RU2121216C1 - High-voltage pulse generator - Google Patents

Abstract

FIELD: high- voltage pulse engineering. SUBSTANCE: generator has grounded electrode forming short-circuited stepped line at input set up of series-connected sections of homogeneous lines with distributed parameters of equal electric length. Inner space of first section of stepped line accommodates high-voltage electrode that separates it into two homogeneous lines. Voltage supply and spark gap are inserted between high-voltage and grounded electrodes; spark gap is placed at joint between first and second sections of stepped line. Parallel-connected resistive load and current chopper are provided at stepped line output. Inserted in series with grounded electrode are parallel-connected current supply and spark gap. Wave impedances of lines formed by high-voltage and grounded electrodes in first section of stepped line are chosen from proposed equation. Generator is characterized in that pre-pulse voltage across generator output is eliminated and bulk of energy is stored in generator in the form of magnetic field. EFFECT: improved efficiency of square pulse across resistive load whose voltage is much higher than generator charging voltage; reduced requirements to electric strength of generator due to full energy storage. 1 dwg

Description

The invention relates to the field of high-voltage pulse technology and can be used in electrophysical installations to produce high-power high-voltage pulses, for example, to generate charged particle beams (10 ⁵ - 10 ⁷ V, 10 ³ - 10 ⁶ A, 10 ⁷ - 10 ^-8 s) .

The known generator [1, fig. 2a], containing two electrodes forming a stepped line (SL), made in the form of series-connected segments of homogeneous lines with distributed parameters of the same electric length T ₀ , a first current chopper and a current source connected in series between the electrodes at the input of the SL, the resistive load and the second current chopper connected in parallel to the output of the SL. When you turn on the first current chopper as a result of wave processes at the optimal ratio of wave impedances
Z _i = Z ₁ • 2 / [i (i + 1)],
Where
i = 1, 2, ...., n is the line segment number counted from the trunk input;
n is the total number of line segments in the trunk;
Z _i - wave impedance of the line segment number i,
the energy stored initially in many segments in the form of a magnetic field is completely concentrated at the output of the SL. The second current chopper is turned on with a delay of time nT ₀ with respect to the moment the first chopper is turned on. At a matched load Z _n = Z _n , a single rectangular voltage pulse of 2T ₀ duration is formed, during which energy is completely transferred to the load. The current in the coordinated mode of operation exceeds the initial current I _{0 by} n / 2 times, the addition of each additional segment to the SL increases the current by the value I _0/2 . Since the load is connected to the output of the SL when the second current chopper is opened at the time of the arrival of the first electromagnetic wave from the first current chopper, there is no prepulse voltage at the generator output.

 The disadvantage of the generator is the lack of such an optimal ratio of wave impedances, in which, in the ideal case, maintaining 100% efficiency, it would be possible to increase the voltage at the load. In the found version, the voltage at the matched load is (n + 1) times less than the voltage occurring at the input of the SL when the first current breaker is turned on, and its value decreases with increasing number of segments of the SL.

= Z_n • 2/[n(n+1)].A high-voltage pulse generator was selected as a prototype [1, fig. 3a], containing a grounded electrode, forming a step line shorted at the input (SL), made in the form of series-connected segments of homogeneous lines with distributed parameters of the same electric length T ₀ , a high-voltage electrode placed in the internal volume of the first segment of the SL and dividing it into two homogeneous lines, a voltage source and a first spark gap connected between the high voltage and grounded electrodes, the spark gap being located at the junction of the first and second segments of the SL, resist vnuyu load at the output of the SL. Under the action of the voltage source, two line segments near the high-voltage electrode are charged to voltage V ₀ , and the energy is stored in the generator in the form of an electric field. When the first spark gap is switched on as a result of wave processes, the energy is concentrated at the output of the SL. From the point of view of achieving maximum efficiency, the following wave resistance ratios are optimal
Z _i = Z _n • 2 / [(n-i + 1) (n-i + 2)],
Where
i = 2, 3, ...., n is the number of the trunk segment;
n is the total number of line segments in the trunk;
Z _i - wave impedance of the line segment number i;
wave impedances of the segments formed by the high-voltage electrode in the first segment of the SL:
- with a spark gap Z _i = Z _n • 2 / [(n + 1) (n + 2)];
- without arrester

= Z _n • 2 / [n (n + 1)].

