RU1333130C - Method of making of magnetic periodic focusing system - Google Patents

Abstract

FIELD: electric engineering. SUBSTANCE: correcting cycles are repeated during process of making of the magnetic system. In the beginning of any cycle, the relation of required amplitude of axial magnetic field is measured in the cell of the system, where magnet is mounted, and values of the same parameters, got in preliminary cycle. Field on the axis of magnet is partially identified in relation to axial magnetic field amplitude in cells of the system according to the values, achieved in the preliminary cycle. The relation is used for determining corrected level of stabilization of any magnet. After axial magnetic field of the system is controlled, achieved error of the system is compared with error, achieved in preliminary cycle by means of subtraction. Repetition is canceled in the cycle, in which the difference is equal to the sum of random components of errors of control equipment. Corrected level of stabilization of magnets is determined for any cycle from the mathematical equation, given in the description of the invention. EFFECT: improved precision of making of focusing system. 2 cl

Description

 The invention relates to electrical engineering, in particular to methods for manufacturing magnetic periodic focusing systems for generating flows of charged particles, and can be used in the assembly and tuning to a predetermined distribution of the axial magnetic field of MPPS for electron beam devices.

 The purpose of the invention is to improve the accuracy of manufacturing MPPS.

 To do this, in the method of manufacturing MPFS, providing for the main and corrective cycles of setting the amplitudes of the axial magnetic field, including magnetizing the magnets to saturation, stabilizing them, controlling the stabilization level, installing each magnet in a cell of two pole pieces, monitoring the axial magnetic field of the system, determining the error manufacturing a system, the subsequent adjustment of the axial magnetic field, determining the relationship between the field on the axis of the magnet and the amplitude of the magnetic field in the cell the systems, determining from this ratio the adjusted levels of stabilization of the magnets and stabilization of the magnets to these levels, repeat the corrective cycles, at the beginning of each of them determine additionally the ratio of the axial magnetic field amplitudes required and received in the previous cycle in the cells of the system, the relationship is partially identified by these relations between the field on the axis of the magnet and the amplitudes of the axial magnetic field in the cells of the system, then from this ratio determine the adjusted level of stable each magnet, and after controlling the axial magnetic field of the system, the resulting system error is compared with the error achieved in the previous cycle by subtraction, repetition is stopped on the cycle in which the difference becomes equal to the sum of the random components of the errors of the control means, then the cycles of manufacturing systems with the required values of the amplitudes from typical magnets, and in the first production cycle, the exact value of the levels of stabilization of the magnets is determined from fully identified with Relations between the field on the axis of the magnet and the amplitudes of the axial magnetic field in the cells of the system.

(a $\genfrac{}{}{0ex}{}{\text{-1}}{\text{ji}}$ )_кH_j,
(1) где (H_i)_k - напряженность осевого поля магнита, до которой дополнительно стабилизируют i-й из n магнитов на k-м цикле коррекции;
H_i - требуемое амплитудное значение напряженности магнитного поля в i-й из n ячеек системы,

,
(2) где (а_ji ^-1)_k и (a_ji ^-1)_k-1 - элементы матриц, скорректированных на k-м и (k-1)-м циклах коррекции соответственно, при этом (а_ji ^-1)_о - элементы матрицы А_о ^-1= { a_ji ^-1} _о, обратной матрице A_o = { a_ji} _o, a (a_ji)_o=

, где Н_ji - напряженность осевого магнитного поля, создаваемого в i-й ячейке магнитом, который помещен в i-ю ячейку и имеет максимальное значение напряженности магнитного поля - Н_о;
^dj⁼

- отношение требуемой величины напряженности поля в i-й ячейке к напряженности поля в этой ячейке, полученной после предыдущего цикла коррекции;
d_i=

- отношение требуемой величины напряженности поля в i-й ячейке к напряженности поля в ней, полученной после предыдущего цикла коррекции.The level of magnetic field strength to which each magnet of the system is stabilized on each correction cycle is determined from the relation
(H _i ) _k =

(a $\genfrac{}{}{0ex}{}{\text{-1}}{\text{ji}}$ ) _to H _j ,
(1) where (H _i ) _k is the axial field strength of the magnet, to which the i-th of n magnets is additionally stabilized on the k-th correction cycle;
H _i - the required amplitude value of the magnetic field in the i-th of n cells of the system,

