RU2149485C1 - Coaxial pulse transformer on heterogeneous line - Google Patents

Abstract

FIELD: communications engineering; splitters. SUBSTANCE: transformer has external and internal coaxial electrodes of which one has gradually varying sectional area, as well as input and output assemblies, the latter being made in the form of n identical coaxial channels whose axes are arranged radially in plane perpendicular to transformer axis at point spaced through certain distance from input assembly; internal and external electrodes of each channel are connected to respective internal and external electrodes of transformer; wave impedances of channels and transformer are matched by selecting relationship between transformer electrode diameters at channel connection plane; shortest distance in this plane over external electrode surface of transformer between adjacent external electrodes of channels and diameter of external electrode are interrelated by calculation equation given in description of invention including preset error of transformer pulse rise time, velocity of light through electrode-to-electrode insulating medium, desired rise time of transformer pulse, and dielectric constant of transformer electrode-to- electrode medium. EFFECT: enlarged functional capabilities and improved operating reliability with desired metrological parameters. 3 dwg

Description

 The invention relates to coaxial communication lines for transmitting high-voltage nanosecond voltage pulses and can be used as a pulsed coaxial transformer on an inhomogeneous line, exciting, for example, a given number of antennas constituting a phased array, designed for directional emission of short ultra-wide-band electromagnetic field pulses, for example, in radar or in the study of the effects of radiation on environments and objects.

 Known pulsed coaxial transformer on a non-uniform line, containing an external electrode in the form of a conducting pipe and an internal electrode made of a group of pipe segments with diameters discretely changing in one direction, the space between the electrodes is filled with transformer oil, the input node of the transformer is designed to be connected to the source of the transformed signal , and the output node to the load [1].

 The main disadvantage of the transformer formed by the cascade connection of segments of homogeneous lines is the presence of large distortions of the transformed signal caused by multiple reflections and re-reflections of the signal at the joints of the stepped sections of the internal electrode.

 Also known is a pulsed coaxial transformer on an inhomogeneous line, which is closest to the described one, containing external and internal electrodes with a dielectric medium between them, while one of the electrodes is made with a cross section that continuously varies in one direction, the input node of the transformer is designed to connect to a source transformable pulse, and the output node to the load, while the output node is located from the input at a distance L, at which the signal is transformed with allowable value of the decline of the peak of the pulse of a given duration [2].

 In this device, which is a prototype, in comparison with an analogue, by replacing a cascading variable section of the electrode with a smoothly changing section in the transformer, the distortion of the transformed signal is significantly reduced, which allows it to be used in transforming, forming, and correcting high-voltage circuits.

 However, the known device does not provide the possibility of its use for multi-element load, which reduces the range of its application.

 The aim of the invention is to expand the range of application of the transformer (and as a splitter) by ensuring the possibility of its synchronous connection to the coaxial load elements while ensuring the reliability of its work with predetermined metrological parameters.

, и в этой плоскости кратчайшее расстояние b по поверхности наружного электрода трансформатора между соседними наружными электродами каналов и диаметром d_к наружного электрода канала связаны соотношением

где c - скорость света в межэлектродной диэлектрической среде;
ε - диэлектрическая проницаемость среды между электродами;
t_ф - заданное значение длительности фронта трансформируемого импульса;
δt_ф - заданное значение погрешности длительности фронта трансформируемого импульса ( δt_ф < 100%).This goal is achieved by the fact that in a pulsed coaxial transformer on an inhomogeneous line containing coaxial external and internal electrodes with a dielectric medium between them, while at least one of the electrodes is made with a cross section that continuously varies in one direction, the input node of the transformer it is designed to connect to the source of the transformed pulse, and the output node to the load, while the output node is located from the input at a distance L, at which the transformation is provided tions signal with an allowable value recession top pulse of predetermined duration, according to the invention the output node of the transformer is in the form of n identical coaxial channels, each of which has an outer and inner electrode with a dielectric medium between them and the wave impedance Z _to channels designed for a harmonized connection to n identical loads, while the channels are uniformly radially outside the aforementioned electrodes of the transformer, and the axis of the channels are in the same plane, which is perpendicular is transverse to the axis of the transformer and is located at the mentioned distance L from the input node, with the inner electrode of each coaxial channel connected to the inner electrode of the transformer and the outer electrode of each channel to the outer electrode of the transformer, while the ratio of the diameters of the outer and inner electrodes of the transformer at the intersection with the plane channel axis corresponds to the impedance

, and in this plane, the shortest distance b along the surface of the transformer outer electrode between adjacent outer channel electrodes and a diameter d _{to the} channel outer electrode is related by

where c is the speed of light in the interelectrode dielectric medium;
ε is the dielectric constant of the medium between the electrodes;
t _f - a given value of the duration of the front of the transformed pulse;
δt _f - set value of the error of the duration of the front of the transformed pulse (δt _f <100%).