In the general case, voltage pulses of alternating polarity with a duration of 2 T ₀ are formed at the SL output. Working is the second voltage pulse. The load is connected when the second spark gap is triggered with a delay of (n + 1) T ₀ with respect to the moment the first spark gap is turned on, that is, with a delay of 2T ₀ with respect to the moment the first electromagnetic wave arrives at the output of the generator. At a matched load Z _n = Z _n , a single voltage pulse is generated with a duration of 2T ₀ , during which all energy is transferred to the load. The voltage at the matched load exceeds the charging one by (n + 1) / 2 times, the inclusion of each additional segment in the SL composition increases the voltage in the matched mode by 0.5V ₀ .

 The disadvantage of the prototype is the presence at the output of the prepulse voltage generator before connecting the load, equal in amplitude and duration, but opposite in polarity to the voltage at the matched load. The presence of a significant pre-pulse voltage, which in this generator is a necessary condition for high efficiency, has negative consequences. Firstly, it is necessary to use a spark gap at the generator output, to which very high demands are made. It must withstand without breakdown a high prepulse voltage, and then, during a relatively short working pulse, let through all the energy originally stored in the generator. Therefore, in some cases, the limiting output parameters of the generator are determined by the capabilities of the prepulse arrester. Secondly, despite the arrester, the prepulse voltage due to the presence of stray electric capacitances partially falls on the load, which in some cases is extremely undesirable. For example, when using a vacuum diode as a generator to generate charged particle beams, a prepulse voltage leads to the formation of a plasma in the accelerating gap, which significantly affects the characteristics of the diode during the operating pulse and impairs the reproducibility of the generator output from pulse to pulse.

 The technical result is the elimination of prepulse voltage at the output of the generator when a rectangular voltage pulse is generated at a matched resistive load with high efficiency, the amplitude of which is significantly higher than the generator charging voltage. Additionally, this technical solution allows a significant part of the energy to be stored in the generator in the form of a magnetic field, which, with the same total energy reserve, reduces the requirements for the electric strength of the generator.

волновые сопротивления отрезков ступенчатой линии без высоковольтного электрода выбраны из соотношения

где
i=2, 3,...., n - номер отрезка ступенчатой линии;
n - число отрезков ступенчатой линии;
α - отношение энергии, запасаемой первоначально в генераторе в виде электрического и в виде магнитного поля;
а отношение величины зарядного напряжения к величине начального тока в генераторе выбрано равным
V₀/I₀=Z_l. (4)
Отсутствие предымпульсного напряжения на выходе генератора в режиме полной передачи энергии в согласованную нагрузку обеспечивается за счет предварительного создания в генераторе магнитного потока. С этой целью в генератор введены источник тока и прерыватель тока. Разрядник, включенный параллельно источнику тока, необходим для отключения последнего от генератора до момента прихода к источнику первой электромагнитной волны. Оптимальные соотношения волновых сопротивлений (1), (2), а также отношение величины зарядного напряжения к величине начального тока в генераторе (4) обеспечивают в ходе волновых процессов полную передачу энергии в нагрузку в течение короткого импульса длительностью 2T₀ с одновременным значительным повышением напряжения на нагрузке по сравнению с зарядным напряжением.The technical result is achieved by the fact that in the generator of high-voltage pulses containing a grounded electrode, forming a short-circuited at the input step line made in the form of series-connected segments of homogeneous lines with distributed parameters of the same electric length, a high-voltage electrode placed in the internal volume of the first segment of the SL and dividing it into two homogeneous lines, a voltage source and a spark gap connected between the high-voltage and grounded electrodes, and the spark gap p located at the junction of the first and second segments of the SL, the load at the output of the SL, parallel to the load at the output of the stepped line includes a current chopper, a grounded electrode is connected to a gap of the current source and a spark gap, the wave resistances of the lines formed by the high-voltage and grounded electrodes in the first lines are equal:

wave impedances of segments of a stepped line without a high-voltage electrode are selected from the relation

