RU135203U1 - PULSE TWO-STAGE MONOBLOCK AMPLIFIER OF MICROWAVE POWER ON AMPLITRONS - Google Patents

Abstract

1. A pulsed two-stage monoblock amplifier for microwave power at amplitrons, comprising the first and second stages of amplification of microwave signals made on amplitrons, each of which includes an anode block, a cathode, resonators of a delay system, bundles, and a microwave signal input and output device, characterized in that two amplitrons are located on one central vertical axis, are electrically and functionally interconnected with a common magnetic system with the possibility of providing equal magnetic induction for both amplitrons, the functional connection of which is carried out by means of a microwave device for connecting the cascades of a power amplifier of an s-shaped design, and the cathodes of both amplitrons have optimal radius sizes. 2. The device according to claim 1, characterized in that the electrical connection between the amplitrons is formed by the corresponding at least four metal groove joints. The device according to claim 1, characterized in that the cathodes of both amplitrons have optimal radius sizes established during the calculation of the electronic efficiency of each amplitron. The device according to claim 4, characterized in that the s-shaped design of the microwave device for connecting the stages of the power amplifier takes into account the same directivity of the magnetic field common to both amplitrons of the magnetic system and provides consistent amplification of the microwave signals by amplitrons of the first and second stages.

Description

The utility model relates to microwave electronic equipment and can be used mainly in multi-stage transmitters of radar detection and target designation, as well as in radio navigation equipment, radio countermeasures, communications systems, telemetry transmitters, high-frequency systems of resonant charged particle accelerators, and microwave heating installations.

The analogue is known of a pulsed two-stage microwave power amplifier (certificate for utility model 34050 U1, publ. 11/20/2003) containing isolation valves, a modulator, a first microwave amplification stage, made, for example, on a traveling wave lamp (TWT), a second microwave signal amplification stage made on an amplitron, a pulse transformer.

An advantage of the analogue, in particular, is the use of a common modulator for the first and second amplification stages. In this case, the TWT cathode is connected to the cathode of the amplitron through a matching resistor and a capacitor parallel to it, and the cathode of the amplitron is connected to the output of the secondary winding of the pulse transformer.

A known analogue microwave pulse power amplifier (patent for the invention 2262183 C1, publ. 10.10.2005), which differs from the previous analogue only in the presence of an additional resistor in the cathode circuit of the amplitron.

Both of the above analogs can be used as two-stage radar station transmitters (radar), or as the first two stages of amplification of a three-stage radar transmitter, in which the output stage of the microwave signal amplification is performed on the second amplitron.

The disadvantage of these analogues is that they cannot be used in the output stages of three-stage radar transmitters in which two amplitrons are connected in series.

Amplitrons, like magnetron backward-wave amplifiers, are structurally closest to multi-resonator magnetrons. The main difference from the magnetron is that the resonator system is replaced by a non-resonant slow-down system in the amplitron by breaking the ligaments in one of the resonators. Moreover, the number of resonators in the amplitron is odd. The physics of the processes taking place in amplitrons is basically similar to the processes taking place in multi-cavity magnetrons [EM Vereshchagin Modulation in microwave generators. - M .: Soviet radio. 1972. 304 p. S. 237, 239]. In this regard, as an analogue, a multi-section magnetron can be considered.

A known analog is a multi-section magnetron (patent for utility model RU 130451 U1, published July 20, 2013), containing for the case of two sections two magnetrons located on one central longitudinal axis, electrically connected together, the magnetic system of which is made common, with the possibility of ensuring equal magnetic induction for both sections.

The advantages of such an analog design open up the possibility of developing a two-stage monoblock microwave power amplifier on amplitrons with improved energy and quality characteristics.

A two-stage microwave power amplifier on amplitrons is known in science and technology, used mainly in amplification chains of multi-stage radar detection transmitters using a ferrite gate for decoupling amplitrons. Moreover, in the output stages, as a rule, the sequential operation of two amplitrons is used [EM Vereshchagin Modulation in microwave generators. - M .: Soviet radio. 1972. 304 p. S. 237-239, 261, 262.]. This analogue is selected as a prototype.

