Double-pulse free electron laser generation device and method based on room temperature accelerator

Abstract

The present invention provides a dual-pulse free electron laser generating device based on a room temperature accelerator, comprising a driving laser system for generating a dual-pulse driving laser, a photocathode electron gun system for generating a dual-pulse electron bunch, a room temperature linear accelerator system for accelerating the dual-pulse electron bunch, and an undulator system for radiating the dual-pulse free electron laser. The present invention also provides a corresponding dual-pulse free electron laser generating method based on a room temperature accelerator. The dual-pulse free electron laser generating device based on a room temperature accelerator of the present invention generates a dual-pulse driving laser, generates a dual-pulse electron bunch in a photocathode electron gun, and then realizes energy acceleration of the dual-pulse electron bunch in a flat-top pulse microwave, and finally realizes the generation of a dual-pulse free electron laser in an undulator, thereby increasing the repetition frequency of the device operation.

Description

Technical Field

[0001] The present invention belongs to the field of free electron laser advanced light source generation, and in particular relates to a double-pulse free electron laser generation device and method based on a room temperature accelerator. Background Art

[0002] Free electron laser technology based on room temperature accelerator is an emerging advanced laser technology. It uses room temperature linear accelerator to accelerate electron beam to relativistic electron energy, and produces coherently amplified ultra-high brightness, ultra-short pulse, wavelength tunable free electron laser radiation through torsional motion in an undulator with periodic magnetic field changes. The excellent performance of free electron laser has a broad and profound influence in cutting-edge scientific research, advanced industrial manufacturing and other fields, and can be used for research in multiple disciplines such as physics, chemistry, materials, and biology.

[0003] However, due to limitations of high-power devices and challenges in equipment complexity, the operating repetition frequency of free electron laser devices based on room-temperature accelerators is generally low, usually ranging from tens of hertz to a hundred hertz, which limits the role of free electron laser devices.

[0004] Therefore, how to further improve the repetition frequency of free electron laser devices based on room-temperature accelerators has important significance and value in science and industry. Summary of the invention

[0005] The object of the present invention is to provide a double-pulse free electron laser generating device and method based on a room temperature accelerator to generate a double-pulse free electron laser with high pulse energy, so as to increase the operating repetition frequency of the device to twice the original repetition frequency.

[0006] In order to achieve the above-mentioned purpose, the present invention provides a dual-pulse free electron laser generating device based on a room-temperature accelerator, comprising a driving laser system for generating a dual-pulse driving laser, a photocathode electron gun system for generating a dual-pulse electron bunch, a room-temperature linear accelerator system for accelerating the dual-pulse electron bunch, and an undulator system for radiating a dual-pulse free electron laser, which are arranged in sequence.

[0007] The driving laser system, the photocathode electron gun system, the room temperature linear accelerator system and the undulator system are sequentially arranged on the first axis.

[0008] The driving laser system is configured to generate two laser pulses with adjustable time intervals and consistent parameters as a double-pulse driving laser;

[0009] The photocathode electron gun system is configured to generate a double-pulse electron bunch with a time interval through a photoelectric effect when the double-pulse driving laser hits the photocathode surface of the photocathode electron gun system.

[0010] The driving laser system includes a laser oscillator, a first regenerative amplifier and a second regenerative amplifier connected to the output end of the laser oscillator, a pulse delayer connected to the control ends of the first regenerative amplifier and the second regenerative amplifier, a beam combiner, a frequency tripler and a transmission optical path module connected in sequence to the output ends of the first regenerative amplifier and the second regenerative amplifier.

[0011] The central wavelengths of the two laser pulses generated by the driving laser system are both 266 nm, the maximum repetition frequency is both 50 Hz, and the time interval between the two laser pulses is adjustable within the range of 0-100 ns.

[0012] The room temperature linear accelerator system is configured to simultaneously accelerate and boost the energy of the double-pulse electron bunches in a flat-top microwave output mode, so as to ensure that the beam parameters and quality of the high-energy double-pulse electron bunches generated by acceleration are substantially consistent.

[0013] The room temperature linear accelerator system is configured to control the power of its microwave power source through its low level control system, thereby realizing switching between the flat-top microwave output mode and the natural attenuation output mode.

