CN114867182B - A compact electrostatic storage ring device for charged particle storage - Google Patents

Abstract

The invention discloses a compact electrostatic storage ring device for charged particle storage, which comprises four beam deflection modules, wherein square beam flight channels are formed; each beam deflection module comprises a beam deflection component and two beam shaping components; each beam deflection component is composed of four-pole deflection electrodes, and voltage is applied to deflect the passing beam by 90 degrees; the four-pole deflection electrode is formed by opposite four right-angle fan-shaped cylinder electrodes, the top and the bottom of each right-angle fan-shaped cylinder electrode are provided with square plate electrodes, the outer side of each right-angle fan-shaped cylinder electrode surrounds an L-shaped electrode, and a side shielding electrode is arranged outside the L-shaped electrode; each beam shaping member is composed of an electrostatic single lens, and a voltage is applied to shape the beam passing through the beam deflection member. The invention has compact structure and low processing difficulty, can be used together with femtosecond laser, overcomes the problem of insufficient light intensity of the femtosecond laser, and is suitable for the study of (particle) photoelectron spectroscopy and dynamic process of the cluster deep energy level full spectrum.

Description

A compact electrostatic storage ring device for charged particle storage

Technical Field

The present invention relates to a storage ring device, and more particularly to a compact electrostatic storage ring device for charged particle storage.

Background technique

The art of experimental physics is to observe the structure of matter and its internal dynamics. Real-time observation (measurement) of the microscopic dynamics of particle chemical reactions will play a key role in truly understanding the chemical reaction properties of particles, and ultrafast laser spectroscopy using femtosecond lasers can achieve this goal. However, there are still many technical problems in the architecture of the experimental device that cannot be solved. The high-order frequency-doubled laser generated by femtosecond lasers is suitable for the study of particle microdynamics. However, its output light flux is very small, so the beam intensity is very high.

The function of the storage ring is to store charged particles, that is, to continuously inject and accumulate particles with a specific energy so that the stored beam reaches the rated value and flies in the storage ring for a long time.

The above problems can be solved by repeatedly injecting beams into the storage ring to enhance the cluster beam intensity and compensate for the low light intensity of the laser with the high beam intensity.

Electrostatic storage rings are small multifunctional non-relativistic particle storage rings developed at the end of the last century. Their operating physical quantities depend only on the kinetic energy/charge ratio of the confined charged particles rather than their mass, so they can store large mass particles, including clusters and biomacromolecules, and even nanoparticles with larger mass numbers.

Electrostatic storage rings are generally composed of a deflection structure and a beam shaping structure. When a quadrupole deflection electrode is used as a deflection component, the traditional symmetrical voltage applied to the quadrupole deflection electrode will produce a focusing and defocusing effect on the beam. Generally, quadrupole third-order lenses are placed at the entrance and exit of the deflection electrode to shape the beam. The reason is that the quadrupole deflection electrode has different focusing and defocusing capabilities for the horizontal and vertical directions of the beam. Therefore, a quadrupole three-lens is required to focus and defocus the beam in the horizontal and vertical directions respectively, so as to compensate for the focusing and defocusing capabilities of the quadrupole deflection electrode. This symmetrical voltage mode structure is very complex and requires high processing accuracy. In addition, the quadrupole third-order lens has many voltage parameters and is not easy to adjust, which increases the error and difficulty in the experiment.

Summary of the invention

In order to solve the above-mentioned existing technical problems, the present invention proposes a compact electrostatic storage ring device for charged particle storage. By adding a new structure to the deflection electrode and applying an asymmetric voltage, the effect of the beam passing through the deflection electrode in parallel and out parallel is achieved, and an electrostatic single lens is used to shape the beam.

The objectives of the present invention are achieved through the following technical solutions.

