Non-invasive diagnostic device and system suitable for X-ray free electron laser and use method

Abstract

The invention provides a non-invasive diagnosis device and system suitable for X-ray free electron laser and a use method, and relates to the technical field of X-ray free electron laser beam line diagnosis. The diagnosis device comprises a vacuum cavity, an optical element is arranged in an inner cavity of the vacuum cavity, a diagnostor mechanism is arranged on the inner wall or the inner top face of the vacuum cavity, the optical element and the diagnostor mechanism are oppositely arranged, and the optical element is used for emitting fluorescent light and photoelectrons; a light inlet channel is arranged on the side wall of the vacuum cavity; the diagnosis device mechanism comprises a mounting plate, a micro-channel plate diagnosis device is arranged on the mounting plate, and photoelectric detection elements are further arranged on the two sides of the micro-channel plate diagnosis device. According to the invention, non-invasive diagnosis of the XFEL can be realized, diagnosis is carried out by using fluorescence and photoelectron signals generated by excitation of the XFEL on the surface of the optical element, a main light beam can be prevented from being shielded, parallel operation with an experiment terminal can be realized, and non-invasive diagnosis of the XFEL can be realized.

Description

Technical Field

[0001] The present invention relates to the technical field of X-ray free electron laser beam line diagnosis, and in particular to a non-invasive diagnostic device, system and use method suitable for X-ray free electron laser. Background Art

[0002] High-repetition-rate X-ray free-electron lasers (XFELs) are characterized by high brightness, short pulses, high coherence, and high average power, making them a powerful tool for scientific research. However, since high-repetition-rate X-ray free-electron lasers have only been developed in recent years, there are still many problems with their diagnostic technology. Traditional invasive diagnostic methods (such as silicon photodiodes and scintillator detectors) require direct blocking of the X-ray beam, which not only leads to signal loss and thermal load problems, but also their high-energy pulses (mJ level) easily saturate the detector, while low-energy pulses (μJ level) face the technical contradiction of insufficient signal-to-noise ratio. Existing technologies are unable to balance wide dynamic range and single-pulse resolution. In terms of single-pulse energy and position diagnosis, non-invasive gas diagnostic devices at high repetition rates are affected by factors such as the ionization channel recovery rate and temperature, resulting in large errors. There is an urgent need to develop a non-invasive X-ray free-electron laser suitable for high repetition rates. Summary of the Invention

[0003] In order to solve the various drawbacks of the above-mentioned invasive diagnosis of XFEL, the present invention provides a non-invasive diagnostic device suitable for X-ray free electron laser, which can realize non-invasive diagnosis of XFEL and utilize the fluorescence and photoelectron signals generated by the surface of the optical element excited by the XFEL for diagnosis, thereby avoiding blocking the main light beam. At the same time, the optical element is an essential element for light beam transmission, so it can also avoid adding additional devices. It can run in parallel with the experimental terminal to realize non-invasive diagnosis of XFEL.

[0004] The present invention provides a non-invasive diagnostic device suitable for X-ray free electron laser, comprising a vacuum chamber, an optical element being provided in the inner cavity of the vacuum chamber, a diagnostic device mechanism being provided on the inner wall or inner top surface of the vacuum chamber, the optical element being arranged opposite to the diagnostic device mechanism, the optical element being used to reflect an XFEL main beam and simultaneously emit fluorescence and photoelectrons; a light inlet channel being provided on the side wall of the vacuum chamber; the diagnostic device mechanism comprising a mounting plate, a microchannel plate diagnostic device being provided on the mounting plate, and photoelectric detection elements being provided on both sides of the microchannel plate diagnostic device.

[0005] In one feasible embodiment, the optical element is made of ultra-smoothly polished single-crystal silicon, and its surface is coated with a boron carbide coating or a metal coating.

[0006] In one feasible embodiment, the positive and negative bias of the photoelectric detection element is adjustable, and the photoelectric detection element is an electron multiplier or a photodiode.

[0007] In a feasible embodiment, the photoelectric detection element is a photodiode, and an aluminum film is provided on a working surface of the photodiode.

[0008] In one feasible embodiment, the photoelectric detection element is located at a position where the distribution of the light spot projected by the XFEL on the optical element changes fastest.

