Cascade drift tube potential well device and using method thereof
阅读说明：本技术 一种级联漂移管电势阱装置及其使用方法 (Cascade drift tube potential well device and using method thereof ) 是由 孙良亭 黄维 谢祖褀 赵红卫 于 2020-06-23 设计创作，主要内容包括：本发明涉及一种级联漂移管电势阱装置及其使用方法,其包括漂移管、电子反射电极、电子枪阴极、电子枪阳极、真空管道、螺线管和铁轭；漂移管设置为多个,并沿轴线方向间隔设置在真空管道内,位于真空管道的入口端设置有所述电子枪阴极和电子枪阳极,位于所述真空管道的出口端设置有所述电子反射电极,多个所述漂移管位于所述电子枪阳极与所述电子反射电极之间；所述真空管道外部设置有所述螺线管,且螺线管的外部设置有所述铁轭。本发明可以将注入的特定电荷态的离子束进行压缩储存,在离子束流储存达到饱和之后,通过快引出或慢引出的方式,可以得到不同脉冲长度的强流离子脉冲束。相比于单个离子源的引出束流,可以有效提高了束流的脉冲强度。(The invention relates to a cascade drift tube potential well device and a using method thereof, wherein the cascade drift tube potential well device comprises a drift tube, an electron reflection electrode, an electron gun cathode, an electron gun anode, a vacuum pipeline, a solenoid and an iron yoke; the drift tubes are arranged in the vacuum pipeline at intervals along the axis direction, the electron gun cathode and the electron gun anode are arranged at the inlet end of the vacuum pipeline, the electron reflection electrode is arranged at the outlet end of the vacuum pipeline, and the drift tubes are arranged between the electron gun anode and the electron reflection electrode; the solenoid is arranged outside the vacuum pipeline, and the iron yoke is arranged outside the solenoid. The invention can compress and store the injected ion beam with specific charge state, and can obtain the high-current ion pulse beams with different pulse lengths by means of fast extraction or slow extraction after the ion beam storage reaches saturation. Compared with the extracted beam of a single ion source, the pulse intensity of the beam can be effectively improved.)
1. A cascaded drift tube potential well device, comprising: drift tube, electron reflection electrode, electron gun cathode, electron gun anode, vacuum pipe, solenoid and iron yoke;
the drift tubes are arranged in the vacuum pipeline at intervals along the axis direction, the electron gun cathode and the electron gun anode are arranged at the inlet end of the vacuum pipeline, the electron reflection electrode is arranged at the outlet end of the vacuum pipeline, and the drift tubes are arranged between the electron gun anode and the electron reflection electrode; the solenoid is arranged outside the vacuum pipeline, and the iron yoke is arranged outside the solenoid.
2. The apparatus of claim 1, wherein: the drift tubes, the electron gun cathode, the electron gun anode and the electron reflection electrode are positioned on the same central axis.
3. The apparatus of claim 1, wherein: each drift tube can independently control the potential; each of the drift tubes has a pore size that matches the full particle size.
4. The apparatus of claim 1, wherein: the cathode of the electron gun adopts a hollow structure; the anode of the electron gun comprises an inner ring anode and an outer ring anode, and the outer ring anode is sleeved outside the inner ring anode; a gap is formed between the outer ring anode and the inner ring anode, and the outer ring anode and the inner ring anode are connected through a ceramic support column; the inner ring anode adopts a hollow structure.
5. A use method based on the device of any one of claims 1 to 4, wherein ten drift tubes are adopted, and the first drift tube to the tenth drift tube are sequentially arranged in the vacuum pipeline from left to right, and the method is characterized by comprising the following steps:
s1, determining the vacuum degree required by the cascade drift tube potential well device;
s2, determining the size and the potential of each electrode in the cascade drift tube potential well device;
s3, compressing and storing the ion beam;
and S4, extracting the ion beam.
