RU2117386C1 - High-voltage pulse generator - Google Patents

Abstract

FIELD: heavy-current pulse electronics. SUBSTANCE: high-voltage pulse generator has butt-to-butt joined first coaxial transmission line formed by first external-electrode section and first internal-electrode section, double coaxial shaping line formed by second external- electrode section, intermediate electrode, and second internal-electrode section, second coaxial transmission line formed by third external-electrode section and third internal-electrode section, load connected to second coaxial line, facilities for charging second double shaping line, and at least one switch whose first lead is connected to intermediate electrode and second one, to second section of one of electrodes arranged in coaxial manner relative to intermediate electrode; coaxial line section located between switch and butt-to-butt joint between double shaping line and first coaxial line has length T₁ expressed in time units; coaxial line section between switch and butt-to-butt joint between double shaping line and second coaxial line has heterogeneous structure and its length T_o= 2T₁; coaxial line of double shaping line that has no switch is of length T_o expressed in time units. EFFECT: improved pulse amplitude across load. 2 cl, 3 dwg

Description

 The invention relates to a pulse technique and can be used to generate short high-voltage pulses in high-current electronics devices.

A generator of high-voltage pulses is known from the prior art (V. Kremnev and G. A. Mesyats. Methods of multiplication and transformation of pulses in high-current electronics. Novosibirsk. Nauka, 1987, pp. 54–55), including a transmission line whose length is L and the impedance ρ, a constant voltage source connected through the resistance R >> ρ to one end of the transmission line, and the active matched load R _n = ρ connected through a normally open switch to the second end of the transmission line. In the known high-voltage pulse generator, the pulse duration at the load is equal to the double range of the electromagnetic wave along the transmission line, and the amplitude of the voltage pulse at the load is half the charging voltage. In the coordinated mode, all the energy accumulated in the transmission line per pulse is transferred to the load.

The disadvantage of this generator of high-voltage pulses is that it does not allow to obtain pulses whose amplitude exceeds half the magnitude of the charging voltage (U _s ).

 A generator of high-voltage pulses is also known (Bulan V.V. and Yampolsky I.R. Multistage high-voltage generator for research on fusion. - 3, 19), taken as a prototype and containing sections n-sequentially connected to each other, means for charging and loading, each section containing a double forming line formed by a coaxially located external electrode, an intermediate electrode and an internal electrode. In addition, the double forming line contains at least one switch connected between the intermediate electrode and the external electrode, and the double forming lines of adjacent sections are separated from each other by line segments formed by sections of the external and internal electrodes.

 The disadvantage of this high-voltage pulse generator is that it has a complex structure. In addition, the double forming line used in the known generator does not allow obtaining a pulse with an amplitude exceeding the value of the charging voltage, the value of which is limited by the dielectric strength of the internal coaxial line dielectric when the intermediate electrode is negatively charged.

 The basis of the invention is the task to develop a high-voltage pulse generator, the constructive implementation of the double coaxial forming line which would provide an increase in the amplitude of the pulse at the load, with the same dielectric strength.

ρ₂= (1,35-1,44)ρ₀,

Z = ρ₀+ρ₂,
где
ρ₁ - волновое сопротивление участка коаксиальной линии между коммутатором и стыком двойной формирующей линии с первой коаксиальной линией передачи, Ом;
ρ₂ - волновое сопротивление участка коаксиальной линии между коммутатором и стыком двойной формирующей линии с второй коаксиальной линией передачи, Ом;
ρ₀ - волновое сопротивление коаксиальной линии, образованной вторым участком внешнего электрода и промежуточным электродом, Ом;
L - индуктивность коммутатора, Гн;
Z - сопротивление нагрузки, Ом.The problem is solved in that in the high-voltage pulse generator containing the first coaxial transmission line stacked together, formed by the first section of the external electrode and the first section of the internal electrode, the double coaxial forming line formed by the second section of the external electrode, the intermediate electrode and the second section of the internal electrode, the second coaxial transmission line formed by the third portion of the external and the third portion of the internal electrodes, the load connected to the second coaxial line, means for charging the double forming line and at least one switch, the first terminal of which is connected to the intermediate electrode, according to the invention, the second terminal of the switch is connected to the second section of one of the electrodes located coaxially to the intermediate electrode, while the section of the coaxial line located between the switch and the junction of the double forming line with the first coaxial line, a length equal to T ₁ expressed in time units is made, a portion of the coaxial line and, located between the switch and the junction of the double forming line with the second coaxial line, is made with a heterogeneous structure and length T ₀ = 2T ₁ , and the coaxial line of the double forming line not containing the switch is made of length T ₀ , expressed in time units. It is advisable that the second output of the switch was connected to the second section of the central electrode, and the coaxial lines of the double forming line were made with wave impedances that satisfy the following relationships:

ρ ₂ = (1.35-1.44) ρ ₀ ,

Z = ρ ₀ + ρ ₂ ,
Where
ρ ₁ - wave impedance of the coaxial line section between the switch and the junction of the double forming line with the first coaxial transmission line, Ohm;
ρ ₂ - wave impedance of the section of the coaxial line between the switch and the junction of the double forming line with the second coaxial transmission line, Ohm;
ρ ₀ - wave impedance of the coaxial line formed by the second portion of the external electrode and the intermediate electrode, Ohm;
L is the inductance of the switch, GN;
Z - load resistance, Ohm.