The compact electrostatic storage ring device for charged particle storage of the present invention comprises four beam deflection modules, which together form a square structure to form a square beam flight channel; each of the beam deflection modules comprises a beam deflection component and two beam shaping components, and the two beam shaping components in each beam deflection module are arranged at an angle of 90° to each other and are respectively located at the entrance and exit of the corresponding beam deflection component;

Each of the beam deflection components is composed of a quadrupole deflection electrode, and by applying a suitable voltage, the passing beam is deflected by 90°; the quadrupole deflection electrode is composed of four right-angled fan-shaped cylindrical electrodes facing each other, and each right-angled fan-shaped cylindrical electrode is provided with a square plate electrode at the top and bottom to curb the longitudinal dispersion of the beam, and each right-angled fan-shaped cylindrical electrode is surrounded by an "L"-shaped electrode, and two side shielding electrodes are provided on the periphery of the "L"-shaped electrode to shield the influence of external stray fields on the beam;

Each of the beam shaping components is composed of an electrostatic single lens, and shapes the beam passing through the beam deflection component by applying a suitable voltage.

A certain distance is left between adjacent beam deflection modules to reserve space in advance for the subsequent installation of photoelectric spectrum electrodes or other devices.

The quadrupole deflection electrode is formed by four right-angled fan-shaped cylindrical electrodes to form a square structure. The four right-angled fan-shaped cylindrical electrodes are arranged at a certain distance from each other. Each right-angled fan-shaped cylindrical electrode and its corresponding "L"-shaped electrode and side shielding electrode are arranged at a certain distance from each other, and are connected and fixed to each other by connecting rods.

A top shielding electrode is arranged at the top of each of the quadrupole deflection electrodes, and the top shielding electrode is connected to the top of the side shielding electrode; a bottom shielding electrode is arranged at the bottom of each of the quadrupole deflection electrodes, and the bottom shielding electrode is connected to the bottom of the side shielding electrode; each right-angled fan-shaped cylindrical electrode of each of the quadrupole deflection electrodes is fixed to the bottom shielding electrode through the square plate electrode at its bottom.

The voltage applied to the quadrupole deflection electrode adopts an asymmetric voltage mode, that is, equal voltages of the same positive and negative are applied to the opposite right-angled fan-shaped cylindrical electrodes in the quadrupole deflection electrode, and unequal voltages of opposite positive and negative are applied to adjacent right-angled fan-shaped cylindrical electrodes; equal voltages of the same positive and negative are applied to the four "L"-shaped electrodes in the quadrupole deflection electrode.

The electrostatic single lens is composed of three coaxially arranged metal cylindrical tube electrodes, which are kept at a certain distance from each other and connected by a connecting rod; wherein the first metal cylindrical tube electrode and the third metal cylindrical tube electrode have the same length and are both shorter than the length of the second metal cylindrical tube electrode.

When voltages are applied to the three metal cylindrical electrodes in the electrostatic single lens respectively, the first metal cylindrical electrode and the third metal cylindrical electrode are grounded.

The electrostatic single lens is wrapped with a grounding shielding tube on the outside.

As the beam deflection module at the beam entrance, the voltage applied to the beam deflection module is in pulse form, and the pulse frequency is consistent with the front-end beam injection frequency, while the voltages applied to the other three beam deflection modules always remain at a constant voltage.

Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

(1) The quadrupole deflection electrode of the present invention adopts a right-angled fan-shaped cylindrical electrode, and square plate electrodes are added to the top and bottom of the electrode, which effectively reduces the divergence of the beam in the vertical direction; an "L"-shaped electrode is added to the outside of the electrode, which successfully reduces the voltage required for the right-angled fan-shaped cylindrical electrode to deflect the beam and stably store the beam in the storage ring. And because the voltage applied to the quadrupole deflection electrode is related to the particle energy (linear relationship, positive correlation), this design can store high-energy particles with a lower voltage.