[0009] The present invention also provides a non-invasive diagnostic system suitable for X-ray free electron laser, comprising the above-mentioned diagnostic device, and also comprising an analog-to-digital conversion module, a host computer and a high-voltage power supply module arranged outside the vacuum chamber, wherein the analog-to-digital conversion module is used to perform analog-to-digital conversion on the electrical signal collected by the photoelectronic detection element, the host computer is used to receive the signal after the analog-to-digital conversion by the analog-to-digital conversion module and perform calculation and analysis, and the high-voltage power supply module serves as the power supply for the microchannel plate diagnostic device and the photoelectric detection element.

[0010] The present invention also provides a non-invasive diagnostic method applicable to X-ray free electron laser, comprising the following steps:

[0011] Step 1) sealing the vacuum chamber and evacuating the chamber;

[0012] Step 2) The XFEL enters the inner cavity of the vacuum chamber through the light inlet channel and irradiates the optical element to stimulate fluorescence and photoelectrons;

[0013] Step 3) Fluorescence and photoelectrons are collected by the microchannel plate diagnostic device and the photodetector element;

[0014] Step 4) The electrical signal collected by the microchannel plate diagnostic device is converted into digital form by the analog-to-digital conversion module and transmitted to the host computer for processing, thereby obtaining the pulse energy measurement value.

[0015] Step 5) The electrical signal collected by the photoelectric detection element is converted into digital form by the analog-to-digital conversion module and transmitted to the host computer for processing, thereby obtaining the relative light beam position.

[0016] In one feasible embodiment, step 3) further includes testing the pulse energy of the same XFEL using a microchannel plate diagnostic device and a standard diagnostic device under the same conditions, and obtaining a calibration coefficient μ1 of the microchannel plate diagnostic device using Formula 1; Formula 1 is as follows:

[0017]

[0018] Wherein, W0 is the pulse energy measurement value collected by the standard diagnostic device, and W1 is the pulse energy measurement value collected by the microchannel plate diagnostic device.

[0019] In one feasible embodiment, step 4) further includes: the host computer integrates the pulses of the electrical signals collected by the microchannel plate diagnostic device, adjusts the positive and negative bias voltages, and suppresses the electronic signal when the bias voltage is negative; and simultaneously detects electrons and XFEL when the bias voltage is positive, thereby obtaining the pulse energy measurement value of the microchannel plate diagnostic device.

[0020] In one feasible implementation, step 5) further includes: obtaining the relative beam position f(y) by formula 2; the formula 2 is as follows:

[0021]

[0022] Among them, I EM1 is the intensity data collected by one of the photoelectron detection elements, I EM2 The intensity data collected by another photoelectron detection element.

[0023] The non-invasive diagnostic device and diagnostic method for X-ray free electron laser provided by the present invention have the following features:

[0024] Beneficial effects:

[0025] 1) The non-invasive diagnostic device provided by the present invention utilizes the fluorescence and photoelectron signals generated by the XFEL on the surface of an optical element for diagnosis, which can avoid blocking the main light beam (in conventional XFEL diagnostic methods, taking a semiconductor detector as an example, the main light beam of the XFEL shines directly on the semiconductor detector). At the same time, the optical element is an essential component for light beam transmission, so it can also avoid the need for additional devices. It can run in parallel with the experimental terminal to achieve non-invasive diagnosis.

[0026] 2) The microchannel plate diagnostic device and the photoelectric detection unit in the present invention cooperate to cover different energy bands, have a high signal-to-noise ratio, a wide dynamic range and high sensitivity.

[0027] 3) The present invention is simple and easy to use as a whole, and position diagnosis and energy diagnosis are separated, which reduces the complexity of manual intervention. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a diagnostic device for diagnosing the horizontal light intensity and position of the XFEL in the present invention.

[0029] Figure 2 It is a diagnostic device for diagnosing the vertical light intensity and position of XFEL in the present invention.

[0030] Figure 3 Schematic diagram of the diagnostic device mechanism of the present invention.

[0031] Figure 4 Schematic diagram of the diagnostic system of the present invention.

[0032] Figure 5 Schematic diagram of the expanded structure of the diagnostic device for diagnosing the horizontal light intensity and position of an XFEL according to the present invention.

