CN119414442A - Synchrotron Radiation X-ray Pulse Time Width Measurement Device - Google Patents

Abstract

The invention relates to a synchronous radiation X-ray pulse time width measuring device which comprises a main clock, time synchronous control equipment, an X-ray stripe camera and an upper computer, wherein the main clock is used for providing a time reference for a synchronous radiation light source, the time synchronous control equipment is connected with the main clock, the X-ray stripe camera is connected with the time synchronous control equipment, the upper computer is respectively connected with the time synchronous control equipment and the X-ray stripe camera, the upper computer is used for enabling the time synchronous control equipment to transmit a trigger signal to the X-ray stripe camera according to the time reference of the main clock, a preset delay is arranged between the trigger signal and the time reference of the main clock, the X-ray stripe camera is used for receiving X-ray pulses generated by the synchronous radiation light source, acquiring and outputting X-ray pulse images under the triggering of the trigger signal, and the X-ray pulse images are transmitted to the upper computer so that the upper computer acquires the time width of the X-ray pulses according to the X-ray pulse images.

Description

Synchronous radiation X-ray pulse time width measuring device

Technical Field

The invention relates to the technical field of synchrotron radiation light sources, in particular to a synchrotron radiation X-ray pulse time width measuring device.

Background

The synchrotron radiation light source is an X-ray source capable of providing high brightness, wide frequency spectrum and short pulse, and is widely applied to the front-edge fields of material science, life science, ultrafast dynamics and the like. One notable feature of synchrotron radiation X-rays is that their pulses have extremely short temporal widths, typically on the order of picoseconds or even sub-picoseconds, which makes them uniquely advantageous in studying ultrafast processes, chemical reaction kinetics, and ultrafast biological imaging.

However, despite these advantages, synchrotron radiation light sources require a hybrid electron beam cluster injection mode in which only a single large electron beam cluster is available for the experiment without affecting the development of other experiments when performing experiments such as laser pumping, X-ray monopulse imaging, etc. The optical density of X-ray pulses generated by a single electron beam cluster is low, signals are weak, and especially when the pulse width is measured in an extremely short time, the number of photons is limited, so that the detection difficulty is increased. For example, the length of an open sea light Source Storage Ring (SSRF) storage ring is 432 meters, the time for a large electron beam cluster to rotate around a synchrotron radiation storage ring is about 1.44 microseconds, the theoretical width of the electron beam cluster pulse is only 80 picoseconds, and the accurate positioning of a narrow pulse under a relatively long convolution time also increases the detection difficulty.

Currently, commonly used X-ray pulse measurement devices include photodiode-based, gas ionization chambers, streak cameras, and the like. However, when these devices face the situations of low X-ray optical density, weak pulse, and great difficulty in signal positioning in synchrotron radiation light sources, it is often difficult to achieve sufficient signal strength while ensuring time resolution. For example, photodiodes are difficult to detect with high sensitivity under low optical density conditions, and the gas ionization chamber has greater difficulty in resolving the time scale of the signal with ultra-narrow pulse widths. Although the streak camera has higher time resolution characteristics, when the streak camera is used for collecting signals with low signal to noise ratio, the measurement accuracy is greatly affected by noise, and signals with enough strength are difficult to collect under the condition of ensuring the time resolution.

Disclosure of Invention

The invention aims to provide a synchronous radiation X-ray pulse time width measuring device, so that enough signals are acquired under the condition of ensuring time resolution, and picosecond-order time width measurement of X-ray pulses is realized.

The invention provides a synchrotron radiation X-ray pulse time width measuring device, which comprises a main clock, a time synchronization control device, an X-ray stripe camera and an upper computer, wherein the main clock is used for providing a time reference for a synchrotron radiation light source, the time synchronization control device is connected with the main clock, the X-ray stripe camera is connected with the time synchronization control device, the upper computer is respectively connected with the time synchronization control device and the X-ray stripe camera, the upper computer is used for enabling the time synchronization control device to transmit a trigger signal to the X-ray stripe camera according to the time reference of the main clock, a preset time delay is arranged between the trigger signal and the time reference of the main clock, the X-ray stripe camera is used for receiving X-ray pulses generated by the synchrotron radiation light source, acquiring and outputting X-ray pulse images under the triggering of the trigger signal, and the X-ray pulse images are transmitted to the upper computer so that the upper computer acquires the time widths of the X-ray pulses according to the X-ray pulse images.

Further, the X-ray stripe camera comprises a light clamping slit, a photocathode, a photoanode, a scanning device, a signal enhancement device, a fluorescent screen and an imaging device, wherein the light clamping slit, the photocathode, the photoanode, the scanning device, the signal enhancement device, the fluorescent screen and the imaging device are sequentially arranged along the X-ray transmission direction, the photocathode is used for generating photoelectrons by generating photoelectric effect with X-ray pulse, the photoanode is used for accelerating the photoelectrons, the scanning device is used for enabling photoelectrons at different times to deflect to different degrees, the fluorescent screen is used for enabling the photoelectrons which are hit on the fluorescent screen to emit light, and the imaging device is used for shooting images of the fluorescent screen.