 The essence of the invention lies in the fact that in the device the output node is made in the form of identical coaxial channels coordinated with the main coaxial for connecting to the load, and due to the geometry of the node and the device parameters selected from condition (1), the transformer, in addition to its main function, acts as a transformable splitter signal to a group of identical loads while ensuring the reliability of the device with the specified metrological parameters.

 In FIG. 1 shows a schematic diagram of a device.

 In FIG. 2 shows a section along A-A 'in FIG. 1.

 In FIG. 3 shows the pulse shape in the plane A-A 'in the form of the dependence of the transmitted voltage U on time t.

 A pulsed coaxial transformer on an inhomogeneous line contains coaxial outer 1 and inner 2 electrodes with a dielectric medium 3 (for example, transformer oil) between them. At least one of the electrodes (or maybe both) (in figures 1, 2, electrode 2) is made with a cross section that varies continuously in one direction. (in figures 1, 2, as an example of the device, the electrode 2 is shown, increasing smoothly in diameter from the input to the output of the transformer, which essentially forms an inhomogeneous coaxial transformer line).

где T₀ - время задержки импульса в трансформаторе.The input node 4 of the transformer (which may contain matching elements that are not considered in this text) is intended to be connected to the source (not shown in the figures) of the transformed pulse. The output node 5 of the transformer is designed to be connected to the load (not shown in the figures). The output node 5 is located from the input node 4 at a distance L, at which the signal is transformed with an acceptable value λ of the decay of the peak of the pulse of a given duration t _and. (Fig. 3). The indicated distance L is determined by known dependences (see [2], p. 16, formula 1.29). Wherein

where T ₀ is the delay time of the pulse in the transformer.

где K_тр - коэффициент трансформации трансформатора.

where K _Tr - the transformation coefficient of the transformer.

где Z_вх - волновое сопротивление входного узла 4 (равное выходному сопротивлению согласованного с трансформатором источника трансформируемого импульса).

where Z _I - wave impedance of the input node 4 (equal to the output impedance of the transformable pulse source matched with the transformer).

. Соотношение диаметров наружного D и внутреннего d электродов трансформатора в месте пересечения с плоскостью каналов соответствует волновому сопротивлению

. Этот признак устройства обеспечивает согласование в указанном месте тракта выходного узла 5 и трактов каналов 6. При этом обеспечено соотношение

где Z_вых - волновое сопротивление выходного узла 5, связанное с соотношением указанных диаметров известной зависимостью (см. К.А.Желтов "Пикосекундные сильноточные ускорители", М., Энергоатомиздат, 1991 г., с. 11):

В указанной плоскости (сечение A-A' фиг. 1) кратчайшее расстояние b (фиг. 2) по поверхности наружного электрода 1 трансформатора между соседними наружными 7 электродами каналов 6 и диаметром d_к наружного электрода 7 канала 6 связаны соотношением (1).The output node 5 of the transformer is made in the form of n identical coaxial channels 6. Each channel 6 has a wave impedance Z _k , an external 7 and an internal 8 electrodes with a dielectric medium 9 between them. Channels are designed for coordinated connection to n identical loads. The channels 6 are located uniformly radially outside the aforementioned electrodes 1 and 2 of the transformer, and the axis of the channels are in the same plane AA '(Fig. 1), which is perpendicular to the axis OO' of the transformer and is located at the mentioned distance L from the input node 4. The inner electrode 8 of each channel 6 is connected to the inner electrode 2 of the transformer. The outer electrode 7 of each channel 6 is connected to the outer electrode 1 of the transformer. In this case, the ratio of the diameters of the outer D (for coaxials is always its internal size) and internal d (for coaxials is always its outer size) of the transformer electrodes 1 and 2 at the intersection of the axis of the channels 6 with the plane AA 'corresponds to the wave resistance

. The ratio of the diameters of the outer D and inner d electrodes of the transformer at the intersection with the plane of the channels corresponds to the wave impedance

. This feature of the device ensures coordination in the specified location of the path of the output node 5 and the paths of the channels 6. This ensures the ratio

where Z _o - wave impedance of the output node 5, associated with the ratio of the indicated diameters to a known dependence (see K.A. Zheltov "Picosecond high-current accelerators", M., Energoatomizdat, 1991, p. 11):

In the indicated plane (section AA 'of Fig. 1), the shortest distance b (Fig. 2) along the surface of the outer electrode 1 of the transformer between adjacent outer 7 electrodes of the channels 6 and a diameter d _{to the} outer electrode 7 of the channel 6 are connected by the relation (1).

