Laser collimation device and method for large-area hot cathode ion source

Abstract

The invention discloses a laser collimation device and method for a large-area hot cathode ion source, and belongs to the technical field of large-area ion sources, the device comprises a laser, a fixed bracket, an ion source base, a plurality of height-adjustable screw rods, a neutralization chamber, a limiter and a target; the laser is vertically installed on the front end face of the ion source base through the fixing support, and it is guaranteed that the laser emitting direction is perpendicular to the plane of the ion source base. Collimated laser emitted by the laser sequentially penetrates through the ion source base, the neutralization chamber and the limiter along the collimation central axis of the laser collimation device for the large-area hot cathode ion source, and finally irradiates the central area of a target; the ion source base, the neutralization chamber, the limiter and the target are all arranged along the same collimation central axis, and the collimation central axis corresponds to the beam axis direction of the large-area hot cathode ion source. According to the invention, the eccentricity degree of the ion beam and the collimation central axis can be accurately evaluated, the beam transmission deviation is effectively reduced, and the neutralization efficiency is improved.

Description

Technical Field

[0001] This invention belongs to the field of large-area ion source technology, specifically relating to a laser collimation device and method for a large-area hot cathode ion source. Background Technology

[0002] In the field of nuclear fusion, large-area hot cathode ion sources are widely used in neutral beam injection (NBI) systems due to their advantages such as high current density, uniform beam current, and stable operation. Neutral beam injection technology is one of the most important external heating methods in magnetic confinement fusion devices. Its basic principle is: a high-energy ion beam is generated by the ion source, and then the ion beam undergoes a charge exchange reaction with gas atoms in the neutralization chamber, thereby converting it into high-energy neutral particles, which are then injected into the plasma at high speed to achieve energy and particle injection.

[0003] In neutral beam injection systems, axial alignment between the ion source, acceleration system, neutralization chamber, and target (or beam collector) is crucial. Misalignment of these components during installation or operation can cause the ion beam transmission path to deviate, resulting in partial ion beam collisions with limiters or neutralization chamber walls within the channel. This not only causes beam loss but may also lead to overheating or damage to the equipment, thereby affecting neutralization efficiency and beam transmission efficiency, ultimately reducing neutral beam injection power and overall system performance.

[0004] In large-area ion sources, due to the large structural volume, numerous components, and limited space, the requirements for alignment are very high.

[0005] (1) The collimation device and method need to be easy to operate and highly repeatable; currently, the collimation process often requires multiple adjustments based on the later beam output.

[0006] (2) High collimation accuracy requirement: The small deviation between the ion beam axis and the geometric center line of the device will be amplified during long-distance transmission. Therefore, the residual deviation between the ion beam axis and the geometric center line of the device after collimation device correction needs to be accurate to the mm level.

[0007] (3) Quantification and visualization of the degree of eccentricity or tilt between components. Existing technologies cannot provide real-time feedback on the degree of eccentricity between the bundle and other components.

[0008] Conventional collimation methods struggle to achieve high-precision alignment. Therefore, there is an urgent need to design a laser collimation device and method for large-area hot cathode ion sources. Summary of the Invention

[0009] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0010] A laser collimation device for a large-area hot cathode ion source includes: a laser, a fixed support, an ion source base, several adjustable height screws, a neutralization chamber, a limiter, and a target;

[0011] The laser is vertically mounted on the front end face of the ion source base via a fixed bracket, ensuring that the laser emission direction is perpendicular to the plane of the ion source base. The collimated laser emitted by the laser passes sequentially through the ion source base, neutralization chamber, and limiter along the collimation central axis of the laser collimation device used for large-area hot cathode ion source, and finally irradiates the central region of the target. The ion source base, neutralization chamber, limiter, and target are all arranged along the same collimation central axis, which corresponds to the beam axis direction of the large-area hot cathode ion source.