Where
i = 2, 3, ...., n is the number of the segment of the stepped line;
n is the number of segments of the stepped line;
α is the ratio of the energy stored initially in the generator in the form of electric and in the form of a magnetic field;
and the ratio of the magnitude of the charging voltage to the magnitude of the initial current in the generator is chosen equal to
V ₀ / I ₀ = Z _l . (4)
The absence of prepulse voltage at the generator output in the mode of complete energy transfer to the matched load is ensured by the preliminary creation of a magnetic flux in the generator. For this purpose, a current source and a current chopper are introduced into the generator. A spark gap connected in parallel with a current source is necessary to disconnect the latter from the generator until the first electromagnetic wave arrives at the source. The optimal ratios of wave resistances (1), (2), as well as the ratio of the magnitude of the charging voltage to the magnitude of the initial current in the generator (4) provide during the wave processes the complete transfer of energy to the load during a short pulse of 2T ₀ duration with a simultaneous significant increase in voltage by load compared to charging voltage.

 The drawing shows a schematic diagram of the proposed high-voltage pulse generator, where 1 is a grounded electrode; 2 - current chopper; 3 - load; 4 - high voltage electrode; 5, 6 - homogeneous lines formed by the high-voltage electrode 4 in the first segment of the stepped line, with and without a spark gap, respectively: 7 - voltage source; 8 - arrester; 9 - current source; 10 - arrester to disconnect the current source; 11 - the second segment of the stepped line.

Между высоковольтным 4 и заземленным электродом 1 включены источник напряжения 7 и разрядник 8, причем разрядник 8 размещен в месте соединения первого и второго отрезков ступенчатой линии. В разрыв заземленного электрода 1 в любом месте включены параллельно соединенные источник тока 9 и разрядник 10. Волновые сопротивления линий 5 и 6, образованных высоковольтным электродом 4 в первом отрезке ступенчатой линии, Z₁ и

выбраны из соотношений (1) и (2) соответственно

Волновые сопротивления отрезков СЛ с номерами i=2, 3..., n выбраны из соотношения (3)

где
i=2, 3,...., n - номер ступенчатой линии;
n - число отрезков ступенчатой линии;
α - отношение энергии, запасаемой первоначально в генераторе в виде электрического и в виде магнитного поля.The generator contains a grounded electrode 1, forming a step line shorted at the input, made in the form of series-connected segments of homogeneous lines with distributed parameters of the same electric length T ₀ . At the output of the step line, a parallel-connected current chopper 2 and resistive load 3 are connected. A high-voltage electrode 4 is placed in the internal volume of the first segment of the step line, dividing the first segment of the SL into two homogeneous lines 5 and 6 with wave impedances equal to Z ₁ and

Between the high voltage 4 and the grounded electrode 1, a voltage source 7 and an arrester 8 are connected, the arrester 8 being located at the junction of the first and second segments of the stepped line. In the gap of the grounded electrode 1, anywhere in parallel are connected a current source 9 and a spark gap 10. The wave resistances of lines 5 and 6 formed by the high-voltage electrode 4 in the first segment of the stepped line, Z ₁ and

selected from relations (1) and (2), respectively

The wave impedances of the SL segments with numbers i = 2, 3 ..., n are selected from relation (3)

Where
i = 2, 3, ...., n is the number of the stepped line;
n is the number of segments of the stepped line;
α is the ratio of the energy stored initially in the generator in the form of electric and in the form of a magnetic field.

The ratio of the magnitude of the charging voltage to the magnitude of the initial current in the generator is chosen equal to
V ₀ / I ₀ = Z _l .