Further, the trigger signals comprise a first trigger signal, a second trigger signal and a third trigger signal, wherein the first trigger signal is used for being transmitted to the scanning device so as to enable the scanning device to start working, the second trigger signal is used for being transmitted to the signal enhancement device so as to enable the signal enhancement device to start working, and the third trigger signal is used for being transmitted to the image pickup device so as to enable the image pickup device to start photographing.

Further, the delay of the first trigger signal with respect to the time reference of the master clock is less than the delay of the second trigger signal with respect to the time reference of the master clock is less than the delay of the third trigger signal with respect to the time reference of the master clock.

Further, the image pickup device is configured to collect a plurality of images within a preset integration time, wherein each image includes a plurality of pixel points, the X-ray stripe camera further includes a data processing module, the data processing module is configured to average, for each pixel point, a pixel value of the pixel point of each image as a pixel value of the pixel point of a new image, and is configured to send the new image to the upper computer as an X-ray pulse image output by the X-ray stripe camera.

Further, the X-ray pulse image includes space width information of the X-ray pulse, and the upper computer is configured to determine a time width of the X-ray pulse according to the space width information of the X-ray pulse.

Further, the signal enhancement device comprises a first micro-channel plate and a second micro-channel plate which are sequentially arranged along the X-ray transmission direction, wherein the first micro-channel plate is used for primarily amplifying the photoelectron signal, and the second micro-channel plate is used for further amplifying the photoelectron signal.

Further, the master clock comprises an alternating current power supply, a radio frequency signal source, a first timing event generator and a first timing signal repeater, wherein the alternating current power supply and the radio frequency signal source are respectively connected with the first timing event generator, the first timing event generator is connected with the first timing signal repeater, and the first timing signal repeater is connected with the time synchronization control equipment.

Further, the time synchronization control device comprises a second timing signal relay, a first signal generating device, a second signal generating device and a third signal generating device, wherein the first signal generating device, the second signal generating device and the third signal generating device are respectively connected with the second timing signal relay, the second timing signal relay is connected with the first timing signal relay, the first signal generating device is used for generating a first trigger signal, the second signal generating device is used for generating a second trigger signal, and the third signal generating device is used for generating a third trigger signal.

Further, the first signal generating device comprises a second timing event generator, a first timing event receiver and a first photoelectric converter which are sequentially connected, wherein the second timing event generator is connected with the second timing signal repeater, and the first photoelectric converter is connected with the scanning device;

The second signal generating device comprises a third timing event generator, a second timing event receiver and a second photoelectric converter which are sequentially connected, wherein the third timing event generator is connected with the second timing signal repeater, and the second photoelectric converter is connected with the signal enhancing device;

The third signal generating device comprises a fourth timing event generator, a third timing event receiver and a third photoelectric converter which are sequentially connected, wherein the fourth timing event generator is connected with the second timing signal repeater, and the third photoelectric converter is connected with the image pickup device.

The synchronous radiation X-ray pulse time width measuring device is synchronous with the main clock through the time synchronous control equipment and outputs the trigger signal for triggering the X-ray stripe camera, so that the X-ray pulse time width measurement with picosecond precision can be realized, and the X-ray pulse image output by the X-ray stripe camera is obtained by integrating pulse images acquired for a plurality of times within the preset time, so that the signal to noise ratio can be improved.

Drawings

FIG. 1 is a schematic diagram of a synchrotron radiation X-ray pulse time width measurement device according to an embodiment of the present invention;

FIG. 2 is a schematic structural view of an X-ray streak camera according to an embodiment of the present invention;

fig. 3 is a schematic structural diagram of a signal enhancement device according to an embodiment of the present invention;

Fig. 4 is a schematic structural view of a master clock and time synchronization control apparatus according to an embodiment of the present invention;

FIG. 5 is a spatial image of an X-ray pulse generated by a large electron beam cluster obtained by an X-ray streak camera at 600 picosecond scan in accordance with an embodiment of the present invention, converted into a temporal image of the X-ray pulse;

fig. 6 is an X-ray pulse time distribution diagram obtained by sequentially performing 4 times of 10 picosecond delay acquisition on X-ray pulses generated by a large electron beam cluster by using an X-ray fringe camera and extracting the X-ray pulses therein for gaussian fitting according to an embodiment of the present invention.

