RU2496178C2 - Method for formation of two-dimensional liner electric field and device for its implementation - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: method for formation of two-dimensional linear electric fields consists in formation of one coordinate of potential average value distribution per working area border using device from flat discrete and hyperbolic electrodes. Flat discrete electrodes consist of thin earthed metal fibres evenly arranged on area borders, and hyperbolic electrodes singly arranged in each quadrant have small sizes of half-axes. Under impact of opposite potentials on adjacent hyperbolic electrodes in planes of discrete electrodes there formed are linear per each axis of potential average value distribution, under their impact in working area there formed is two-dimension linear field.

EFFECT: minimising sizes and improving design-process parameters of electrode systems for formation of two-dimension linear electric fields with working areas expanded along one axis.

2 dwg

Description

The invention relates to the fields of electron-ion optics and mass spectrometry based on the movement of charged particles in static and variable two-dimensional linear electric fields, and can be used to improve the design and manufacturing technology of spatio-temporal focusing and mass separation of charged particles. Hyperbolic electrode systems are not effective for creating mass analyzers with a working area extended along one axis due to the significant size of the electrodes in all coordinates [1]. The problem is solved by systems of flat electrodes with a discrete-linear distribution of potential [2], with discrete-varying electrical transparency [3] and discretely-varying charge density [4]. The technical task of the invention is to improve the structural and technological characteristics of devices for the formation of two-dimensional linear electric fields with a working area extended along one axis, using hyperbolic and flat discrete equipotential electrodes.

Two-dimensional linear electric fields in the working area with dimensions 2x _c , 2y _c , L along the X, Y, Z axes under the condition y _c >> x _c can be formed using flat discrete surfaces from nonequipotential conductive elements distributed along the Y axis with a constant step ∆y [2] or equipotential conductive elements unevenly distributed along the Y axis [3, 4]. Closest to the claimed solution is the method described in [4], which consists in the formation of a linear electric field using equipotential elements unevenly distributed along the Y axis. However, the drawbacks of these systems are difficulties of a design-technological nature that will complicate the manufacturing process of ion-optical devices and ion analyzers using flat discrete electrodes.

In all cases, when using flat discrete electrodes, the problem of generating two-dimensional linear electric fields in the XOY plane reduces to creating at the boundaries of the region x = ± x _c linear distributions of the average potential value along the Y axis:

$${\varphi }_{\mathrm{from}R}(y_i)=\frac{\mathrm{one}}{\Delta y_i}{\displaystyle \underset{y_i-\Delta y/2}{\overset{y_i+\Delta y/2}{\int }}}{\varphi }_{\partial i}(y)dy=\frac{{\varphi }_{mcp}}{y_c}{y}_i,\left(\mathrm{one}\right)$$

where φ _∂i (y) is the potential distribution in the planes x = ± x _{c of the} i-th discrete element, Δy _i is the discrete step of the electrodes, φ _mav = φ _av (y _c ).

For the practical implementation of ion-optical systems with two-dimensional linear electric fields, it is of interest to use flat discrete surfaces formed from uniformly distributed conductive elements, threads or strips, uniformly distributed along the Y axis with a step Δy, parallel to the Z axis. However, the use of only planar discrete with a constant step ∆y equipotential surfaces does not solve the problem of the formation of two-dimensional linear electric fields. The problem is solved with the help of additional 4 hyperbolic potential surfaces, which make it possible to form a linear distribution along the Y axis of the average potential value in the planes x = ± x _{c of} discrete surfaces. The hyperbolic surfaces 2 are located in the region | x |> x _c and the opposite potentials φ ₀ and −φ ₀ are set on adjacent surfaces (FIG. 1). The presence of discrete surfaces 1 allows you to shift the coordinate origin of the hyperbolic surfaces 2 along the X axis by a distance of x ₀ for surfaces in I and IV quadrants and by a distance of x ₀ for surfaces in II and III quadrants and thereby significantly reduce the value of their geometric parameter r ₀ - the actual semi-axis of hyperbole. The amount of displacement is determined by the ratio:

$$x_0\approx x_c-0.45\Delta y.\left(\text{2}\right)$$

Hyperbolic surfaces in this case are described by the equation:

$$y=\pm r_0^2/2(x\pm x_0).\left(\text{3}\right)$$

Under the action of opposite potentials φ ₀ and -φ ₀ on adjacent hyperbolic surfaces in cross sections x = ± x _c , potential distributions φ (± x _c , y) - are formed (curve 1, Figure 2), the average values of which are φ _cf (± x _c , y) when condition (2) is fulfilled, they will change according to a linear law (curve 2, Figure 2):

$${\varphi }_{\mathrm{from}R}(x_c,y)=E_m\cdot y,\left(\text{four}\right)$$

. При этом в рабочей области |x|<x_c, |y|<y_c образуется поле с распределением потенциала вида:Where $$E_m=0.9\Delta y{\varphi }_0/r_0^2$$