6. The use of claim 5, wherein the dimensions and potentials of the electrodes are determined by:
s21, providing needed ions with specific charge states by using an ECR ion source, and determining the inner diameter of a drift tube positioned at the central position in the cascade drift tube potential well device according to the size of the extracted beam; according to the magnetic field values at different positions in the axial direction, calculating to obtain the inner diameters of the other drift tubes according to the principle that the ratio of the radius of the drift tube to the radius of the electron beam is not changed;
s22, determining the energy of the electron beam in the potential well according to the ionization threshold of the ion beam of the specific charge state required to be restricted, so that the energy is lower than the ionization threshold of the ion, thereby obtaining the voltage values loaded by the anode of the electron gun and the first nine drift tubes from left to right, wherein the voltage loaded by the anode of the electron gun and the first drift tube is higher than the voltage values of the second drift tube to the ninth drift tube;
s23, after the ECR ion source extracts the needed ions with specific charge states, the loading voltages of the tenth drift tube and the electron reflection electrode are determined according to the transmission simulation of beam current, and meanwhile, the electron beams are guaranteed to reach the electron reflection electrode after being emitted from the electron gun and are reflected.
7. The method of use of claim 5, wherein said compression and storage method comprises the steps of:
s31, after the ion beam is injected into the cascade drift tube potential well device from the outside of the reflection electrode, the ion beam encounters high potential at the sixth drift tube and is reflected, when the ion beam returns to the tenth drift tube, the potential of the tenth drift tube is increased, and the ion beam is confined between the sixth drift tube and the tenth drift tube;
s32, slowly increasing the potential of the ninth drift tube to realize compression of the ion beam, and after the potential is increased, decreasing the potential of the tenth drift tube;
s33, reducing the potential of the sixth drift tube to make the ion beam enter the potential well, when the ion beam moves forwards, the ion beam meets the high potential of the first drift tube to be reflected, and meanwhile, slowly increasing the potential of the eighth drift tube to propel the ion beam into the potential well;
s34, after the potential of the eighth drift tube is increased, the potential of the ninth drift tube is reduced, and meanwhile, the potential of the seventh drift tube is slowly increased, so that the ion beam is further propelled;
s35, after the potential of the seventh drift tube is increased, the potential of the eighth drift tube is reduced, and meanwhile, the potential of the sixth drift tube is slowly increased;
s36, after the potential of the sixth drift tube is improved, the potential of the seventh drift tube is reduced, and at the moment, the potential distribution of all drift tubes is consistent with that when ion beams led out by an ECR ion source are injected into the cascade drift tube potential well device;
and S37, repeating the steps S31 to S36 until the ion beam stored in the potential well reaches saturation.
8. The use method as claimed in claim 5, wherein the extraction of the ion beam is divided into a fast extraction scheme and a slow extraction scheme according to the pulse length of the ion beam.
9. The use of claim 8, wherein the fast extraction scheme is: the voltages of the anode of the electron gun and the first drift tube are reduced to be consistent with the voltage of the second drift tube, and the voltages of the second drift tube to the fifth drift tube are sequentially increased to form an electric field along the direction of the electron gun in the axial direction, and the ion beam in the potential well is transmitted through holes in the anode of the electron gun and the cathode structure of the electron gun along the direction of the electric field and is led out.
10. The use of claim 8, wherein the slow extraction scheme is: reducing the voltage of the anode of the electron gun and the first drift tube to be still higher than that of the second drift tube, wherein a part of high-energy ions axially escape from the first drift tube and are led out, and the other part of ions are still confined in the device; continuously and slowly increasing the potential of the second to fifth drift tubes, and keeping the direction of the formed axial electric field pointing to the electron gun in the process of increasing the potential so that the ion beam is continuously led out; the increasing speed of the electric potential of the second to the fifth drift tubes is determined according to the pulse time requirement of the extracted beam current, and finally the electric potential is increased to be consistent with the electric potential of the first drift tube, and all the ion beams in the potential well are extracted.
Technical Field
The present invention relates to a potential well, and more particularly, to a cascade drift tube potential well device and a method for using the same.