Advantageously, the wave resistance of the first coaxial transmission line is purely inductive and exceeds the load resistance. This embodiment of the high-voltage pulse generator provides an increase (up to 50%) in the amplitude of the pulse on the load with the same dielectric strength due to the fact that in addition to the two waves propagating in the double coaxial forming line towards the load, using a line segment of length T ₁ , expressed in time units, an additional wave is formed, propagating from the plane in which the switches are located in the opposite direction. At the same time, the time required for this wave to reach the idle end of a line of length T ₁ is half the time required for the main waves to reach the ends of the coaxial lines associated with the load. As a result, after reflection of the additional wave from the idle end of the line, it will reach the plane in which the switches are located, simultaneously with the moment the main waves reach the ends of the lines associated with the load, and the inductance of the switches becomes the load for the additional wave. In other words, the currents add up to the inductance, and consequently, the voltage rises.

 In FIG. 1 is a schematic diagram of a preferred embodiment of a generator of positive high voltage pulses; in FIG. 2 - output voltage pulse in a matched mode; in FIG. 3 - output voltage pulse when the fronts of the main and additional waves coincide.

The high-voltage pulse generator contains an external electrode 1, an intermediate electrode 2, an internal electrode 3, switches 4 mounted on a circle between the intermediate 2 and internal 3 electrodes at the same angular distance from each other, a charging capacitor 5 connected via a key 6 to the intermediate electrode 2, and load 7. Section 8 of electrode 1 and section 9 of electrode 3 form a first coaxial transmission line, section 10 of electrode 1, intermediate electrode 2 and section 11 of inner electrode 3 form a double forming a line, and a portion 12 of the electrode 1 and a portion 13 of the electrode 3 form a second coaxial transmission line. The double forming line includes an external coaxial line formed by a portion 10 of the electrode 1 and an intermediate electrode 2 having a wave resistance of ρ ₀ and a length T ₀ expressed in time units, as well as an internal coaxial line formed by a portion 11 of the electrode 3 having a diameter larger than the diameter section 9, and the electrode 2. The internal coaxial line contains two sections located on both sides of the switches 4, while the first section is made with a wave impedance ρ ₁ and a length T ₁ , and the second section is made n with a wave impedance ρ ₂ and a length T ₀ expressed in time units. The matching condition for the junction of the first section of the internal coaxial line and the first coaxial line is to provide an idle mode for waves propagating in the first section of the internal coaxial line. If the length of the second coaxial transmission line is much shorter than T ₀ , then the condition for matching the resistance Z of the load 7 with the double forming line has the form Z = ρ ₀ + ρ ₂ , while the maximum output power is achieved when the ratio ρ ₂ to ρ ₀ = 1.35 - 1.44.

 The equality of the lengths of the outer coaxial line and the second portion of the inner coaxial line is ensured by the fact that the second portion of the inner coaxial line is made with an inhomogeneous structure. To reduce the effect of inter-capacitive coupling between inhomogeneities, the depressions are filled with a material having a lower dielectric constant.

 Switches 4 (in principle, there can be one switch) can be installed between intermediate 2 and external electrode 1. In this case, when the intermediate electrode 2 is negatively polished, the generated pulse does not have a positive polarity (as in the generator described above), but a negative polarity. The proposed device uses standard switches (G. Mesyats. Generation of powerful nanosecond pulses. M: Sov. Radio, 1974, p. 81 - 102) and inductive loads.

 The high-voltage pulse generator operates as follows.

, где τ_ф - длительность переднего фронта "основного" импульса напряжения, соответствующего энергии волн E₀ и E₂, поскольку сложение энергии волны E₁ с энергией волн E₀ и E₂ происходит после окончания длительности переднего фронта "основного" импульса. Увеличение амплитуды выходного импульса достигает 50%.Using the key 6, the intermediate electrode 2 (negative polarity) is charged relative to the external 1 and internal 3 electrodes. When the switches 4 are activated, the wave E _{0 is} excited in the external coaxial line (Fig. 1), which propagates to the load, and two waves E ₁ and E ₂ , which propagate in opposite directions, are excited in the internal coaxial line. After time T _{1, the} wave E ₁ reaches the junction with the first coaxial line, and after time T _{0 the} waves E ₀ and E ₂ reach the junction with the second coaxial line. If T ₁ = 0.5T ₀ , then the wave E ₁ , reaching the junction with the first coaxial line, which provides idle speed, will be reflected in the opposite direction and after a time equal to T ₀ will reach the cross section in which the switches 4 are located, and their inductance becomes a load for wave E ₁ . Thus, at T ₁ = 0.5T _{0, the} wave E ₁ reaches the cross section in which the switches 4 are located, simultaneously with the arrival of waves E ₀ and E ₂ at the junction with the second coaxial line. With the correct selection of the inductance value of the switches 4, most of the energy of the wave E ₁ is allocated to the inductance of the switches 4, in other words, the currents combine inductance, and therefore, the voltage increases (Fig. 2). Indeed, the amplitude of the voltage pulse is maximum at

where τ _f is the duration of the leading edge of the "main" voltage pulse corresponding to the energy of the waves E ₀ and E ₂ , since the addition of the energy of the wave E ₁ with the energy of the waves E ₀ and E ₂ occurs after the end of the duration of the leading edge of the "main" pulse. The increase in the amplitude of the output pulse reaches 50%.