A coaxial transformer on an inhomogeneous line can be either increasing or decreasing, which depends on the ratio of the wave impedances of the input and output nodes (Z _in and Z _out ). Since Z _{in is} determined by the resistance of the source of the transformed pulse, in order to ensure an increase in the amplitude of the pulse, a decrease in the diameter of the internal electrode of variable cross-section must take place (or a corresponding change in the ratio of diameters if both electrodes smoothly change), and to ensure a decrease in amplitude, the transformer must have an increase in the diameter of the internal variable the electrode along the length L, which is shown as an embodiment of the device in FIG. 1. The dielectric medium in the channels 6 may be the same as in the gap between the electrodes 1 and 2, or another, for example polyethylene, fluoroplastic, etc.

 The device operates as follows.

A voltage pulse U (t) (Fig. 3) with an amplitude, for example, 100 ... 500 kV, is supplied to the input node 4 of the coaxial transformer. In this case, between the outer 1 and inner 2 electrodes in the input node 4 there is a voltage pulse of the corresponding value. Due to the fact that at least one of the electrodes is made with a cross section that varies continuously in one direction, the coaxial line of the transformer is inhomogeneous, while the wave impedance in different sections of the line cross section is uneven and varies in accordance with the ratio of the diameters of the electrodes 1 and 2. the length L of the transformer, which is provided on the allowable pulse peak value λ recession predetermined duration t _and the voltage pulse is transformed in accordance with the change of the wave const otivleniya transformer.

, т.е.

трансформируемый импульс без искажения (за счет согласованных переходов) "расходится" по n коаксиальным идентичным каналам, предназначенным для согласованного подключения к n идентичным элементам нагрузки. Таким образом, трансформатор помимо трансформации импульса выполняет функцию разветвителя этого импульса.In the output node 5, located at a distance L from the input node, there is a coordination of the path of the node of the electrodes 1, 2 and all paths of the coaxial channels 6 leading to the load. Due to the fact that the ratio of the diameters D and d at the point of connection of the electrodes 1 and 2 to the corresponding electrodes 7 and 8 of the channels 6 corresponds to the wave impedance

, i.e.

the transformable pulse without distortion (due to coordinated transitions) "diverges" along n coaxial identical channels designed for coordinated connection to n identical load elements. Thus, the transformer in addition to the transformation of the pulse performs the function of a splitter of this pulse.

Due to the fact that all coaxial channels 6 are uniformly radially outside the electrodes 1, 2, and their axes are in the same plane perpendicular to the axis of the transformer, the branched pulse is simultaneously transmitted to the load, and the paths are not identical on the surfaces of the electrodes 1, 2 , these paths are minimal, which ensures the reliability of the transformer-splitter, reduces the error δt _{f of the} front duration t _f , which inevitably accompanies an increase in the length of the electrical connection ode 2 and internal electrodes of 8 channels with a different arrangement of channels from 90 ^o relative to the axis OO 'of the transformer.

 Examples of the device.

For the following examples of the execution of the device is common:
- electrodes 1, 2 are made of aluminum alloy D16T;
- channel electrodes - from a coaxial cable of the type RK 50-9-11;
- in the interelectrode gaps of the device (between electrodes 1 and 2 and at the points of their connection with channels 6), a dielectric medium was used - transformer oil with a breakdown electric field strength E _pr = 20 kV / mm, ε = 22 and polyethylene with ε = 2.2 in channels 6 (except for the place of their connection with electrodes 1 and 2);
- the amplitude of the transformed pulse U _a1 = 200 kV;
- the number of coaxial channels n = 36 (selected for a given number of antennas in the phased array - transformer load);
- the wave impedance of each channel of the output node Z _to = 50 Ohms (this value corresponds to the wave impedance of each load-antenna element);
- a given value of the duration of the front of the transformable pulse t _f = 0.25 ns;
- the set value of the error of the duration of the front of the transformed pulse δt _f = 10%;
- axial length of the transformer L = 0.5 m.

