CN106547013A - A kind of ion source beam diagnostics subtended angle measuring instrument - Google Patents

Abstract

The invention belongs to the technical field of isotope electromagnetic separators, and in particular relates to an ion source beam current diagnosis opening angle measuring instrument, which is arranged on an isotope electromagnetic separator. The isotope electromagnetic separator includes an ion source arranged in a vacuum chamber and provided with an extraction electrode , the ion source emits an ion beam from the extraction slot of the extraction electrode, the ion beam converges in the direction of the Y axis, and diverges in the direction of the X axis. The sheet angle measuring instrument includes a first probe and a second probe arranged in a vacuum chamber. The current signal measured by the first probe can obtain the beam current intensity of the ion beam, and the current signal obtained by the measurement of the second probe can obtain the ion beam intensity. The spatial density distribution of the beam current can obtain the beam opening angle of the ion beam through the spatial density distribution; it also includes a PLC module that can collect and record the spatial position signal of the probe and the current signal of the ion beam. The measuring instrument can measure the beam current density distribution on-line.

Description

An Ion Source Beam Angle Measuring Instrument for Diagnosis

technical field

The invention belongs to the technical field of isotope electromagnetic separators, and in particular relates to an opening angle measuring instrument for ion source beam current diagnosis.

Background technique

The electromagnetic separation method has an indispensable position in the field of isotope separation. The electromagnetic separation method uses ions with the same energy and different masses to achieve isotope separation in a transverse magnetic field with different rotation radii. The isotope electromagnetic separator is a device that uses electromagnetic separation to separate isotopes. The ion beam to be separated is extracted from the ion source of the isotope electromagnetic separator, separated by the magnetic field in the isotope electromagnetic separator, and then received by the receiving device to complete the separation of isotopes.

Among them, the analytical magnetic field of the isotope electromagnetic separator adopted in the present invention can achieve directional focusing for ion beams with an ion beam opening angle within 14.5°, and can perform isotope separation; otherwise, the ion beam is defocused and cannot achieve isotope separation. Therefore, it is necessary to measure the beam opening angle of the ion source.

The ion source used in the present invention is an arc discharge ion source with a three-electrode extraction system, and the ion beam is extracted from the ion source exit slot through the three-electrode system. The ion beam converges in the longitudinal direction, which is beneficial to the longitudinal focus (determined by the curvature of the electrode), and the horizontal direction is a divergent beam. The opening angle is α, and the opening angle α is determined by the extraction system parameters and discharge parameters. It is not a constant quantity, but With the change of extraction parameters and discharge parameters, that is, with the change of the beam current of the extracted ion beam, the influence of various parameters of the ion source on the opening angle can be obtained through the measurement of the opening angle, which provides the basis for obtaining the best separation operation parameters .

The measurement of the opening angle can be calculated from the full width at half maximum of the lateral distribution of the beam current density in the ion beam. Currently, there are beam current transformers (BCT), DC current transformers (DCCT), wall current probes (WCM), Faraday cups and other methods for measuring the beam current of high-current ion beams. In addition to the Faraday cage, other measurement methods are to obtain the size of the beam through the magnetic flux generated by the beam, which can avoid the direct contact between the probe and the beam, and has many applications in the field of accelerators. However, the angle measuring instrument needs to measure the spatial distribution of the beam current density. Among these detection devices, only the Faraday cup can scan the beam to obtain the distribution of the beam current density.

Contents of the invention

In order to realize the measurement of the beam current of the low-energy high-current arc discharge ion source, a small Faraday cup is used to scan and measure the spatial density distribution of the beam current, so as to give the beam opening angle, and the measurable opening angle reaches ±14.5°. At the same time, a large The Faraday cup measures the total beam current intensity of the ion source, and the measurable current intensity reaches 35mA.

In order to achieve the above purpose, the technical solution adopted by the present invention is a beam angle measuring instrument for ion source beam current diagnosis, which is arranged on the isotope electromagnetic separator, and the isotope electromagnetic separator includes a vacuum chamber with an extraction electrode. An ion source, the ion source emits an ion beam from the extraction slot of the extraction electrode, the ion beam converges in the Y-axis direction, and diverges in the X-axis direction, and the Y-axis direction is the emission of the ion beam direction, wherein, the beam angle measuring instrument for ion source beam current diagnosis includes a first probe and a second probe arranged in the vacuum chamber, and the current signal measured by the first probe can obtain the current signal of the ion beam Beam current intensity, the current signal measured by the second probe can obtain the beam current density distribution of the ion beam, and the beam current angle of the ion beam can be obtained through the spatial density distribution; it also includes A PLC module capable of collecting and recording the spatial position signal of the probe and the current signal of the ion beam.

