CN110223796B - Isotope production equipment - Google Patents

Abstract

The invention discloses an isotope production equipment. It includes a linear accelerator and a corresponding target system; the linear accelerator includes a normal-temperature front-end accelerator, several identical acceleration units or several acceleration modules connected in series behind the normal-temperature front-end accelerator, and the acceleration from the end an end-extracting beamline drawn from the output end of the unit; the acceleration module comprises a plurality of acceleration units connected in series; the end-extracting beamline is used to output a proton beam used by the target system, and the target system uses for the production of isotopes. The isotope production equipment of the invention can meet the needs of various isotope production, improve the isotope production capacity and efficiency, and save the equipment manufacturing cost. On this basis, the acceleration unit is further modularized and the number of lead-out beamlines is increased, so that one isotope production equipment of the present invention can meet the requirements of simultaneous production of multiple isotopes, and the isotope production efficiency is increased by dozens of times.

Description

A kind of isotope production equipment

technical field

The invention relates to an isotope production equipment, belonging to the technical field of isotope production equipment.

Background technique

The discovery of nature more than 100 years ago has caused a great change in the updating of the universe and knowledge. In today's world, radioactive elements and radioisotopes are used in various fields such as medicine, industry, agriculture and scientific research. In many applications, there is no substitute for radioisotopes. Radioactive isotopes are used in nearly every country in the world, 50 of which have facilities for isotope production and separation.

Large quantities of radioisotope production typically use research reactors and cyclotrons. Isotope production facilities also include nuclear power plants, isotope separation facilities and general accelerators not specialized in isotopes. There are 600 research reactors in operation worldwide, but only nearly 100 are used for isotope production. There are about 50 cyclotrons in the world dedicated to the production of radiopharmaceuticals, and the isotopes produced are mainly ²⁰¹ TI, etc., and about 125 cyclotrons are used for tomography PET work. 25 new ones are needed, and the isotopes from the PET cyclotron are ¹⁸ F, ¹¹ C, etc. Various countries have a strong need for isotopes, but virtually no country is self-sufficient in the isotopes used. The need to improve isotope production capacity and production efficiency is very urgent.

Since the disadvantages of reactors for isotope production stem from the high cost and safety of the reactors themselves, and the fact that reactors are typically used for isotope production for only 5% or more of their operating time, reactors in Europe and the United States are aging and once Closed, isotope production capacity will decline and new units will need to replace them.

Therefore, cyclotrons are mostly used in the production of radioisotopes. However, the shortcomings of cyclotrons used for isotope production are also very obvious, mainly reflected in the following two aspects.

(1) The intensity of the extracted beam is low, and the isotope production efficiency is low

The cyclotron is used for isotope production, and the extracted beam intensity is low, and the highest level is only in the order of hundreds of μA. This is mainly because the cyclotron is a weakly focused structure. Once the current intensity increases, the beam space charge force will be very significant. The efficiency of the cyclotron will be reduced, the better cyclotron efficiency is close to 90%, and the efficiency of some cyclotrons is even less than 30%. The loss of beam current will bring obvious thermal problems and radiation activation problems. In order to reduce the radiation dose to human acceptable level, thick concrete is also required to shield the entire accelerator. On the other hand, it is also difficult to extract the cyclotron beam, and the increase of the current intensity will further increase the thermal problems and activation problems caused by the extraction.

(2) The extracted beam energy is fixed, and the isotope production capacity is single

The beam energy drawn by the cyclotron is fixed, which means that each cyclotron can only produce a specific isotope. For the production of different isotopes, multiple cyclotrons are required with a single function. In order to achieve adjustable energy, an energy modulator is usually followed by a cyclotron, and the energy of the beam is reduced by scattering. However, this method will generate a large amount of radiation, which is easy to activate the device and increase the shielding cost. Moreover, the quality of the scattered beam is poor, most of the beam will be lost, and the passing efficiency is low.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide an isotope production equipment. The isotope production equipment of the present invention has the characteristics of high efficiency and low beam loss. One equipment can provide the beam currents required for the production of various isotopes, thereby greatly improving the isotope production capacity and efficiency.