[0014] The undulator system is configured to satisfy the resonance relationship formula of the free electron laser, so that the high-energy double-pulse electron bunch radiates double-pulse free electron laser after passing through the undulator system.

[0015] On the other hand, the present invention provides a method for generating a double-pulse free electron laser based on a room temperature accelerator, comprising:

[0016] S1: providing the above-mentioned dual-pulse free electron laser generating device based on a room temperature accelerator, and using a driving laser system to generate two laser pulses with adjustable time intervals and consistent parameters as a dual-pulse driving laser;

[0017] S2: The dual-pulse driving laser is injected into the photocathode electron gun system to generate a dual-pulse electron bunch; the dual-pulse electron bunch is injected into the room-temperature linear accelerator system to generate a high-energy dual-pulse electron bunch; the high-energy dual-pulse electron bunch is injected into the undulator system to generate a dual-pulse free electron laser.

[0018] In the step S1, a driving laser system is used to generate two laser pulses with adjustable time intervals and consistent parameters as a double-pulse driving laser, specifically including:

[0019] S11: Turn on the first regenerative amplifier of the driving laser system, turn off the second regenerative amplifier, inject the first single pulse laser into the photocathode electron gun system to generate the first single pulse bunch, scan the accelerating tube phase of the normal temperature linear accelerator system to obtain the maximum energy gain near the peak phase, inject the first single pulse bunch into the undulator system, and realize the separate light amplification of the first single pulse bunch, so as to verify that the first single pulse bunch can work;

[0020] S12: Turn off the first regenerative amplifier, turn on the second regenerative amplifier, inject the second single pulse laser into the photocathode electron gun to generate a second single pulse bunch, adjust the beam parameters to make the parameters of the two electron bunches consistent; inject the second single pulse bunch into the undulator system, so that the second single pulse bunch is amplified separately to verify that the second single pulse bunch can work;

[0021] S13: Fixed working status of photocathode electron gun system, room temperature linear accelerator system and undulator system;

[0022] S14: turning off the second regenerative amplifier and turning on the first regenerative amplifier to make the first single pulse bunch work and the second single pulse bunch stop working; scanning the time delay of the laser system to enable the first single pulse bunch to generate free electron laser radiation;

[0023] S15: Turn on the first regenerative amplifier and the second regenerative amplifier simultaneously, so that the two laser pulses output by the driving laser system with adjustable time intervals and consistent parameters are injected into the photocathode electron gun system as double-pulse driving lasers.

[0024] The double-pulse free electron laser generating device based on a room temperature accelerator of the present invention generates a double-pulse driving laser, generates a double-pulse electron bunch in an electron gun, and then realizes energy acceleration of the double-pulse electron bunch in a flat-top pulse microwave, and finally realizes double-pulse free electron laser generation in an undulator to increase the repetition frequency. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic structural diagram of a double-pulse free electron laser generating device based on a room temperature accelerator of the present invention.

[0026] Figure 2 yes Figure 1 The schematic diagram of the structure of the driving laser system of the dual-pulse free electron laser generating device is shown.

[0027] Figure 3 yes Figure 1 The figure shows a comparison between the flat-top microwave output mode for accelerating double-pulse bunches and the conventional natural attenuation output mode of the room-temperature linear accelerator system of the double-pulse free electron laser generating device.

[0028] Figure 4 It is a longitudinal phase space distribution diagram of a high-energy double-pulse electron bunch generated in an experiment by the double-pulse free electron laser generating device based on a room temperature accelerator of the present invention.

[0029] Figure 5 The present invention is a result of measuring the energy of free electron laser pulses generated by a double-pulse free electron laser generating device based on a room temperature accelerator in an experiment, when the high-energy double-pulse electron bunch is operated individually and simultaneously. DETAILED DESCRIPTION

[0030] The present invention will be further described below in conjunction with embodiments and drawings, but the protection scope of the present invention shall not be limited thereto.