The disadvantage of amplitrons, including those used in the prototype, is the low gain of microwave signals in power - about 10 ... 15 dB with a working frequency band of up to 10% [Vereshchagin EM Modulation in microwave generators. - M .: Soviet radio. 1972. 304 p. S. 254.]. In order to provide the necessary amplification of microwave signals in terms of power, a series connection of two amplitrons is used. This explains the need for a two-stage construction on the amplitrons of the output part of a multi-stage detection radar transmitter.

The disadvantages and features of the prototype are as follows. Amplitron in the absence of a modulating pulse (anode supply) passes to the output the microwave signals received at its input. In order to exclude the direct passage of microwave signals through the amplitron to the antenna-waveguide path or to the input of the next amplification stage on the amplitron, pulse modulation is also carried out in the previous amplification stage on the amplitron.

Amplitron with anode power turned on, but in the absence of microwave signals at the input, generates noise oscillations. The noise generation of the amplitron is suppressed by the preliminary supply of microwave signals to the input of the amplitron, which anticipates the arrival of a modulating pulse at the amplitron.

The amplification of microwave pulsed signals by amplitrons is accompanied by a time delay and distortion. These phenomena are limited to the use of ferrite gates that allow only direct microwave signals to pass through with attenuation of 0.5 dB (attenuation for feedback signals of the order of 20 dB) and a decrease in the width of the spectrum of signals in the previous amplification stages. The narrowing of the spectrum of microwave signals is achieved by increasing the duration of the modulating pulses in the preliminary amplification stages. Thus, the anode power of each amplitron is provided by its own pulse modulator. [Vereshchagin E.M. Modulation in microwave generators. - M .: Soviet radio. 1972. 304 p. S. 261-263.].

The disadvantages of the prototype also include the need for alignment of the amplitrons when replacing them, the large weight and dimensions of the amplitrons, the need for a complex cooling system, the high cost of devices, the deterioration of the energy parameters of amplitrons with increasing operating frequency. Amplitrons relate to microwave vacuum devices of the magnetron type, specifically to devices with an emitting negative electrode and a closed electron beam operating on the backward wave. Amplitrons are characterized by efficiency in the decimeter frequency range up to 90%, at 3 GHz - up to 80%, at 10 GHz - up to 53%, at 17 GHz - up to 30% [Kukarin S.V. Electronic microwave devices. - M .: Radio and communication. 1981. 272 p. S. 28, 59]. With an increase in the operating frequency, the energy parameters of amplitrons and, above all, efficiency, deteriorate. Therefore, an increase in efficiency is relevant, which in turn contributes to:

- facilitation of thermal conditions;

- increase the reliability of the amplitron;

- simplification and (or) reduction in cost of the cooling system;

- reduction of weight and size characteristics.

An increase in the efficiency and output power of the amplitrons is achieved through the use of cathodes with optimal sizes of radii r _Copt, which are established in the process of calculating the electronic efficiency of each ampilitron, as proposed for multi-section magnetrons (patent for utility model RU 130451 U1, published on July 20, 2013). In the case of the amplitron, the parameter α = Δf / f _cf = 10 ^{-1 is used} , which corresponds to the working frequency band of the amplitron 10% (Δf = 0.1f _cf , where f _cf is the average frequency).

The technical task of the claimed utility model is the development of a new pulsed two-stage monoblock microwave power amplifier on amplitrons, the structural and functional features of which allow the monoblock design of a two-stage microwave power amplifier on amplitrons, to increase efficiency and output power, reduce weight and size characteristics, and reduce cost.

The implementation of the indicated technical task by the claimed utility model provides the following technical result, which is the sum of the obtained technical effects:

- the location of two amplitrons on one central vertical axis, electrically and functionally interconnected, with a common magnetic system allows you to implement a monoblock design of a two-stage microwave power amplifier;

- the monoblock design of a two-stage microwave power amplifier on amplitrons with a common magnetic system reduces the overall dimensions of the amplifier, reduces its cost, eliminates the need for alignment of amplitrons when replacing them;

- the electrical connection between the amplitrons is formed by the corresponding at least four metal groove joints, which creates an air gap between the amplitrons in the region of the groove joints and leads to additional air cooling of the outer surface of the anode blocks;

- the functional connection between the amplitrons is carried out by means of a microwave device for connecting the stages of the power amplifier and ensures the sequential operation of two amplitrons;

