slice).

[0028] The wiggler 130 is set to satisfy the resonance relation formula of free electron laser:

[0029] 。

[0030] Among them, is the wiggler radiation resonance wavelength, that is, the free electron laser radiation wavelength, γ is the relativistic factor of the electron beam bunch, which is related to the electron energy, is the wiggler period, that is, the period of the electron beam bunch's pendulum motion, is the wiggler magnetic field parameter. By changing γ, and , the radiation resonance wavelength can be continuously adjusted. The undulator 130 can be in the self-amplified spontaneous emission (SASE) mode or the externally seeded free electron laser high-gain high-harmonic generation (HGHG) mode. For the generation of zeptosecond γ-ray pulses, the undulator 130 can only be selected in the self-amplified spontaneous emission mode, and the resonance radiation wavelength is set to X-rays less than 1 nanometer.

[0031] The combined functions of the injector 110, the first linear accelerator 120, and the undulator 130 need to be satisfied. After the electron beam generated by the injector 110 is accelerated by the first linear accelerator 120, the quality and energy of the electron beam are sufficient to generate a sufficiently good microbunching structure in the undulator 130. The degree of microbunching in the electron beam is quantified by the bunching factor, and the amplitude of the bunching factor is between 0 and 1, and the amplitude of the bunching factor is preferably greater than 0.4.

[0032] Based on the use of Figure 2 The method for generating zeptosecond γ-ray pulses by the zeptosecond γ-ray pulse generation device of the zeptosecond electron beam slicing generation system 100 includes the following steps:

[0033] S510: The injector 110 generates an electron beam, and the electron beam is accelerated by the first linear accelerator 120 to a preset energy. The electron beam with the preset energy oscillates laterally in the undulator 130 to form a microbunching structure with a period of the undulator radiation wavelength, and the undulator radiation wavelength is at least less than 1 nanometer;

[0034] S520: The electron beam with the microbunching structure undergoes Compton scattering with the pulsed laser in the interaction cavity to generate zeptosecond γ-ray pulses. The angle between the incident pulsed laser and the propagation direction of the electron beam is adjustable to control the energy of the generated scattered γ-rays;

[0035] S530: Since the pulse width of the generated pulse is extremely narrow, the propagation process will cause the pulse to broaden. Therefore, a collimation device 400 is also required to collimate the zeptosecond γ-ray pulses.

[0036] As Figure 3 shown, in some embodiments, the zeptosecond electron beam slicing generation system 100 may include a photocathode electron gun 140, a transverse emittance exchange system 150, a second linear accelerator 160, and a chromatic dispersion-driven microbunching system 170. The photocathode electron gun 140 is used to generate a circular electron beam bunch with a uniform transverse emittance. The transverse emittance exchange system 150 is used to convert the circular electron beam bunch into a flattened bunch with a larger transverse emittance in one direction and a smaller transverse emittance in the other direction. The second linear accelerator 160 is used to accelerate the flattened bunch to a preset energy (for example, 1.5 GeV). The chromatic dispersion-driven microbunching system 170 is used to introduce chromatic dispersion to the flattened bunch with the preset energy and convert the flattened bunch into a circular bunch with a more uniform emittance to obtain a zeptosecond-scale electron beam with a high-density slice.

[0037] As shown Figure 4 In some embodiments, as shown, the transverse emittance exchange system 150 includes a solenoid coil 151, an accelerating cavity 152, and an inclined quadrupole iron group 153 arranged in sequence along a first axis. The cathode of the photocathode electron gun 140 is immersed inside the solenoid coil 151. The solenoid coil 151 is used to magnetize the electron beam generated by the photocathode electron gun 140. Specifically, from the generation of the electron beam to its exit from the solenoid coil, due to the different intensity distributions of the magnetic field along the radial direction at the exit of the solenoid coil 151, it will cause the particles moving longitudinally to form a coupling in the transverse direction. Such an electron beam is called a magnetized electron beam; the accelerating cavity 152 is used to accelerate the magnetized electron beam to increase its energy to several megaelectron volts, and the inclined quadrupole iron group 153 is used to convert the magnetized electron beam into a flattened bunch. The ratio of the emittance in the y direction to the emittance in the x direction of the flattened bunch is about 5.

[0038] In some embodiments, the inclined quadrupole iron group 153 includes a first focusing inclined quadrupole iron 1531, a defocusing quadrupole iron 1532, and a second focusing inclined quadrupole iron 1533 arranged in sequence along the first axis.

[0039] In some embodiments, the angular dispersion-driven microbunching system 170 includes a dipole iron 171, a few-cycle laser system 172, a modulation section 173, and a compression section 174. The dipole iron 171 is used to introduce angular dispersion to the electron beam with a preset energy. The few-cycle laser system 172 is used to generate a few-cycle laser. The electron beam with introduced angular dispersion interacts with the few-cycle laser in the modulation section 173 to generate an energy modulation, and its modulation depth is close to 100 times the energy spread of the electron beam; the energy modulation of the electron beam is converted into a density modulation in the compression section 174, thereby generating local extremely high-density electron slices in the electron beam, and the emittance of the electron beam in the x direction and the emittance in the y direction tend to be equal. The modulation section 173 can be a single-cycle undulator composed of periodic magnet blocks, and the compression section 174 is composed of two dipole irons with the same intensity and opposite magnetism.