Background
The development of modern technology requires that the accelerator be capable of providing increasingly stronger heavy ion beams with high charge states. For example, the U.S. FrIB (facility for Rare Isotope beams) project under construction in the United states requires approximately 470e μ A of U34+Ion beam current, due to limited ion source generating capacity, adopts a compromise dual charge state technique, namely U33++U34+A dual ion beam acceleration method; the RIBF (radio Isotrope Beam facility) apparatus of RIKEN (RIkagaku KENkyusho/Institute of Physical and Chemical Research) in Japan requires 525 e. mu.A of U.S.35+(ii) a Require U34+The ion beam current intensity reaches more than 1emA, which is more than twice of the current international best level.
At present, devices for obtaining a high-charge state Ion Beam mainly include an Electron Cyclotron Resonance Ion Source (ECRIS) and an Electron Beam Ion Source (EBIS). In order to improve the performance of the device, both ion sources have applied superconducting technology and other auxiliary means, for example, ECR ion source also adopts bias plate technology, aluminum is used as the material of the plasma arc chamber, etc. However, other auxiliary techniques have been promoted to a limited extent, and the superconducting wire used is also developed from NbTi superconducting material to Nb3The manufacturing cost of the Sn superconducting material and the ion source is continuously improved, and the technical difficulty is also improved.
Disclosure of Invention
In view of the above problems, an object of the present invention is to provide a cascaded drift tube potential well device and a method for using the same, which are low in cost and capable of effectively increasing the ion beam current intensity.
In order to achieve the purpose, the invention adopts the following technical scheme: a cascade drift tube potential well device comprises a drift tube, an electron reflection electrode, an electron gun cathode, an electron gun anode, a vacuum pipeline, a solenoid and an iron yoke; the drift tubes are arranged in the vacuum pipeline at intervals along the axis direction, the electron gun cathode and the electron gun anode are arranged at the inlet end of the vacuum pipeline, the electron reflection electrode is arranged at the outlet end of the vacuum pipeline, and the drift tubes are arranged between the electron gun anode and the electron reflection electrode; the solenoid is arranged outside the vacuum pipeline, and the iron yoke is arranged outside the solenoid.
Furthermore, the drift tubes, the electron gun cathode, the electron gun anode and the electron reflection electrode are positioned on the same central axis.
Further, each drift tube can independently control the potential; each of the drift tubes has a pore size that matches the full particle size.
Further, the cathode of the electron gun adopts a hollow structure; the anode of the electron gun comprises an inner ring anode and an outer ring anode, and the outer ring anode is sleeved outside the inner ring anode; a gap is formed between the outer ring anode and the inner ring anode, and the outer ring anode and the inner ring anode are connected through a ceramic support column; the inner ring anode adopts a hollow structure.
A use method based on the device is characterized in that ten drift tubes are adopted, the first drift tube to the tenth drift tube are sequentially arranged in the vacuum pipeline from left to right, and the method comprises the following steps:
s1, determining the vacuum degree required by the cascade drift tube potential well device;
s2, determining the size and the potential of each electrode in the cascade drift tube potential well device;
s3, compressing and storing the ion beam;
and S4, extracting the ion beam.
Further, the method for determining the size and the potential of each electrode comprises the following steps:
s21, providing needed ions with specific charge states by using an ECR ion source, and determining the inner diameter of a drift tube positioned at the central position in the cascade drift tube potential well device according to the size of the extracted beam; according to the magnetic field values at different positions in the axial direction, calculating to obtain the inner diameters of the other drift tubes according to the principle that the ratio of the radius of the drift tube to the radius of the electron beam is not changed;
s22, determining the energy of the electron beam in the potential well according to the ionization threshold of the ion beam of the specific charge state required to be restricted, so that the energy is lower than the ionization threshold of the ion, thereby obtaining the voltage values loaded by the anode of the electron gun and the first nine drift tubes from left to right, wherein the voltage loaded by the anode of the electron gun and the first drift tube is higher than the voltage values of the second drift tube to the ninth drift tube;
s23, after the ECR ion source extracts the needed ions with specific charge states, the loading voltages of the tenth drift tube and the electron reflection electrode are determined according to the transmission simulation of beam current, and meanwhile, the electron beams are ensured to be reflected from the electron gun to the electron reflection electrode.