- the microwave device for connecting the stages of the power amplifier contains waveguide sections of the input and output signals of the microwave amplitrons of the first and second stages, a ferrite gate with a waveguide input and output. A ferrite gate passes only direct microwave signals from the first amplitron to the second amplitron with a attenuation of about 0.5 dB and practically does not pass back microwave signals from the second amplitron to the first amplitron. Microwave return attenuation of the order of 20 dB. The waveguide sections of the input and output signals of microwave amplitrons of the first and second stages provide a serial connection of input and output devices of microwave amplitrons of the first and second stages through a ferrite gate with a waveguide input and output;

- the microwave device for connecting the stages of the power amplifier has a special s-shaped design. This takes into account the same directivity of the magnetic field common to both amplitrons of the magnetic system and ensures consistent amplification of microwave signals by amplitrons of the first and second stages;

- the magnetic system is made general, with the possibility of providing equal magnetic induction for both amplitrons, which allows to improve the quality mass and size characteristics of a pulsed two-stage monoblock power amplifier on amplitrons;

- the cathodes of both amplitrons have the optimal radius sizes established in the process of calculating the electronic efficiency for each amplitron, providing maximum values of the efficiency and increased output power of the amplitrons and, in general, a pulsed two-stage monoblock microwave power amplifier on amplitrons.

To achieve the technical result, a “Pulse two-stage monoblock microwave power amplifier on amplitrons” is proposed, containing the first and second stages of amplification of microwave signals made on amplitrons, each of which includes an anode block, a cathode, slow-wave system resonators, bundles, and a signal input and output device Microwave located on one central vertical axis, electrically and functionally interconnected, with a common magnetic system, the functional connection of which is carried out in the middle Twomey microwave power amplifier cascade connection apparatus s-shaped structure, and both cathodes amplitron have optimal dimensions radii.

The fundamental difference between the proposed device and the prototype is that two amplitrons are located on the same central vertical axis, are electrically and functionally interconnected, with a common magnetic system with the ability to provide equal magnetic induction for both amplitrons, the functional connection of which is through a microwave device connecting the amplifier stages s-shaped power, and the cathodes of both amplitrons have optimal radius sizes.

Additional differences are that the electrical connection between the amplitrons is formed by the corresponding at least four metal groove joints, which creates an air gap between the amplitrons in the region of the groove joints and leads to additional air cooling of the outer surface of the anode blocks, and the s-shaped design of the microwave device connecting the stages of the power amplifier takes into account the same directivity of the magnetic field common to both amplitrons of the magnetic system and ensuring It has a sequential amplification of microwave signals by amplitrons of the first and second stages.

Other additional differences are that the cathodes of both amplitrons have the optimal radius sizes established during the calculation of the electronic efficiency for each amplitron, providing maximum values of the efficiency and increased output power of the amplitrons and, in general, a pulsed two-stage monoblock microwave power amplifier on amplitrons.

Such a mutual arrangement of structural elements and their interrelation are necessary for the implementation of a monoblock design of a two-stage microwave power amplifier on amplitrons, to increase the efficiency and output power.

It is the presence in the claimed utility model of common distinctive and additional distinguishing features that allows not only to increase the basic energy parameters such as output power and efficiency, but also significantly improve the overall dimensions and reduce the cost of the claimed device.

The essence of the utility model is illustrated by drawings:

- FIG. 1 - Pulse two-stage monoblock amplifier for microwave power on amplitrons, general view, side view;

- FIG. 2 - Pulse two-stage monoblock microwave power amplifier on amplitrons, microwave device for connecting the cascades of a power amplifier, general view, front view;

- FIG. 3 - Pulse two-stage monoblock amplifier of microwave power at amplitrons, functional diagram.

In FIG. 1 shows a Pulse two-stage monoblock amplifier of microwave power at amplitrons, general view, side view:

1. Amplitron (1st cascade);

1.1. Anode block;

1.2. Cathode (r _C1opt is the optimal size of the cathode radius);

1.3. Resonators of a retarding system (ZS) (N is an odd number of resonators of an ZS);

1.4. Microwave signal input and output device;

2. Amplitron (2nd cascade);

2.1. Anode block;

2.2. Cathode (r _C2opt is the optimal size of the cathode radius);

2.3. Resonators of the slowing system (ZS) - an odd number of resonators of the ZS);

2.4. Microwave signal input and output device;

3. Magnetic system;

4. Metal grooved connection of amplitrons;

5. A microwave device for connecting cascades of a power amplifier;

5.1. The waveguide section of the input and output signals of the microwave amplitron of the first stage;

5.2. Transverse septum;

5.3. Flange connections;

5.4. Ferrite gate with waveguide input and output;

5.5. The waveguide section of the input and output signals of the microwave amplitron of the second stage;

5.6. Transverse septum.

Two amplitrons 1, 2 of FIG. 1 are located on one central vertical axis both electrically and functionally interconnected. The electrical connection between the amplitrons 1, 2 of FIG. 1 is formed by the corresponding at least four metal groove joints 4 of FIG. 1. The air gap between the amplitrons in the region of the grooved joints leads to additional air cooling of the outer surface of the anode blocks 1.1, 2.1 of FIG. one.

The functional relationship between the amplitrons 1, 2 of FIG. 1 is carried out by means of a microwave device for connecting the stages of a power amplifier 5 of FIG. 1 and provides sequential operation of two amplitrons 1, 2 of FIG. one.

The design of the microwave device for connecting the stages of the power amplifier 5 of FIG. 1 s-shaped takes into account the same directivity of the magnetic field common to both amplitrons 1, 2 of FIG. 1 of the magnetic system 3 of FIG. 1 and thereby provides a consistent amplification of microwave signals by amplitrons 1, 2 of FIG. 1 of the first and second cascades.

The supply of microwave signals to the amplitron 1 of FIG. 1 and the output of the amplified microwave signal from the amplitron 1 of FIG. 1 is carried out using the waveguide section of the input and output signals of the microwave amplitron of the first stage 5.1 of FIG. 1 and microwave signal input and output devices 1.4 of FIG. one.

The supply of microwave signals to the amplitron 2 of FIG. 1 and the output of the amplified microwave signal from the amplitron 2 of FIG. 1 is carried out using the waveguide section of the input and output signals of the microwave amplitron of the second stage 5.5 of FIG. 1 and microwave signal input and output devices 2.4 of FIG. one.

The input and output of the waveguide sections of the input and output signals of the microwave amplitrons of the first and second stages 5.1, 5.5 of FIG. 1 are separated from each other by transverse partitions 5.2, 5.6 of FIG. one.

The passage of microwave signals from the output of the waveguide section of the input and output signals of the microwave amplitron of the first stage 5.1 of FIG. 1 to the input of the waveguide section of the input and output signals of the microwave amplitron of the second stage 5.5 of FIG. 1 is carried out through a ferrite gate with a waveguide input and output 5.4 of FIG. one.

The connection of the waveguide sections of the input and output signals of the microwave amplitrons of the first and second stages 5.1, 5.5 of FIG. 1 with a ferrite gate with a waveguide input and output 5.4 of FIG. 1 is made by means of flange connections 5.3 of FIG. one.

The waveguide sections of the input and output signals of the microwave amplitrons of the first and second stages 5.1, 5.5 of FIG. 1 provide a serial connection of input and output devices of microwave signals 1.4, 2.4 of FIG. 1 amplitrons 1, 2 of FIG. 1 through a ferrite gate with a waveguide input and output 5.4 of FIG. one.

The magnetic system of FIG. 1 is made general, with the possibility of providing equal magnetic induction for amplitrons 1, 2 of FIG. one.

Cathodes 1.2, 2.2 of FIG. 1 amplitrons 1, 2 of FIG. 1 have the electronic efficiency of each amplitron 1, 2 of FIG. 1 optimal radius sizes r _C1opt , r _C2opt as is done for multi-section magnetrons (patent for utility model RU 130451 U1, published July 20, 2013), providing maximum values of efficiency and increased output power of amplitrons 1, 2 of FIG. 1 and in general a pulsed two-stage monoblock microwave power amplifier.

Into the interaction space between the cathode 1.2 of FIG. 1 and the anode block 1.1 of FIG. 1 between the cathode 2.2 of FIG. 1 and the anode block 2.1 of FIG. 1 with the supply of operating voltage to the amplitrons 1, 2 of FIG. 1, the crossed (mutually perpendicular) constant electric field and constant magnetic field of the common magnetic system 3 of FIG. one.

The number N of resonators of the retardation systems 1.3, 2.3 of FIG. 1 amplitrons 1, 2 of FIG. 1 odd.