An isotope production equipment provided by the present invention comprises a linear accelerator and a target system corresponding to it;

The linear accelerator includes a normal-temperature front-end accelerator, several identical acceleration units or several acceleration modules connected in series behind the normal-temperature front-end accelerator, and a terminal extraction beamline drawn from the output end of the acceleration unit at the terminal; the acceleration unit The module comprises a plurality of acceleration units coupled in series;

The end extraction beamline is used to output a proton beam for use by the target system for isotope production.

In the present invention, being located behind the normal-temperature front-end accelerator refers to being located behind the outlet end of the normal-temperature front-end accelerator.

In the above isotope production equipment, the normal temperature front-end accelerator and each of the acceleration units are provided with independent radio frequency power sources, feeding systems and low-level control systems;

The radio frequency power source provides radio frequency power for the normal temperature front-end accelerator and the acceleration unit; the feeding system is used to feed the radio frequency power from the radio frequency power source to the normal temperature front-end accelerator and the acceleration unit; the The low-level control system described above is used to adjust the magnitude and phase of the radio frequency power.

In the present invention, the radio frequency power and synchronization phase of each acceleration unit can be continuously adjusted through its low-level control system, thereby realizing continuous adjustment of its output energy gain, and finally realizing continuous adjustment of output energy on the end-extracted beamline.

In the above isotope production equipment, the normal temperature front-end accelerator and each of the acceleration units are provided with the same signal reference line, which is used to provide a same phase reference point for the acceleration units.

In the above isotope production equipment, one of the acceleration units includes an acceleration cavity with a high acceleration gradient and a corresponding coupler and a tuner; the power of the coupler is coupled into the acceleration cavity, and the tuner is used for Adjustment of the frequency of the acceleration cavity. Specifically, the acceleration gradient of the acceleration cavity with high acceleration gradient may be greater than 5MV/m.

In the above isotope production equipment, the radio frequency power source adopts a solid-state amplifier (SSA for short);

The low level control system adopts digital low level;

The acceleration cavity adopts low temperature superconducting material;

Each acceleration cavity can provide acceleration capability of 0-2MeV.

In the above isotope production equipment, the normal temperature front-end accelerator includes an ion source, a low-energy transmission section, a high-frequency quadrupole field accelerator and a medium-energy transmission section arranged in sequence;

The ion source adopts an electron cyclotron resonance type ion source (ie, ECR ion source), which provides proton or alpha particle beam currents of different current intensities, and the extraction high voltage is 20kV-100kV; the low-energy transmission section matches the ion source beam currents Injected into the high-frequency quadrupole field accelerator, the high-frequency quadrupole field accelerator completes beam shaping and preliminary acceleration, and the beam energy at the outlet is 500keV-5MeV; The quality is measured offline, and the beam current is matched into the subsequent acceleration unit or the acceleration module.

In the above isotope production equipment, the target system includes a target body, a radiation shield, a beam current diagnostic system and a cooling system; the selection of the target body material depends on the type of isotope produced, and the beam current diagnostic system is used for beam energy. and monitoring of flow intensity, the cooling system is used to remove heat, the design of which depends on the target material and structure.

In the above isotope production equipment, the output end of each acceleration module is provided with a corresponding extraction beamline, and the extraction beamline is used to output a proton beam used by the target system operating therewith.

In the present invention, the energy of a single acceleration module is continuously adjustable mainly because the electric field amplitude and phase of the acceleration unit included in it are independently adjustable.

In the above-mentioned isotope production equipment, a beam splitting device is provided on both the end extraction beamline and the extraction beamline to extract the beam current;

Specifically, the beam splitting device may be composed of a cutting magnet and a kicker with a rising edge in milliseconds or a kicker cavity with a rising edge in nanoseconds. Specifically, the cutting magnet works in the DC mode, the kicker magnet or the kicker cavity works in the pulse mode, and the cutting magnet has two channels, one for realizing the straight transmission of the beam, and the other for transferring the beam from the side The channel is deflected by 45°, so that the beam is deflected to the first-stage extraction beamline.

In the above isotope production equipment, both the terminal extraction beamline and the extraction beamline lead out three secondary extraction beamlines through the beam splitting device.

The present invention has the following advantages:

1. In the present invention, the energy of the linear accelerator is continuously adjustable (which can be achieved by adjusting the radio frequency power and synchronous phase of the acceleration unit through the low-level control system), and the beamline drawn from the end can provide the beam current required for the production of various isotopes, which means A single isotope production equipment can meet the needs of a variety of isotope production (in practical application, the production of different kinds of isotopes can be carried out at different times), which greatly improves the isotope production capacity and efficiency, and also saves the cost of equipment manufacturing.

