High-energy high-dose-rate microfocus X-ray source and working method thereof

Abstract

The invention relates to the technical field of ray sources, and provides a high-energy large-dose-rate micro-focus X-ray source, which comprises an injector, an X-ray source, a high-energy large-dose-rate micro-focus X-ray source and a high-energy large-dose-rate An inlet of a high-frequency cavity of the petal accelerator is aligned with an outlet of the injector, and the petal accelerator is used for accelerating the electron beam current; an inlet of the focusing assembly is aligned with an outlet of a high-frequency cavity of the petal accelerator, and the focusing assembly is used for focusing the accelerated electron beam current; and a target disc of the rotating target is used for receiving the focused electron beam, and the rotating center of the rotating target is not aligned with the outlet of the focusing assembly. The invention further provides a working method. The working method comprises the following steps that S1, electron beams emitted by the injector enter the petal accelerator to be accelerated; s2, the accelerated electron beam enters a focusing assembly to be focused; and S3, the focused electron beams bombard the rotating target, and the electron beams are uniformly arranged in a power deposition area on a target disc of the rotating target in the circumferential direction of the rotating target.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ray sources, in particular to a high-energy large-dose-rate micro-focus X-ray source and a working method thereof. BACKGROUND

[0002] At present, the high-energy X-ray source of the traditional linear accelerator technology route has a focal spot size of 1-2 mm when the dose rate is not less than 3000 cGy / min. If the focal spot size is required to reach 100 pm or below, the accelerator beam quality and X-ray fixed conversion target heat dissipation will face great challenges.

[0003] Specifically, for the high-energy X-ray source of the traditional linear accelerator technology route, in order to keep the average power of the electron beam unchanged and reduce the focal spot size of the X-ray to 100 pm or below, the traditional X-ray fixed conversion target will bear extremely high electron beam energy deposition power density (inversely proportional to the square of the focal spot size), which will cause the target disc temperature of the X-ray fixed conversion target to be as high as 5000 K, far exceeding the melting point of typical target materials (such as the melting point of tantalum is 3290 K). In addition, under the typical short pulse mode (about 10 ps) driven by the klystron, due to the energy concentration within the pulse, the energy deposition power density on the target is higher, thereby causing greater instantaneous local temperature rise. In summary, the traditional linear accelerator technology cannot reliably operate at a smaller focal spot size and will thus sacrifice the dose rate. SUMMARY

[0004] In view of the defects in the prior art, the purpose of the present application is to provide a high-energy large-dose-rate micro-focus X-ray source and a working method thereof, which can reliably operate at a smaller focal spot size without sacrificing the dose rate.

[0005] The present application is divided into the following two aspects. In the first aspect, the present application provides a high-energy large-dose-rate micro-focus X-ray source, comprising:

[0006] an injector for emitting an electron beam;

[0007] a petal accelerator, an inlet of a high-frequency cavity of the petal accelerator is aligned with an outlet of the injector, and the petal accelerator is used for accelerating the electron beam;

[0008] a focusing assembly, an inlet of the focusing assembly is aligned with an outlet of the high-frequency cavity of the petal accelerator, and the focusing assembly is used for focusing the accelerated electron beam;

[0009] a rotating target, a target disc of the rotating target is used for receiving the focused electron beam, and a rotation center of the rotating target is misaligned with an outlet of the focusing assembly.

[0010] Furthermore, the injector includes an electron gun and a focusing cavity;

[0011] The electron beam emitted from the cathode of the electron gun is voltage-gated to achieve longitudinal pulsed output, and the focusing cavity is used to modulate the energy of the passing electron beam.

[0012] Furthermore, the focusing assembly includes a quadrupole and a solenoid;

[0013] The quadrupole is used to correct the asymmetry of the electron beam in the transverse plane, and the solenoid is located behind the quadrupole.