[0033] Reference numerals

[0034] Vacuum chamber 1

[0035] Light channel 11

[0036] Optical element 2

[0037] Diagnostic device 3

[0038] Mounting plate 31

[0039] Microchannel plate diagnostic device 32

[0040] Photoelectric detection element 33

[0041] Host computer 4

[0042] High voltage power module 5 DETAILED DESCRIPTION

[0043] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. In the description of the present invention, it should be noted that the orientation or position relationship indicated by the terms "left side", "right side", "upper side", "lower side", "above", "below", etc. is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0044] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0045] Furthermore, in the description of the present invention, unless otherwise specified, “plurality” means two or more.

[0046] The present invention provides a non-invasive diagnostic device suitable for X-ray free electron laser. Figures 1 to 3 , including a vacuum cavity 1, an optical element 2 is provided in the inner cavity of the vacuum cavity 1. Generally speaking, the optical element 2 is a reflector, and the optical element 2 is made of ultra-smooth polished single-crystal silicon, and its surface is plated with a boron carbide coating or a metal coating, and the metal coating is preferably a gold coating. A diagnostic mechanism 3 is provided on the inner wall or inner top surface of the vacuum cavity 1. The optical element 2 and the diagnostic mechanism 3 are arranged relative to each other. The relative arrangement means that the optical element 2 and the diagnostic mechanism 3 are kept parallel. The optical element 2 is used to reflect the XFEL main beam and is excited by the XFEL to produce fluorescence and photoelectrons. Figure 1 and Figure 2 The solid line in the middle is the optical path of the XFEL main beam, and the dotted line is the movement trajectory of electrons and fluorescence. A light inlet channel 11 is provided on the side wall of the vacuum chamber 1, and the light inlet channel 11 is used to allow the XFEL to irradiate the optical element 2. The diagnostic mechanism 3 includes a mounting plate 31, and a microchannel plate diagnostic device 32 is provided on the mounting plate 31. Photoelectric detection elements 33 are also provided on both sides of the microchannel plate diagnostic device 32. Therefore, the non-invasive diagnostic device provided by the present invention uses the fluorescence and photoelectron signals generated by the XFEL on the surface of the optical element 2 to perform diagnosis, which can avoid blocking the main beam (the conventional XFEL diagnostic method, taking the semiconductor detector as an example, the main beam of the XFEL is directly shone on the semiconductor detector), is compatible with multiple experimental terminals running in parallel, and realizes non-invasive diagnosis.

[0047] For illustration, there are typically two sets of devices: one for horizontal XFEL diagnostics, i.e., monitoring and adjusting the horizontal direction of the XFEL beam; and the other for vertical XFEL diagnostics, i.e., monitoring and adjusting the vertical direction of the XFEL beam. In the device for horizontal XFEL diagnostics, the diagnostic mechanism 3 is located on the inner wall of the vacuum chamber 1, and the optical element 2 is also located on the inner wall of the vacuum chamber 1. In the device for vertical XFEL diagnostics, the diagnostic mechanism 3 is located on the inner top surface of the vacuum chamber 1, and the optical element 2 is located on the inner bottom surface of the diagnostic mechanism 3.

[0048] As a supplemental explanation, the photodetection element 33 is an electron multiplier or a photodiode. The positive and negative bias of the photodetection element 33 are adjustable. When the photodetection element 33 is a photodiode, a reverse bias is generally applied. When the photodetection element 33 is an electron multiplier, as with the microchannel plate diagnostic device 32, the voltage can be adjusted according to the gain requirements. A negative bias can suppress electron signals, while a positive bias can simultaneously detect electrons and XFELs. If the photodetection element 33 is a photodiode, an aluminum film can also be provided on the working surface of the photodiode. The aluminum film can block photoelectrons and can be covered on the working surface of the photodiode when photoelectron diagnosis is not required. The aluminum film is generally less than 200 nm thick.

[0049] In a preferred embodiment, the photoelectric detection element 33 is located at a position where the distribution of the light spot projected by the XFEL on the optical element 2 changes fastest, which is usually the half-width position of the Gaussian distribution.

