RU2792172C1 - Method for manufacturing magnetic periodic focusing systems for o-type microwave devices - Google Patents

Abstract

FIELD: microwave electronics.

SUBSTANCE: creating magnetic periodic focusing systems (MPFS) for focusing an electron beam in vacuum electronic devices. When manufacturing MPFS, all magnets have a strictly limited level of the transverse component, and adjacent magnets have a limitation on the difference in the value of the transverse component of magnetic induction, not exceeding 0 to 15-50% of the maximum allowable value; the exact value of the allowable difference is selected depending on the type of MPFS and electronic device. This ratio allows to provide the necessary compensation for the effect of the transverse component of the magnetic induction on the electron beam in a small area of the device.

EFFECT: reduced labour intensity and a significantly reduced setting time of the electrovacuum device.

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Description

The invention relates to microwave electronics in the field of creating magnetic periodic focusing systems (MPFS) for focusing an electron beam in vacuum electronic devices.

A known method of manufacturing MPFS, consisting of permanent ring magnets separated by magnetically soft pole pieces, includes setting the MPFS according to the level of the longitudinal magnetic field according to the given amplitude values of the magnetic induction on the axis of individual magnets and according to the given average level of amplitude values in the regular region of the MPFS, including selected ring magnets having a certain value of the transverse component of the magnetic induction, which should not exceed the specified value. The method for measuring and selecting ring magnets according to the level of the transverse component is described in detail in the work of E.I. Kanevsky, E.A. Mayorova, O.I. Romanov "Relationship between the transverse component of the focusing magnetic field and the current settling of the electron beam" [1].

This method of manufacturing MPFS allows limiting the transverse component of magnetic induction only by the maximum specified value and allows the presence of magnets with almost zero and maximum allowed values, which does not allow compensating their effect on the electron beam when tuning the electronic device without additional tuning elements. This drawback leads to a significant increase in the setup time of the device and the mandatory use of additional tuning elements.

In the prototype [Ed. USSR No. 1464784, IPC: H01J 23/087] the difficulty of mutual compensation of the influence of the transverse component on the formation of an electron beam in adjacent magnets is eliminated by selecting neighboring ring magnets both by the maximum level and by the difference in the level of the transverse magnetic component in adjacent MPFS magnets, determined by according to the suggested formulas. The disadvantages of this method are: firstly, the proposed mandatory location of adjacent magnets with a turn of 180 degrees in the direction of the transverse component, which is difficult to implement on an electronic device due to the presence of geometric tolerances on assembly parts that introduce their own change in the transverse component, and the inability to control the transverse component on the axis of the evacuated vacuum electronic device, since the measurements of the transverse component are carried out on a single magnet; secondly, when calculating according to the indicated formulas, the allowable deviation in the transverse component is about 3% (0.1 mT) of the maximum allowable level of the transverse component (2.7 mT) with a total measurement error of the value of the transverse component itself of at least ±15% of its true meaning. This ratio of values significantly increases the complexity of the selection of suitable magnets. The method has not been widely used in practice due to the need to conduct a large number of measurements of the transverse component in a large number of magnets with their rejection. In addition, the indicated values of the maximum allowable transverse component and its allowable difference in adjacent magnets are presented for the number of magnets N=10, with the actual number of magnets in the MPFS of the order of 30-50, the allowable deviation should be even less, which is very difficult to implement.

The present invention proposes a method for manufacturing MPFS, which includes setting the MPFS according to the level of amplitude values of the longitudinal component of magnetic induction, with additional selection of ring magnets in adjacent ring magnets with such a level of the transverse component that the difference in the transverse component in them does not exceed from 0 to 15-50 % of the maximum allowable level of the transverse component, which is measured in a magnetic cell consisting of a ring magnet and two pole magnetic tips. Such a selection of adjacent magnets according to a certain difference in the transverse component is quite simply carried out due to the large number of identical magnets that make up the MPFS, and the possibility of rearranging them by serial numbers.

The technical result of the invention is to reduce the complexity and significantly reduce the setup time of the electrovacuum device.

