A solenoid bunch confinement model and charged particle bunch current compression method

Abstract

The application provides a solenoid bundle confinement model and a charged particle beam current compression method, and relates to the technical field of charged particle beam current compression of accelerators. The model comprises a main solenoid assembly for forming a uniform magnetic field inside the solenoid; an introduction assembly for sequentially introducing a plurality of charged particle beam bundles into the uniform magnetic field, so that the charged particle beam bundles spiral move; a confinement zone assembly which is similar to a magnetic mirror structure and confines the sequentially incident charged particle beams to reciprocally spiral move in the confinement zone until the average flow intensity of the beam in the confinement zone reaches a preset value; and an extraction assembly for extracting the charged particle beam with the average flow intensity reaching the preset value from the confinement model. The application makes the charged particle beam reciprocally move in the confinement zone, thereby doubling the number of beam bundles and the average current in the confinement model, and solves the problems of large volume, high cost of the charged particle beam current compression device and the fact that the average current of the compressed beam can only reach the order of mA.

Description

Technical Field

[0001] This application relates to the field of accelerator charged particle beam current compression technology, and in particular to a solenoid bundle confinement model and a charged particle bundle current compression method. Background Technology

[0002] Accelerator-generated charged particle beams are characterized by their controllability and high stability, making them widely used in medical, industrial, and scientific research fields. However, current advancements in science have created a demand for higher-intensity (~kA) high-energy charged particle beams. For example, z-pinch in nuclear fusion research could utilize high-energy electron beams with average currents in the ~kA range to bombard a fusion target for ignition. However, if the photocathode electrons with an average current in the kA range are directly accelerated to ~10MeV using traditional methods, klystrons or magnetrons with average power in the tens of megawatts range would be needed to power the accelerating tube. Given the current level of klystron development, only pulse power in the tens of megawatts range can be provided. For z-pinch ignition, tens of thousands of klystrons would need to operate simultaneously to meet the power requirements, the cost of which is unimaginable. Furthermore, the spacing of the charged particle clusters is also limited by the charged particle emission source, making it very difficult to directly generate charged particle clusters with a repetition frequency of ~10GHz.

[0003] Therefore, by first accelerating a low-repetition-rate, low-average-current charged particle beam to a specified energy using an accelerating structure, and then compressing the electron beam spacing, the goal can be achieved at an acceptable cost. CLIC's CTF3 device is a typical electron beam bunch average current compression device. The preceding structure first accelerates an electron beam with a repetition rate of 3 GHz to 350 MeV, and then the bunches are injected sequentially into the combining ring. The compressed electron beam bunch spacing is reduced from 333 ps to 33 ps, the repetition rate reaches 30 GHz, and the electron beam power reaches ten times that before compression. It is then extracted to the tail field accelerating structure to accelerate colliding particles. In addition to this method of increasing the electron beam bunch repetition rate, the storage ring is also a common charged particle average current compression device. The difference is that the successively injected electron beam bunches are combined into a single bunch, rather than the spacing is reduced, until the bucket phase space is filled and the expected average current is reached. Then the charged particles can be extracted to the subsequent structure.

[0004] However, among the charged particle beam compression methods in related technologies, CTF3 and storage rings have limitations such as large size and high cost, and the maximum achievable average current intensity is limited by the parameters of the ring. Currently, the average current of the electron beam cluster in the storage ring can only reach the mA level, which is far from meeting the requirements of applications such as Z-pinch. Summary of the Invention

[0005] This application provides a solenoid bundle confinement model and a charged particle bundle current compression method to solve the limitations of related technologies that use CTF3 and storage rings to achieve charged particle bundle compression, such as large size and high cost, and the fact that the average current of the electron bundle in the storage ring can only reach the mA level, which cannot meet the requirements of applications such as Z-pinch.

[0006] The first aspect of this application proposes a solenoid bundle confinement model, comprising: a main solenoid assembly for forming a uniform magnetic field inside the solenoid; an introduction assembly for sequentially introducing multiple charged particle bundles into the uniform magnetic field, causing the charged particle bundles to undergo helical motion; a confinement region assembly for causing the sequentially incident charged particle bundles to reciprocate helically between pairs of reflecting magnets until the average current intensity of the charged particle beam reaches a preset value; and an extraction assembly for extracting the charged particle beam with the average current intensity reaching the preset value from the confinement model.