[0050] The present invention also provides a non-invasive diagnostic system suitable for X-ray free electron laser, comprising the above-mentioned diagnostic device, see Figure 4 , also includes a host computer 4 and a high-voltage power supply module 5 arranged outside the vacuum chamber 1, the host computer 4 is used to receive signals from the microchannel plate diagnostic device 32 and the photoelectric detection element 33 and perform calculation and analysis, and the high-voltage power supply module 5 serves as a bias voltage for the microchannel plate diagnostic device 32 and the photoelectric detection element 33.

[0051] The present invention also provides a non-invasive diagnostic method applicable to X-ray free electron laser, comprising the following steps:

[0052] Step 1) sealing the vacuum chamber 1 and evacuating the chamber;

[0053] Step 2) The XFEL enters the inner cavity of the vacuum chamber 1 through the light inlet channel 11 and irradiates the optical element 2 to stimulate fluorescence and photoelectrons;

[0054] Step 3) Fluorescence and photoelectrons are collected by the microchannel plate diagnostic device 32 and the photoelectric detection element 33;

[0055] Step 4) The electrical signal collected by the microchannel plate diagnostic device 32 is converted into digital form by an analog-to-digital conversion module (ADC) and transmitted to the host computer 4 for processing, thereby obtaining a pulse energy measurement value.

[0056] Step 5) The electrical signal collected by the photoelectric detection element 33 is converted into digital form by an analog-to-digital conversion module (ADC) and transmitted to the host computer 4 for processing, thereby obtaining the relative light beam position.

[0057] In a specific embodiment, step 3) further includes:

[0058] Under the same conditions, the pulse energy of the same XFEL is tested using the microchannel plate diagnostic device 32 and the standard diagnostic device, and the calibration coefficient μ1 of the microchannel plate diagnostic device 32 is obtained by formula 1, which is as follows:

[0059]

[0060] Where W0 is the pulse energy measurement value collected by the standard diagnostic device, and W1 is the pulse energy measurement value collected by the microchannel plate diagnostic device 32. After obtaining the calibration coefficient μ1, the pulse energy measurement value W2 obtained by the microchannel plate diagnostic device 32 needs to be calculated in combination with μ1. One processing method is: actual pulse energy value = W2 / μ1.

[0061] In a specific embodiment, step 4) further includes:

[0062] The host computer 4 integrates the pulses of the electrical signals collected by the microchannel plate diagnostic device 32 and adjusts the positive and negative bias voltages. When the bias voltage is negative, the electronic signal can be suppressed; when the bias voltage is positive, the electrons and XFEL are detected at the same time, thereby obtaining the pulse energy measurement value of the microchannel plate diagnostic device 32.

[0063] In a specific embodiment, step 5) further includes:

[0064] The relative beam position f(y) is obtained by formula 2, which is as follows:

[0065]

[0066] Among them, I EM1 is the intensity data collected by one of the photoelectron detection elements, I EM2 The intensity data collected by another photoelectron detection element.

[0067] Example 1 Diagnosis of XFEL Horizontal Light Intensity and Position

[0068] In this embodiment, see Figure 1 and Figure 5 , Figure 5 The solid line in the center represents the XFEL optical path, and the dashed line represents the trajectory of electrons and fluorescence. Diagnostic mechanism 3 is secured to the inner wall of vacuum chamber 1 via an adapter bracket. Optical element 2 is also secured to the inner wall of vacuum chamber 1 via an adapter bracket, meaning that optical element 2 is positioned vertically. This embodiment can detect the intensity and position of fluorescence and photoelectrons excited by the XFEL in the horizontal direction.

[0069] Example 2: XFEL vertical light intensity and position diagnosis

[0070] In this embodiment, see Figure 2 Diagnostic device 3 is fixed to the inner top surface of vacuum chamber 1 via an adapter bracket, and optical element 2 is also fixed to the inner bottom surface of vacuum chamber 1 via an adapter bracket, i.e., optical element 2 is placed horizontally. This embodiment can detect the intensity and position of fluorescence and photoelectrons excited in the vertical direction by the XFEL.

[0071] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.