Энергия запасается в указанных отрезках в виде электрического поля. Одновременно под действием источника тока 9 в первоначально замкнутом контуре, образованном электродом 1 и прерывателем тока 2, создается ток I₀ и энергия запасается дополнительно во всем объеме ступенчатой линии в виде магнитного поля. Соотношение величин V₀ и I₀ выбраны в соответствии с уравнением (4). (Полярность напряжения V₀ и направления тока I₀ выбираются таким образом, чтобы после включения разрядника 8 в линии 5 происходило уменьшение тока). Величины V₀ и I₀ определяются и фиксируются до начала зарядки генератора путем выбора использования соответствующих источников напряжения или тока, либо путем предварительного регулирования выходных параметров этих источников. При достижении максимального тока I₀ и максимального зарядного напряжения V₀ включается разрядник 8. Для дальнейшего анализа волновых процессов этот момент времени удобно обозначить как t=0. (Разрядник 10, отсоединяющий источник тока 9 от ступенчатой линии, включается после достижения максимального тока I₀ до прихода к нему первой электромагнитной волны от разрядника 8, например, в момент времени t= o). При включении разрядника 8 по линии 5 будет распространяться волна разрядки - V₀, после прохождения которой напряжение в линии 5 становится равным нулю. Одновременно по линии 6 побежит волна напряжения V_o(α+n-2)/[2(α+n-1)], а по линии 11 - волна напряжения - V_o(α+n)/[2(α+n-1)]. Будем считать полярность напряжения положительной, если вектор напряженности электрического поля на рассматриваемом рисунке направлен снизу вверх. Так как под действием волны разрядки в линии 5 создается ток - V₀/Z₁, равный в соответствии с (4) по амплитуде, но противоположный по направлению начальному току I₀, то в результате суперпозиции в данной линии становится равным нулю не только напряжение, но и ток. Таким образом, после прохождения волны разрядки из линии 6 отбирается полностью не только электрическая, но и магнитная энергия. В момент времени t=T₀ волна разрядки, распространяющаяся по линии 5, достигает места ее соединения с линией 6. В результате в линию 6 пойдет волна напряжения

То есть в результате взаимной компенсации двух волн амплитуды волны, отраженной в момент времени t=T₀ в линию 5, равна нулю. В линию 6 пойдет волна напряжения

Энергия полностью отобрана из линии 5, и начинается отбор энергии из линии 6. В этот же момент времени волна разрядки, распространяющаяся по линии 11, достигает места ее соединения с линией, имеющей волновое сопротивление Z₃. В линию 11 отразится волна напряжения.The generator operates as follows. Under the action of a voltage source 7, pulse charging is carried out to a voltage V _{0 of the} electric capacitance of two segments 5 and 6 with impedances Z ₁ and

Energy is stored in these segments in the form of an electric field. At the same time, under the action of a current source 9, a current I ₀ is created in the initially closed circuit formed by the electrode 1 and the current chopper 2 and the energy is stored additionally in the entire volume of the step line in the form of a magnetic field. The ratio of the values of V ₀ and I ₀ selected in accordance with equation (4). (The polarity of the voltage V ₀ and the direction of the current I ₀ are selected so that after the arrester 8 is switched on, the current decreases in line 5). The values of V ₀ and I _{0 are} determined and fixed before the start of charging the generator by choosing to use the appropriate voltage or current sources, or by pre-adjusting the output parameters of these sources. Upon reaching the maximum current I ₀ and the maximum charging voltage V _{0, the} arrester 8 is turned on. For further analysis of wave processes, this time is conveniently designated as t = 0. (The arrester 10, disconnecting the current source 9 from the stepped line, turns on after reaching the maximum current I ₀ until the first electromagnetic wave arrives from it from the arrester 8, for example, at time t = o). When the arrester 8 is turned on, a discharge wave — V ₀ — will propagate along line 5, after passing through which the voltage in line 5 becomes zero. At the same time, a voltage wave V _o (α + n-2) / [2 (α + n-1)] will run along line 6, and a voltage wave - V _o (α + n) / [2 (α + n) will run along line 11 -one)]. We assume that the polarity of the voltage is positive if the vector of the electric field in the figure in question is directed upward. Since under the action of the discharge wave in line 5 a current is created - V ₀ / Z ₁ , which is equal in amplitude in accordance with (4), but opposite in direction to the initial current I ₀ , not only the voltage becomes equal to zero as a result of superposition in this line but also current. Thus, after the passage of the discharge wave, not only electrical, but also magnetic energy is completely taken from line 6. At time t = T _{0, the} discharge wave propagating along line 5 reaches its junction with line 6. As a result, a voltage wave will go to line 6

That is, as a result of mutual compensation of two waves, the wave amplitude reflected at time t = T ₀ in line 5 is equal to zero. A voltage wave will go to line 6

The energy is completely taken from line 5, and energy begins to be taken from line 6. At the same time, the discharge wave propagating along line 11 reaches its junction with a line having a wave impedance of Z ₃ . A voltage wave will be reflected in line 11.