[0014] Secondly, the present invention provides a working method, comprising the following steps:

[0015] S1. The electron beam emitted by the injector enters the petal accelerator for acceleration;

[0016] S2. The accelerated electron beam enters the focusing assembly for focusing;

[0017] S3. The focused electron beam bombards the rotating target, and the power deposition area of ​​the electron beam on the target disk of the rotating target is uniformly arranged along the circumference of the rotating target.

[0018] Further, in step S1,

[0019] The electron beam emitted from the cathode of the electron gun passes through the voltage gate, forming a pulsed electron beam in the longitudinal direction;

[0020] The pulsed electron beam passes through the focusing cavity, which modulates the energy of the electron beam to form a short-pulse electron beam.

[0021] Furthermore, in step S2, the focused electron beam forms a symmetrical circular focal point on the target disk.

[0022] The beneficial effects of this invention are as follows: This invention provides a high-energy, high-dose-rate microfocus X-ray source and its operating method. It employs a rotating target to alleviate the local temperature rise problem caused by the microfocus, and effectively reduces local temperature rise by diffusing the power deposition area of ​​the electron beam on the rotating target. Compared with fixed-target technology, the rotating target can diffuse the power deposition area of ​​the electron beam in a circumferential direction, thereby making the equivalent power deposition density inversely proportional to the electron beam focal size, significantly improving heat dissipation. This allows for reliable operation with a smaller focal size without sacrificing the dose rate. Attached Figure Description

[0023] Fig. 1 This is a schematic diagram of the structure of the present invention;

[0024] Fig. 2 A focal point distribution diagram of the electron beam after passing through the focusing assembly;

[0025] Fig. 3 To maintain a constant electron beam power, a schematic diagram of the simulated target disk temperature rise of the rotating target under different focal spot sizes.

[0026] Figure reference numerals: 10-electron gun, 11-focusing cavity, 20-high frequency cavity, 30-quadrupole, 31-solenoid, 40-rotating target. Detailed Implementation

[0027] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0028] In this application, unless otherwise expressly specified and limited, the terms "connection" and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0029] In the description of this application, it should be understood that the terms "longitudinal", "horizontal", "level", "top", "bottom", "upper", "lower", "inner" and "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0030] Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly defined.

[0031] like Figs. 1-3 As shown, the present invention provides a high-energy, high-dose-rate microfocus X-ray source, including an injector, a petal accelerator, a focusing assembly, and a rotating target 40.

[0032] The injector is used to emit an electron beam.

[0033] The inlet of the high-frequency cavity 20 of the petal accelerator is aligned with the outlet of the injector. The petal accelerator is used to accelerate the electron beam. Through multiple round trips, the energy of the electron beam is increased to above 9 MeV. The typical number of accelerations for the petal accelerator is 10, but higher energies can be obtained by increasing the number of accelerations.

[0034] The inlet of the focusing component is aligned with the outlet of the high-frequency cavity 20 of the petal accelerator. The focusing component is used to precisely focus the accelerated electron beam onto the target disk of the rotating target 40, ensuring that the focal size of the electron beam on the target disk of the rotating target 40 is 100μm or less.

[0035] The target disk of the rotating target 40 is used to receive the focused electron beam. The rotation center of the rotating target 40 is not aligned with the exit of the focusing assembly. Under high-speed rotation, typically with a linear velocity of 20-30 m / s, the target disk of the rotating target 40 can uniformly distribute the power deposition area of ​​the electron beam on the target disk, thereby significantly reducing local temperature rise and improving the service life of the target material. The target disk of the rotating target 40 can rotate automatically. The transmission structure of the target disk can use magnetohydrodynamic seals or other methods that can achieve dynamic sealing, combined with conventional motor drive technology or a technology combining an induction motor with a vacuum bearing. The transmission structure is a very common existing technology, and its specific structure will not be described in detail here.