[0007] Furthermore, the main solenoid assembly includes: a ferromagnetic material shielding shell, an aluminum cylinder, a ferromagnetic material support column, and a main coil, wherein the ferromagnetic material support column is used to fix multiple magnetic elements inside the main solenoid and together with the ferromagnetic material shielding shell, forms a magnetic circuit.

[0008] Furthermore, the introduced component includes:

[0009] An inlet hole is provided for introducing the plurality of charged particle bundles;

[0010] A magnet is introduced to cause the introduced bundle of charged particles to move in a spiral motion around the solenoid axis.

[0011] Furthermore, the confinement zone component includes:

[0012] An introducing side reflector is used. When the charged particle cluster passes the introducing side reflector, the current is turned off. After the charged particle cluster passes the introducing side reflector, the current is turned on. This ensures that the incident electrons can enter the confinement zone while providing a deflection force to the cluster in the confinement zone, so that the charged particle clusters introduced in sequence reciprocate in a spiral motion within the confinement zone.

[0013] A focusing magnet is used to provide a gradient field to improve the stability of the reciprocating helical motion of the charged bundle;

[0014] The lead-out side reflective magnet is used to provide a reverse deflection force to the confined clump, ensuring that the clump can reciprocate spirally between the lead-out side reflective magnetic strip and the lead-out side reflective magnet; when the average current intensity of the charged particle beam in the confined area reaches a preset value, the current is cut off, so that the charged particle beam spirals to the lead-out component.

[0015] Furthermore, the extraction component includes an extraction hole and an extraction magnet for extracting a beam of charged particles with an average current intensity reaching a preset value.

[0016] A second aspect of this application proposes a method for compressing the current of charged particle bundles in accelerators, applied to the solenoid bundle confinement model of the first aspect, the method comprising:

[0017] A uniform magnetic field is formed inside the solenoid;

[0018] Multiple bundles of charged particles are sequentially introduced into the uniform magnetic field, causing the bundles of charged particles to move in a spiral motion.

[0019] The charged particle beams that are incident sequentially are made to reciprocate in a spiral motion between pairs of reflecting magnets until the average current intensity of the charged particle beams within the confined area reaches a preset value.

[0020] A charged particle beam with an average current intensity reaching a preset value is extracted from the confined model.

[0021] Furthermore, the charged particle cluster reciprocates in a spiral motion between the reflecting magnet pairs until the average current intensity of the charged particle cluster reaches a preset value, including:

[0022] After the charged particle beam enters the confined area, it travels at an axial incident velocity v z0 The spiral motion leads to the reflective magnet on the extraction side;

[0023] The charged particle cluster is deflected by the reflecting magnet on the extraction side, and then moves in the opposite direction at an axial velocity of -v. z0 The spiral motion leads to the reflective magnet on the side of the introduction.

[0024] The charged particle cluster reciprocates in a spiral motion within the confined area until the average current intensity of the charged particle beam within the confined interval reaches a preset value.

[0025] Furthermore, if the time interval before the introduction of adjacent bundles is T b Before reaching the extraction assembly, the number of reciprocating cycles within the confinement assembly differs by n. Upon reaching the extraction assembly, the interval between adjacent bundles is:

[0026] T′ b =T b -nNT c

[0027] Where N is the number of round-trip spiral motions of the charged particle cluster within the confined area, and T... c The gyration period of the charged particle bundle as it spirals in the uniform magnetic field.

[0028] Optionally, when the charged particle bundle is extracted, the compression factor of the repetition frequency and average current of the charged particle bundle compared to when it was introduced is:

[0029]

[0030] Among them, T b The interval between the multiple charged particle clusters when they enter the introduction component is N, where N is the number of round-trip spiral motions of the charged particle clusters within the confinement zone, and T is T. c The gyration period of the charged particle cluster in the uniform magnetic field is denoted as n, and the difference between the number of cycles of reciprocating motion of adjacent clusters within the confinement component before reaching the extraction component is denoted as n.