[0031] like Figure 1 FIG. 1 is a schematic structural diagram of a double-pulse free electron laser generating device based on a room temperature accelerator according to an embodiment of the present invention. Figure 2 yes Figure 1 A schematic structural diagram of a driving laser system of a dual-pulse free electron laser generating device shown; Figure 3 yes Figure 1 A comparison diagram of a flat-top microwave output mode for accelerating a double-pulse bunch and a conventional natural decay output mode of a room temperature linear accelerator system of a double-pulse free electron laser generating device shown; Figure 4 It is the longitudinal phase space distribution of the double-pulse electron bunch generated by the double-pulse free electron laser generating device based on the room temperature accelerator in the experiment of the present invention; Figure 5 It is the energy measurement result of the free electron laser pulses generated when the dual pulse bunches operate separately and simultaneously in the experiment.

[0032] like Figure 1 As shown, the dual-pulse free electron laser generating device based on a room temperature accelerator of the present invention comprises a driving laser system 1 for generating a dual-pulse driving laser 11, a photocathode electron gun system 2 for generating a dual-pulse electron bunch 21, a room temperature linear accelerator system 3 for accelerating the dual-pulse electron bunch 21, and an undulator system 4 for radiating a dual-pulse free electron laser 41. The driving laser system 1, the photocathode electron gun system 2, the room temperature linear accelerator system 3 and the undulator system 4 are sequentially arranged on the first axis along the direction of the dual-pulse driving laser and the dual-pulse electron bunch.

[0033] like Figure 2The device diagram of the driving laser system 1 is shown, and the driving laser system 1 includes a laser oscillator 10, a first regenerative amplifier 12 and a second regenerative amplifier 13 connected to the output end of the laser oscillator 10, a pulse delayer 14 connected to the control end of the first regenerative amplifier 12 and the second regenerative amplifier 13, a beam combiner 15, a frequency tripler 16 and a transmission optical path module 17 connected to the output ends of the first regenerative amplifier 12 and the second regenerative amplifier 13 in sequence. The driving laser system 1 is configured to generate two laser pulses with adjustable time intervals and consistent parameters as a double-pulse driving laser 11.

[0034] In this embodiment, the wavelength of the laser pulse output by the oscillator 10 is 800nm, and the laser pulse enters the first regenerative amplifier 12 and the second regenerative amplifier 13 for power amplification (the regenerative amplifier 12 and the regenerative amplifier 13 can work independently). The pulse delayer 14 controls the time interval between the two laser pulses output by the regenerative amplifier 12 and the regenerative amplifier 13 by controlling the delay of the laser pulse output by the regenerative amplifier 12 and the regenerative amplifier 13. After the two laser pulses are combined by the beam combiner 15 and passed through the tripler 16, the wavelength is converted to 266nm, and then injected into the photocathode electron gun system 2 through the transmission optical path module 17, thereby driving the photocathode electron gun system 2 to generate a double-pulse electron beam. The central wavelength of the two laser pulses generated by the driving laser system 1 is 266nm, the maximum repetition frequency is 50Hz, and the time interval between the two laser pulses is adjustable in the range of 0-100ns.

[0035] By the above Figure 2 The double pulse driving laser 11 generated by the driving laser system 1 is injected into Figure 1 In the photocathode electron gun system 2 shown. The photocathode electron gun system 2 is configured to generate a double-pulse electron bunch 21 with a time interval through a photoelectric effect when the double-pulse driving laser 11 hits the photocathode surface of the photocathode electron gun system 2. The principle of the photoelectric effect of the double-pulse driving laser 11 interacting with the electron gun photocathode to generate an electron bunch is that the double-pulse driving laser 11 interacts with the photocathode surface, and the photon energy is transferred to the electrons of the cathode material, so that they obtain sufficient energy to be excited and escape, forming an electron bunch.

[0036] The photocathode electron gun system 2 is also configured to accelerate the double-pulse electron bunches through a microwave radio frequency field and focus them through a focusing system to form a high-brightness, high-energy double-pulse electron bunch. The advantages of the photocathode electron gun system 2 include high emission brightness, short pulse width, high energy, and good beam quality and controllability.

[0037] The central wavelength, pulse energy and repetition frequency of the dual-pulse driving laser 11 have a decisive influence on the characteristics of the electron beam. In this embodiment, the characteristics of the dual-pulse electron bunch generated by the dual-pulse driving laser irradiating the photocathode electron gun system are as follows: the energy is ~5MeV, the charge is 500 / 470pC respectively, and the time interval between the dual bunches is about 2.1ns.