Further, the compression and storage method comprises the following steps:
s31, after the ion beam is injected into the cascade drift tube potential well device from the outside of the reflection electrode, the ion beam is reflected when encountering high potential at the sixth drift tube, and when the ion beam returns to the tenth drift tube, the potential of the tenth drift tube is increased, and the ion beam is confined between the sixth drift tube and the tenth drift tube;
s32, slowly increasing the potential of the ninth drift tube to realize compression of the ion beam, and after the potential is increased, decreasing the potential of the tenth drift tube;
s33, reducing the potential of the sixth drift tube to make the ion beam enter the potential well, when the ion beam moves forwards, the ion beam meets the high potential of the first drift tube to be reflected, and meanwhile, slowly increasing the potential of the eighth drift tube to propel the ion beam into the potential well;
s34, after the potential of the eighth drift tube is increased, the potential of the ninth drift tube is reduced, and meanwhile, the potential of the seventh drift tube is slowly increased, so that the ion beam is further propelled;
s35, after the potential of the seventh drift tube is increased, the potential of the eighth drift tube is reduced, and the potential of the sixth drift tube is increased slowly;
s36, after the potential of the sixth drift tube is improved, the potential of the seventh drift tube is reduced, and the potential distribution of all the drift tubes is consistent with that of the ion beam led out by the ECR ion source when the ion beam is injected into the cascade drift tube potential well device;
and S37, repeating the steps S31 to S36 until the ion beam stored in the potential well reaches saturation.
Furthermore, the extraction of the ion beam is divided into two schemes of fast extraction and slow extraction according to the pulse length of the ion beam.
Further, the fast extraction scheme is as follows: and the voltage of the anode of the electron gun and the voltage of the first drift tube are reduced to be consistent with the voltage of the second drift tube, and the voltages of the second drift tube to the fifth drift tube are sequentially increased to form an electric field along the direction of the electron gun in the axial direction, and the ion beam in the potential well is transmitted through holes in the anode structure of the electron gun and the cathode structure of the electron gun along the direction of the electric field and is led out.
Further, the slow extraction scheme is as follows: reducing the voltage of the anode of the electron gun and the first drift tube to be still higher than that of the second drift tube, wherein a part of high-energy ions axially escape from the first drift tube and are extracted, and another part of ions are still confined in the device; continuously and slowly increasing the potential of the second to fifth drift tubes, and keeping the direction of the formed axial electric field pointing to the electron gun in the process of increasing the potential so that the ion beam is continuously led out; the increasing speed of the electric potential of the second to the fifth drift tubes is determined according to the pulse time requirement of the extracted beam current, and finally the electric potential is increased to be consistent with the electric potential of the first drift tube, and all the ion beams in the potential well are extracted.
Due to the adoption of the technical scheme, the invention has the following advantages: the invention has the aperture matched with the size of the whole particle, and can be installed and controlled at any position downstream of the leading-out end of the ion source; because the cascade drift tube potential well device adopts a plurality of drift tubes, and each drift tube can independently control the potential, the ion beam with the injected specific charge state can be compressed and stored, and after the ion beam storage reaches saturation, the strong current ion pulse beams with different pulse lengths can be obtained by a fast extraction or slow extraction mode. Compared with the extracted beam of a single ion source, the pulse intensity of the beam can be effectively improved.
Drawings
FIG. 1 is a schematic view of the overall structure of the present invention;
FIG. 2 is an enlarged view of the cathode structure of the electron gun of the present invention;
FIG. 3 is an enlarged view of the anode structure of the electron gun of the present invention.
Detailed Description
In the description of the present invention, it is to be understood that the terms "upper", "lower", "inside", "outside", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are only for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention. The invention is described in detail below with reference to the figures and examples.