а в линию в волновым сопротивлением Z₃ пройдет волна разрядки

В момент времени t= 2T к месту соединения линий 6 и 11 приходят две волны: по линии 6 - волна V_o(α+n)/[2(α+n-1)], а по линии 11 - волна -V_o(α+n)/[2(α+n-1)(α+n-2)]. В результате суммарная амплитуда волны напряжения, отраженной в линию 6, равна нулю

а в линию 11 побежит волна напряжения

В момент времени 2T₀ завершается полный отбор энергии из отрезка 6 и начинается отбор энергии из отрезка 11. Отбор энергии из остальных отрезков СЛ осуществляется аналогичным образом - первая электромагнитная волна начинает отбор энергии, а завершает этот процесс волна, приходящая со стороны разрядника 8 с задержкой 2 T₀. В дальнейшем достаточно рассмотреть распространение по ступенчатой линии только первой электромагнитной волны. В момент времени t= 0 в линию 11 с волновым сопротивлением Z₂ побежит волна напряжения -V_o(α+n)/[2(α+n-1)]. При прохождении неоднородностей в местах соединения отрезков ступенчатой линии волна будет изменять свою амплитуду. В интервале времени (i-2)T₀ - (i-1)T₀ волна будет распространяться по отрезку СЛ с номером i и ее амплитуда V $\genfrac{}{}{0ex}{}{\text{i}}{\text{1}}$ будет равна

В момент времени t=(n-1)T₀, когда первая волна напряжения

приходит к выходу генератора, включается прерыватель тока 2, подключающий резистивную нагрузку 3 с импедансом Z_н. В результате прихода волны на нагрузке 3 формируется импульс напряжения

а в результате размыкания прерывателя тока - импульс напряжения

Суммарная амплитуда импульса напряжения, возникающего на нагрузке 3 в момент времени t=(n-1)T₀, равна

и остается постоянной в интервале времени (n-1)T₀ - (n+1)T₀. В дальнейшем в общем случае на нагрузке формируется импульс напряжения ступенчатой формы с длительностью ступеней, равной 2T₀. Генератор имеет наибольший КПД в согласованном режиме, когда Z_н=Z_n. В этом случае на нагрузке 3 формируется одиночный прямоугольный импульс напряжения амплитудой V_o(α+n)/2αи длительностью 2T₀. Энергия, переданная в течение импульса в согласованную нагрузку 3

равна по величине энергии, запасенной первоначально в генераторе

где
E_C и E_L - энергия, запасаемая в генераторе в электрическом и магнитном поле соответственно; C и L - электрическая емкость и индуктивность линий с соответствующими волновыми сопротивлениями.

and in the line in the impedance Z ₃ will pass the discharge wave

At time t = 2T two waves come to the junction of lines 6 and 11: along the line 6 - the wave V _o (α + n) / [2 (α + n-1)], and along the line 11 - the wave -V _o (α + n) / [2 (α + n-1) (α + n-2)]. As a result, the total amplitude of the voltage wave reflected in line 6 is zero

and a voltage wave will run to line 11

At time 2T ₀ , the complete selection of energy from segment 6 ends and the selection of energy from segment 11 begins. The selection of energy from the remaining segments of the SL is carried out in a similar way - the first electromagnetic wave begins the selection of energy, and the wave arriving from the spark gap 8 terminates this process with a delay 2 T ₀ . In the future, it suffices to consider the propagation along the step line of only the first electromagnetic wave. At time t = 0, a voltage wave -V _o (α + n) / [2 (α + n-1)] will run into line 11 with wave impedance Z ₂ . With the passage of inhomogeneities at the junction of segments of the stepped line, the wave will change its amplitude. In the time interval (i-2) T ₀ - (i-1) T _{0, the} wave will propagate along the SL segment with number i and its amplitude V $\genfrac{}{}{0ex}{}{\text{i}}{\text{1}}$ will be equal