Further, the second probe is set in the vacuum chamber by a probe moving device, close to the lead-out slit, and the probe moving device can drive the second probe to move, and the two-dimensional movement range of the second probe includes along The X-axis moves ±115mm, and the Z-axis perpendicular to the X-axis and Y-axis moves ±100mm.

Further, the first probe is set in the vacuum chamber by a probe moving device, away from the extraction slit; the probe moving device can turn the first probe to a position away from the ion beam.

Further, the probe moving device is installed through the vacuum chamber, and the rotating dynamic seal is used to realize the movement of the probe moving device between the vacuum environment and the non-vacuum environment.

Furthermore, the first probe is composed of a large Faraday cage, and the beam current intensity that can be measured by the large Faraday cage reaches 50mA.

Further, the large Faraday cage is cooled by water cooling.

Further, the second probe includes a probe panel and several small Faraday cages with openings in the same direction arranged on the probe panel.

Furthermore, the diameter of the small Faraday cage is less than 1 mm.

Further, a shielding cover is provided on the periphery of the small Faraday cage.

Further, a probe insulator is provided between the small Faraday cage and the shielding case.

The beneficial effects of the present invention are:

1. This design adopts the Faraday cylinder measurement method. Through the small Faraday cylinder movement stroke as the measuring probe, the beam current density distribution can be precisely measured online, and the measurable beam opening angle can reach ±14.5°.

2. The moving device of the probe adopts a rotary dynamic seal, which realizes the movement penetration of the atmosphere and the vacuum.

3. While measuring the beam opening angle, it can also measure the total extraction beam current of the ion source online, and the measurable current intensity can reach 50mA.

Description of drawings

Fig. 1 is the schematic diagram of the opening angle measuring instrument for ion source beam current diagnosis described in the specific embodiment of the present invention;

Fig. 2 is the front view of the opening angle measuring instrument for beam current diagnosis of the ion source described in the specific embodiment of the present invention;

Fig. 3 is a top view of the opening angle measuring instrument for ion source beam diagnosis in the specific embodiment of the present invention;

Fig. 4 is a side view of the beam angle measuring instrument for ion source beam diagnosis in the specific embodiment of the present invention;

Fig. 5 is the schematic diagram of the second probe driving structure described in the specific embodiment of the present invention

Fig. 6 is the front view of the second probe described in the specific embodiment of the present invention;

Fig. 7 is a top view of the second probe in a specific embodiment of the present invention;

Fig. 8 is a schematic diagram of measurement data of the beam angle measuring instrument for ion source beam diagnosis in the specific embodiment of the present invention;

In the figure: 1-mounting flange, 2-screw driver, 3-second probe drive shaft, 4-first probe drive shaft, 5-second probe, 6-first probe, 7-second probe drive structure , 8-vacuum chamber wall, 9-ion beam, 10-exit slot, 11-vacuum chamber, 12-probe panel, 13-fixed piece, 14-screw, 15-shielding cover, 16-probe insulator, 17-small Faraday cage, 18-transmission gear, 19-transmission rod, 20-probe driving rod, 21-reversing transmission gear, 22-probe thread guide rod, 23-probe installation rod, 24-aviation plug, 25-observation window, 26 - the first stepping motor, 27 - the second stepping motor, 28 - the third stepping motor.

detailed description

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

As shown in Fig. 1, a kind of ion source beam diagnosis provided by the present invention uses the opening angle measuring instrument (abbreviation opening angle measuring instrument), is arranged on the isotope electromagnetic separator, and the isotope electromagnetic separator includes being arranged in the vacuum chamber 11, An ion source with an extraction electrode is provided. The ion beam 9 is emitted from the extraction slot 10 of the extraction electrode. The ion beam 9 is converged in the Y-axis direction and diverges in the X-axis direction. The Y-axis direction is the emission direction of the ion beam 9 . The opening angle of the ion beam 9 is measured by an opening angle measuring instrument installed in front of the extraction slit 10 (also called the exit slit, the specific position is on the arc discharge chamber of the ion source) of the ion source.