[0031] The technical solutions provided by the embodiments of this disclosure have at least the following beneficial effects:

[0032] After being introduced into a uniform field within a solenoid, charged particle clusters can move stably in a spiral motion. By controlling the deflection magnets that reciprocate the electron clusters within the confinement zone, the clusters can be confined within the structure. Simultaneously, clusters are injected into the structure sequentially. The power supply to the deflection magnet coil is switched off at the moment of cluster injection and then quickly switched on again after injection, continuing to reflect the clusters within the structure. This multiplies the number of clusters and the current within the confined structure. When the beam current intensity within the structure reaches a set value, the current of the extraction magnet is switched off, allowing the compressed beam to be extracted sequentially. This achieves the compression of the charged particle beam, enabling accelerator charged particle beam current compression with an average current on the order of kA. The structure is compact, meeting the requirements of applications such as Z-pinch.

[0033] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0034] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0035] Figure 1 This is a schematic diagram of the structure of the solenoid bundle confinement model provided according to the embodiments of this application;

[0036] Figure 2 This is a flowchart of an accelerator charged particle bunch current compression method according to an embodiment of this application;

[0037] Figure 3 This is a flowchart of an accelerator charged particle bunch current compression method according to an embodiment of this application;

[0038] Figure 4This is a schematic diagram illustrating the principle of confining charged particle clumps according to an embodiment of this application;

[0039] Figure 5 This is a schematic diagram of the time structure of the charged particle bundle before and after compression according to an embodiment of this application;

[0040] Figure 6 This is a schematic diagram showing the change in field intensity when a time-varying current is applied to the inlet and outlet side reflecting magnets according to an embodiment of this application. Detailed Implementation

[0041] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0042] Figure 1 This is a schematic diagram of the structure of a solenoid bundle confinement model provided in an embodiment of this application.

[0043] In this embodiment, as Figure 1 As shown, the main solenoid assembly is used to form a uniform magnetic field inside the solenoid. The main solenoid assembly includes: a ferromagnetic material shielding shell 1, an aluminum cylinder 2, a ferromagnetic material support 3, and a main coil 4. The ferromagnetic material support 3 is used to fix multiple magnetic elements inside the main solenoid and together with the ferromagnetic material shielding shell 1, forms a magnetic circuit.

[0044] The introduction component 5 is used to sequentially introduce multiple charged particle bundles into a uniform magnetic field, causing the charged particle bundles to move in a spiral motion. The introduction component includes an introduction hole 10 and an introduction magnet 11. The introduction hole 11 is used to introduce multiple charged particle bundles, and the introduction magnet 12 is used to cause the introduced charged particle bundles to move in a spiral motion with the solenoid axis as the central axis.

[0045] The confinement zone assembly is used to make the charged particle beam reciprocate in a spiral motion between pairs of reflective magnets until the average current intensity of the charged particle beam reaches a preset value. The confinement zone assembly includes: an inlet-side reflective magnet 7, an outlet-side reflective magnet 8, and a focusing magnet 9.

[0046] Among them, the side-reflecting magnet 7 is introduced. When the charged particle cluster passes the side-reflecting magnet, the current is turned off. After the charged particle cluster passes the side-reflecting magnet, the current is turned on to ensure that the sequentially incident clusters can be introduced into the confinement zone.

[0047] After entering the confined zone, the bundle continues its spiral motion to the lead-out side reflecting magnet 8. After being deflected, it spirals back towards the lead-in side reflecting magnet in the opposite direction. When the bundle already within the confined zone passes the lead-in side reflecting magnet, its current is on, thus it is deflected, and then it spirals back towards the lead-out side reflecting magnet. This process repeats. The bundle is sequentially introduced into the pair of reflecting magnets and then confined within that zone by the same pair of reflecting magnets, thus gradually increasing the number of bundles undergoing this confining action within that zone.

[0048] The lead-out side reflective magnet 8 provides a reverse deflection force to the cluster in the confined area, ensuring that the cluster can reciprocate spirally between the lead-out side reflective magnetic strip and the lead-out side reflective magnet. When the average current intensity of the charged particle beam in the confined area reaches a preset value, the current is cut off, causing the charged particle beam to spirally move to the lead-out component. Then, it moves from the lead-out component to the subsequent device.

[0049] Focusing magnet 9 is used to provide a gradient field to improve the stability of the charged bundle's helical reciprocating motion within the confined space.

[0050] Among them, the lead-in magnet 7, the lead-out magnet 8, and the focusing magnet 9 are all coil magnets, and the inside of the solenoid is a vacuum.

[0051] The extraction component 6 is an electron extraction structure, including an extraction hole and an extraction magnet, used to extract charged particle bundles with an average current intensity reaching a preset value, and the extraction component 6 and the introduction component 5 are symmetrically arranged.