Detailed Description

Preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

As shown in fig. 1, the synchrotron radiation X-ray pulse time width measuring apparatus of the embodiment of the present invention is used for measuring the time width of an X-ray pulse of a synchrotron radiation light source 100, and comprises a master clock 200, a time synchronization control device 300, an X-ray stripe camera 400 and an upper computer 500, wherein the master clock 200 is used for providing a stable and accurate time reference for the synchrotron radiation light source 100, which can synchronize the operation of each component of the synchrotron radiation light source 100 by distributing a time signal thereof, the time synchronization control device 300 is connected with the master clock 200 and is located under the same clock network as the master clock 200, the X-ray stripe camera 400 is connected with the time synchronization control device 300, the upper computer 500 is respectively connected with the time synchronization control device 300 and the X-ray stripe camera 400, the upper computer 500 is used for enabling the time synchronization control device 300 to generate a trigger signal according to the time reference of the master clock 200 and enabling the time synchronization control device 300 to transmit the trigger signal to the X-ray stripe camera 400, wherein the trigger signal and the time reference of the master clock 200 have a preset time delay (i.e. the trigger signal is generated after the time of the preset time delay from the time reference of the master clock 200), the trigger signal is started, the X-ray stripe camera 400 is used for receiving the X-ray image acquisition of the X-ray image acquisition pulse image of the X-ray pulse, and the X-ray image acquisition of the X-ray pulse image is obtained by the X-ray pulse image acquisition of the X-ray pulse image of the X-ray pulse camera is obtained by the upper computer 500, and the upper computer 500.

As shown in fig. 2, in some embodiments, the X-ray stripe camera 400 includes a light blocking slit 410, a photocathode 420, a photoanode 430, a scanning device 440, a signal enhancement device 450, a fluorescent screen 460 and an image pickup device 470 sequentially arranged along the X-ray transmission direction, wherein the light blocking slit 410 is used for reducing the area of incident X-rays and preventing the image pickup device 470 from overexposure, and the photocathode 420 is used for generating photoelectrons by generating photoelectric effect with the X-rays, and gold material is selected as a cathode, so that the photoelectrons have high photoelectric conversion efficiency in the X-ray energy range of 5KeV to 30 KeV; the photo anode 430 is used for accelerating photoelectrons generated at the photo cathode 420, the scanning device 440 is used for forming a changed electric field according to a changed scanning voltage, the changed electric field deflects the photoelectrons when the photoelectrons pass through the scanning device 440, when the photoelectrons at different times pass through the scanning device 440, the photoelectrons deflect to different degrees due to the difference of the electric field, thus the time information of the photoelectrons can be converted into space information, for example, the scanning device 440 can generate a linearly enhanced electric field through a voltage which increases linearly with time, so that the photoelectrons passing through the scanning device 440 later deviate farther, the photoelectrons passing through the scanning device 440 at different positions of the fluorescent screen 460 are amplified by the signal enhancement device 450, the signal intensity is increased, the signal to noise ratio is increased, the photoelectrons are sequentially passed through the scanning device 440 and the signal enhancement device 450 and are irradiated on the fluorescent screen 460, the image pickup device 470 is used for shooting images of the fluorescent screen 460, the photoelectrons at different degrees of deflection when passing through the scanning device 440, the positions of the fluorescent screen are different, that is, the spatial positions of photoelectrons at different times on the X-ray pulse image are also different, and the time interval between two photoelectrons can be obtained through the spatial distance between any two photoelectrons on the image. The scanning device 440 may have a plurality of scanning steps, and each scanning step corresponds to a different speed of the scanning voltage with respect to time, and also corresponds to a different scanning range (i.e., a time range of photoelectrons that can be displayed on the image of the image capturing device 470). The upper computer 500 is configured to control the scanning position of the scanning device 440, that is, during measurement, the upper computer 500 can set a desired scanning position, and then the upper computer 500 can make the scanning device 400 operate in the scanning position, so as to obtain an image of photoelectrons that are driven on the fluorescent screen 460 in a time corresponding to the scanning position.

In some embodiments, the time synchronization control apparatus 300 may include three channels, each of which may generate a trigger signal, namely, a first trigger signal S1, a second trigger signal S2 and a third trigger signal S3, respectively, where the trigger signals include the first trigger signal S1, the second trigger signal S2 and the third trigger signal S3, the first trigger signal S1 is used for transmitting to the scanning device 440, the scanning device 440 is used for starting to operate after receiving the first trigger signal S1 (i.e. generating a varying electric field to deflect photoelectrons), the second trigger signal S2 is used for transmitting to the signal enhancement device 450, the signal enhancement device 450 starts to operate after receiving the second trigger signal S2 (i.e. amplifying the photoelectric signal), the third trigger signal S3 is used for transmitting to the image capturing device 470, the image capturing device 470 captures the image on the screen 460 after receiving the third trigger signal S3, so as to obtain the X-ray pulse image, and the image capturing device 470 will transmit the image to the host computer 500, and the host computer 500 determines the time width of the X-ray pulse according to the image.