In addition, because the linear accelerator is a strong focusing accelerator, the linear accelerator has almost no beam loss, low activation probability, and greatly reduces the cost of radiation shielding, which is beneficial to the long-term stable operation of the linear accelerator.

2. Based on the present invention, the entire linear accelerator is capable of providing mA-level proton beams, and a certain extraction beamline usually extracts hundreds of μA beams for isotope production. The present invention further modulates the linear accelerator with continuously adjustable energy, couples some acceleration units together to form one acceleration module, and then sets the extraction beamline at the output end of each acceleration module, so that the linear accelerator of the present invention is extracted from the end except the end. In addition to the beamline, there are other more extraction beamlines that can simultaneously provide beams with different energies, realize the simultaneous supply of beams from multiple target systems, and meet the needs of simultaneous production of multiple isotopes.

3. In the present invention, the normal temperature front-end accelerator further adopts ECR ion source and RFQ accelerator, and the acceleration cavity in the acceleration unit is a low-temperature superconducting cavity, so that the linear accelerator of the present invention has the ability to transmit a beam with an average current intensity of tens of mA, In this way, even if all the extraction beamlines work at the same time, the beams with an average current intensity of several mA can be extracted, and several secondary extraction beamlines can be separated on the beamline by beam splitting, so as to achieve more target systems. For the beam supply, there is still a beam with an average current intensity of about several hundred μA on each target system, which can still meet the needs of isotope production, and the isotope production efficiency is increased by dozens of times. In simple terms, one isotope production equipment of the present invention can meet the needs of simultaneous production of multiple isotopes, which also means that one linear accelerator of the present invention can complete the tasks of dozens of cyclotrons, which greatly saves the manufacturing cost. On the basis of two points, the production capacity and efficiency of isotopes have been significantly improved.

Description of drawings

FIG. 1 is a schematic structural diagram of an isotope production equipment provided in an embodiment of the present invention.

FIG. 2 is a schematic diagram of synchronous phase-stabilized acceleration of an acceleration unit in a linear accelerator according to an embodiment of the present invention.

The marks in the figure are as follows:

11—Ion source, 12—Low energy transmission section, 13—RFQ accelerator, 14—Medium energy transmission section; 21—First acceleration module, 22—Second acceleration module, 23—Third acceleration module, 24—Fourth acceleration module .

Detailed ways

The experimental methods used in the following examples are conventional methods unless otherwise specified.

The materials, reagents, etc. used in the following examples can be obtained from commercial sources unless otherwise specified.

The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

Embodiment 1,

An embodiment of the present invention provides an isotope production equipment, which specifically includes a linear accelerator and a corresponding target system; with reference to FIG. 1 , the linear accelerator includes a normal-temperature front-end accelerator, N identical acceleration units arranged in series behind it, and acceleration units from the end. The extraction beamline drawn from the output end of the unit, the end extraction beamline is used to output the proton beam used by the target system, and the target system is used for the production of isotopes.

The normal temperature front-end accelerator and each acceleration unit have their own independent RF power source, feeding system and low-level control system; the RF power and synchronization phase of each acceleration unit can be continuously adjusted through its low-level control system, thereby realizing The continuous adjustment of its output energy gain finally realizes the continuous adjustment of the output energy on the end-extracted beamline. Among them, the radio frequency power source is used to provide radio frequency power for the acceleration unit, specifically a solid-state amplifier SSA can be used; the feeding system is used to feed the radio frequency power from the radio frequency power source to the acceleration unit; the low-level control system LLRF is used to adjust the size of the radio frequency power and phase, specifically digital low level can be used. In practical applications, a signal reference line is also included to provide a same phase reference point for all acceleration units.

An acceleration unit refers to an acceleration cavity with a high acceleration gradient and a corresponding coupler and tuner. The power of the coupler is coupled into the acceleration cavity, and the tuner is used to adjust the frequency of the acceleration cavity. Each acceleration cavity can provide 0 ~2MeV acceleration capability. It can be understood that the value of the total number N of acceleration units depends on the maximum acceleration capability required by the entire linear accelerator. The acceleration cavity of the acceleration unit is made of low-temperature superconducting materials with low resistance. Almost all the radio frequency power is converted into beam power, which is carried away by the beam. There is no thermal problem, so it has the ability to operate the beam in the continuous wave mode.