[0052] According to the solenoid bundle confinement model proposed in this application, charged particle bundles, after being introduced into a uniform field within the solenoid, can move stably in a spiral motion. By controlling the deflection magnet currents on both sides of the confinement zone, the introduced bundles can be confined within the structure. When sequentially injecting bundles into the structure, the power supply to the deflection magnet coils is switched off at the instant of bundle injection and then quickly switched on again after injection, continuing to reflect the bundles already within the confinement structure. This multiplies the number of bundles and the average current within the confined structure. When the beam current intensity in the structure reaches a set value, the current of the extraction magnet is switched off, allowing the compressed beam to be extracted sequentially, thus achieving charged particle beam compression and enabling accelerator charged particle beam current compression with an average current on the order of kA. This device has a compact structure and can compress relativistic charged particle beams to extremely high current intensities.

[0053] Figure 2 This is a flowchart of an accelerator charged particle beam current compression method according to an embodiment of this application. Figure 2 As shown, the method includes the following steps:

[0054] Step 101: Create a uniform magnetic field inside the solenoid;

[0055] Step 102: Multiple bundles of charged particles are sequentially introduced into a uniform magnetic field, causing the bundles of charged particles to move in a spiral motion.

[0056] Step 103: The charged particle beams that are injected in sequence are made to reciprocate in a spiral motion between the pairs of reflecting magnets until the average current intensity of the charged particle beam in the confined area reaches a preset value.

[0057] Step 104: Extract the charged particle bundle with an average current intensity of a preset value from the confinement model.

[0058] Regarding the methods in the above embodiments, the specific ways in which each method performs its operations have been described in detail in the embodiments related to the model, and will not be elaborated here.

[0059] Figure 3 The flowchart below shows a method for compressing the current of charged particle bundles in an accelerator according to an embodiment of this application. Figure 3 As shown, step 103 also includes:

[0060] Step 201: After the charged particle beam enters the confined area, it is incident at an axial velocity v z0 The spiral motion leads to the reflective magnet on the extraction side;

[0061] Step 203: The charged particle cluster is deflected by the reflecting magnet on the extraction side and then moves in the opposite direction with an axial velocity of -v. z0 The spiral motion leads to the reflective magnet on the side of the introduction.

[0062] Step 203: The charged particle beam moves back and forth in a spiral motion within the confined area until the average current intensity of the charged particle beam within the confined area reaches a preset value.

[0063] like Figure 4 As shown, the charged particle cluster continues to move at an axial velocity v after entering the confined region. z After spiraling for N / 2 cycles to the lead-out side reflecting magnet 8, it is subjected to a deflection force and then reverses direction with an axial velocity of -v. z The spiral travels for N / 2 cycles until the side reflecting magnet 7 is introduced, and this process is repeated. The duration of each confinement cycle is NT. C , where v z Let N be the vector velocity of the charged particle beam incident on the field, and N be the number of times the electron rotates back and forth in the confined region. It can be any positive even number depending on the design.

[0064] Furthermore, if the time interval before the introduction of adjacent bundles is T b Before reaching the extraction assembly, the number of reciprocating cycles within the confined zone assembly differs by n. Upon reaching the extraction assembly, the interval between adjacent bundles is:

[0065] T′ b =Tb -nNT c

[0066] Where N is the number of round-trip spiral motions of the charged particle beam within the confined area, and T... c It is the gyroscopic period of a bundle of charged particles spiraling in a uniform magnetic field.

[0067] Furthermore, when the charged particle bundle is extracted, the compression ratio of the charged particle bundle repetition frequency and average current compared to when it was introduced is as follows:

[0068]

[0069] Among them, T b The interval between multiple charged particle clumps entering the introduction component is N, where N is the number of round-trip spiral motions of the charged particle clumps within the confinement zone, and T is T. c denoted as , where is the cyclotron period of the charged particle bundle in the uniform magnetic field, and n is the number of revolutions that adjacent bundles undergo before reaching the extraction component and within the confinement component.

[0070] The following will illustrate the current compression method for charged particle bundles in accelerators with a specific example. This embodiment achieves a 10-fold current compression for 10 electron bundles with a charge of 1 nC and a value of 6.511 MeV.