The technical result is achieved due to the fact that the application of the proposed method can significantly reduce the number of additional tuning elements, both magnetically soft in the form of steel small parts, and magnetically hard in the form of parts of permanent magnets. In the manufacture of MPFS, all magnets have a strictly limited level of the transverse component, adjacent magnets must have a limit on the difference in the value of the transverse component of magnetic induction, not exceeding 0 to 15-50% of the maximum allowable value, the exact value of the allowable difference is selected depending on the type of MPFS and electronic device. This ratio allows to provide the necessary compensation for the effect of the transverse component of magnetic induction on the electron beam in a small area of the device, while the angle of rotation of adjacent magnets in the direction of the transverse component is not regulated, but is selected according to the best current flow in the electronic device.

The proposed method was tested in the production of MPFS electronic devices at JSC NLP Almaz.

An example of the implementation of the method:

- MPFS was tuned according to the level of the longitudinal component of the magnetic induction by partial demagnetization of each ring magnet according to the technological chart of adjustment according to the values of magnetic induction depending on the serial number of the magnet in the MPFS, and for each serial number 3-4 magnets were selected;

- the control of the transverse component was carried out in each ring magnet by rotating the measuring probe and finding the maximum value of the transverse component with further calculation according to the formula known from the prior art [1]:

V _p \u003d (V _pmax - V _p180 ) / 2; where B _p is the true value of the transverse component of magnetic induction on the axis of the ring magnet or magnetic cell, V _pmax is the maximum measured value of the transverse component of magnetic induction on the axis of the ring magnet or magnetic cell during rotation of the measuring probe, B _p180 is the measured value of the transverse component of magnetic induction on the axis of the ring magnet or magnetic cell when the measuring probe is rotated 180 degrees relative to the direction of the maximum value of the transverse component of magnetic induction on the axis of the ring magnet or magnetic cell;

- Magnets adjacent by serial numbers were selected taking into account the allowable difference in the transverse component of no more than 30% of the allowable maximum value of 1.8 mT (the difference between adjacent magnets was allowed no more than 0.54 mT); several allowable selections of magnets for several MPFS were obtained at once.

The following example shows how the proposed method for manufacturing MPFS for O-type microwave devices can reduce the number of additional tuning elements and reduce the device tuning time. Prior to the use of this method in the manufacture of MPFS, the level of the permissible transverse component in 44 magnets did not exceed 1.8 mT, and the difference in adjacent magnets ranged from 0 to 90% of the level of the permissible transverse component. The number of additional tuning elements varied within 50-120 pieces, the tuning time was 18-23 hours.

In the manufacture of MPFS according to the proposed method with the same level of permissible transverse component and a difference within 25-45% of the level of the permissible transverse component of magnetic induction, the number of additional tuning elements was 15-25 pieces, and the device tuning time was reduced by half.

Fig. 1 and FIG. 2 demonstrate that the use of the proposed method can significantly reduce the number of tuning elements. In FIG. 1 shows an electronic device with MPFS without limitation in the level difference of the transverse component in adjacent magnets. In FIG. 2 shows a tuned MPFS electronic device with a 25-30% limitation in the level difference of the transverse component in adjacent magnets.

This method provides a sufficient level of compensation for the effect of the transverse component in adjacent magnets of the MPFS assembled on an electronic device, which significantly reduces the complexity of setting the device and provides a minimum number of additional tuning elements when adjusting the electronic device in static and dynamic modes of operation. Also, the proposed method does not involve an increase in labor intensity and increased material costs in its implementation. The method was tested on three types of MPFS, its use made it possible to reduce the tuning time by half, the number of additional tuning elements was reduced by 3 times.

Information sources:

1. E.I. Kanevsky, E.A. Mayorova, O.I. Romanov "Relationship between the transverse component of the focusing magnetic field and the current settling of the electron beam." - Electronic technology, series 1, 1970, No. 6.

2. USSR author's certificate No. 1464784 A1, 5, H01J 23/087. Andrushkevich B.C., Grigoriev Yu.A., Perelygin A.V., Sakhadzhi V.Yu., Yavchunovskiy V.Ya. Method for manufacturing magnetic focusing systems for O-type microwave devices.

Claims (1)

A method for manufacturing magnetic periodic focusing systems for O-type microwave devices, including assembling a system of coaxial pole pieces and ring magnets, monitoring the parameters of each ring magnet and completing the magnetic system, while systems are considered suitable for rejection, the ring magnets of which have a limitation by the maximum level of the transverse component and by the difference in the transverse component in adjacent magnets, characterized in that the allowable difference between the transverse components in adjacent MPFS magnets must be in the range from 0 to 15-50% of the maximum allowable value of the transverse component, and the allowable difference is determined for each MPFS type and electronic device separately in the specified range.

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