Amplitron 1 of FIG. 1, as the first microwave signal amplification stage, less powerful than the amplitron 2 of FIG. 1 of the second stage amplification of microwave signals. Therefore, the transverse dimensions of the amplitron 1 of FIG. 1, especially the anode block and the cathode, can be smaller than the same transverse dimensions of the more powerful amplitron 2 of FIG. one.

In FIG. 2 shows a Pulse two-stage monoblock amplifier of microwave power on amplitrons, a device for microwave connection of cascades of a power amplifier, general view, front view:

1.4. Microwave signal input and output device;

1.4.1. Microwave signal input;

1.4.2. Microwave signal output;

1.5. Ligaments;

2.4. Microwave signal input and output device;

2.4.1. Microwave signal input;

2.4.2. Microwave signal output;

2.5. Ligaments;

5. A microwave device for connecting cascades of a power amplifier;

5.1. The waveguide section of the input and output signals of the microwave amplitron of the first stage;

5.1.1. Entrance;

5.1.2. Exit;

5.2. Transverse septum;

5.3. Flange connections;

5.4. Ferrite gate with waveguide input and output;

5.4.1. Ferrite valve;

5.4.2. Waveguide entrance;

5.4.3. Waveguide exit;

5.5. The waveguide section of the input and output signals of the microwave amplitron of the second stage;

5.5.1. Entrance;

5.5.2. Exit;

5.6. Transverse septum.

Microwave signals are input 5.1.1 of FIG. 2 of the waveguide section of the input and output signals of the microwave amplitron of the first stage 5.1 of FIG. 2 and on to input microwave signals 1.4.1 and bundles 1.5 of FIG. 2 microwave signal input and output devices 1.4 of FIG. 1, 2 of the amplitron 1 of FIG. one.

Amplified microwave signals from amplitron 1 of FIG. 1 enter through ligaments 1.5 of FIG. 2 to output microwave signals 1.4.2 of FIG. 2 and on to output 5.1.2 of FIG. 2 of the waveguide section of the input and output signals of the microwave amplitron of the first stage 5.1 of FIG. 1, 2, and further through the flange connections 5.3 of FIG. 1, 2 and through a ferrite gate with a waveguide input and output 5.4 of FIGS. 1, 2 go to input 5.5.1 of FIG. 2 of the waveguide section of the input and output signals of the microwave amplitron of the second stage 5.5 of FIG. 12.

Ferrite valve 5.4.1 of FIG. 2 has a waveguide input 5.4.2 of FIG. 2 and the waveguide output 5.4.3 of FIG. 2.

Microwave signals from input 5.5.1 of FIG. 2 arrive at the input of microwave signals 2.4.1 and bundles 2.5 of FIG. 2 microwave signal input and output devices 2.4 of FIG. 1, 2 amplitron 2 of figure 1.

Amplified microwave signals from amplitron 2 of FIG. 1 enter through ligaments 2.5 of FIG. 2 to output microwave signals 2.4.2 of FIG. 2 and on to output 5.5.2 of FIG. 2 of the waveguide section of the input and output signals of the microwave amplitron of the second stage 5.5 of FIG. 12.

The input and output of the waveguide sections of the input and output signals of the microwave amplitrons of the first and second stages 5.1, 5.5 of FIG. 1, 2 are separated from each other by transverse partitions 5.2, 5.6 of FIG. 12.

In FIG. 3 shows a pulse two-stage monoblock amplifier of microwave power at amplitrons, functional diagram:

1. Amplitron (1st cascade);

2. Amplitron (2nd cascade);

5.1.1. Entrance;

5.1.2. Exit;

5.4.1. Ferrite valve;

5.5.1. Entrance;

5.5.2. Exit.

Microwave signals from the previous stage are fed to input 5.1.1 of FIG. 2, 3 pulsed two-stage monoblock microwave power amplifier on amplitrons. Amplitron amplified 1 of FIG. 1, 3 microwave signals are output 5.1.2 of FIG. 2, 3 and further through the ferrite valve 5.4.1 of FIG. 1, 2, 3 and input 5.5.1 of FIG. 2, 3 per amplitron 2 of FIG. 13.