[0036] The specific working process of this invention is as follows: The injector emits an electron beam, which enters the petal accelerator and undergoes multiple round trips for acceleration, increasing the energy of the electron beam to above 9 MeV. The accelerated electron beam then enters the focusing assembly for focusing, ensuring that the focal size of the electron beam on the target disk is 100 μm. The focused electron beam is precisely positioned on the target disk of the rotating target 40, and the target disk generates high-energy X-rays for high-precision X-ray imaging.

[0037] In one embodiment, the injector includes an electron gun 10 and a focusing cavity 11. The electron beam emitted from the cathode of the electron gun 10 is voltage-gated to achieve longitudinal pulsed output, and the focusing cavity 11 is used to modulate the energy of the passing electron beam.

[0038] Specifically, the electron beam emitted from the cathode of the electron gun 10 passes through a voltage gate, forming a pulsed electron beam in the longitudinal direction. The pulsed electron beam passes through the focusing cavity 11, which modulates the energy of the electron beam to form a short-pulse electron beam. At this time, the electron beam has the characteristic of short pulse width (the radio frequency phase width occupied in the longitudinal direction can be less than 20°), so that the energy dissipation is low due to the phase width during the acceleration process of the downstream petal accelerator.

[0039] In one embodiment, the focusing component includes a quadrupole 30 and a solenoid 31.

[0040] The quadrupole 30 is used to correct the asymmetry of the electron beam in the transverse plane. Applying a low-gradient quadrupole magnetic field to the quadrupole 30 makes the transverse distribution of the electron beam closer to rotational symmetry, and the finally focused electron beam forms a more symmetrical circular focal spot on the bar disk of the rotating target 40. The solenoid 31 is located behind the quadrupole 30.

[0041] In this embodiment,

[0042] The injector parameters are as follows:

[0043] The average emission current of the cathode of electron gun 10 is 0.1-0.5 mA;

[0044] The voltage-gated electron gun 10 and the operating frequency of the focusing cavity 11 are 100-500MHz.

[0045] Focused cavity 11 resonant structure: quarter-wavelength resonance;

[0046] Electron beam duty cycle: 1-100%

[0047] Longitudinal phase width of the output electron beam: ≤20°.

[0048] Petal Accelerator Parameters:

[0049] The high-frequency cavity 20 operates at a frequency of 100-500MHz, which is usually consistent with the voltage-gated electron gun 10 and the operating frequency of the focusing cavity 11.

[0050] High-frequency cavity 20 resonant structure: half-wavelength resonance;

[0051] Speed-up attempts: 10 or more;

[0052] Output electron beam energy: 9-15 MeV;

[0053] Electron beam current RMS stability: <1%.

[0054] Rotating target 40 parameters:

[0055] Linear velocity of the target disk: 20-30 m / s;

[0056] Target material: tantalum or other high-melting-point materials;

[0057] Full width at half maximum (FWHM) focal size of electron beam: ≤100μm.

[0058] This invention solves the technical challenge of balancing high dose rate and small focal size by combining a petal accelerator with a rotating target 40. Furthermore, by combining an electron gun 10 with a focusing cavity 11, an injector capable of generating short-pulse electron beams is formed, which, when combined with the petal accelerator, produces high-quality electron beams.

[0059] This invention enables an X-ray source with a focal spot size of less than 100 μm at a dose rate of not less than 3000 cGy / min. The small focal spot size greatly improves the resolution of the X-ray source, while the high dose rate ensures the signal-to-noise ratio after the X-rays penetrate high-density, high-atomic-number objects. Therefore, it has important application value for high-precision non-destructive testing, especially in the imaging and analysis of high-density, complex-structured materials.

[0060] It is worth noting that the embodiments of the present invention can also achieve X-ray sources with different focal sizes and dose rates by adjusting the operating parameters of the petal accelerator, such as the number of accelerations, the energy of the electron beam, and the linear velocity of the rotating target 40. By optimizing these parameters, the resolution and penetration capability of the X-ray source can be further improved to adapt to different application scenarios.