In measurement, it is generally desirable to operate the scanning device 440 when the photoelectrons are transmitted to the scanning device 440, to operate the signal enhancing device 450 after the photoelectrons are transmitted to the signal enhancing device 450, and to make the image capturing device 470 capture images of the screen 460 after the photoelectrons are captured on the screen 460, so that other parasitic images can be prevented from being captured, and noise can be reduced, and thus the delays of the first trigger signal S1, the second trigger signal S2, and the second trigger signal S3 relative to the time reference of the main clock 200 are different, and in particular, the delays are related to the time when the first photoelectrons generated by the X-ray pulse generated by the electron beam to be measured are captured on the screen 460 and the structural parameters of the X-ray stripe camera 400. Specifically, assuming that the time delay of the first photoelectron generated by the X-ray pulse generated by the electron beam to be measured when it strikes the phosphor screen 460 is T0 with respect to the time reference of the main clock 200, i.e., the time delay of the first photoelectron generated by the X-ray pulse generated by the electron beam to be measured when it strikes the phosphor screen 460 after passing through T0 is T0, the time delay of the third trigger signal S3 with respect to the time reference may be set to be T0, the time delay of the second trigger signal S2 with respect to the time reference of the main clock 200 is T0- Δt1, and the time delay of the third trigger signal S3 with respect to the time reference of the main clock 200 is T0- Δt2, where Δt1 and Δt2 are parameters related to the structure of the X-ray stripe camera 400, for example, Δt1=Δt2=1 microsecond. Therefore, the delay of the first trigger signal S1 is smaller than the delay of the second trigger signal S2 is smaller than the delay of the third trigger signal S3.

The method for determining T0 in the embodiment of the invention is as follows:

By adjusting the scanning voltage to have the maximum scanning range of the X-ray streak camera 400, that is, by setting the time-varying scanning voltage to the slowest level, the time scale of the image presented on the image pickup device 470 is the maximum level, for example, the scanning range of the X-ray streak camera 400 may be made to be 4 microseconds, that is, the captured image may display photoelectrons occurring within 4 microseconds, and the period of the electron beam mass to be measured for generating the X-ray pulse in the synchrotron radiation light source 100 is generally smaller than the maximum scanning range of the X-ray streak camera 400, for example, 1.44 microseconds, so that the X-rays generated by the electron beam mass to be measured at least twice may be seen when the X-ray streak camera 400 uses the 4 microsecond level for scanning. in this gear, all photoelectrons generated by the X-ray pulse generated by the electron beam cluster to be measured can be displayed on the image captured by the X-ray streak camera 400, and then the rough value of T0 can be estimated from the image. However, since the pixel of the image capturing apparatus 470 adopted in the present invention is 2048×2048 Pixels ², in the 4 microsecond range, the time width corresponding to a single pixel is about 2ns, which is far greater than the pulse width of the X-ray pulse of the electron beam cluster to be detected, so that the X-ray pulse of the electron beam cluster to be detected observed in the maximum scanning range is only a bright spot of one pixel, and only the T0 moment with 2ns precision can be obtained according to the bright spot. therefore, the first trigger signal S1 is obtained according to the rough value of T0, The time delay of the second trigger signal S2 and the third trigger signal S3 is reduced by one step, the scanning range of the X-ray stripe camera 400 is reduced by one step, an image under the reduced scanning range is shot, if all photoelectrons of the X-ray pulse are not displayed in the image, the time delay of each trigger signal needs to be regulated again, all photoelectrons of the X-ray pulse can be displayed in the image, if all photoelectrons of the X-ray pulse can be displayed in the image, the regulation is not needed, a new T0 is obtained according to the image of all photoelectrons capable of displaying the X-ray pulse, then the new time delay of each trigger signal is set according to the new T0, then the scanning range of the X-ray stripe camera 400 is reduced again, an image is shot under the reduced scanning range and the new time delay of each trigger signal, an updated T0 value is determined according to the image of all photoelectrons capable of displaying the X-ray pulse under the reduced scanning range, then the operation is repeated until the scanning range of the X-ray stripe camera 400 is regulated to the minimum T0, and the maximum accurate T0 is obtained. For example, the scanning range of the X-ray streak camera 400 is 4 microseconds, 20 nanoseconds, 10 nanoseconds, 5 nanoseconds, 2 nanoseconds and 600 picoseconds in order from large to small, when determining T0, the scanning range is made to be 4 microseconds, T0 under the scanning range is acquired, then the scanning range is adjusted to 20 nanoseconds, T0 under 20 nanoseconds is acquired, and so on until T0 under 600 microseconds is acquired, at a gear of 600 picoseconds, the precision of a single pixel is about 0.3 picoseconds, and at this time T0 is also a required accurate value.

After determining T0, the delays of the first trigger signal S1, the second trigger signal S2, and the third trigger signal S3 may be obtained respectively, then the upper computer 500 may obtain an X-ray pulse image output by the X-ray stripe camera 400 in a minimum scanning range within a preset time (usually 1 second), and according to the image, a spatial distance between a first photon and a last photon of an X-ray pulse of the electron beam to be measured may be calculated, and then a time interval of the first photon and the last photon may be determined according to the spatial distance, where the time interval is a time width of the X-ray pulse of the electron beam to be measured.