(2) The voltage applied to the quadrupole deflection electrodes in the present invention is an asymmetric voltage mode, that is, the relative electrode voltages are the same, while the adjacent electrode voltages are of different magnitudes and opposite in positive and negative. This voltage mode can reduce the problem of different focusing and defocusing conditions in the horizontal and vertical directions of the beam caused by the symmetrical voltage, thereby achieving the purpose of deflecting the beam while ensuring the same degree of divergence in the horizontal and vertical directions, providing convenience for subsequent beam shaping.

(3) The beam shaping component of the present invention adopts an electrostatic single lens, that is, three coaxially arranged metal cylinders as electrodes, and only the middle metal cylinder electrode needs to be powered, and the metal cylinders on both sides can be grounded; this metal cylinder is easier to process and has a simpler power-on method than the traditional quadrupole third-order lens. Adding a shielding cylinder outside the electrostatic single lens can also reduce the influence of stray fields on the beam.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is an overall schematic diagram of a storage ring device of the present invention;

FIG2 is a structural cross-sectional view of a beam deflection module in the present invention;

FIG3 is a three-dimensional mechanical diagram of a right-angled sector-shaped cylindrical electrode, an "L"-shaped electrode, and a side shielding electrode in the present invention;

FIG. 4 is an optical approximation model of the present invention.

Figure numerals: 1-beam deflection component; 2-beam shaping component; 3-beam; 4-right-angle fan-shaped cylindrical electrode; 5-"L"-shaped electrode; 6-side shielding electrode; 7-electrostatic single lens; 8-ground shielding tube, 9-square plate electrode.

Detailed ways

To make the content of the present invention clearer, the content of the present invention is further described below in conjunction with the accompanying drawings and embodiments of the specification. However, the present invention is not limited to the specific embodiments, and general modifications and replacements known in the art are also within the protection scope of the present invention.

As shown in FIG1 , the compact electrostatic storage ring device for charged particle storage of the present invention includes four beam deflection modules, which are respectively placed in four corners to form a square structure together, forming a square beam flight channel. Each of the beam deflection modules includes a beam deflection component 1 and two beam shaping components 2. The two beam shaping components 2 in each beam deflection module are at an angle of 90° to each other and are respectively located at the entrance and exit of the corresponding beam deflection component 1. A certain distance is left between adjacent beam deflection modules to reserve sufficient space in advance for the subsequent installation of photoelectric spectrum electrodes or other devices.

Each of the beam deflection components 1 is composed of a quadrupole deflection electrode. By applying a suitable voltage, the beam passing through the beam deflection component 1 is deflected by 90°. As shown in Figures 2 and 3, the quadrupole deflection electrode is composed of four right-angled fan-shaped cylindrical electrodes 4 facing each other to form a square structure. The top and bottom of each right-angled fan-shaped cylindrical electrode 4 are provided with square plate electrodes 9 to curb the longitudinal dispersion of the beam 3. The voltage on the square plate electrode 9 and the right-angled fan-shaped cylindrical electrode 4 is the same. The periphery of each right-angled fan-shaped cylindrical electrode 4 is surrounded by an "L"-shaped electrode 5, which is used to reduce the voltage of the right-angled fan-shaped cylindrical electrode 4, and the optimal voltage for deflecting the beam 3 and making the beam 3 fly stably can be effectively reduced. Two side shielding electrodes 6 are arranged on the periphery of the "L"-shaped electrode 5 to shield the influence of external stray fields on the beam 3. A top shielding electrode is provided at the top of each quadrupole deflection electrode, and the top shielding electrode is connected to the top of the side shielding electrode 6; a bottom shielding electrode is provided at the bottom of each quadrupole deflection electrode, and the bottom shielding electrode is connected to the bottom of the side shielding electrode 6; each right-angled sector-shaped cylindrical electrode 4 of each quadrupole deflection electrode is fixed to the bottom shielding electrode through a square plate electrode 9 at its bottom, and the quadrupole deflection electrode is fixed in the space surrounded by the side shielding electrode 6, the top shielding electrode and the bottom shielding electrode. Among them, the right-angled sector-shaped cylindrical electrode 4 can adopt a quarter cylindrical electrode, and the side shielding electrode 6, the top shielding electrode, and the bottom shielding electrode can all adopt a grounding plate.

