CN110957198B

CN110957198B - An ion lens system with inverse pressure gradient transmission

Info

Publication number: CN110957198B
Application number: CN201911273046.XA
Authority: CN
Inventors: 骆智训; 杨梦周; 黄奔奔; 崔超男
Original assignee: Institute of Chemistry CAS
Current assignee: Institute of Chemistry CAS
Priority date: 2019-12-12
Filing date: 2019-12-12
Publication date: 2021-03-05
Anticipated expiration: 2039-12-12
Also published as: CN110957198A

Abstract

The invention relates to an ion lens system with reverse pressure gradient transmission, comprising: a first electrostatic lens group and a second electrostatic lens group connected in series from the incident direction of the ion beam; the number of lenses in the first electrostatic lens group is greater than or equal to three, And its number is an odd number; each electrostatic lens in the first electrostatic lens group is coaxially arranged, the voltage applied by the odd-numbered first electrostatic lens is U ₁ , the voltage applied by the even-numbered first electrostatic lens is U ₂ , and U ₁ is not equal to U ₂ ; the number of lenses in the second electrostatic lens group is greater than or equal to two, each electrostatic lens in the second electrostatic lens group is coaxially arranged, and a through hole is provided in the center of each second electrostatic lens group, and The aperture of each through hole decreases along the incident direction of the ion beam. The device can precisely adjust the voltage of each electrostatic lens in the ion transmission process, reduce the ion flux loss during pressure gradient transmission, and is coupled with a reverse pressure injector to achieve effective ion transmission under reverse pressure gradient.

Description

Ion lens system with inverse pressure gradient transmission

Technical Field

The invention relates to an ion lens system with inverse pressure gradient transmission, belonging to the technical field of ion optics.

Background

An electrostatic lens generally refers to a device that focuses or images an electron beam by having an electrostatic field generated by a charged conductor. It is widely used in electronic devices such as cathode ray oscilloscopes, electron microscopes and gas phase reaction instruments. The ion lens system is composed of a plurality of electrostatic lenses. Certain direct current voltages are respectively added on conductor electrodes of a plurality of rotationally symmetric electrostatic lenses to form rotationally symmetric electrostatic fields. The main function of the ion lens system is to deliver a large fraction of the ions in the ionization chamber to the target devices, such as mass analyzers, reaction tubes, ion traps, etc., with a small divergence angle.

The counter pressure gradient refers to the condition that when a plurality of vacuum cavities are differentially connected in various forms, the vacuum degree in an upstream cavity is higher than that in a downstream cavity, and the vacuum gradient is opposite to the ion conveying direction.

At present, most ion lens systems are used in high vacuum without pressure gradient, and no good solution exists for effectively focusing and transmitting ions under the condition of existence of inverse pressure gradient.

Disclosure of Invention

In view of the above problems, an object of the present invention is to provide an ion lens system with reverse pressure gradient transmission, which can precisely adjust the voltage of each electrostatic lens during ion transmission, reduce the ion flux loss during reverse pressure gradient transmission, and couple with a reverse pressure injector to realize effective transmission of ions under reverse pressure gradient.

In order to achieve the purpose, the invention adopts the following technical scheme: the invention provides an ion lens system with inverse pressure gradient transmission, which comprises: the first electrostatic lens group and the second electrostatic lens group are sequentially connected in series from the incident direction of the ion beam; the number of the first electrostatic lenses of the first electrostatic lens group is more than or equal to three, and the number of the first electrostatic lenses is an odd number; each first electrostatic lens in the first electrostatic lens group is coaxially arranged, wherein the voltage applied by the odd first electrostatic lenses is U₁The voltage applied to the even number of first electrostatic lenses is U₂，U₁Is not equal to U₂(ii) a The number of the second electrostatic lenses of the second electrostatic lens group is more than or equal to two, and each second electrostatic lens in the second electrostatic lens group is coaxially arranged, wherein a through hole is formed in the center of each second electrostatic lens, and the aperture of each through hole is gradually reduced along the incident direction of the ion beam; applying a direct current having a potential gradient to each of the second electrostatic lenses to form a funnel-shaped ion lens.

Furthermore, a back pressure injector is arranged in the direction of the second electrostatic lens group far away from the first electrostatic lens group.