. Moreover, in the work area | x | <x _c , | y | <y _c , a field is formed with a potential distribution of the form:

$$\varphi (x,y)=\frac{E_m}{x_c}xy,\left(\text{5}\right)$$

which corresponds to a two-dimensional linear electric field with projections of the field strength on the X and Y axis:

$$E_x=\frac{E_m}{x_c}y,E_y=\frac{E_m}{x_c}x.\left(\text{6}\right)$$

It follows from (5) and (6) that a system of 2 planar equipotential discrete and 4 hyperbolic surfaces with 2 flat with a constant step ∆y allows the formation of two-dimensional linear electric fields in the working areas 4 | x | <x _c , | y _c | <y with an arbitrary ratio of parameters x _c , y _c . Moreover, for a fixed axis length r _{0 of} hyperbolic surfaces, by choosing the parameters x _c and ∆y, the dimensions of the working area along the X axis can vary widely.

The device for forming a two-dimensional linear electric field according to the method proposed in claim 1, consists of 2 flat discrete electrodes 1 of length L >> 2x _c and 4 hyperbolic electrodes 2 of length L >> 2x _c (Figure 1). Discrete electrodes 1 with a size of y _a >> x _c along the Y axis are located in the planes x = ± x _c and are formed from equipotential filaments uniformly distributed along the Y axis with a step ∆y of diameter d << ∆y parallel to the Z axis. The coordinates of the hyperbolic electrodes are shifted in pairs along the X axis by a distance of ± x ₀ and have finite coordinates x = ± x _a , y = ± y _a , where x _a ≥ (x _c + 1.5r ₀ ), y _a ≥ (y _c + 1.5x _c ). Hyperbolic electrodes are located outside the work area 4 (Figure 1) | x |> x _c , one in each quadrant. The geometric parameter r _{0 of the} hyperbolic electrodes is determined by the discrete step ∆y of the flat electrodes and their size y _a along the Y axis:

. $$r_0=\sqrt{2y_a\Delta y}$$

.

Given the parameters x _c , y _{c of the} working area, the geometrical parameter r _{0 of the} hyperbolic electrodes used in conjunction with flat discrete electrodes with a constant step Δy turns out to be significantly less than the parameter r _{0 of the} hyperbolic electrodes 3 (Figure 1), which create the same field in the absence of discrete electrodes. This allows analyzers with elongated work areas 4 along the Y axis (Fig. 1), when y _c >> x _c, by minimizing the value of the parameter r _{0 of} hyperbolic electrodes, by 2–2.5 times reducing the dimensions of the electrode systems of analyzers along the X axis. Size L electrodes 1 and 2 along the Z axis are selected based on the permissible level of deviation of the field from the linear in the working area of the analyzer due to edge effects:

L≥4x _c .

The use of metallic filaments uniformly distributed along the Y axis as flat discrete electrodes in combination with hyperbolic electrodes simplifies the design and manufacturing technology, as well as reduces the size of analyzers with two-dimensional linear electric fields.

LITERATURE

1. Gurov B.C., Mamontov E.V., Diaghilev A.A. Electrode systems with a discrete linear distribution of high-frequency potential for charged particle mass analyzers // Mass spectrometry. 2007. No4 (2). - S.139-142.

2. Patent RU No. 23237245 of 05/03/2006, Method for mass-selective analysis of ions by time of flight and a device for its implementation.

3. Patent RU No. 2387043 of 04/10/2008, A method for forming a linear field and a device for its implementation.

4. Patent RU No. 2422939 of 11.25.2009, A method of forming a two-dimensional linear electric field and a device for its implementation.

Claims (2)

1. The method of forming a two-dimensional linear electric field, which consists in creating along the borders x = ± x _{c of the} working area | x | <x _c , | y | <y _c parallel to the Z axis of flat discrete conductive surfaces with dimensions 2y _a , L along the Y axes , Z, consisting of a set of thin conductive filaments distributed along the Y axis parallel to the Z axis, characterized in that the equipotential filaments are distributed uniformly along the Y axis with a step Δy, with hyperbolic one in each quadrant outside the boundaries of the working area | x |> x _c conductive surfaces $$y=\pm r_0^2/2(x\pm x_0)$$

, where | x ₀ | <| x _c |, r ₀ is the real semi-axis of the hyperbolas, and opposite potentials φ ₀ and -φ _{0 are} established on adjacent surfaces. 2. Device for the formation of a two-dimensional linear electric field, containing at the boundaries of the working area x = ± x _c parallel to the Z axis electrodes of length L >> 2x _c from conductive thin filaments distributed along the Y axis parallel to the Z axis, characterized in that two are used in planes x = ± x _c discrete with a size y _a >> x _c along the Y axis of the electrode from equipotential filaments with a diameter d << Δy uniformly distributed with a step Δy along the Y axis and four, one in each quadrant, hyperbolic electrodes with an actual axis axis r ₀ shifted in pairs along the X axis by yanie ± x _0, with end coordinates x = ± x _a,
y = ± y _a , where x _a ≥ (x _c + 1,5r ₀ ), y _a ≥ (y _c + 1,5x _c ).

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