The four right-angled sector-shaped cylindrical electrodes 4 in the quadrupole deflection electrode are arranged at a certain distance from each other, and each right-angled sector-shaped cylindrical electrode 4 and its corresponding "L"-shaped electrode 5 and side shielding electrode 6 are arranged at a certain distance from each other, and are connected and fixed to each other by connecting rods. The connecting rods can be insulating rods made of peek (polyetheretherketone), ceramics, etc., or stainless steel rods, or peek or ceramic tubes with insulating outer sheaths.

The voltage applied to the quadrupole deflection electrode does not adopt the conventional symmetrical voltage mode (i.e., the relative electrode voltages are the same, and the adjacent electrode voltages are equal in magnitude and opposite in positive and negative), but innovatively adopts an asymmetrical voltage mode, i.e., the relative electrode voltages are the same, and the adjacent electrode voltages are equal in magnitude and opposite in positive and negative, so as to reduce the influence of different degrees of beam divergence in the horizontal and vertical directions caused by the symmetrical voltage mode. Specifically, equal and positive voltages are applied to the relative right-angled fan-shaped cylindrical electrodes 4 in the quadrupole deflection electrode, and unequal and opposite voltages are applied to the adjacent right-angled fan-shaped cylindrical electrodes 4 in the quadrupole deflection electrode. In addition, equal and positive voltages are applied to the four "L"-shaped electrodes 5 in the quadrupole deflection electrode.

Each of the beam shaping components 2 is composed of an electrostatic single lens 7, and shapes the beam passing through the beam deflection component 1 by applying a suitable voltage. Each of the beam shaping components 2 can be arranged at a central position on the side of the corresponding beam deflection component 1.

The electrostatic single lens 7 is composed of three coaxially equidistantly arranged metal cylindrical tube electrodes, which are spaced a certain distance apart from each other and connected by a connecting rod; wherein the first metal cylindrical tube electrode and the third metal cylindrical tube electrode have the same length and are both shorter than the second metal cylindrical tube electrode. In order to avoid the influence of the divergent field on the movement of particles, the electrostatic single lens is wrapped with a grounded shielding tube 8 on the outside, and the grounded shielding tube 8 is fixedly connected to the side shielding electrode 6 of the corresponding beam shaping component 2. When voltages are applied to the three metal cylindrical tube electrodes in the electrostatic single lens 7, the first metal cylindrical tube electrode and the third metal cylindrical tube electrode are grounded.

In addition, as the beam inlet, the voltage applied to the beam deflection module is in pulse form to facilitate the injection of the beam into the storage ring device of the present invention from the front end, while the voltages applied to the other three beam deflection modules are always kept at a constant pressure to ensure that the beam can fly stably in the storage ring.

Since the motion trajectory of charged particles in an electric field is similar to the propagation of light in an optical medium, the stable operating state of charged particles in the storage ring device of the present invention can be analyzed by an optical transmission matrix. As shown in FIG4 , this is an optical approximation model of the electrostatic storage ring. In this model, the beam deflection component 1 is approximated as a plane mirror, that is, the beam 3 passes through the beam deflection component and only changes the flight direction by 90°, and basically does not defocus or focus in the horizontal and vertical directions. The electrostatic single lens 7 is approximated as an optical lens, which has a focusing effect on the beam, ensuring that the beam can fly stably in the storage ring device. By using the calculation software for calculation, it is found that when the geometric dimensions are constant, by changing the focal length of the electrostatic single lens 7, the beam can be ensured to oscillate stably in the model without divergence, thereby verifying that the beam can fly stably in the storage ring under this mode.

Example:

The compact electrostatic storage ring device for charged particle storage of the present invention has an area of less than 1.5 ^m2 . The center distance between adjacent beam deflection modules is 720 mm, and the minimum distance between the electrostatic single lenses 7 of adjacent beam deflection modules is 194 mm, which reserves sufficient position and space for the subsequent addition of electrode sheets or other devices of the photoelectron energy spectrum device.