Откуда получаем

Экспериментально установлено, что максимальная амплитуда импульса имеет место при

.The duration of the leading edge of the "main" pulse depends on the inductance L _{to the} switches 4 as follows:

Where do we get

It was experimentally established that the maximum pulse amplitude occurs at

.

, то сложение энергии волны E₁ с энергией волн E_o и E₂ происходит во время переднего фронта основного импульса (пунктирная линия на фиг. 3). В результате перед вершиной "основного" импульса имеет место всплеск напряжения. Выходной импульс приобретает сложную форму, при этом амплитуда его увеличивается на 40 - 45%. Однако в ряде случаев данная сложная форма выходного импульса может найти практическое применение. Следует отметить, что указанное выше соотношение между ρ₁ и ρ₂ является оптимальным с точки зрения достижения максимального значения амплитуды.The idle mode for wave E ₁ at the junction with the first coaxial line is provided if the wave resistance of the first coaxial transmission line is purely inductive and exceeds the load resistance. If

, then the addition of wave energy E ₁ with wave energy E _o and E ₂ occurs during the leading edge of the main pulse (dashed line in Fig. 3). As a result, a surge of voltage occurs in front of the peak of the "main" pulse. The output pulse takes on a complex shape, while its amplitude increases by 40 - 45%. However, in some cases, this complex form of the output pulse can find practical application. It should be noted that the above ratio between ρ ₁ and ρ ₂ is optimal from the point of view of achieving the maximum value of the amplitude.

The characteristic of the output pulse is also determined by the number of commutators 4, which is caused by distortions of the wave fronts E ₁ and E ₂ during the transformation of cylindrical waves excited when the commutators 4 are triggered, into plane waves propagating along line segments.

In the case of placing switches 4 between the intermediate 2 and external 1 electrodes, the generator operates in the same way as described above, with the only difference being that two waves E ' ₁ and E' ₂ propagate (after the triggering of the switches) in the external coaxial line of the double forming line, and internal coaxial line - one wave E ' ₀ . With a negative polarity of the intermediate electrode, the output pulse has a negative polarity.

Thus, the proposal allows to obtain short high-voltage pulses with an amplitude equal to 3 / 2U _s .

Claims (2)

1. A high-voltage pulse generator, comprising a first coaxial transmission line stacked together, formed by a first portion of an external electrode and a first portion of a central electrode, a double coaxial shaping line formed by a second portion of an external electrode, an intermediate electrode and a second portion of a central electrode, a second coaxial transmission line, formed by the third section of the outer and third section of the central electrodes, the load connected to the second coaxial line, medium VA for charging the double forming line and at least one switch, the first output of which is connected to the intermediate electrode, characterized in that the second output of the switch is connected to the second portion of one of the electrodes located coaxially to the intermediate electrode, a portion of the internal coaxial line of the double coaxial forming line, located between the switch and the junction of the double forming line with the second coaxial line, is made with a heterogeneous structure, while
T ₁ = 0.5 T ₀ ,
where T ₁ is the time during which the wave E ₁ , excited when the switch is triggered, propagating in the internal coaxial line of the double coaxial generating line, reaches the junction with the first coaxial line;
T ₀ is the time during which the wave E ₂ excited when the switch is triggered propagates in the internal coaxial line of the double coaxial forming line in the opposite direction relative to wave E ₁ , and the wave E ₀ propagating in the external coaxial line of the double coaxial forming line reaches the junction with second coaxial line. 2. The generator according to claim 1, characterized in that the second output of the switch is connected to the second portion of the central electrode, and the external and internal coaxial lines of the double forming line are made with wave impedances that satisfy the following relationships:

ρ ₂ = (1.35 ÷ 1.44) ρ ₀ ,

Z = ρ ₀ + ρ ₂ ,
where ρ ₁ is the wave impedance of the portion of the internal coaxial line between the switch and the junction of the double forming line with the first coaxial transmission line, (Ohm);
ρ ₂ - wave impedance of the portion of the internal coaxial line between the switch and the junction of the double forming line with the second coaxial transmission line, Ohm;
ρ ₀ - wave impedance of the external coaxial line formed by the second portion of the external electrode and the intermediate electrode, Ohm;
L _k is the inductance of the switch, G;
Z - load resistance, Ohm.

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