,
(2) where (a _ji ^-1 ) _k and (a _ji ^-1 ) _k-1 are the elements of the matrices adjusted on the kth and (k-1) -th correction cycles, respectively, while (a _ji ^-1 ) _о - elements of the matrix A _о ^-1 = {a _ji ^-1 } _о , inverse matrix A _o = {a _ji } _o , a (a _ji ) _o =

where Н _ji is the axial magnetic field strength created in the i-th cell by a magnet, which is placed in the i-th cell and has the maximum value of the magnetic field strength - Н _о ;
^d j ⁼

- the ratio of the required field strength in the i-th cell to the field strength in this cell obtained after the previous correction cycle;
d _i =

- the ratio of the required field strength in the i-th cell to the field strength in it obtained after the previous correction cycle.

 In the simplest embodiment, this method of manufacturing magnetic periodic focusing systems is carried out, for example, as follows.

(a $\genfrac{}{}{0ex}{}{\text{-1}}{\text{ji}}$ )_oH_j (3) определяют уровни дополнительной стабилизации магнитов и стабилизируют магниты до этих уровней. Затем устанавливают магниты в ячейки (собирают) МПФС, контролируют осевое магнитное поле системы, измеряют его амплитуды Н_ai в каждой ячейке, определяют погрешность изготовления S_о, равную максимальному значению относительного отклонения поля в ячейке от требуемых значений, определяют годность системы, сравнивая S_o c S_H, где S_H - требуемая погрешность изготовления МПФС. Далее по предлагаемому способу проводят один за другим корректирующие циклы.In accordance with widely known methods, MPPS is equipped with typical magnets with similar forms of demagnetization characteristics. A typical magnet is placed in the MPPS prototype from the pole pieces and, by measuring the magnetic field strength at the centers of the cells, the matrices A _about and A _about ^{-1 are} determined. From the relation
H _i =

(a $\genfrac{}{}{0ex}{}{\text{-1}}{\text{ji}}$ ) _o H _j (3) determine the levels of additional stabilization of the magnets and stabilize the magnets to these levels. Then, magnets are installed in the cells (assembled) by MPPS, the axial magnetic field of the system is monitored, its amplitudes H _ai are measured in each cell, the manufacturing error S _о equal to the maximum value of the relative deviation of the field in the cell from the required values is determined, the suitability of the system is determined by comparing S _o c S _H , where S _H is the required manufacturing error of MPPS. Further, the proposed method conducts one after the other corrective cycles.

At the beginning, the matrix A ^{-1 is} modified according to the expression (2), and from the expression (1), the stabilization level of each magnet is determined. Then the magnets are stabilized to these levels by removing from the system together with their pole pieces and installing them in turn in the magnetic processing device. After all the magnets are stabilized and each of them is installed in the intended cell (system assemblies), the amplitudes of the axial magnetic field of the system are controlled, during which the error S _{1 of} the system setting is determined, it is compared with the error S _о obtained in the previous cycle. If the difference | S ₁ -S _o | > δ, where δ is the sum of the random components of the instrumental errors of the means of monitoring the magnetic field of the system and the device for stabilizing the induction of magnets, the correction cycle is repeated in the described sequence. On the cycle with number k, in which the difference | S _k -S _k-1 | ≅ δ, repetition of adjustments is stopped.

The matrix A _to ^{-1 of the} relation (2) is fully identified for the MPPS of this design, this type of magnets, the required values of the amplitudes H _1j . The fully identified matrix A _to ^-1 - {a _ij ^-1 } _to relation (2) is removed from the main memory of the computer to an intermediate storage medium (punched tape, magnetic disk).

Then, for manufacturing under production conditions, MPPS with identical structural and magnetic parameters, a fully identified working matrix A _to ^-1 is introduced into the computer memory from the carrier, as well as the required values of the amplitudes H _i .

At the beginning of the first production cycle of MPPS, solving the relation (1) with a matrix A _to ^-1 using a computer for the required amplitudes H _j , determine the exact levels of magnet stabilization. After the magnets are stabilized to these levels, their installation in the appropriate cells of the system during the control process, they obtain a minimum error in the production of MPPS S _min equal to 0.5-0.6%, with a random error in each control channel of the axial magnetic field of MPPS and magnets characterized by standard deviation 0.2-0.3%.