[0038] The double pulse electron bunch 21 generated by the photocathode electron gun system 2 is injected into Figure 1 In the room temperature linear accelerator system 3 shown, the flat-top microwave power pulses in the room temperature linear accelerator system 3 are used to continuously accelerate the double-pulse electron bunch 21, and finally generate a high-energy double-pulse electron bunch 31.

[0039] The room temperature linear accelerator system 3 is composed of several sets of microwave acceleration units, each of which has a low-level control system, a microwave power source and an acceleration structure connected in sequence, and is configured to control the power of the microwave power source through the low-level control system, thereby realizing the switching between the flat-top microwave output mode and the natural attenuation output mode. Among them, the low-level control system uses an adaptive algorithm to control the output waveform, so as to arbitrarily select two output modes, and has an energy multiplier (SLED) that can use an adaptive algorithm to output flat-top microwave power pulses for dual-pulse electron bunch acceleration. In the present invention, the room temperature linear accelerator system 3 is configured to simultaneously accelerate and boost the energy of the dual-pulse electron bunch 21 in the flat-top microwave output mode to ensure that the beam parameters and quality of the high-energy dual-pulse electron bunch 31 generated by the acceleration are basically consistent.

[0040] Figure 3 The diagram shows a comparison of the flat-top microwave output mode (solid line with a flat top) and the conventional natural attenuation output mode (solid line with a peak) of the room temperature linear accelerator system 3 for accelerating the dual pulse bunches. Due to the characteristics of the energy multiplier, the microwave power distribution of the normal microwave power output has a peak, and the acceleration capabilities corresponding to different phases in the pulse vary greatly, which cannot meet the requirements of the dual bunches running at the same energy at different times. Therefore, it is necessary to feed-forward modulate the input signal of the energy multiplier to achieve a microwave power pulse output mode with a flat-top distribution. The flat-top microwave output mode needs to ensure that the difference in acceleration energy between the two bunches when they pass by does not exceed 1%. This flat-top microwave output mode is original to this case.

[0041] The low-level control system uses an adaptive algorithm to control the flat-top microwave output waveform. The adaptive control algorithm can automatically adjust the control strategy by online identification of the dynamic characteristics of the environment, input data or model system to ensure that the best control effect can always be achieved. In this embodiment, the low-level control system pre-sets the target power to be controlled as the flat-top microwave power output pulse, and constrains the conditions, and then performs multiple matrix multiplication operations to make the entire output waveform approach the actual required flat-top output waveform. Compared with the natural attenuation output mode, the flat-top microwave output mode has a wider flat-top microwave pulse width, and the flat-top microwave pulse width exceeds 500ns. The dual-pulse electron bunch 21 can be accelerated under basically the same conditions at the same time, so that the dual-pulse electron bunch maintains a basically consistent beam quality, which is conducive to the ultimate use of the dual-pulse electron bunch to simultaneously realize the dual-pulse free electron laser working and luminescence.

[0042] Figure 4 The longitudinal phase space distribution diagram of the high-energy double-pulse electron bunch generated by the double-pulse free electron laser generating device based on the room temperature accelerator of the present invention in the experiment is shown, with the horizontal axis being the beam energy and the vertical axis being the time. The energy of the high-energy double-pulse electron bunch 31 is about 660 MeV, and the time interval is about 2.1 ns. In this embodiment, the energy of the high-energy double-pulse electron bunch 31 is about 660 MeV, and other beam parameters such as emittance and peak current intensity remain basically the same.

[0043] The undulator system 4 includes several radiation-segment undulators with adjustable gaps. It is a key component in synchrotron light sources and free electron lasers, and is mainly used to generate extremely bright X-ray and ultraviolet light sources. The main function of the undulator is to force the electron beam to move along a specific trajectory through a periodic magnetic field, thereby generating free electron laser radiation.

[0044] In the present invention, the undulator system 4 is configured to satisfy the resonance relationship formula of the free electron laser, so that the high-energy double-pulse electron bunch 31 radiates double-pulse free electron laser after passing through the undulator system 4. Thus, the double-pulse free electron laser is operated simultaneously, and the repetition frequency of the device is improved.