Further, the reverse pressure injector comprises an assembly flange, and an addition funnel, an inner ring air hole disc and an outer ring air hole disc which are arranged on the assembly flange, wherein the addition funnel, the inner ring air hole disc and the outer ring air hole disc are separated by a sealing rubber ring.

Furthermore, the charging funnel is connected with the second electrostatic lens group, and collects the ion beam collected and accelerated by the second electrostatic lens group to the central hole of the back pressure injector; the flux of the ion beam in the charging funnel is adjusted by adjusting the dc voltage applied to the charging funnel.

Furthermore, a closed space formed by isolating the charging funnel and the inner ring air hole disc and isolating the inner ring air hole disc and the outer ring air hole disc is a carrier gas residence pool; and the assembly flange is provided with an air duct communicated with the carrier gas residence tank.

Furthermore, the first electrostatic lens group is a bottomless metal cylinder, and the directional transmission and focusing of the ion beam are realized by forming a rotationally symmetric electrostatic field between the odd number metal cylinders and the even number metal cylinders.

Further, the second electrostatic lens group is a metal ring whose inner diameter is reduced in order.

Further, the first electrostatic lens group and the second electrostatic lens group are fixed through a fixing device, the fixing device comprises a fixing flange and a fixing rod, the fixing flange is used for fixing the first electrostatic lens group, and the fixing rod is used for fixing the second electrostatic lens group.

Further, the second electrostatic lens assembly is coaxially sleeved on the fixing rod.

Due to the adoption of the technical scheme, the invention has the following advantages: 1. the device can accurately adjust the voltage of each electrostatic lens in the ion transmission process, reduce the ion flux loss in the reverse pressure gradient transmission process, and is coupled with the reverse pressure injector to realize the effective transmission of ions under the reverse pressure gradient. 2. The device can accurately control the potential difference between the electrostatic lenses in the ion transmission process and the potential difference between the electrostatic lenses and the back pressure injector, particularly the design of the funnel-shaped electrostatic lens with adjustable potential gradient and the series connection of the funnel-shaped electrostatic lens with adjustable potential gradient and the cylindrical electrostatic lens, and can greatly increase the ion transmission efficiency under the condition of back pressure gradient.

Drawings

FIG. 1 is a front view of an ion lens system with inverse pressure gradient propagation in accordance with an embodiment of the present invention;

FIG. 2 is a left side view of an ion lens system with inverse pressure gradient propagation in accordance with an embodiment of the present invention;

FIG. 3 is a right side view of an ion lens system with inverse pressure gradient propagation in accordance with an embodiment of the present invention;

FIG. 4 is a schematic diagram of a back pressure injector according to an embodiment of the present invention.

Reference numerals:

1-a first electrostatic lens group; 11-an odd number of first electrostatic lenses; 12-an even number of first electrostatic lenses; 2-a second electrostatic lens group; 3-power connection pins; 4-a counter pressure injector; 41-assembling a flange; 42-an addition funnel; 43-inner ring orifice disc; 44-outer ring orifice disc; 45-sealing rubber ring; 46-carrier gas residence tank; 5-a fixing device; 51-a fixed flange; 52-a fixation rod; 53-ceramic gaskets.

Detailed Description

The present invention is described in detail below with reference to the attached drawings. It is to be understood, however, that the drawings are provided solely for the purposes of promoting an understanding of the invention and that they are not to be construed as limiting the invention. In describing the present invention, it is to be understood that the terminology is used for the purpose of description only and is not intended to be interpreted as indicating or implying any relative importance.