[0012] The present invention has the following beneficial effects:

[0013] (1) The present invention achieves alignment adjustment through the ion source base, which is simple to operate and highly repeatable. Only the adjustable height screw of the ion source base needs to be adjusted to achieve rapid alignment, saving debugging time.

[0014] (2) This invention achieves precise control of the base angle by adjusting the number of turns of the adjustable height lead screw, and combines the visualization measurement method of laser path to help improve the collimation accuracy and achieve high-precision collimation.

[0015] (3) By fixing the laser on the ion source base, the laser collimation of the present invention allows for direct observation of the relative position of the laser path with the neutralization chamber, limiter and target for large-area ion sources. It can accurately assess the degree of eccentricity between the ion beam and the collimation center axis, effectively reduce beam transmission deviation and improve neutralization efficiency. Attached Figure Description

[0016] Figure 1 This is a structural diagram of the laser collimation device for a large-area hot cathode ion source according to the present invention, wherein 1-laser, 2-fixed bracket, 3-ion source base, 4-adjustable height screw, 5-neutralization chamber, 6-limiter, 7-target;

[0017] Figure 2 This is a cross-sectional view of the laser collimation device for a large-area hot cathode ion source of the present invention after collimation, wherein 1-laser, 2-fixed bracket, 3-ion source base, 4-adjustable height screw, 5-neutralization chamber, 6-limiter, 7-target, 201-collimated laser, 202-distance between laser and edge of neutralization chamber, 203-distance between laser and edge of limiter, 204-distance between laser and edge of target, 301-metal bellows, 302-upper plate of ion source base, 303-lower plate of ion source base. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0019] The purpose of this invention is to provide a laser collimation device and method for a large-area hot cathode ion source, which precisely adjusts the axial position of the ion source and related components through laser calibration to achieve high-precision beam alignment and meet the needs of assembly and debugging.

[0020] like Figure 1 , Figure 2 As shown, the laser collimation device (or simply laser collimation device) for a large-area hot cathode ion source of the present invention includes: a laser 1, a fixed support 2, an ion source base 3, several adjustable height screws 4, a neutralization chamber 5, a limiter 6, and a target 7. The laser 1 is vertically mounted on the front end face of the ion source base 3 via the fixed support 2, ensuring that the laser emission direction is perpendicular to the plane of the ion source base 3. During the collimation process, the collimating laser 201 is used to simulate the transmission path of the high-energy ion beam extracted from the large-area hot cathode ion source. After collimation is completed, the laser 1 and the fixed support 2 are removed, and the large-area hot cathode ion source is installed in the corresponding position. The ion source base 3, the neutralization chamber 5, the limiter 6, and the target 7 are all arranged along the same collimation central axis, which corresponds to the beam axis direction of the large-area hot cathode ion source, i.e., the designed propagation direction of the ion beam during normal operation. The collimated laser 201 emitted by the laser 1 passes sequentially through the ion source base 3, the neutralization chamber 5 and the limiter 6 along the collimation center axis of the laser collimation device used for a large-area hot cathode ion source, and finally irradiates the central region of the target 7.

[0021] An adjustable height screw 4 is installed at every 90 degrees along the circumference of the ion source base 3, and all four adjustable height screws 4 are connected to the ion source base 3 circumferentially by threads.

[0022] The ion source base 3 includes an upper plate 302 and a lower plate 303 connected by a metal bellows 301, with the lower plate 303 fixed. One end of an adjustable height lead screw 4 is threaded to the lower plate 303, and the other end supports the upper plate 302. By rotating the lead screw 4, the depth of its screw thread is changed, causing axial displacement of the lead screw 4 relative to the lower plate 303, thereby causing a corresponding height change in the upper plate 302 supported by it. During height adjustment, the metal bellows 301 located between the upper and lower plates 302 extends and retracts synchronously with the axial displacement of the lead screw 4, ensuring that the ion source base 3 maintains good airtightness while achieving height adjustment.