As shown in Fig. 1, the opening angle measuring instrument for ion source beam diagnosis provided by the present invention includes a first probe 6 and a second probe 5 arranged in a vacuum chamber 11, and the first probe 6 and the second probe 5 can detect Current signal of ion beam 9. Wherein, the current signal obtained by measuring the first probe 6 can obtain the beam current intensity of the ion beam 9, and the current signal obtained by measuring the second probe 5 can obtain the spatial density distribution of the beam current of the ion beam 9. Through the spatial density distribution Can obtain the beam current angle of ion beam 9; Also comprise PLC module, PLC module can collect, record the spatial position signal of probe and the current signal of ion beam (in the present embodiment, use aviation plug 24 to realize the access to signal and Measurement and control, as shown in Figure 4, the aviation plug 24 is set on the mounting flange 1).

As shown in FIG. 1 , the second probe 5 is close to the lead-out slit 10 , and the first probe 6 is away from the lead-out slit 10 (the second probe 5 is between the lead-out slit 10 and the first probe 6 ). At y=110mm, or y=150mm, the second probe 5 is installed on the central plane of z=0 (that is, the origin of the coordinate system is the lead-out slit 10, and the second probe 5 is arranged 110mm or 150mm before the lead-out slit 10 position), scan along the X-axis direction (that is, approximately perpendicular to the direction of travel of the ion beam 9), measure the current density distribution j(x) of the ion beam 9 along the X-axis direction, and determine the ion beam 9 by j(x) Zhang Jiao.

As shown in Figures 1-3, the second probe 5 is set in the vacuum chamber 11 through the probe moving device, which can drive the second probe 5 to move, and the two-dimensional movement range of the second probe 5 includes moving along the X-axis direction ±115mm, move ±100mm along the Z-axis direction perpendicular to the X-axis and Y-axis.

The first probe 6 is arranged in the vacuum chamber 11 through the probe moving device; the probe moving device can turn the first probe 6 to a position deviated from the ion beam 9, without affecting the normal beam output of the ion source, and without blocking the beam current of the ion beam 9 . The first probe 6 is composed of a large Faraday cage, and the beam current intensity that can be measured by the large Faraday cage reaches 50mA. The large Faraday cage is cooled by water cooling. In this embodiment, the flip angle of the large Faraday cage of the first probe 6 is 90°.

The probe movement device is set on the isotope electromagnetic separator through the installation flange 1 .

As shown in Figures 1-3, the probe moving device is installed on the vacuum chamber 11 of the isotope electromagnetic separator, and the rotating dynamic seal is used to realize the movement of the probe moving device between the vacuum environment and the non-vacuum environment. The probe movement unit includes:

The first stepper motor 26 that controls the first probe 6 to perform flipping motion, the second stepper motor 27 and the third stepper motor 28 that control the second probe 5 to perform two-dimensional movement.

Connect and drive the first probe drive shaft 4 that moves the first probe 6, the first stepping motor 26 is arranged on one end of the first probe drive shaft 4 (in a non-vacuum environment), and the first stepping motor 26 is driven by the first stepping motor The probe driving shaft 4 can turn the first probe 6 to a position deviated from the ion beam 9;

The lead screw driver 2, the second probe drive shaft 3, the second probe drive structure 7, etc., which are connected to drive the second probe 5 to move, can drive the second probe 5 to move ±115mm along the X-axis direction; wherein, the second stepping motor 27 is arranged at one end of the second probe driving shaft 3 (in a non-vacuum environment), and the third stepper motor 28 is arranged at one end of the lead screw driver 2 (in a non-vacuum environment).

Wherein the second probe drive structure 7 (as shown in Figure 5) comprises again: transmission gear 18, transmission rod 19, probe drive rod 20, reversing transmission gear 21, probe thread guide rod 22 and probe installation rod 23; 5. Connect the lead screw driver 2 and the second probe drive shaft 3 through the second probe drive structure 7, and be able to move ±100mm along the Z axis perpendicular to the X axis and Y axis under the drive of the second probe drive structure 7 motion control.

As shown in Fig. 6 and Fig. 7, the second probe 5 includes a probe panel 12 and a plurality of openings arranged on the probe panel 12 toward the same small Faraday cage 17 (in this embodiment, there are two small Faraday cages 17) . The diameter of the small Faraday cage 17 is less than 1 mm. The probe panel 12 is fixed on the second probe driving structure 7 through the fixing piece 13 and the screw 14 . The small Faraday cage 17 is also fixed on the probe panel 12 with screws 14 , the periphery of the small Faraday cage 17 is provided with a shielding cover 15 , and a probe insulator 16 is provided between the small Faraday cage 17 and the shielding cover 15 .