[0061] Secondly, the present invention provides a working method, comprising the following steps:

[0062] S1. The electron beam emitted by the injector enters the petal accelerator for acceleration. The electron beam undergoes multiple round trips within the petal accelerator, increasing its energy to over 9 MeV.

[0063] S2. The accelerated electron beam enters the focusing assembly for focusing, ensuring that the focal size of the electron beam on the target disk is 100μm.

[0064] S3. The focused electron beam is precisely positioned on the target disk of the rotating target 40. The focused electron beam bombards the rotating target 40. The power deposition area of ​​the electron beam on the target disk of the rotating target 40 is uniformly arranged along the circumference of the rotating target 40. The target disk generates high-energy X-rays for high-precision X-ray imaging.

[0065] In one embodiment, in step S1

[0066] The electron beam emitted from the cathode of the electron gun 10 passes through voltage gating and forms a pulsed electron beam in the longitudinal direction;

[0067] The pulsed electron beam passes through the focusing cavity 11, which modulates the energy of the electron beam to form a short-pulse electron beam.

[0068] Specifically, the electron beam emitted from the cathode of the electron gun 10 passes through a voltage gate, forming a pulsed electron beam in the longitudinal direction. The pulsed electron beam passes through the focusing cavity 11, which modulates the energy of the electron beam to form a short-pulse electron beam. At this time, the electron beam has the characteristic of short pulse width (the radio frequency phase width occupied in the longitudinal direction can be less than 20°), so that the energy dissipation is low due to the phase width during the acceleration process of the downstream petal accelerator.

[0069] In one embodiment, in step S2, the focused electron beam forms a symmetrical circular focal point on the target disk.

[0070] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or basic characteristics. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0071] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A high-energy, high-dose-rate microfocus X-ray source, characterized in that: include: Injector, the injector being used to emit an electron beam; A petal accelerator, wherein the inlet of the high-frequency cavity of the petal accelerator is aligned with the outlet of the injector, and the petal accelerator is used to accelerate the electron beam; A focusing assembly, the inlet of which is aligned with the outlet of the high-frequency cavity of the petal accelerator, is used to focus the accelerated electron beam. A rotating target, wherein the target disk of the rotating target is used to receive the focused electron beam, and the rotation center of the rotating target is not aligned with the outlet of the focusing assembly.

2. The high-energy, high-dose-rate microfocus X-ray source according to claim 1, characterized in that: The injector includes an electron gun and a focusing cavity; The electron beam emitted from the cathode of the electron gun is voltage-gated to achieve longitudinal pulsed output, and the focusing cavity is used to modulate the energy of the passing electron beam.

3. A high-energy, high-dose-rate microfocus X-ray source according to claim 2, characterized in that: The focusing assembly includes a quadrupole and a solenoid; The quadrupole is used to correct the asymmetry of the electron beam in the transverse plane, and the solenoid is located behind the quadrupole.

4. A working method applied to the high-energy, high-dose-rate microfocus X-ray source of claim 3, characterized in that: Includes the following steps: S1. The electron beam emitted by the injector enters the petal accelerator for acceleration; S2. The accelerated electron beam enters the focusing assembly for focusing; S3. The focused electron beam bombards the rotating target, and the power deposition area of ​​the electron beam on the target disk of the rotating target is uniformly arranged along the circumference of the rotating target.

5. A high-energy, high-dose-rate microfocus X-ray source according to claim 1, characterized in that: In step S1, The electron beam emitted from the cathode of the electron gun passes through the voltage gate, forming a pulsed electron beam in the longitudinal direction; The pulsed electron beam passes through the focusing cavity, which modulates the energy of the electron beam to form a short-pulse electron beam.

6. A high-energy, high-dose-rate microfocus X-ray source according to claim 1, characterized in that: In step S2, the focused electron beam forms a symmetrical circular focal point on the target disk.

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