The normal temperature front-end accelerator mainly includes an ion source 11 , a low-energy transmission section 12 , a high-frequency quadrupole field accelerator 13 (ie, an RFQ accelerator) and a medium-energy transmission section 14 . The ion source 11 specifically adopts the electron cyclotron resonance type (ie ECR ion source), which provides proton or alpha particle beam currents of different current intensities, and the extraction high voltage is 20kV-100kV; the low-energy transmission section 12 injects the ion source beam current matching into the RFQ accelerator 13 , the RFQ accelerator 13 completes the beam shaping and preliminary acceleration, and the beam energy at the exit is hundreds of keV to several MeV; the medium-energy transmission section 14 measures the beam quality offline, and matches the beam into the subsequent acceleration structure.

The target system includes the target body, radiation shielding, beam diagnosis and cooling system. The choice of target material depends on the type of isotope produced. The beam diagnosis system is used to monitor the beam energy and current intensity, and the cooling system is used to remove heat. , whose design depends on the target material and structure.

In practical applications, the beam energy at the outlet of the RFQ accelerator can be designed from hundreds of keV to several MeV. Once the RFQ accelerator is fabricated, its outlet energy Erfq is fixed. After a series of independent acceleration units with high acceleration gradients, a stable acceleration of tens of MeV can be achieved.

The working principle of the linear accelerator of the present invention is described as follows.

The energy gain of an acceleration unit E = particle charge q * electric field strength E * transit time factor T * unit length L * cos synchronization phase φ _s (ie E=q*E*T*L*cosφ _s ), refer to Figure 2 The schematic diagram of synchronous phase-stabilized acceleration is shown. The radio frequency power of each acceleration unit can be adjusted through the low-level control system, that is, the electric field intensity E is adjustable. Through the adjustment of the radio frequency power, the energy gain obtained by the acceleration unit can be obtained from 0～Maximum qETLcosφ _s is continuously adjustable; the synchronization phase of each acceleration unit can also be adjusted by adjusting the relative value of the extraction phase and the reference phase of the acceleration unit through the low-level control system. When the synchronization phase is adjusted to 0°, the maximum energy is obtained Gain qETL, when the synchronization phase is adjusted to 180°, the particle gets the maximum deceleration -qETL.

After the proton beam passes through N acceleration units, the energy range of the extracted beam is from Erfq-NqETL to Erfq+NqETL, and the maximum energy gain of one acceleration unit is 2MeV. Assuming that a stable acceleration of 25MeV needs to be obtained, about 25-28 acceleration units are required. One reason is that the transit time factor T varies with the particle velocity, ranging from 0.4 to 0.8. Another reason is that the phase of some acceleration units is negative, which means However, some acceleration units do not provide the maximum acceleration capability. This is to satisfy the principle of longitudinal phase stabilization of the accelerator, so that the beam can be accelerated laterally and longitudinally to avoid beam loss. It can be understood that the value of the total number N of acceleration units depends on the maximum acceleration capability required by the entire linear accelerator.

In the actual production process, the production of PET tomography isotopes requires proton energy acceleration to 7-12MeV, and the production of SPECT isotopes requires proton energy acceleration to 15-19MeV, which is used for ²¹¹ At through the ²⁰⁹ Bi(a, 2n) ²¹¹ At reaction The production of α-particles requires acceleration of a-particles above 20MeV. The end of the linear accelerator has the ability to supply 3 different energy beams, and the production of 3 different isotopes can be realized with the corresponding target system.

In the process of using the isotope production equipment of the present invention, according to the energy required for the production of various isotopes, through a series of optimization and adjustment of the radio frequency power and synchronization phase of the acceleration unit, the beam line is drawn from the end of the linear accelerator to obtain the beam current of any desired energy.

In the actual adjustment process, the phase of some of the accelerating units participating in the work can be negative to satisfy the principle of longitudinal phase stabilization of the accelerator, so that the beam can be accelerated laterally and vertically, avoiding beam loss and achieving low beam loss. . Moreover, the risk of linac activation is low, saving a lot of shielding costs.