[0040] The wavelength of the few-cycle laser can be 400 nanometers, and the duration is about 3 femtoseconds; the resonance wavelength of the modulation section 173 is also 400 nanometers, which satisfies the free electron laser resonance formula.

[0041] Based on the method for generating a zeptosecond γ-ray pulse by the zeptosecond γ-ray pulse generating device of the zeptosecond electron beam slicing system 100 using Figure 3 includes the following steps:

[0042] S610: The photocathode electron gun 140 generates a circular electron beam with a uniform transverse emittance. The circular electron beam passes through the transverse emittance exchange system 150 and is converted into a flattened bunch with a larger emittance in one transverse direction and a smaller emittance in the other transverse direction.

[0043] S620: The flattened beam is accelerated to a preset energy by the second linear accelerator 160, and the electron beam with the preset energy enters the chromaticity-driven microbunching system 170;

[0044] S630: The chromaticity-driven microbunching system 170 is used to introduce chromaticity to the flattened beam bunch with the preset energy and convert the flattened beam into a circular beam with a relatively uniform emittance, so as to obtain an electron beam with a zeptosecond order of magnitude and high-density slices;

[0045] S640: The electron beam with a zeptosecond order of magnitude and high-density slices undergoes Compton scattering with the pulsed laser in the interaction cavity to generate a zeptosecond γ-ray pulse;

[0046] S650: The collimation device 400 collimates the zeptosecond γ-ray pulse.

[0047] The device for generating zeptosecond γ-ray pulses according to the embodiments of the present invention obtains γ-ray pulses with an extremely short duration, that is, γ-ray pulses with a zeptosecond order of magnitude, by using the microbunching structure generated during the free electron laser process or the high-density electron slices generated by the multi-dimensional phase space manipulation method to perform Compton scattering with the pulsed laser. Moreover, the ultrafast zeptosecond γ-ray pulses generated by this method are absolutely synchronized with the Compton scattering laser system, which is the key to the pump-probe technology. This technology can generate ultrafast high-energy (a few MeV to hundreds of MeV) γ-ray pulses with an attosecond and zeptosecond order of magnitude, and has important applications in aspects such as detecting nuclear dynamics processes and exploring physical phenomena under extreme conditions.

[0048] The above-mentioned are only the preferred embodiments of the present invention, and are not intended to limit the scope of the present invention. Various changes can be made to the above embodiments of the present invention. That is, all simple, equivalent changes and modifications made according to the claims and the content of the specification of the present invention application fall within the scope of the claims of the present invention patent. The content not described in detail in the present invention is all conventional technical content.

Claims

1. A device for generating picosecond γ-ray pulses, characterized in that, It includes a zeptosecond-scale electron beam slicing generation system, a cavity, a Compton scattering laser system, and a collimation device. The zeptosecond-scale electron beam slicing generation system, the cavity, and the collimation device are arranged in sequence along a first axis; the zeptosecond-scale electron beam slicing system is used to generate a zeptosecond-scale electron beam with high-density slices, the cavity is used to provide an interaction cavity, the Compton scattering laser system is used to generate pulsed laser, and the pulsed laser and the zeptosecond-scale electron beam with high-density slices undergo Compton scattering in the interaction cavity to generate a zeptosecond-scale γ-ray pulse; the collimation device is used to collimate the zeptosecond-scale γ-ray pulse. The zeptosecond-scale electron beam slicing generation system includes a photocathode electron gun, a transverse emittance exchange system, a second linear accelerator, and a chromaticity-driven microbunching system. The photocathode electron gun is used to generate a circular electron beam with uniform transverse emittance. The transverse emittance exchange system is used to convert the circular electron beam into a flattened beam with a larger transverse emittance in one direction and a smaller transverse emittance in the other direction. The second linear accelerator is used to accelerate the flattened beam to a preset energy. The chromaticity-driven microbunching system is used to introduce chromaticity to the flattened beam with the preset energy and convert the flattened beam into a circular beam with relatively uniform emittance to obtain the zeptosecond-scale electron beam with high-density slices.

2. The generating device for zepto-second γ-ray pulses according to claim 1, wherein, The transverse emittance exchange system includes a solenoid coil, an accelerating cavity, and an oblique quadrupole iron group. The cathode of the photocathode electron gun is immersed in the interior of the solenoid coil. The solenoid coil is used to magnetize the electron beam generated by the photocathode electron gun. The accelerating cavity is used to accelerate the magnetized electron beam. The oblique quadrupole iron group is used to convert the accelerated magnetized electron beam into a flattened beam.

3. The generating device for the zepto-second γ-ray pulse according to claim 2, wherein, The oblique quadrupole iron group includes a first focusing oblique quadrupole iron, a defocusing quadrupole iron, and a second focusing oblique quadrupole iron arranged in sequence.

4. The generating device of the zepto-second γ-ray pulse according to claim 2, wherein, The ratio of the y-direction emittance to the x-direction emittance of the flattened beam is 5.

5. The generating device of the zepto-second γ-ray pulse according to claim 1, wherein The chromaticity-driven microbunching system includes a dipole magnet, a few-cycle laser system, a modulation section, and a compression section. The dipole magnet is used to introduce chromaticity to the electron beam. The few-cycle laser system is used to generate a few-cycle laser. The electron beam with introduced chromaticity interacts with the few-cycle laser in the modulation section to generate energy modulation. The energy modulation is converted into density modulation in the compression section to obtain the zeptosecond-scale electron beam with high-density slices.

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