[0045] Among them, the resonance relationship formula of free electron laser is:

[0046]

[0047] in is the resonance wavelength, i.e. the wavelength of free electron laser radiation, is the relativistic factor of the high-energy electron bunch, is the undulator period, i.e. the period of the electron bunch wiggling motion, is the undulator magnetic field parameter.

[0048] Thus, the high energy double pulse electron bunch 31 is injected into Figure 1 The undulator system 4 shown is used to simultaneously generate dual-pulse free electron laser radiation. In the present invention, a self-amplified spontaneous radiation mechanism is used to generate dual-pulse free electron lasers, and its principle is: the relativistic electron bunch performs periodic torsional motion in the undulator, and the radiation light generated by each periodic motion of the electrons is in the same phase as the radiation light generated by the previous periodic motion, so that the radiation light is coherently enhanced, and at the same time, the enhanced radiation light will react on the electron bunch, so that a micro-cluster structure with a period consistent with the radiation wavelength is gradually formed in the high-energy electron beam, and these micro-cluster structures will directly generate super-strong coherent light when they continue to generate radiation, and continue to amplify in subsequent periodic torsional motion until saturation is finally reached.

[0049] In the present invention, each electron bunch can generate free electron laser radiation. Therefore, under the condition of satisfying the above-mentioned resonance relationship formula of the free electron laser principle, the double-pulse high-energy electron bunch can simultaneously generate double-pulse free electron laser radiation to improve the repetition frequency of the device operation. At the same time, the time interval of the double-pulse free electron laser can be changed by changing the time delay of the double-pulse electron bunch.

[0050] Figure 5 The figure shows the pulse energy detection results of the free electron laser of the high-energy double-pulse electron bunch generated in the double-pulse free electron laser generating device based on the room temperature accelerator of the present invention when operating alone and simultaneously, wherein the scatter point 1 is the intensity of the first pulse of the double-pulse free electron laser, and the intensity detection result of the X-ray gas detector (XGMD) is 662pA (maximum value), the scatter point 2 is the light intensity of the second pulse of the double-pulse free electron laser, and the XGMD detection result is 1067pA (maximum value), the scatter point 3 is the sum of the pulse energy detection of the double-pulse free electron laser, and the XGMD measurement result is 1351pA (maximum value), the solid line 1 is the normalized charge of the first electron bunch of the double-pulse electron bunch 0.7, the solid line 2 is the normalized charge of the second electron bunch of the double-pulse electron bunch 0.6, and the solid line 3 is the total charge of the double-pulse electron bunch 1. This measurement was repeated twice, so there are two groups of results, and due to the existence of factors such as diagnostic methods and measurement errors, the charge of the double bunch and the intensity measurement results of the double pulse are not a simple superposition of the single bunch operation.

[0051] According to the above-mentioned double-pulse free electron laser generating device based on a room temperature accelerator, the double-pulse free electron laser generating method based on a room temperature accelerator comprises the following steps:

[0052] Step S1: providing the above-mentioned double-pulse free electron laser generating device based on a room temperature accelerator, and using a driving laser system 1 to generate two laser pulses with adjustable time intervals and consistent parameters as a double-pulse driving laser 11;

[0053] In this embodiment, the central wavelengths of the two laser pulses generated by the driving laser system 1 are both 266 nm, the maximum repetition frequency is both 50 Hz, and the time interval between the two pulses is adjustable from 0 to 100 ns.

[0054] In this embodiment, by setting the pulse delayer 5, the time interval between two laser pulses is about 2.1ns. The time interval can be adjusted individually as needed without affecting other device parameters and states. The adjustment range is 0-100ns.