[0023] By rotating the four adjustable height screws 4, precise micro-adjustments can be made to the pitch angle, roll angle, and plane height of the ion source base upper plate 302. This causes a slight change in the attitude of the laser 1 fixed on the ion source base upper plate 302, achieving precise correction of the laser transmission path. Each adjustable height screw 4 has a locking nut at the end connected to the ion source base lower plate 303 to fix the position of the adjustable height screw 4 after adjustment, preventing loosening or displacement during long-term operation.

[0024] The neutralization chamber 5 is fixedly installed at the rear end of the ion source base 3. The neutralization chamber 5 is a metal rectangular cylinder structure with an internal gas channel for the charge exchange reaction between high-energy ions extracted from the large-area hot cathode ion source and the neutral gas, thereby generating high-energy neutral particles. To ensure that the central axis of the neutralization chamber 5 is aligned with the collimation central axis, this laser collimation device determines its coaxiality deviation by measuring the laser irradiation position.

[0025] Limiter 6 is installed at the rear end of neutralization chamber 5 to limit the effective channel diameter of the high-energy neutral particle beam. By observing the distance between the laser beam and the upper and lower edges of limiter 6 as it passes through, the alignment of the ion source base 3 with the center of the neutralization chamber can be visually determined. When the laser beam deviates within the aperture of limiter 6, the ion source base 3 can be finely adjusted by adjusting the adjustable height screw 4 according to the direction and distance of the deviation until the laser beam completely coincides with the rectangular geometric center of the limiter 6 along its axis.

[0026] Target 7 is installed after limiter 6 to receive and absorb the high-energy beam. Target 7 has a V-shaped structure with internal heat exchange channels to accommodate circulating cooling water or other cooling media to remove the high-temperature heat generated by the beam bombardment. Target 7 is made of oxygen-free copper, making the laser beam impact point clearly visible for observation and recording. During debugging, the distances between the laser impact point and the upper and lower edges of the neutralization chamber 5, limiter 6, and target 7 are measured: laser distance to the neutralization chamber edge 202, laser distance to the limiter edge 203, and laser distance to the target edge 204 (e.g., ...). Figure 2 As shown in the figure, the eccentricity distance between the laser beam and the collimation center axis can be calculated.

[0027] This invention also provides a laser collimation method for a large-area hot cathode ion source, comprising:

[0028] Step 1: Ensure that laser 1 is installed vertically and turn on the power. Turn on the laser and observe the laser path to ensure that the collimated laser 201 propagates along the collimation center axis.

[0029] Step 2: By observing the position of the laser spot on the neutralization chamber 5, the limiter 6 and the target 7 respectively, record the precise distance between the laser and the upper and lower edges of the neutralization chamber 5, the limiter 6 and the target 7, and calculate the eccentricity distance between the laser beam and the collimation center axis based on the distance.

[0030] Step 3: Based on the eccentricity distance between the laser beam and the collimation center axis obtained in Step 2, if the laser spot deviates from the axial geometric center line of each component, the corresponding adjustable height screw 4 is selected for micro-adjustment according to the degree of eccentricity. This will cause a slight change in the height of the ion source base 3 on the screw side, thereby adjusting the small angle of the laser path until the laser remains collinear at the center of the three key components. After adjustment, the distance difference between the laser target point and the upper and lower edges of the target 7 should not exceed 5mm to ensure the accuracy requirements of the collimation center axis.

[0031] The above description is merely an embodiment of the present invention and does not limit the scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification and drawings, or direct or indirect applications in other related system fields, are similarly included within the protection scope of the present invention.

[0032] The contents not described in detail in this specification are existing technologies known to those skilled in the art.

Claims

1. A laser collimation device for a large-area thermionic cathode ion source, characterized in that, include: Laser, fixed bracket, ion source base, several adjustable height screws, neutralization chamber, limiter and target; The laser is vertically mounted on the front end face of the ion source base via a fixed bracket, ensuring that the laser emission direction is perpendicular to the plane of the ion source base. The collimated laser emitted by the laser passes sequentially through the ion source base, neutralization chamber, and limiter along the collimation central axis of the laser collimation device used for large-area hot cathode ion source, and finally irradiates the central region of the target. The ion source base, neutralization chamber, limiter, and target are all arranged along the same collimation central axis, which corresponds to the beam axis direction of the large-area hot cathode ion source.