The invention provides a cascade drift tube potential well device which is used for storing injected ion beam flow with a specific charge state, and finally leading out the ion beam in the potential well at one time to obtain a pulse ion beam, wherein the beam intensity of the pulse ion beam is higher than that of the beam obtained by singly using ECRIS or EBIS. Different potentials are loaded on each drift tube, the ion beam is constrained in the axial direction through the different potentials, and the ion beam is constrained in the radial direction through space charge force generated by electron beams incident from an electron gun, so that the cascade drift tube potential well device is called.
As shown in fig. 1, the present invention includes a plurality of drift tubes 1, electron reflection electrodes 5, electron gun cathodes 3, electron gun anodes 4, vacuum pipes 2, solenoids 6, and yokes 7. In this embodiment, the drift tubes are preferably arranged in ten.
A plurality of drift tubes 1 are arranged in a vacuum pipeline 2 at intervals along the axis direction, an electron gun cathode 3 and an electron gun anode 4 are arranged at the inlet end of the vacuum pipeline 2, an electron reflection electrode 5 is arranged at the outlet end of the vacuum pipeline 2, and the drift tubes 1 are arranged between the electron gun anode 4 and the electron reflection electrode 5. The vacuum pipe 2 is externally provided with a solenoid 6, and the solenoid 6 is externally provided with an iron yoke 7.
In the above embodiment, the drift tubes 1 are located on the same central axis as the electron gun cathode 3, the electron gun anode 4, and the electron reflection electrode 5.
In the above embodiments, each drift tube 1 is individually connected to different control power supplies, so that each drift tube 1 can independently control the potential; wherein the control power source is generally a voltage source.
In the above embodiments, the lengths of the drift tubes 1 are different.
In the above embodiments, each drift tube 1 has a pore size corresponding to the full particle size, i.e., the inner diameter of the drift tube 1.
In the above embodiments, as shown in fig. 2, the electron gun cathode 3 has a hollow structure. As shown in fig. 3, the electron gun anode 4 includes an
Based on the device, the invention also provides a using method of the cascade drift tube potential well device, the method adopts ten drift tubes 1, the first drift tube 1 to the tenth drift tube 1 are sequentially arranged in the vacuum pipeline 2 from left to right, and the using method comprises the following steps:
and S1, determining the vacuum degree required by the cascade drift tube potential well device.
By U34+For example, the calculated vacuum degree is better than 10-10mbar。
And S2, determining the size and the potential of each electrode in the cascade drift tube potential well device.
The specific determination method comprises the following steps:
and S21, providing ions with specific charge states as required by using the ECR ion source, and determining the inner diameter of the drift tube 1 positioned at the central position in the cascade drift tube potential well device according to the size of the extracted beam current. The solenoid 6 provides an axial magnetic field, the iron yoke 7 on the outer layer of the solenoid 6 enables the magnetic field in the potential well to be uniform, and the inner diameters of the rest drift tubes 1 are calculated according to the magnetic field values at different positions in the axial direction and the principle that the ratio of the radius of the drift tube 1 to the radius of the electron beam is not changed;
s22, determining the energy of the electron beam in the potential well according to the ionization threshold of the ion beam of the specific charge state which is restrained as required, and making the energy of the electron beam lower than the ionization threshold of the ion, so as to avoid the ion being further stripped into ions with higher charge states by the electron, thereby obtaining the voltage values loaded by the anode 4 of the electron gun and the first nine drift tubes 1 from left to right in the potential well;
the first drift tube 1 has a voltage value about 1kV higher than the anode of the electron gun, acts as a second anode, accelerates electrons, and the voltages of the second to ninth drift tubes 1 (lower than the voltage of the first drift tube 1) determine the energies of the electrons in the cascaded drift tube potential well devices;
s23, after the ECR ion source extracts needed ions with specific charge states, the loading voltages of the tenth drift tube 1 and the electron reflection electrode 5 are determined according to the transmission simulation of beam current, and meanwhile, the electron beams are guaranteed to reach the electron reflection electrode 5 and are reflected after being emitted from the electron gun.