[0055] Wherein, in the step S1, the driving laser system 1 is used to generate two laser pulses with adjustable time intervals and consistent parameters as the double-pulse driving laser 11, which specifically includes:

[0056] Step S11: Turn on the first regenerative amplifier 12 of the driving laser system 1, turn off the second regenerative amplifier 13, inject the first single pulse laser into the photocathode electron gun system 2 to generate the first single pulse bunch, scan the accelerating tube phase of the room temperature linear accelerator system 3 to obtain the maximum energy gain near the peak phase, inject it into the downstream undulator system 4, perform FEL debugging, realize the separate light amplification of the first single pulse bunch, and verify that the first single pulse bunch can work;

[0057] Step S12: turn off the first regenerative amplifier 12, turn on the second regenerative amplifier 13, inject the second single pulse laser into the photocathode electron gun to generate a second single pulse bunch, adjust the beam parameters so that the parameters of the two electron bunches are basically the same, and inject into the downstream undulator system 4 so that the second single pulse bunch is amplified separately to verify that the second single pulse bunch can work;

[0058] Step S13: Fix the working states of the photocathode electron gun system, the room temperature linear accelerator system and the undulator system to ensure that the light emission of the second single pulse bunch is not affected.

[0059] Step S14: turn off the second regenerative amplifier 13, turn on the first regenerative amplifier 12, make the first single pulse bunch work, and stop the second single pulse bunch; scan the time delay of the laser system 1 to enable the first single pulse bunch to generate free electron laser radiation.

[0060] Step S15: Turn on the first regenerative amplifier 12 and the second regenerative amplifier 13 simultaneously, so that the two laser pulses with adjustable time intervals and consistent parameters output by the driving laser system 1 are injected into the photocathode electron gun system 2 as a double-pulse driving laser 11 .

[0061] Step S2: The dual-pulse driving laser 11 is injected into the photocathode electron gun system 2 to generate a dual-pulse electron bunch 21; the dual-pulse electron bunch 21 is injected into the room-temperature linear accelerator system 3 to generate a high-energy dual-pulse electron bunch 31; the high-energy dual-pulse electron bunch 31 is injected into the undulator system 4 to generate a dual-pulse free electron laser 41.

[0062] The double-pulse free electron laser generating device based on a room temperature accelerator of the present invention generates a double-pulse driving laser with an adjustable time interval of 0-100 ns by adopting a double-pulse driving laser system, which acts on the surface of the electron gun photocathode, generates a double-pulse electron bunch by the photoelectric effect, and then accelerates and increases the energy of the double-pulse electron bunch in the flat-top microwave pulse output by the room temperature linear accelerator system. Then the high-energy electron bunch is injected into the downstream undulator system, thereby radiating light with a double-pulse free electron laser, thereby improving the repetition frequency of such free electron laser devices based on room temperature accelerators, and further improving the experimental light efficiency of users of terminal experimental stations.

[0063] In addition, the pulse time interval of the double-pulse free electron laser radiation can be changed by adjusting the double-pulse driving laser system in the present invention, and can be used to carry out advanced free electron laser pumping-free electron laser detection experiments.

[0064] The above is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. The above embodiments of the present invention can also be modified in various ways. All simple, equivalent changes and modifications made according to the claims and the description of the present invention fall within the scope of protection of the claims of the present invention. The contents not described in detail in the present invention are all conventional technical contents.

Claims

1. A double-pulse free electron laser generating device based on a room temperature accelerator, characterized in that: It includes a driving laser system for generating a double-pulse driving laser, a photocathode electron gun system for generating a double-pulse electron bunch, a room-temperature linear accelerator system for accelerating the double-pulse electron bunch, and an undulator system for radiating a double-pulse free electron laser.

2. The double-pulse free electron laser generating device based on a room temperature accelerator according to claim 1, characterized in that: The driving laser system, the photocathode electron gun system, the room temperature linear accelerator system and the undulator system are sequentially arranged on the first axis.

3. The double-pulse free electron laser generating device based on a room temperature accelerator according to claim 1, characterized in that: The driving laser system is configured to generate two laser pulses with adjustable time intervals and consistent parameters as a double-pulse driving laser; The photocathode electron gun system is configured to generate a double-pulse electron bunch with a time interval through a photoelectric effect when the double-pulse driving laser hits the photocathode surface of the photocathode electron gun system.

4. The double-pulse free electron laser generating device based on a room temperature accelerator according to claim 3, characterized in that: The driving laser system includes a laser oscillator, a first regenerative amplifier and a second regenerative amplifier connected to the output end of the laser oscillator, a pulse delayer connected to the control ends of the first regenerative amplifier and the second regenerative amplifier, a beam combiner, a frequency tripler and a transmission optical path module connected in sequence to the output ends of the first regenerative amplifier and the second regenerative amplifier.