The quadrupole deflection electrode is composed of four right-angled fan-shaped cylindrical electrodes 4 with a radius of 45mm facing each other. The top and bottom of the right-angled fan-shaped cylindrical electrodes 4 are both square plate electrodes 9 with a side length of 58mm and a thickness of 2mm. The height of the right-angled fan-shaped cylindrical electrodes 4 is 160mm. The maximum distance between the opposite right-angled fan-shaped cylindrical electrodes 4 in the same quadrupole deflection electrode is 170mm. The periphery of each right-angled fan-shaped cylindrical electrode 4 is surrounded by an "L"-shaped electrode 5 with a thickness of 6mm. The distance between adjacent "L"-shaped electrodes 5 in the same beam deflection component 1 is 44mm, and the distance between the right-angled fan-shaped cylindrical electrode 4 and the corresponding "L"-shaped electrode 5 in the same beam deflection component 1 is 7mm. Two side shielding electrodes 6 are arranged on the periphery of each "L"-shaped electrode 5. The length, width and height of each side shielding electrode 6 are 190mm, 52.5mm and 8mm, respectively, and the distance between the side shielding electrode 6 and the "L"-shaped electrode on its side is 7mm.

In order to satisfy the beam deflection component 1 described in FIG. 4 that only has a function similar to a plane mirror, the voltage applied to the quadrupole deflection electrode adopts an asymmetric voltage mode. For safety and cost considerations, it is necessary to minimize the voltage on the quadrupole deflection electrode, and a structure of adding an "L"-shaped electrode 5 outside the quadrupole deflection electrode is adopted to achieve the purpose of reducing the voltage on the quadrupole deflection electrode. For particles with a mass of 2000amu and an energy of 100eV, the voltage of a group of relative right-angled fan-shaped cylindrical electrodes 4 in each quadrupole deflection electrode is 410V, and the voltage of another group of relative right-angled fan-shaped cylindrical electrodes 4 is -1910V, and the voltage of all "L"-shaped electrodes 5 in each beam deflection component 1 is 700V. When the energy of the particle changes, the voltage on the electrode changes proportionally.

The electrostatic single lens 7 is composed of three coaxially arranged metal cylindrical electrodes. The three metal cylindrical electrodes are spaced 5 mm apart from each other. The first metal cylindrical electrode and the third metal cylindrical electrode are of the same length, both 20 mm, and the second metal cylindrical electrode is longer, 120 mm. The inner radius of the three metal cylindrical electrodes is 35 mm, and the outer radius is 50 mm. In order to avoid the influence of the divergent field on the particle movement, a grounded shielding tube 8 is used to wrap the electrostatic single lens 7.

In order to satisfy the focusing function of the electrostatic single lens 7 on the beam 3 as described in Figure 4, for particles with a mass of 2000amu and an energy of 100eV, the voltage on the first metal cylindrical electrode and the third metal cylindrical electrode of each electrostatic single lens 7 is zero, and the voltage applied to the second metal cylindrical electrode is 700V.

In order to ensure that charged particles can be continuously injected into the storage ring device of the present invention from the front end, the voltage applied to the beam deflection module as the beam entrance is in a pulse form, that is, whenever a beam arrives at the entrance of the storage ring from the front end, the voltage of each electrode of the beam deflection module drops to 0, allowing the beam to fly into the storage ring without obstacles. After that, the voltage of each electrode of the beam deflection module at the entrance is restored to the original value, while the voltage applied by the other three beam deflection modules always remains at a constant voltage.

Although the functions and working processes of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the above-mentioned specific functions and working processes. The above-mentioned specific implementation methods are merely illustrative rather than restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the purpose of the present invention and the claims, which are all within the protection of the present invention.