In the case of using atypical magnets with a wide variation in the forms of demagnetization characteristics for manufacturing MPPS, as well as when setting amplitudes different from the previous required H _j values in the first manufacturing cycle, solving relation (1) with the working matrix A _n ^-1 determines the first approximation of the levels accurate stabilization of magnets. Further, manufacturing cycles are carried out similarly to identification cycles. In this case, the cycle is repeated if the minimum error S _{min of} manufacturing MPPS is not achieved in the previous one.

The first production cycle in the case of using atypical magnets in most cases provides the required error S ₁ ≈ 2-5% of real complex MPPS with the number of cells 25-70. The second manufacturing cycle in this case, as a rule, allows to achieve the minimum manufacturing error.

 The proposed method has the following technical and economic advantages. It indicates the limit of repetition of corrective cycles, methods for obtaining the exact ratio between the field on the axis of the magnet and the required amplitudes of the axial magnetic field in the cells of the system. It also stipulates the condition and makes it possible to obtain an error in the production of MPPS with the required values of the axial magnetic field amplitudes, provides a monotonous decrease in the relative error in the production of MPPS to the level of random components of the instrumental errors of the means for controlling the amplitudes of the axial magnetic field of the system and induction of stabilization of the magnets, allows in production conditions to go to automated, optimal in accuracy control of the production of real MPFS, does not have the fundamental limitations of the scope on the part of the number of MPFS cells, it increases the efficiency of using the metrological parameters of the applied monitoring tools, allows to improve the quality indicators of serial devices by improving the focus of the electron beam by improving the accuracy of manufacturing MPFS. (56) Melnikov, Yu.A. Permanent magnets of microwave electric devices. - M.: Sov. Radio, 1967, p. 108-109.

 USSR author's certificate N 656123, cl. H 01 J 23/087, 1979.

Claims (2)

1. METHOD FOR PRODUCING A MAGNETIC PERIODIC FOCUSING SYSTEM, including conducting the main and corrective cycles of adjusting the amplitudes of the axial magnetic field in each of its cells, magnetizing the magnets to saturation and stabilizing them, controlling the level of magnet stabilization, installing each magnet in a cell of two pole tips, axial magnetic field of the system, determination of the manufacturing error of the system, subsequent adjustment of the axial magnetic field, determination of the relationship between the field on the axis of the mag the magnitude and amplitude of the magnetic field in the cell of the system, determining from this ratio the adjusted levels of stabilization of the magnets to these levels, characterized in that, in order to improve the accuracy of manufacturing the system, repeat the corrective cycles until the difference in the error of manufacturing the system at the k-th and the (k-1) -th correction cycles become less than the sum of the random components of the errors of the means for controlling the magnetic field strength, while the adjusted level of magnet stabilization at each cycle is determined from the relation
(H _i ) _k =

(a $\genfrac{}{}{0ex}{}{\text{-1}}{\text{ji}}$ ) _to H _j ,
where (H _i ) _k is the axial field strength of the magnet, to which the i-th of n magnets is additionally stabilized on the k-th correction cycle;
H _j - the required amplitude value of the magnetic field in the i-th of n cells of the system,

,
where (a _ji ^-1 ) _k and (a _ji ^-1 ) _k-1 are the elements of the matrices adjusted on the k-th (k-1) -th correction cycles, respectively, while (a _ji ^-1 ) _{о are the} elements of the matrix A $\genfrac{}{}{0ex}{}{\text{-}}{\text{o}}$ ¹ = {a $\genfrac{}{}{0ex}{}{\text{-1}}{\text{ji}}$ } _o , the inverse of the matrix
A _o = a (a _ji ) _o =

,
where H _ji is the intensity of the axial magnetic field created in the i-th cell by a magnet, which is placed in the j-th cell and has the maximum value of the magnetic field strength H ₀ ;
^d j ⁼

- the ratio of the required field strength in the i-th cell to the field strength in this cell obtained after the previous correction cycle;
d _i =

- the ratio of the required field strength in the i-th cell to the field strength in it obtained after the previous correction cycle. 2. The method according to p. 1, characterized in that in the manufacture of subsequent identical systems in determining the level of initial stabilization of the magnets, as the matrices A _about ^-1 , a fully identified matrix A _to ^{-1 is used} , obtained at the last k-th correction cycle, when manufacturing the previous system.