Specifically, for any two photons a and B, assuming a time interval of Δt, the scan voltage of photon a is V _A as it passes through scanning device 400, the scan voltage of photon B is V _B as it passes through scanning device 400, the spatial interval of photons a and B present on phosphor screen 460 is Δx, and the conversion relationship between Δt and Δx is:

ΔX=ΔT×|V_A-V_B|

The frequencies of the first trigger signal S1, the second trigger signal S2 and the third trigger signal S3 may be set to be the same, and in theory, they are preferably the same as the frequency of the X-ray pulse, but in consideration of the fact that the frequency is too high to cause damage to the X-ray streak camera 400 due to the too high temperature, their frequencies may be set to any value below the highest value that the X-ray streak camera 400 can withstand, and the higher their frequencies, the more accurate the measurement result will be.

In some embodiments, the X-ray streak camera 400 may further include a data processing module (not shown in the figure), where the data processing module has a function of multiple integration, specifically, the image capturing device 470 may collect N times of data within the integration time according to the integration time set by the host computer 500, that is, collect N images, where N is a value obtained by rounding down the product of the integration time and the frequency of the trigger signal, and the data processing module averages, for each pixel of the image, the pixel value of the pixel of the N images, as the pixel value of the pixel of a new image, where the new image is the result of multiple pulse triggering and collection integration, and then sends the new image to the host computer 500 as an X-ray pulse image output by the X-ray streak camera 400, where the host computer 500 calculates the time width of the X-ray pulse according to the new image.

Since the time synchronization control device 300 can synchronize with the master clock 200 of the synchrotron radiation light source 100, so that the delay length of the output pulse of the time synchronization control device 300 is kept constant, and the first trigger signal S1, the second trigger signal S2 and the third trigger signal S3 are provided by the time synchronization control device 300, the respective constant delay lengths of the X-ray pulses generated by the electron beam cluster to be detected can be respectively kept constant, so that the same pulse signal can be acquired by the X-ray stripe camera 300 for multiple times at the same position, and a method for improving the signal to noise ratio by integrating the multiple acquisitions becomes possible.

In some embodiments, the image capture device 470 may be a CCD (charge coupled device) camera.

As shown in fig. 3, in some embodiments, the signal enhancement device 450 may include a first micro-channel plate 451 and a second micro-channel plate 452 sequentially disposed, where the first micro-channel plate 451 is used for primarily amplifying the optoelectronic signal, and the gain coefficient of the first micro-channel plate 451 is G1, and the second micro-channel plate 452 is used for further enhancing the optoelectronic signal, and if the intensity of the optoelectronic signal of the input signal enhancement device 450 is Sin and the intensity of the optoelectronic signal of the output signal enhancement device 450 is Sout, there is sout=sin×g1×g2.

As shown in fig. 4, the master clock 200 may include an ac power source 210, a radio frequency signal source 220, a first timing event generator 230 and a first timing signal repeater 240, where the ac power source 210 and the radio frequency signal source 220 are connected to the first timing event generator 230, the first timing event generator 230 is connected to the first timing signal repeater 240, the first timing signal repeater 240 is connected to the time synchronization control device 300, the ac power source 210 is used to supply power, the radio frequency signal source 220 is used to generate a crystal oscillator clock signal, the first timing event generator 230 is used to generate and distribute various timing signals, the first timing signal repeater 240 is used to distribute the crystal oscillator clock signal to the time synchronization control device 300, and the first timing signal repeater 240 is also used to distribute the crystal oscillator clock signal to each line station to ensure time synchronization.

The time synchronization control apparatus 300 may include a second timing signal repeater 310, a first signal generating device 320, a second signal generating device 330 and a third signal generating device 340, the first signal generating device 320, the second signal generating device 330 and the third signal generating device 340 being respectively connected to the second timing signal repeater 310, the second timing signal repeater 310 being connected to the first timing signal repeater 240, the second timing signal repeater 310 being for maintaining stability of the timing signal transmitted over a long distance, the first signal generating device 320 being for generating the first trigger signal S1, the second signal generating device 330 being for generating the second trigger signal S2, the third signal generating device 340 being for generating the third trigger signal S3.

The first signal generating device 320 may include a second timing event generator 321, a first timing event receiver 322, and a first photoelectric converter 323 connected in sequence, the second timing event generator 321 is configured to transmit a new timing signal according to a timing signal transmitted by the master clock 100, the first timing event receiver 322 is configured to receive and decode the timing signal transmitted by the second timing event generator 321, and transmit the timing signal to the first photoelectric converter 323, the first photoelectric converter 323 is configured to convert an optical signal into an electrical signal, that is, a first trigger signal S1, and the first photoelectric converter 323 is connected with the scanning device 440 to transmit the first trigger signal S1 to the scanning device 440; the second signal generating means 330 may include a third timing event generator 331, a second timing event receiver 332, and a second photoelectric converter 333 connected in sequence, the third timing event generator 331 for transmitting a new timing signal according to the timing signal transmitted from the master clock 100, the second timing event receiver 332 for receiving the timing signal transmitted from the third timing event generator 331 and decoding it to transmit to the second photoelectric converter 333, the second photoelectric converter 333 for converting the optical signal into an electrical signal, i.e., a second trigger signal S2, the second photoelectric converter 333 being connected to the signal enhancing means 450 to transmit the second trigger signal S2 to the signal enhancing means 450, the third signal generating means 340 may include a fourth timing event generator 341, a third timing event receiver 342, and a third photoelectric converter 343 connected in sequence, the third timing event generator 341 for transmitting the new timing signal according to the timing signal transmitted from the master clock 100, the third timing event receiver 342 for receiving the fourth timing event generator 341 and transmitting the third trigger signal to decoding it to the third photoelectric converter 343, the third photoelectric converter 343 is configured to convert the optical signal into an electrical signal, i.e., a third trigger signal S3, and the third photoelectric converter 343 is connected to the image capturing device 470 to send the third trigger signal S3 to the image capturing device 470.