2. The laser collimation device for a large-area thermionic ion source according to claim 1, characterized in that, The ion source base includes an upper plate and a lower plate connected by a metal bellows; one end of an adjustable height screw is threaded to the lower plate of the ion source base, and the other end supports the upper plate of the ion source base.

3. The laser collimation device for a large-area thermionic ion source according to claim 2, characterized in that, By rotating the lead screw to change the depth of the lead screw in the thread, the lead screw is axially displaced relative to the lower plate, thereby causing the upper plate of the ion source base supported by it to change its height accordingly; during the height adjustment process, the metal bellows set between the upper plate and the lower plate of the ion source base expands and contracts synchronously with the axial displacement of the lead screw.

4. The laser collimation device for a large-area thermionic ion source according to claim 2, characterized in that, Each adjustable height lead screw has a locking nut at the end where it connects to the lower plate of the ion source base.

5. The laser collimation device for a large-area thermionic ion source according to claim 1, characterized in that, The neutralization chamber is fixedly installed at the rear end of the ion source base; the neutralization chamber is a metal rectangular cylinder structure with a gas channel inside, which is used for the charge exchange reaction between high-energy ions drawn from the large-area hot cathode ion source and neutral gas to generate high-energy neutral particles.

6. The laser collimation device for a large-area thermionic ion source according to claim 1, characterized in that, The limiter is installed at the rear end of the neutralization chamber to limit the effective channel diameter of the high-energy neutral particle beam. The center consistency between the ion source base and the neutralization chamber is visually judged by observing the distance between the laser beam and the upper and lower edges of the limiter when the laser beam passes through the limiter. When the laser beam deviates within the limiter hole, the ion source base is finely adjusted by adjusting the adjustable height screw according to the direction and distance of the deviation until the laser beam completely coincides with the rectangular geometric center of the limiter axis.

7. The laser collimation device for a large-area thermionic ion source according to claim 1, characterized in that, The target is installed after the limiter to receive and absorb the high-energy beam. The target has a V-shaped structure and an internal heat exchange channel to accommodate circulating cooling water or other cooling media to remove the high-temperature heat generated by the beam bombardment.

8. The laser collimation device for a large-area thermionic ion source according to claim 1, characterized in that, The target is made of oxygen-free copper. During the debugging process, the distances between the laser target point and the neutralization chamber, the limiter, and the upper and lower edges of the target were measured respectively, and the eccentricity distance between the laser beam and the collimation center axis was calculated.

9. A laser collimation method for a large-area thermionic ion source, used in the laser collimation device for a large-area thermionic ion source as described in any one of claims 1 to 8, characterized in that, include: Step 1: Ensure the laser is installed vertically and turn on the power. Turn on the laser and observe the laser path to ensure the collimated laser propagates along the collimation center axis. Step 2: By observing the position of the laser spot on the neutralization chamber, the limiter, and the target respectively, record the precise distance between the laser and the upper and lower edges of the neutralization chamber, the limiter, and the target, and calculate the eccentricity distance between the laser beam and the collimation center axis based on the distance. Step 3: Based on the eccentricity distance between the laser beam and the collimation center axis obtained in Step 2, if the laser spot deviates from the axial geometric center line of each component, the corresponding adjustable height screw is selected for micro-adjustment according to the degree of eccentricity. As a result, the height of the ion source base corresponding to the screw side will change slightly, thereby achieving a slight adjustment of the laser path angle until the laser remains collinear at the center of the three key components.

10. The laser collimation method for a large-area thermionic cathode ion source according to claim 9, characterized in that, In step 3, after the adjustment is completed, the distance difference between the laser target point and the upper and lower edges of the target should not exceed 5mm to ensure the accuracy requirements of the collimation center axis.

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