Embodiment 2,

Based on the isotope production equipment disclosed in the above embodiment 1, in the embodiment 2 of the present invention, the linear accelerator with continuously adjustable energy is modularized, and some acceleration units are coupled together to form each acceleration module, that is, N A plurality of acceleration units adjacent to one another in the acceleration unit are coupled to form an acceleration module. The output end of each acceleration module is provided with a corresponding extraction beamline, and these extraction beamlines are used to output the proton beam used by the target system running with it. . It can be understood that the energy of a single acceleration module can be continuously adjusted mainly because the electric field amplitude and phase of the acceleration units included in it are independently adjustable.

Among them, the extraction of the beam is realized by a beam splitting device. The beam splitting device can be composed of a cutting magnet and a kicker cavity magnet with a nanosecond rising edge; the cutting magnet works in DC mode, and the kicker magnet or kicker cavity works in pulse mode. , the cutting magnet has two channels, one is a channel for beam transmission in a straight line, and the other is a channel for deflecting the beam by 45° from the side, so that the beam is deflected to the first-level lead-out beamline.

As shown in Fig. 1, the total number of acceleration units is N=23, and the number of acceleration modules is 4, which specifically includes: a first acceleration module 21 formed by serial coupling of 1-6 acceleration units, a first acceleration module 21 formed by serial coupling of 7-12 acceleration units Two acceleration modules 22, a third acceleration module 23 formed by serial coupling of acceleration units 13-17, and a fourth acceleration module 24 formed by serial coupling of acceleration units 18-23. Correspondingly, the first-level lead-out beamline includes lead-out beamline 1, lead-out beamline 2, lead-out beamline 3 and lead-out beamline 4 corresponding to the output end of each acceleration module, and lead-out beamline 4 is also the end lead-out beamline of the entire linear accelerator. .

In the actual application process, the ECR ion source provides a proton beam of 20-60keV, and the normal temperature front-end accelerator (ECR ion source + RFQ accelerator) provides a proton beam of 2.5MeV. The extraction beamline 1 can provide a 5-7MeV proton beam through the normal temperature front-end accelerator + the first acceleration module 21 , and the extraction beamline 2 can provide a 7-12MeV proton beam through the normal temperature front-end accelerator + the first acceleration module 21 + the second acceleration module 22 flow, for the production of PET tomographic imaging isotopes; the extraction beamline 3 can provide 15-19MeV proton beam current for SPECT through the normal temperature front-end accelerator + first acceleration module 21 + second acceleration module 22 + third acceleration module 23 The production of isotopes; the extraction beam line 4 provides 20-25MeV proton beam current through the normal temperature front-end accelerator + the first acceleration module 21 + the second acceleration module 22 + the third acceleration module 23 + the fourth acceleration module, and passes through ²⁰⁹ Bi(a, 2n ) ²¹¹ At reaction was used for the production of ²¹¹ At.

The entire linear accelerator of the present invention is capable of providing mA-level proton beams, and a certain extraction beamline usually extracts several hundreds of μA beams for isotope production. When applying, refer to the above content, select the components that actually participate in the work and lead out beamlines, and quickly realize the supply of beam currents in a specific energy range according to the established radio frequency power and optimized synchronization phase of the series of acceleration units.

To sum up, in addition to the end-extracted beamline 4 that can provide a stable beam of any energy, the linear accelerator of the present invention also has other extraction beamlines 1 to 3 that can simultaneously provide beams with different specific energy ranges, so as to achieve multiple The beams of the target system are supplied at the same time to meet the demand for simultaneous production of multiple isotopes, and the isotope production efficiency is further improved on the basis of the embodiment.

Embodiment 3,

Based on the isotope production equipment disclosed in the above Embodiment 1 and Embodiment 2 of the present invention, in Embodiment 3 of the present invention, the ECR ion source and the RFQ accelerator are used for the normal temperature front-end accelerator in the linear accelerator, and the acceleration cavity of the acceleration unit is a low temperature superconducting cavity. body, the entire linear accelerator of the present invention can provide tens of mA-level proton beams for all extraction beamlines, so that even if all extraction beamlines work at the same time, the beam with an average current intensity of several mA can be extracted. The beam splitting method separates several secondary extraction beam lines, and each target system still has a beam current with an average current intensity of about several hundred μA, which can still meet the needs of isotope production.