In some embodiments, the upper computer 500 may be provided with first software written in python language for controlling the state monitoring and parameter setting of the time synchronization control device 300, where the first software has a state monitoring module, which may be used to set the time synchronization control device 300 to synchronize with the master clock 200 and detect the synchronization state with the master clock 200, and the state monitoring module may also have functions of receiver state monitoring, system-integrated enabled state monitoring and device internal hardware connection state monitoring, so as to facilitate fault detection when the device works abnormally. The upper computer 500 may further be provided with second software for controlling parameter setting and status monitoring of the X-ray stripe camera 400, where the second software includes functions of static/dynamic mode switching, scanning range selection, triggering on-off switching, camera status monitoring, camera acquisition parameter setting, image preview and storage, etc. Wherein, the static mode is a single acquisition mode, and the dynamic acquisition is a cyclic acquisition mode. The optional scan range ranges are 600 ps, 2 ns, 5 ns, 10 ns, 20 ns, 4 μs. Triggering on-off switching is the selection of an external trigger source and an internal trigger source. The camera state monitoring comprises the functions of scanning circuit bias voltage state monitoring, MCP gain voltage state monitoring, photoelectric cathode and anode voltage state monitoring and the like. The camera acquisition parameter setting comprises functions of integration time setting, trigger mode setting, scanning gear setting and the like. The image preview and storage includes functions of display contrast setting, image storage path setting, whether the picture is stored or not, and image preview. The user can operate the high-precision X-ray stripe camera 400 through the second software of the upper computer 500 and preview and store the data acquisition result. The first software and the second software are packaged software, and can be formed into two functional modules after being installed in the upper computer 500, and the time synchronization control device 300 and the X-ray stripe camera 400 can be controlled by the two functional modules respectively, so that high-precision time width measurement is realized.

For example, synchrotron radiation light source 100 can be a synchrotron radiation storage ring with a circumference of 432 meters, and an electron beam cluster needs 1.44 microseconds around the storage ring, so that the frequency of the electron beam cluster generating X-ray pulses is about 694KHz. In the hybrid cluster injection mode, there is one large cluster of 80 picoseconds and 200 small clusters of 20 picoseconds in width in the storage ring. The large electron beam bolus is spaced 400 nanoseconds from the small electron beam bolus, and the spacing between the small electron beam boluses is 3.2 nanoseconds. In experiments, large electron beam clusters are common, and therefore, the time width of the X-ray pulses generated by the large electron beam cluster needs to be measured by the measuring device of the present invention. The frequency of the main clock 200 is 500MHz, so that the frequencies of the first trigger signal S1, the second trigger signal S2 and the third trigger signal S3 are all 173.5Hz in consideration of that the trigger frequency of the X-ray stripe camera 400 cannot be too fast, that is, when the large electron beam group winds around the synchrotron radiation storage ring 4000 times, the X-ray pulse image is acquired by the X-ray stripe camera 400 once, and since the large electron beam group in the synchrotron radiation storage ring is relatively stable on the time scale of picosecond, for example, on the order of 10 picoseconds, the stability of each trigger signal is required to realize repeated measurement of multiple pulses. The clock jitter of the time synchronization control device 300 of the measuring device of the invention is maximally 3.36 picoseconds, which is smaller than the time resolution of the X-ray fringe camera 400 by 7.3 picoseconds and smaller than the time width of the large electron beam group by 10 picoseconds, so that the time synchronization control device can completely meet the picosecond-level stability requirement of each trigger signal in the measurement of the time width of the X-ray pulse. That is, the accuracy of the time synchronization control apparatus 300 of the present invention can reach the picosecond level, and thus the synchrotron radiation X-ray pulse time width measuring device of the present invention can realize measurement of picosecond accuracy. The specific experimental measurement results are as follows:

As shown in FIG. 5, the time image of the X-ray pulse converted from the image of the large electron beam cluster generated by the X-ray stripe camera 400 in 600 picoseconds is shown, the width of the white light spot along the ordinate direction is the time width of the X-ray pulse, and the time width of the X-ray pulse is about 80 picoseconds and is similar to the theoretical time width of the large electron beam cluster from the result in the figure, and the noise point in the figure is less, so that the measuring device can effectively improve the signal-to-noise ratio and solve the problem of low signal-to-noise ratio when the X-ray stripe camera is independently used for collecting single pulse. As shown in fig. 6, an X-ray pulse time distribution diagram obtained by performing gaussian fitting on X-ray pulses generated by a large electron beam group at an original position and sequentially performing 4 times of 10 picosecond delay collection and extracting the X-ray pulses therein by using an X-ray stripe camera 400 is shown, wherein the original position collection refers to the collection of the first trigger signal S1, the second trigger signal S2 and the third trigger signal S3 respectively with the delays of T0-2 microseconds, T0-1 microseconds and T0, the 10 picosecond delay collection refers to the collection of each trigger signal on the basis of the original position, namely, the first trigger signal S1, the second trigger signal S2 and the third trigger signal S3 respectively with the delays of T0-2 microseconds-10 picoseconds, T0-1 microsecond-10 picoseconds and T0-10 picoseconds, the first trigger signal S1, the second trigger signal S2 and the third trigger signal S3 respectively with the delays of T0-20 picoseconds, the delays of T0-20 picoseconds and the delays of 20 picoseconds, and the data obtained by performing the delays of T0-20 picoseconds. In fig. 6, the dashed circle marks the original position data, namely the position acquired at the original position, the black square marks the data after delaying for 10 picoseconds, the pentagonal marks the data after delaying for 20 picoseconds, the inverted triangle marks the data after delaying for 30 picoseconds, the left triangle marks the data after delaying for 40 picoseconds, the data above the pulse waveform is used for representing the pixel number corresponding to the moment corresponding to the pulse peak, the pixel number is respectively 56, 72, 88, 113 and 134, the pixel number is respectively 24.08ps, 30.96ps, 37.845ps, 48.59p and 57.62ps after being converted into the time, the difference value is within the error range, the effectiveness of the time synchronization control device 300 with picosecond precision is proved, and the invention is further proved to be applicable to the measurement of the pulse time width of the synchrotron radiation X-ray with picosecond precision.

The method for measuring by adopting the synchrotron radiation X-ray pulse time width measuring device provided by the embodiment of the invention comprises the following steps:

S10, in order to prevent abnormality, a synchronous state monitoring zone bit exists in the upper computer 500, the state of the zone bit is observed, and the synchronous state of the time synchronous control equipment 300 and the main clock 100 is checked;

S20, setting the output frequency and the pulse width of a first trigger signal S1, a second trigger signal S2 and a third trigger signal S3 of the time synchronization control device 300 on the upper computer 500 according to the repetition frequency of X-ray pulses, wherein the output frequency and the pulse width are two independent parameters, the output frequency can be set to 125MHz/N _{Frequency division} according to an input frequency division parameter N _{Frequency division} , the pulse width can be set to 8ns multiplied by N _{Pulse width} according to an input pulse width parameter N _{Pulse width} , the setting time requirement N _{Pulse width} is smaller than N _{Frequency division} , and the time delays of the first trigger signal S1, the second trigger signal S2 and the third trigger signal S3 are respectively set to 1 microsecond, 2 microsecond and 3 microsecond;

S30, setting the scanning range of the X-ray streak camera 400 to be the maximum scanning range (for example, 4 microseconds) on the upper computer 500, setting the acquisition time of the X-ray streak camera 400 (for example, 1 second), and setting the triggering mode of the X-ray streak camera 400 to be external triggering;

s40, adjusting the scanning range of the X-ray stripe camera 400 from large to small for a plurality of times until the scanning range is adjusted to a preset scanning range, and displaying the X-ray pulse of the electron beam cluster to be detected in the image acquired by the X-ray stripe camera by adjusting the delay length of each trigger signal when the scanning range is adjusted to a certain scanning range each time so as to determine T0 under the scanning range;

s50, determining delays of the first trigger signal S1, the second trigger signal S2 and the third trigger signal S3 according to T0 of the X-ray streak camera 400 in a preset scanning range (for example, 600 picoseconds), for example, setting the delays to be T0-2 microseconds, T0-1 microsecond and T0 respectively;

S60, collecting an X-ray pulse image by the X-ray stripe camera 400, and determining the time width of the X-ray pulse according to the X-ray pulse image by the upper computer 500.

According to the synchronous radiation X-ray pulse time width measuring device, the time synchronization control device 300 is synchronized with the main clock 200, and the trigger signal for triggering the X-ray stripe camera 400 is output, so that picosecond-precision X-ray pulse time width measurement can be achieved, and the X-ray pulse image output by the X-ray stripe camera 400 is obtained by integrating pulse images acquired for multiple times within the preset time, so that the signal to noise ratio can be improved.