[0071] (1) Ten electron beams spaced 48 ns apart, with a charge of 1 nC and an energy of 6.511 MeV, are introduced into a solenoid structure (e.g., Figure 1 (As shown). According to the design, the solenoid uniform field strength is approximately 0.1T, the radius of the electron beam's helical motion trajectory is ~25cm, and the motion period is 5.4ns. Other relevant parameters: solenoid inner diameter 40cm, and the distance between the reflecting magnets on the lead-in and lead-out sides is 150cm.

[0072] (2) When a time-varying current is passed through the reflecting magnets on the introduction and extraction sides, the field strength changes as follows: Figure 6 As shown, the magnetic field introduced by the side-reflecting magnet 7 is such that the electron incident interval T b The instantaneous shutdown is performed with a period of 48ns, and the shutdown duration is Δt = 0.2ns. The lead-out side reflective magnet 8 is normally open in the early stage, and the shutdown is performed after all 10 bundles have entered the confinement zone.

[0073] (3) The number of cycles of adjacent clusters moving between the reflecting magnet pairs differs by 1. When they reach the extraction structure, the interval T′ between the charged particle clusters is... b =T b -nNT c =4.8ns, the repetition frequency and average current are 10 times that at the time of incidence, achieving a 10-fold compression of the average current.

[0074] It should be noted that the foregoing explanation of the embodiment of the solenoid bundle confinement model also applies to the current compression method of the charged particle bundle in the accelerator in this embodiment, and will not be repeated here.

[0075] According to the accelerator charged particle beam current compression method proposed in this application, the charged particle beam is introduced into a uniform field inside a solenoid and can move stably in a spiral motion. By controlling the deflection magnets that reciprocate the reflection of the electron beam in the confinement region, the beam can be confined in the structure. At the same time, the beam is injected into the structure sequentially. The power supply of the deflection magnet coil is turned off at the moment of beam injection and then quickly turned on again after injection to continue to reflect the beam in the structure, thereby multiplying the number of beams and the current in the confined structure. When the beam current intensity in the structure reaches a set value, the current of the magnet on the extraction side is turned off, and the compressed beam can be extracted sequentially to achieve the compression of the charged particle beam. This achieves accelerator charged particle beam current compression with an average current on the kA level, and the structure is compact, meeting the requirements of applications such as Z-pinch.

[0076] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0077] Furthermore, the terms "first" and "second" 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. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "N" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0078] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A method for compressing the current of charged particle bundles in accelerators, applied to a solenoid bundle confinement model, characterized in that, include: A uniform magnetic field is formed inside the solenoid; Multiple bundles of charged particles are sequentially introduced into the uniform magnetic field, causing the bundles of charged particles to move in a spiral motion. The charged particle beams that are incident sequentially are made to reciprocate in a spiral motion between pairs of reflecting magnets until the average current intensity of the charged particle beams within the confined area reaches a preset value. A charged particle beam with an average current intensity reaching a preset value is extracted from the confined model.

2. The method according to claim 1, characterized in that, The charged particle cluster reciprocates in a spiral motion between the pairs of reflecting magnets until the average current intensity of the charged particle cluster reaches a preset value, including: After the charged particle beam enters the confined area, it travels at an axial incident velocity. The spiral motion leads to the reflective magnet on the extraction side; The charged particle cluster is deflected by the reflecting magnet on the extraction side, and then moves in the opposite direction at an axial velocity. The spiral motion leads to the reflective magnet on the side of the introduction. The charged particle cluster reciprocates in a spiral motion within the confined area until the average current intensity of the charged particle beam within the confined interval reaches a preset value.

3. The method according to claim 1, characterized in that, If the time interval before the introduction of adjacent bundles is Before reaching the extraction assembly, the number of reciprocating cycles within the confinement assembly differs by n. Upon reaching the extraction assembly, the interval between adjacent bundles is: Where N is the number of round-trip spiral motions of the charged particle cluster within the confined area. The gyration period of the charged particle bundle as it spirals in the uniform magnetic field.

4. The method according to claim 1, characterized in that, When the charged particle bundle is extracted, the compression factor of the repetition frequency and average current of the charged particle bundle compared to when it was introduced is: in, The interval between the multiple charged particle clusters when they enter the introduction component is denoted by N, and N is the number of round-trip spiral motions of the charged particle clusters within the confinement zone. The gyration period of the charged particle bundle as it undergoes helical motion in the uniform magnetic field is given. It is the difference in the number of cycles of reciprocating motion of adjacent bundles within the confined zone assembly before reaching the extraction assembly.

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