Based on this, the end of at least one extraction beamline leads out a plurality of secondary extraction beamlines through the beam splitting device, and these secondary extraction beamlines are used for outputting proton beams directly used by the target system operating therewith. For example, as shown in FIG. 1 , the ends of the lead-out harnesses 1 to 4 all lead out three secondary lead-out harnesses. It is understandable that when extracting secondary beamlines, it is necessary to ensure that the average current of the extracted beams per beamline is greater than several hundred μA to meet the isotope production requirements.

Among them, the main reasons why the entire linear accelerator of the present invention can provide tens of mA-level proton beam currents are as follows: the first point is the ECR ion source, which can provide high-quality beam currents of hundreds of mA; the second point is the use of As a front-end accelerator, the RFQ accelerator can simultaneously focus the ion beam laterally and vertically, and can efficiently accelerate the 100-mA high-current ion beam to several MeV per nucleus to obtain high-quality beam current. ; The third point is that the acceleration module is a linear accelerator, and the linear accelerator is a strong focusing accelerator, which can constrain the strong current beam of tens of mA, maintain a high beam current quality, and hardly lose the beam current; further, make the linear accelerator The medium acceleration module adopts low-temperature superconducting material with low resistance. Almost all RF power is converted into beam power and carried away by the beam. There is no thermal problem, and it has the ability to operate the beam at a high duty cycle. A beam with an average current intensity of tens of mA.

The technical solutions provided by the present invention have been introduced in detail above. The principles and implementations of the present invention are described herein by using specific examples, and the descriptions of the above embodiments are only used to help understand the method and the core idea of the present invention. It should be pointed out that for those skilled in the art, without departing from the principle of the present invention, several improvements and modifications can also be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims (5)

1. an isotope production equipment, is characterized in that: it comprises linear accelerator and corresponding target system; The linear accelerator includes a normal-temperature front-end accelerator, several identical acceleration units or several acceleration modules connected in series behind the normal-temperature front-end accelerator, and a terminal extraction beamline drawn from the output end of the acceleration unit at the terminal; the acceleration unit The module comprises a plurality of acceleration units coupled in series; the end extraction beamline is used to output a proton beam for use by the target system, the target system is used for isotope generation; One of the acceleration units includes an acceleration cavity with a high acceleration gradient and a corresponding coupler and a tuner; the coupler power is coupled into the acceleration cavity, and the tuner is used for the frequency of the acceleration cavity. adjust; The acceleration cavity adopts low temperature superconducting material; The normal temperature front-end accelerator includes an ion source, a low-energy transmission section, a high-frequency quadrupole field accelerator and a medium-energy transmission section arranged in sequence; A beam splitting device is arranged on both the end lead-out beamline and the lead-out beamline to lead out the beam current; The beam splitting device is any of the following: 1) composed of a cutting magnet and a kicker magnet; 2) composed of a cutting magnet and a kicker cavity; The room temperature front-end accelerator and each of the acceleration units are provided with independent radio frequency power sources, feeding systems and low-level control systems; The radio frequency power source provides radio frequency power for the normal temperature front-end accelerator and the acceleration unit; the feeding system is used to feed the radio frequency power from the radio frequency power source to the normal temperature front-end accelerator and the acceleration unit; the The low-level control system described above is used to adjust the magnitude and phase of the radio frequency power. 2. The isotope production equipment according to claim 1, wherein the normal temperature front-end accelerator and each acceleration unit are provided with the same signal reference line for providing an identical phase reference for the acceleration unit point. 3. isotope production equipment according to claim 1 or 2, is characterized in that: described radio frequency power source adopts solid-state amplifier; The low level control system adopts digital low level; Each acceleration cavity can provide 0~2MeV acceleration capability. 4. The isotope production equipment according to claim 1 or 2, characterized in that: the output end of each of the acceleration modules is provided with a corresponding lead-out beamline, and the lead-out beamline is used for outputting all the corresponding output beams for supporting operation therewith. The proton beam used by the target system described above. 5 . The isotope production equipment according to claim 1 , wherein the end extraction beamline and the extraction beamline both lead out three secondary extraction beamlines through the beam splitting device. 6 .

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