5. The double-pulse free electron laser generating device based on a room temperature accelerator according to claim 3, characterized in that: The central wavelengths of the two driving laser pulses generated by the driving laser system are both 266 nm, the maximum repetition frequency is both 50 Hz, and the time interval between the two laser pulses is adjustable within the range of 0-100 ns.

6. The double-pulse free electron laser generating device based on a room temperature accelerator according to claim 1, characterized in that: The room temperature linear accelerator system is configured to simultaneously accelerate and boost the energy of the double-pulse electron bunches in a flat-top microwave output mode, so as to ensure that the beam parameters and quality of the high-energy double-pulse electron bunches generated by acceleration are substantially consistent.

7. The double-pulse free electron laser generating device based on a room temperature accelerator according to claim 6, characterized in that: The room temperature linear accelerator system is configured to control the power of its microwave power source through its low level control system, thereby realizing switching between the flat-top microwave output mode and the natural attenuation output mode.

8. The double-pulse free electron laser generating device based on a room temperature accelerator according to claim 1, characterized in that: The undulator system is configured to satisfy the resonance relationship formula of the free electron laser, so that the high-energy double-pulse electron bunch radiates double-pulse free electron laser after passing through the undulator system; The resonance relationship formula of free electron laser is: , in is the resonance wavelength, i.e. the wavelength of free electron laser radiation, is the relativistic factor of the high-energy electron bunch, is the undulator period, i.e. the period of the electron bunch wiggling motion, is the undulator magnetic field parameter.

9. A method for generating a double-pulse free electron laser based on a room temperature accelerator, characterized in that: include: Step S1: providing a dual-pulse free electron laser generating device based on a room temperature accelerator as described in any one of claims 1 to 8, and using a driving laser system to generate two laser pulses with adjustable time intervals and consistent parameters as a dual-pulse driving laser; Step S2: injecting a double-pulse driving laser into the photocathode electron gun system to generate a double-pulse electron bunch; The double-pulse electron bunch is injected into the room-temperature linear accelerator system to produce a high-energy double-pulse electron bunch; the high-energy double-pulse electron bunch is injected into the undulator system to produce a double-pulse free electron laser.

10. The method for generating double-pulse free electron laser based on room temperature accelerator according to claim 9, characterized in that: The driving laser system comprises a laser oscillator, a first regenerative amplifier and a second regenerative amplifier connected to the output end of the laser oscillator, a pulse delayer connected to the control ends of the first regenerative amplifier and the second regenerative amplifier, a beam combiner, a frequency tripler and a transmission optical path module connected in sequence to the output ends of the first regenerative amplifier and the second regenerative amplifier; In the step S1, a driving laser system is used to generate two laser pulses with adjustable time intervals and consistent parameters as a double-pulse driving laser, specifically including: Step S11: turning on the first regenerative amplifier of the driving laser system and turning off the second regenerative amplifier, injecting the first single pulse laser into the photocathode electron gun system to generate the first single pulse bunch, scanning the accelerating tube phase of the normal temperature linear accelerator system to obtain the maximum energy gain near the peak phase, injecting the first single pulse bunch into the undulator system to achieve the separate light amplification of the first single pulse bunch, so as to verify that the first single pulse bunch can work; Step S12: turn off the first regenerative amplifier, turn on the second regenerative amplifier, inject the second single pulse laser into the photocathode electron gun to generate a second single pulse bunch, adjust the beam parameters to make the parameters of the two electron bunches consistent; inject the second single pulse bunch into the undulator system, so that the second single pulse bunch is amplified separately to verify that the second single pulse bunch can work; Step S13: fixing the working states of the photocathode electron gun system, the room temperature linear accelerator system and the undulator system; Step S14: turning off the second regenerative amplifier and turning on the first regenerative amplifier to make the first single pulse bunch work and the second single pulse bunch stop working; scanning the time delay of the laser system to make the first single pulse bunch generate free electron laser radiation; Step S15: turning on the first regenerative amplifier and the second regenerative amplifier simultaneously, so that the two laser pulses output by the driving laser system with adjustable time intervals and consistent parameters are injected into the photocathode electron gun system as double-pulse driving lasers.

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