Regarding the performance test of the beam angle measuring instrument for ion source beam diagnosis provided by the present invention, when measuring the angle of opening of the ion beam 9 , the angle measuring instrument measures the cross section near the extraction slit 10 of the ion source. The obtained data is roughly shown in Figure 8. I is the current signal of the second probe 5 , Z is the distance in the X-axis direction in FIG. 8 , and d is the full width at half maximum of the signal. The size of the opening angle α/2 of the ion beam 9 can be obtained from the half maximum width d.

According to the formula:

Wherein, L is the vertical distance between the second probe 5 of the opening angle measuring instrument and the extraction slit 10 of the ion source. The size of L can be obtained from the physical design of the opening angle measuring instrument. On the isotope electromagnetic separator used in this embodiment, L=173mm. According to the index of the opening angle measuring instrument: α/2=14.5°, the distance to be scanned is: d=2×173×tan 14.5°≈89.5mm

Therefore, during the test, when the second probe 5 of the opening angle measuring instrument moves to 89.5 mm in the X-axis direction, the opening angle can be measured up to 14.5°.

The device described in the present invention is not limited to the examples described in the specific implementation manner. Other implementation manners obtained by those skilled in the art according to the technical solution of the present invention also belong to the technical innovation scope of the present invention.

Claims (10)

1. a kind of ion source beam diagnostics subtended angle measuring instrument, is arranged on Electromagnetic isotope separator, the isotope electromagnetism Separator includes the ion source for being arranged in vacuum chamber (11), being provided with extraction electrode, and the ion source is from the extraction electrode Ion beam (9) is projected in drawing seam (10), the ion beam (9) is drawn in the Y-axis direction, dissipated in the X-axis direction, the Y Direction of principal axis is the direction of the launch of the ion beam (9), it is characterized in that：The ion source beam diagnostics subtended angle measuring instrument includes setting The first probe (6) in the vacuum chamber (11), the second probe (5) are put, by the described first probe (6) electricity for obtaining of measurement Stream signal is obtained in that the Bunch current of the ion beam (9), the current signal energy obtained by the described second probe (5) measurement The Spatial Density Distribution of the line of the ion beam (9) is enough obtained, the ion can be obtained by the Spatial Density Distribution The line subtended angle of beam (9)；Also including the electricity of the locus signal and the ion beam (9) that can gather, record the probe The PLC module of stream signal.

2. subtended angle measuring instrument as claimed in claim 1, is characterized in that：Second probe (5) is set by probe movement device Putting in the vacuum chamber (11), seam (10) being drawn near described, the probe movement device can drive second probe (5) move, the two dimensional motion scope of second probe (5) includes moving ± 115mm along the X-direction, along perpendicular to institute State the Z-direction motion ± 100mm of X-axis, Y-axis.

3. subtended angle measuring instrument as claimed in claim 1, is characterized in that：First probe (6) is set by probe movement device Put in the vacuum chamber (11), seam (10) is drawn away from described；The probe movement device can make first probe (6) It is turned to the position for deviateing the ion beam (9).

4. subtended angle measuring instrument as claimed in claim 2 or claim 3, is characterized in that：The probe movement device is described through being arranged on On vacuum chamber (11), fortune of the probe movement device between vacuum environment and non-vacuum environment is realized using rotary dynamic seal It is dynamic to run through.

5. the subtended angle measuring instrument as described in claim 1 or 3, is characterized in that：First probe (6) is by a big Faraday cup Constitute, the Bunch current that the big Faraday cup can be measured reaches 50mA.

6. subtended angle measuring instrument as claimed in claim 5, is characterized in that：The big Faraday cup adopts cooling by water.

7. subtended angle measuring instrument as claimed in claim 1 or 2, is characterized in that：Second probe (5) is including probe panel (12) And described several openings popped one's head on panel (12) are arranged on towards consistent little Faraday cup (17).

8. subtended angle measuring instrument as claimed in claim 7, is characterized in that：The diameter of the little Faraday cup (17) is less than 1mm.

9. subtended angle measuring instrument as claimed in claim 8, is characterized in that：Little Faraday cup (17) periphery is provided with radome (15)。

10. subtended angle measuring instrument as claimed in claim 9, is characterized in that：The little Faraday cup (17) and the radome (15) probe insulation (16) is provided between.