Given these values, the diameter of the channel d _to defined as follows.

Напряженность электрического поля на выходном узле и в каналах (см. К.А. Желтов, Пикосекундные сильноточные ускорители, М., Энергоатомиздат, 1991 г., с. 9)

где a_к - диаметр внутреннего электрода 8 коаксиального канала 6 (фиг. 2).The amplitude of the pulse at the output node 5 of the transformer

Electric field strength at the output node and in the channels (see K.A. Zheltov, Picosecond high-current accelerators, M., Energoatomizdat, 1991, p. 9)

where a _to - the diameter of the inner electrode 8 of the coaxial channel 6 (Fig. 2).

Принимаем E = E_пр = 20 кВ/мм и, решая совместно (2), (3), (4), получаем

Таким образом, подставляя найденное значение d_к в соотношение (1), получаем допустимый интервал значений b:
b + d_к = 10,1 ... 25,3 мм; b = 0,8 ... 16 мм
Далее в примерах выполнения устройства приведен анализ указанного интервала путем эксперимента.

We take E = E _pr = 20 kV / mm and, solving together (2), (3), (4), we obtain

Thus, substituting the found value of d _to in relation (1), we obtain an allowable range of values of b:
b + d _k = 10.1 ... 25.3 mm; b = 0.8 ... 16 mm
Further, in examples of the device, an analysis of the specified interval by experiment is given.

 Example 1

b = 16.5 mm. A device with the specified value of b gave an error of δt _f = 11%, which exceeded the set value.

 Example 2

b = 16 mm ⇒ δt _f = 9.9% - satisfies the condition.

 Example 3

b = 8 mm ⇒ δt _f = 7.3%.

 Example 4

b = 0.8 mm ⇒ δt _f = 3%.

 Example 5

b = 0.75 mm ⇒ δt _f = 3%, there were great technological difficulties with securing the channels.

Conclusions: the range of values (b + d _к ) selected in relation (1) ensures the transformation of the pulse signal within the specified error δt _{f of the} front duration.

The upper limit of values corresponds to a given δt _f .

 All values below the upper limit satisfy the specified error condition, however, the device is technologically practically not feasible when leaving the values below the lower limit in (1) due to the proximity of the channel elements to each other and the impossibility of their stable attachment to the corresponding electrodes 1 and 2.

 Thus, a review of examples of the device showed that the described pulsed coaxial transformer on a non-uniform line has a greater application than the prototype, because In addition to signal transformation, it also provides branching of this signal, while ensuring the reliability of its operation with specified metrological parameters.

 The device can be used in pulsed technology, in radar, in the excitation of a group of antennas that make up the phased array, as well as in studies of the effects of radiation on media and objects.

Sources of information taken into account
1. VV Kremnev, G. A. Mesyats "Methods of multiplication and transformation of impulses", Novosibirsk, "Science" S.O., 1987, p. 14-15.

 2. Ibid., Pp. 15-16 - prototype.

Claims (1)

A pulsed coaxial transformer on an inhomogeneous line containing coaxial external and internal electrodes with a dielectric medium between them, while at least one of the electrodes is made with a variable cross-section that smoothly changes to one side, the input node of the transformer is designed to be connected to the source of the transformed pulse, and the output node to the load, while the output node is located from the input at a distance L, at which the signal is transformed with an allowable drop value pulse tops of a given duration, characterized in that the output node of the transformer is made in the form of n identical coaxial channels, each of which has an external and internal electrodes with a dielectric medium between them and a wave impedance Zк, the channels are designed to coordinate the connection to n identical loads, while the channels are uniformly radially outside the aforementioned electrodes of the transformer, and the axis of the channels are in the same plane, which is perpendicular to the axis of the transformer and is located on curved distance L from the input node, and the inner electrode of each coaxial channel is connected to the inner electrode of the transformer, and the outer electrode of each channel is connected to the outer electrode of the transformer, while the ratio of the diameters of the outer and inner electrodes of the transformer at the intersection with the plane of the channel axes corresponds to the wave resistance

, and in this plane, the shortest distance b along the surface of the outer electrode of the transformer between adjacent outer channel electrodes and a diameter d _{to the} outer channel electrode is related by the ratio:

where c is the speed of light in an interelectrode dielectric medium;
ε is the dielectric constant of the medium between the electrodes;
t _f - a given value of the duration of the front of the transformed pulse;
δt _f - set value of the error of the duration of the front of the transformed pulse (δt _f <100%).

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