S3, compressing and storing the ion beam.
S31, after the ion beam is injected into the cascade drift tube potential well device from the outside of the reflection electrode, the ion beam is reflected when encountering high potential at the sixth drift tube 1, when the ion beam returns to the tenth drift tube 1, the potential of the tenth drift tube 1 is increased, and the ion beam is confined between the sixth drift tube 1 and the tenth drift tube 1;
s32, slowly increasing the potential of the ninth drift tube 1 to realize compression of the ion beam, and after the potential is increased, reducing the potential of the tenth drift tube 1;
s33, lowering the potential of the sixth drift tube 1 to make the ion beam enter the potential well, and when the ion beam moves forward, the ion beam will encounter the high potential of the first drift tube 1 to be reflected, and at the same time, slowly raising the potential of the eighth drift tube 1 to propel the ion beam into the potential well;
s34, after the potential of the eighth drift tube 1 is increased, the potential of the ninth drift tube 1 is reduced, and meanwhile, the potential of the seventh drift tube 1 is slowly increased, so that the ion beam is further propelled;
s35, after the potential of the seventh drift tube 1 is increased, the potential of the eighth drift tube 1 is reduced, and meanwhile, the potential of the sixth drift tube 1 is slowly increased;
and S36, after the potential of the sixth drift tube 1 is increased, reducing the potential of the seventh drift tube 1, wherein the potential distribution of all the drift tubes is consistent with the injection of the ion beam led out by the ECR ion source into the cascade drift tube potential well device.
And S37, continuously repeating the steps S31 to S36 until the ion beam stored in the potential well is saturated, and then extracting the ion beam.
And S4, extracting the ion beam.
According to the requirement of the pulse length of the ion beam current, the method can be divided into two schemes of fast extraction and slow extraction.
(1) If the fast extraction is carried out, the voltages of the electron gun anode 4 and the first drift tube 1 are reduced to be consistent with the voltage of the second drift tube 1, and the voltages of the second drift tube 1 to the fifth drift tube 1 are sequentially increased to form an electric field along the electron gun direction in the axial direction, and the ion beam in the potential well is transmitted through the holes in the structures of the electron gun anode 4 and the electron gun cathode 3 (namely the hollow structure of the electron gun cathode 3) along the electric field direction and is extracted;
(2) if the extraction is slow, the voltage of the anode 4 of the electron gun and the voltage of the first drift tube 1 are reduced to be still higher than the voltage of the second drift tube 2, and at the moment, a part of high-energy ions can escape from the first drift tube 1 along the axial direction to be extracted, and the other part of ions are still confined in the device; and simultaneously, the potentials of the second drift tube 1 to the fifth drift tube 1 are continuously and slowly increased, the direction of the formed axial electric field is kept pointing to the electron gun in the process of increasing the potentials, so that the ion beam is continuously extracted, and the pulse length of the extracted beam is determined by the increasing speed of the potentials of the second drift tube 1 to the fifth drift tube 1. The increasing speed of the electric potential of the second to the fifth drift tubes 1 is determined according to the pulse time requirement of the extracted beam current, and finally the electric potential is increased to be consistent with the electric potential of the first drift tube 1, and all ion beams in the potential well are extracted.
In the above steps, ion beam current with different pulse lengths can be obtained by modulating the potential of the drift tube 1 in the ion beam extraction process.
In summary, the invention starts from the prior art, adopts a normal temperature magnet technology, has a cost far lower than that of the current superconducting equipment, and proposes to use a structure of a cascade drift tube as a potential well device, store strong current ion beams generated by an ECR ion source in the potential well device, and finally extract the strong current pulse ion beams to achieve the purpose of improving the ion beam intensity.
The above embodiments are only for illustrating the present invention, and the structure, size, arrangement position and shape of each component can be changed, and on the basis of the technical scheme of the present invention, the improvement and equivalent transformation of the individual components according to the principle of the present invention should not be excluded from the protection scope of the present invention.
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