The present embodiment provides an ion lens system with inverse pressure gradient transmission, as shown in fig. 1 to 4, including: a reverse pressure gradient-propagating ion lens system, comprising: a first electrostatic lens group 1 and a second electrostatic lens group 2 which are connected in series in sequence from the ion beam incidence direction; the number of the first electrostatic lenses of the first electrostatic lens group 1 is more than or equal to three, and the number of the first electrostatic lenses is an odd number; each first electrostatic lens in the first electrostatic lens group 1 is coaxially arranged, wherein the voltage applied by the odd-numbered first electrostatic lenses 11 is U₁The voltage applied to the even-th first electrostatic lens 12 is U₂，U₁Is not equal to U₂(ii) a The number of the second electrostatic lenses of the second electrostatic lens group 2 is more than or equal to two, each second electrostatic lens in the second electrostatic lens group is coaxially arranged, wherein a through hole is formed in the center of each second electrostatic lens, and the aperture of each through hole is gradually reduced along the incident direction of the ion beam; and applying direct current with potential gradient to each second electrostatic lens to form a funnel-shaped ion lens so as to realize the functions of directional transmission, focusing, acceleration and the like of the ion beam. The direct current with potential gradient is generally along the incident direction of ion beam, and the voltage applied to each electrostatic lens is decreased in equal difference. For example, the first electrostatic lens in the second electrostatic lens group 2 applies 10V, the second electrostatic lens applies 8V, the third electrostatic lens applies 6V, and so on. The voltage U applied by the first electrostatic lens group 1₁And U₂The specific value is determined by the initial kinetic energy of the ion beam, and the two are not equal to each other and are not specificThe magnitude relationship of (1). The device in the embodiment can accurately adjust the voltage of each electrostatic lens in the ion transmission process, reduce the ion flux loss in the reverse pressure gradient transmission, and is coupled with the reverse pressure injector 4 to realize the effective transmission of ions under the reverse pressure gradient; and the potential difference between the electrostatic lenses and the back pressure injector 4 in the ion transmission process can be accurately controlled, particularly the design of the funnel-shaped electrostatic lens with adjustable potential gradient and the series connection of the funnel-shaped electrostatic lens and the cylindrical electrostatic lens can greatly increase the ion transmission efficiency under the back pressure gradient condition.

The first electrostatic lens group 1 is a bottomless metal cylinder, and the directional transmission and focusing of the ion beam are realized by forming a rotationally symmetric electrostatic field between the odd number metal cylinders and the even number metal cylinders. The second electrostatic lens group is a metal ring with the inner diameter decreasing in sequence. In this embodiment, the first electrostatic lens group 1 includes three bottomless metal cylinders, and the second electrostatic lens group includes eight metal rings. Wherein, each metal cylinder or metal ring is provided with at least two electric pins 3 for applying voltage to the metal cylinder or metal ring. The metal cylinder or the metal ring is made of metal with excellent conductivity, such as stainless steel, copper, gold and the like. The inner diameter of the eight metal rings preferably decreases in the range of 14mm to 11 mm.

In this embodiment, the second electrostatic lens group 2 is further provided with a reverse pressure injector 4 in a direction away from the first electrostatic lens group 1. The back pressure injector 4 comprises a mounting flange 41 and an adding funnel 42, an inner ring air hole disc 43 and an outer ring air hole disc 44 which are arranged on the mounting flange, wherein the adding funnel 42, the inner ring air hole disc 43 and the outer ring air hole disc 44 are separated by a sealing rubber ring 45. The charging funnel 42 is connected with the second electrostatic lens group 2, and the charging funnel 42 collects the ion beam collected and accelerated by the second electrostatic lens group 2 to the central hole of the back pressure injector 4; the flux of the ion beam in the charging funnel 42 is adjusted by adjusting the dc voltage applied to the charging funnel 42. A sealed space formed by isolating the charging funnel 42 and the inner ring air hole disc 43 and isolating the inner ring air hole disc 43 and the outer ring air hole disc 44 is a carrier gas residence tank 46; the mounting flange 41 is provided with an air duct communicating with the carrier gas retention tank 46. The gas introduced in the gas-guide tube is preferably helium. Helium with a certain flow is introduced into the backpressure injector 4, the helium flows out of the inner/outer ring air holes through the carrier gas residence tank 46, under the loading of the downstream roots blower, the helium forms radial circulation in the area to generate local negative pressure, the ion beam is attracted to pass through the central hole, and finally the effect of improving the backpressure transmission flux of the ion beam is achieved. Of course, other gases which can achieve the above effects can be introduced into the gas guide pipe.

As shown in fig. 1 to 4, the first electrostatic lens group 1 and the second electrostatic lens group 2 are fixed by a fixing device 5, the fixing device 5 includes a fixing flange 51 and a fixing rod 52, the fixing flange 51 is used for fixing the first electrostatic lens group 1, and the fixing rod 52 is used for fixing the second electrostatic lens group 2. The fixing rods 52 are fixed on a fixing flange 51, the fixing rods 52 are uniformly distributed on the fixing flange 51 in the circumferential direction, and the second electrostatic lens assembly 2 is coaxially sleeved on the fixing rods 52. In order to ensure the safety of the whole system and prevent electric leakage, the fixing rod 52 is also sleeved with a ceramic gasket 53, and the ceramic gasket 53 also has the function of preventing each electrostatic lens from moving.