Claims (8)

1. The compact electrostatic storage ring device for charged particle storage is characterized by comprising four beam deflection modules, wherein the four beam deflection modules jointly form a square structure to form a square beam flight channel; each beam deflection module comprises a beam deflection component (1) and two beam shaping components (2), the included angle between the two beam shaping components (2) in each beam deflection module is 90 degrees, and the beam deflection components are respectively positioned at the inlet and the outlet of the corresponding beam deflection component (1);

Each beam deflection component (1) is composed of a quadrupole deflection electrode, and the passing beam is deflected by 90 degrees by applying voltage to the quadrupole deflection electrode; the voltage applied to the quadrupole deflection electrode adopts an asymmetric voltage mode, namely voltages with equal positive and negative values are applied to opposite right-angle sector column electrodes (4) in the quadrupole deflection electrode, and voltages with unequal positive and negative opposite values are applied to adjacent right-angle sector column electrodes (4); applying voltages with equal positive and negative values to four L-shaped electrodes (5) in the quadrupole deflection electrode; the four-pole deflection electrode is composed of four right-angle fan-shaped cylinder electrodes (4) which are opposite, square plate electrodes (9) are arranged at the top and the bottom of each right-angle fan-shaped cylinder electrode (4) to suppress longitudinal dispersion of beam current, the periphery of each right-angle fan-shaped cylinder electrode (4) surrounds an L-shaped electrode (5), and two side shielding electrodes (6) are arranged at the periphery of the L-shaped electrode (5) to shield the influence of external stray fields on the beam current;

Each beam shaping component (2) is composed of an electrostatic single lens (7), and the beam passing through the beam deflection component (1) is shaped by applying voltage to the electrostatic single lens (7).

2. The compact electrostatic storage ring device for charged particle storage of claim 1, wherein a distance is left between adjacent beam deflection modules, and a space is reserved in advance for installing a photoelectrode plate or other devices.

3. The compact electrostatic storage ring device for charged particle storage according to claim 1, wherein the quadrupole deflection electrode is enclosed by four right angle sector cylinder electrodes (4) into a square structure, the four right angle sector cylinder electrodes (4) are arranged at a certain interval, each right angle sector cylinder electrode (4) and the corresponding L-shaped electrode (5) and side shielding electrode (6) are arranged at a certain interval, and are connected and fixed with each other through connecting rods.

4. Compact electrostatic storage ring device for charged particle storage according to claim 1, characterized in that the top of each of said quadrupole deflection electrodes is provided with a top shielding electrode connected with the top of a side shielding electrode (6); the bottom of each quadrupole deflection electrode is provided with a bottom shielding electrode which is connected with the bottom of the side shielding electrode (6); each right-angle sector column electrode (4) of each quadrupole deflection electrode is fixed on the bottom shielding electrode through a square plate electrode (9) at the bottom of the electrode.

5. Compact electrostatic storage ring device for charged particle storage according to claim 1, characterized in that said electrostatic einzel lens (7) consists of three metal cylinder electrodes coaxially arranged, kept at a certain distance from each other and connected by a connecting rod; the length of the first metal cylindrical electrode is the same as that of the third metal cylindrical electrode, and the lengths of the first metal cylindrical electrode and the third metal cylindrical electrode are smaller than that of the second metal cylindrical electrode.

6. The compact electrostatic storage ring device for charged particle storage of claim 5, wherein the first metal cylinder electrode and the third metal cylinder electrode are grounded when voltages are applied to the three metal cylinder electrodes, respectively, in the electrostatic einzel lens (7).

7. Compact electrostatic storage ring device for charged particle storage according to claim 5, characterized in that said electrostatic einzel lens (7) is externally wrapped with a grounded shielding tube (8).

8. The compact electrostatic storage ring device for charged particle storage of claim 1, wherein as a beam deflection module of the beam entrance, the voltage applied to the beam deflection module takes the form of pulses, the pulse frequency is consistent with the front end beam injection frequency, and the voltages applied to the other three beam deflection modules are kept constant at all times.