Amplitron amplified 2 of FIG. 1, 3 microwave signals through output 5.5.2 of FIG. 2, 3 are fed from a pulsed two-stage monoblock microwave power amplifier on amplitrons to the antenna-waveguide path of the radar, or to other devices, installations for their intended purpose.

The device operates as follows

A pulsed two-stage monoblock microwave power amplifier on amplitrons is designed to amplify microwave signals in the output stages of multi-stage transmitters of radar detection and target designation.

With the preliminary supply of microwave signals to the input 5.1.1 of FIG. 3 amplitron 1 of FIG. 1, 3, pre-emptive receipt on the amplitron 1 of FIG. 1, 3 of the modulating pulse U _{A1 of} FIG. 3, and the input to the amplitron 1 of FIG. 1, 3 of the modulating pulse U _{A1 of} FIG. 3, amplitron 1 of FIG. 1, 3 amplifies microwave signals. The amplified microwave signals from output 5.1.2 of FIG. 2, 3 of the amplitron 1 of FIG. 1, 3 are fed through a ferrite valve 5.4.1 of FIG. 2, 3 and input 5.5.1 of FIG. 2, 3 per amplitron 2 of FIG. 1, 3, anticipating receipt on the amplitron 2 of FIG. 1, 3 of the modulating pulse U _{A2 of} FIG. 3. With the receipt on the amplitron 2 of FIG. 1, 3 of the modulating pulse U _{A2 of} FIG. 3, amplitron 2 of FIG. 1, 3 amplifies microwave signals. The amplified microwave signals from output 5.5.2 of FIG. 3 amplitron 2 of FIG. 1, 3 are fed from a pulsed two-stage monoblock microwave power amplifier on amplitrons to the radar antenna-waveguide path.

The claimed utility model “Two-stage pulsed monoblock microwave power amplifier on amplitrons” is a new device, not used in science and technology prior to the priority date of the claimed utility model, for amplifying microwave signals. The claimed device has the following advantages:

- the location of two amplitrons on the same central vertical axis, electrically and functionally interconnected, with a common magnetic system allows you to implement a monoblock design of a two-stage microwave power amplifier, which reduces the overall dimensions of the amplifier, reduces its cost, eliminates the need to align the amplitrons when replacing them;

- the electrical connection between the amplitrons, formed by at least four metal grooved joints, creates an air gap between the amplitrons in the region of the grooved joints and leads to additional air cooling of the outer surface of the anode blocks;

- the microwave device for connecting the stages of the power amplifier has a special s-shaped design, which takes into account the same directivity of the magnetic field common to both amplitrons of the magnetic system and thereby provides a consistent amplification of microwave signals by amplitrons of the first and second stages;

- the magnetic system is made general, with the possibility of ensuring equal magnetic induction for both amplitrons, which allows to improve the qualitative mass and size characteristics of a pulsed two-stage monoblock power amplifier on amplitrons;

- the cathodes of both amplitrons have the optimal radius sizes established in the process of calculating the electronic efficiency for each amplitron, providing maximum values of the efficiency and increased output power of the amplitrons and, in general, a pulsed two-stage monoblock microwave power amplifier on amplitrons.

The claimed device is industrially applicable, since its implementation uses widely known materials and production technologies of amplitrons, ferrite gates, waveguide sections of conventional design.

Claims (4)

1. A pulsed two-stage monoblock amplifier for microwave power at amplitrons, comprising the first and second stages of amplification of microwave signals made on amplitrons, each of which includes an anode block, a cathode, resonators of a delay system, bundles, and a microwave signal input and output device, characterized in that two amplitrons are located on one central vertical axis, are electrically and functionally interconnected with a common magnetic system with the possibility of providing equal magnetic induction for both amplitrons, the functional connection of which is carried out by means of a microwave device for connecting the cascades of a power amplifier of an s-shaped design, and the cathodes of both amplitrons have optimal radius sizes. 2. The device according to claim 1, characterized in that the electrical connection between the amplitrons is formed by the corresponding at least four metal groove joints. 3. The device according to claim 1, characterized in that the cathodes of both amplitrons have optimal radius sizes established in the process of calculating the electronic efficiency of each amplitron. 4. The device according to claim 4, characterized in that the s-shaped design of the microwave device for connecting the stages of the power amplifier takes into account the same directivity of the magnetic field common to both amplitrons of the magnetic system and provides consistent amplification of the microwave signals by amplitrons of the first and second stages.

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