When the ion lens system with the backpressure gradient transmission works, an ion beam with certain initial velocity distribution and dispersion radius enters from one side of the cylindrical lens, is converged and accelerated by the first electrostatic lens group 1 and the second electrostatic lens group 2, and reaches the central hole of the backpressure injector 4. Helium with a certain flow is introduced into the backpressure injector 4, the helium flows out of the air holes of the inner ring air hole disc 43 and the outer ring air hole disc 44 through the carrier gas residence pool 46, under the loading of the downstream roots blower, the helium forms radial circulation in the middle of the inner ring air hole disc 43 and the outer ring air hole disc 44 to generate local negative pressure, the ion beam is attracted to pass through the center hole, and finally the effect of improving the backpressure transmission flux of the ion beam is achieved.

The above embodiments are only used for illustrating the present invention, and the structure, connection mode, manufacturing process, etc. of the components may be changed, and all equivalent changes and modifications performed on the basis of the technical solution of the present invention should not be excluded from the protection scope of the present invention.

Claims

1. An ion lens system for reverse pressure gradient transmission, characterized in that it comprises: a first electrostatic lens group and a second electrostatic lens group sequentially connected in series from the incident direction of the ion beam;

The number of the first electrostatic lenses of the first electrostatic lens group is greater than or equal to three, and the number is an odd number; each first electrostatic lens in the first electrostatic lens group is coaxially arranged, wherein the odd-numbered first electrostatic lens The voltage applied by the lens is U ₁ , the voltage applied by the even-numbered first electrostatic lens is U ₂ , and U ₁ is not equal to U ₂ ;

The number of second electrostatic lenses in the second electrostatic lens group is greater than or equal to two, and each second electrostatic lens in the second electrostatic lens group is coaxially arranged, wherein a through hole is formed in the center of each second electrostatic lens , and the aperture of each through hole decreases along the incident direction of the ion beam; apply a direct current with a potential gradient to each of the second electrostatic lenses to form a funnel-shaped ion lens;

A reverse pressure injector is also provided in the direction of the second electrostatic lens group away from the first electrostatic lens group.

2 . The ion lens system according to claim 1 , wherein the reverse pressure injector comprises a mounting flange, and an electrification funnel and an inner ring air hole arranged on the mounting flange. 3 . The disk and the outer ring air hole disk, the electrification funnel, the inner ring air hole disk and the outer ring air hole disk are separated by a sealing rubber ring.

3. The ion lens system according to claim 2, wherein the electrification funnel is connected to the second electrostatic lens group, and the electrification funnel will be collected through the second electrostatic lens group The accelerated ion beam is collected at the central hole of the counter-pressure injector; the flux of the ion beam in the electrification funnel can be adjusted by adjusting the DC voltage applied to the electrification funnel.

4 . The ion lens system for reverse pressure gradient transmission according to claim 2 , wherein the electrification funnel and the inner ring air hole disk and the airtight space isolated between the inner ring air hole disk and the outer ring air hole disk are formed. 5 . It is a carrier gas retention pool; the assembly flange is provided with an air conduit communicating with the carrier gas retention pool.

5. The ion lens system according to any one of claims 1-4, wherein the first electrostatic lens group is a bottomless metal cylinder, and the first electrostatic lens group is a bottomless metal cylinder. A rotationally symmetric electrostatic field is formed between the metal cylinders to realize the directional transmission and focusing of the ion beam.

6 . The ion lens system according to any one of claims 1 to 4 , wherein the second electrostatic lens group is a metal ring whose inner diameter decreases sequentially. 7 .

7. The ion lens system according to any one of claims 1-4, wherein the first electrostatic lens group and the second electrostatic lens group are fixed by a fixing device, and the fixing The device includes a fixing flange and a fixing rod, the fixing flange is used for fixing the first electrostatic lens group, and the fixing rod is used for fixing the second electrostatic lens group.

8 . The ion lens system according to claim 7 , wherein there are a plurality of said fixing rods, and a plurality of said fixing rods are fixed on one of said fixing flanges, and are arranged on said fixing flange. 9 . The fixing flanges are evenly distributed in the circumferential direction, and the second electrostatic lens group is coaxially sleeved on the fixing rod.