The foregoing description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, and various modifications can be made to the above-described embodiment of the present invention. For example, the photoelectric cathode used in the present invention may be replaced by other materials having higher photoelectric conversion efficiency for X-rays, the software program in the upper computer 500 may be written in other programming languages besides python, and the X-ray pulse time width measuring device of the present invention may be used for time width measurement of other picosecond-order X-ray pulse light sources, as long as it has periodicity, can provide time synchronization signals, and can be acquired by an X-ray fringe camera. All simple, equivalent changes and modifications made in accordance with the claims and the specification of this application fall within the scope of the patent claims. The present invention is not described in detail in the conventional art.

Claims (10)

1. The synchronous radiation X-ray pulse time width measuring device is characterized by comprising a main clock, time synchronous control equipment, an X-ray stripe camera and an upper computer, wherein the main clock is used for providing a time reference for a synchronous radiation light source, the time synchronous control equipment is connected with the main clock, the X-ray stripe camera is connected with the time synchronous control equipment, the upper computer is respectively connected with the time synchronous control equipment and the X-ray stripe camera, the upper computer is used for enabling the time synchronous control equipment to transmit a trigger signal to the X-ray stripe camera according to the time reference of the main clock, a preset delay is arranged between the trigger signal and the time reference of the main clock, the X-ray stripe camera is used for receiving X-ray pulses generated by the synchronous radiation light source and acquiring and outputting X-ray pulse images under the triggering of the trigger signal, and the X-ray pulse images are transmitted to the upper computer so that the upper computer acquires the time width of the X-ray pulses according to the X-ray pulse images.

2. The apparatus according to claim 1, wherein the X-ray stripe camera comprises a light-blocking slit, a photocathode for generating photoelectrons by generating a photoelectric effect with an X-ray pulse, a photoanode for accelerating the photoelectrons, a scanning device for deflecting the photoelectrons at different times to different extents, a signal enhancement device for emitting light from the photoelectrons, a screen for capturing an image of the screen, and an image capturing device arranged in this order along the X-ray transmission direction.

3. The synchrotron radiation X-ray pulse time width measurement apparatus according to claim 2, wherein the trigger signal comprises a first trigger signal, a second trigger signal and a third trigger signal, the first trigger signal is used for being transmitted to the scanning apparatus to start the scanning apparatus, the second trigger signal is used for being transmitted to the signal enhancement apparatus to start the signal enhancement apparatus, and the third trigger signal is used for being transmitted to the image pickup apparatus to start photographing by the image pickup apparatus.

4. A synchrotron radiation X-ray pulse time width measurement apparatus according to claim 3, wherein the delay of the first trigger signal with respect to the time reference of the master clock is less than the delay of the second trigger signal with respect to the time reference of the master clock is less than the delay of the third trigger signal with respect to the time reference of the master clock.

5. The synchrotron radiation X-ray pulse time width measurement apparatus according to claim 2, wherein the image pickup apparatus is configured to collect a plurality of images each including a plurality of pixels within a preset integration time, the X-ray streak camera further includes a data processing module configured to average, for each pixel, a pixel value of the pixel of each image as a pixel value of the pixel of a new image, and configured to send the new image to the host computer as an X-ray pulse image output by the X-ray streak camera.

6. The apparatus according to claim 2, wherein the X-ray pulse image includes spatial width information of the X-ray pulse, and the upper computer is configured to determine the time width of the X-ray pulse according to the spatial width information of the X-ray pulse.

7. The apparatus according to claim 2, wherein the signal enhancement means comprises a first microchannel plate for initially amplifying the photoelectron signal and a second microchannel plate for further amplifying the photoelectron signal, which are sequentially arranged along the X-ray transmission direction.

8. The apparatus according to claim 2, wherein the master clock comprises an ac power source, a radio frequency signal source, a first timing event generator and a first timing signal repeater, the ac power source and the radio frequency signal source being respectively connected to the first timing event generator, the first timing event generator being connected to the first timing signal repeater, the first timing signal repeater being connected to the time synchronization control device.

9. The apparatus according to claim 8, wherein the time synchronization control device comprises a second timing signal repeater, a first signal generating means, a second signal generating means and a third signal generating means, the first signal generating means, the second signal generating means and the third signal generating means being respectively connected to the second timing signal repeater, the second timing signal repeater being connected to the first timing signal repeater, the first signal generating means being adapted to generate a first trigger signal, the second signal generating means being adapted to generate a second trigger signal, the third signal generating means being adapted to generate a third trigger signal.

10. The apparatus according to claim 9, wherein the first signal generating means comprises a second timed event generator, a first timed event receiver and a first photoelectric converter connected in sequence, the second timed event generator being connected to the second timed signal repeater, the first photoelectric converter being connected to the scanning means;

The second signal generating device comprises a third timing event generator, a second timing event receiver and a second photoelectric converter which are sequentially connected, wherein the third timing event generator is connected with the second timing signal repeater, and the second photoelectric converter is connected with the signal enhancing device;

The third signal generating device comprises a fourth timing event generator, a third timing event receiver and a third photoelectric converter which are sequentially connected, wherein the fourth timing event generator is connected with the second timing signal repeater, and the third photoelectric converter is connected with the image pickup device.