Claims

1. A non-invasive diagnostic device suitable for X-ray free electron laser, characterized by: The invention comprises a vacuum cavity (1), wherein an optical element (2) is provided in the inner cavity of the vacuum cavity (1), a diagnostic device (3) is provided on the inner wall or inner top surface of the vacuum cavity (1), the optical element (2) and the diagnostic device (3) are arranged opposite to each other, and the optical element (2) is used to reflect the XFEL main beam and is simultaneously excited to produce fluorescence and photoelectrons; and a light inlet channel (11) is provided on the side wall of the vacuum cavity (1); The diagnostic device mechanism (3) comprises a mounting plate (31), a microchannel plate diagnostic device (32) is provided on the mounting plate (31), and photoelectric detection elements (33) are provided on both sides of the microchannel plate diagnostic device (32).

2. The non-invasive diagnostic device for X-ray free electron laser according to claim 1, characterized in that: The optical element (2) is made of ultra-smoothly polished single-crystal silicon, and its surface is plated with a boron carbide coating or a metal coating.

3. The non-invasive diagnostic device for X-ray free electron laser according to claim 1, characterized in that: The positive and negative bias of the photoelectric detection element (33) is adjustable, and the photoelectric detection element (33) is an electron multiplier or a photodiode.

4. The non-invasive diagnostic device for X-ray free electron laser according to claim 3, characterized in that: The photoelectric detection element (33) is a photodiode, and an aluminum film is provided on the working surface of the photodiode.

5. The non-invasive diagnostic device for X-ray free electron laser according to claim 1, characterized in that: The photoelectric detection element (33) is located at a position where the distribution of the light spot projected by the XFEL on the optical element (2) changes fastest.

6. A non-invasive diagnostic system suitable for X-ray free electron laser, comprising the diagnostic device according to any one of claims 1 to 5, characterized in that: The device also includes an analog-to-digital conversion module, a host computer (4), and a high-voltage power supply module (5) arranged outside the vacuum chamber (1); the analog-to-digital conversion module is used to receive signals from the microchannel plate diagnostic device (32) and the photoelectric detection element (33); the host computer (4) performs calculation analysis; and the high-voltage power supply module (5) serves as a bias voltage for the microchannel plate diagnostic device (32) and the photoelectric detection element (33).

7. A diagnostic method for a non-invasive X-ray free electron laser system according to claim 6, comprising the following steps: Step 1) sealing the vacuum chamber (1) and evacuating the chamber; Step 2) The XFEL enters the inner cavity of the vacuum chamber (1) from the light inlet channel (11) and irradiates the optical element (2) to excite fluorescence and photoelectrons; Step 3) Fluorescence and photoelectrons are collected by the microchannel plate diagnostic device (32) and the photoelectric detection element (33); Step 4) The electrical signal collected by the microchannel plate diagnostic device (32) is converted into digital form by an analog-to-digital conversion module and transmitted to a host computer (4) for processing, thereby obtaining a pulse energy measurement value. Step 5) The electrical signal collected by the photoelectric detection element is converted into digital form by the analog-to-digital conversion module and transmitted to the host computer (4) for processing, thereby obtaining the relative light beam position.

8. The non-invasive diagnostic method applicable to X-ray free electron laser according to claim 7, wherein step 3) further comprises: Under the same conditions, the pulse energy of the same XFEL is tested using a microchannel plate diagnostic device (32) and a standard diagnostic device, and the calibration coefficient μ1 of the microchannel plate diagnostic device (32) is obtained by formula 1; the formula 1 is as follows: Wherein, W0 is the pulse energy measurement value collected by the standard diagnostic device, and W1 is the pulse energy measurement value collected by the microchannel plate diagnostic device (32).

9. The non-invasive diagnostic method applicable to X-ray free electron laser according to claim 7, wherein step 4) further comprises: The host computer (4) cooperates with the analog-to-digital conversion module to integrate the pulse of the electrical signal collected by the microchannel plate diagnostic device (32), adjust the positive and negative bias voltages, and suppress the electronic signal when the bias voltage is negative; and simultaneously detect the electrons and XFEL when the bias voltage is positive, thereby obtaining the pulse energy measurement value of the microchannel plate diagnostic device (32).

10. The non-invasive diagnostic method applicable to X-ray free electron laser according to claim 7, wherein step 5) further comprises: The relative beam position f(y) is obtained by formula 2; the formula 2 is as follows: Among them, I EM1 is the intensity data collected by one of the photoelectron detection elements, I EM2 The intensity data collected by another photoelectron detection element.

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