At time t = (n-1) T ₀ , when the first voltage wave

comes to the output of the generator, the current chopper 2 is turned on, connecting the resistive load 3 with an impedance Z _n . As a result of the arrival of the wave at load 3, a voltage pulse is formed

and as a result of opening the current chopper, a voltage pulse

The total amplitude of the voltage pulse occurring at load 3 at time t = (n-1) T ₀ is

and remains constant in the time interval (n-1) T ₀ - (n + 1) T ₀ . In the future, in the general case, a step-shaped voltage pulse with a duration of steps equal to 2T ₀ is formed on the load. The generator has the highest efficiency in a coordinated mode when Z _n = Z _n . In this case, a single rectangular voltage pulse with an amplitude of V _o (α + n) / 2α and a duration of 2T ₀ is formed at load 3. Energy transferred during the pulse to the matched load 3

equal to the amount of energy stored initially in the generator

Where
E _C and E _L are the energy stored in the generator in an electric and magnetic field, respectively; C and L are the electric capacitance and inductance of the lines with the corresponding wave resistances.

Therefore, by the time t = (n + 1) T ₀ , the energy stored in the generator is completely transferred to the matched load 3, and the voltage and current in any section of the generator become equal to zero.

Since the load 3 is connected to the output of the generator when the current chopper 2 opens at the time of the arrival of the first electromagnetic wave from the arrester 8, there is no prepulse voltage at the generator output. In the coordinated mode, when the generator in the ideal case has 100% efficiency, a rectangular voltage pulse with an amplitude of V ₀ (α + n) / 2α is formed at the load, which, when choosing α less than 1, exceeds the voltage at the matched load of the prototype generator equal to V ₀ (n + 1) / 2. For example, when α = 0.5, the excess voltage is [2-1 / (n + 1)] times. Since in the generator under consideration the number of segments n cannot be selected less than 1, the voltage gain is at least 1.5 times. The gain increases with an increase in the number of SL segments and a decrease in α. The optimal choice of the number of SL segments and the value of α should be carried out separately for each specific application.

 The correctness of the method of analysis of wave processes in high-voltage generators on step lines, similar to that carried out above, was repeatedly confirmed when creating a number of high-current pulsed electron accelerators with systems for generating accelerating voltage pulses on step lines [2 - 4].

 The generator can be made in versions using strip, coaxial and radial lines with distributed parameters.

Sources of information
1. Bossamykin VS, Gordeev VS, Pavlovskii AI. New schemes for high-voltage pulsed generators based on stepped transmission lines // 9th International Conference on High-Power Particle Beams, BEAMS-92, Washington, DC, May 25-29, 1992; Springfield, VA, NTIS. 1992. V. I, PP. 511-516 (analogue - p. 512, fig. 2a; prototype - p. 513, fig. Za).

 2. Bossamykin V.S., Gordeev V.S., Pavlovskii A.I. et. al. Pulsed power electron accelerator with the forming systems based on stepped transmission lines // 9th International Conference on High-Power Particle Beams, BEAMS-92, Washington, DC, May 25-29, 1992; Springfield, VA, NTIS. 1992. V. I, PP. 505-510.

3. Bossamykin VS, Gordeev VS, Pavlovskii AI et. al. STRAUS-2 electron pulsed accelerator // 9 ^th IEEE Internat. Pulsed Power Conf., Albuquerque, NM, June 21-23, 1993; Springfield, VA, NTIS. 1993. V.2. PP 910-912.

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Claims (1)

A high-voltage pulse generator containing a grounded electrode forming a step line shorted at the input, made in the form of series-connected segments of homogeneous lines with distributed parameters of the same electrical length, a high-voltage electrode located in the internal volume of the first segment of the step line and dividing it into two homogeneous lines, source voltage and a spark gap connected between the high voltage and grounded electrodes, and the spark gap is located at the junction the first and second segments of the stepped line, the load at the output of the stepped line, characterized in that a current chopper is connected to the load at the output of the stepped line, a current source and a spark gap connected in parallel to the ground electrode gap, and wave impedances of the lines formed by the high-voltage and grounded electrodes in the first segment of the stepped line equal

the wave impedances of the segments of the stepped line without a high-voltage electrode are selected from the relation:

Where
i = 2,3, ..., n is the number of the step line segment;
n is the number of segments of the stepped line;
α- is the ratio of the energy stored initially in the generator in the form of electric and in the form of a magnetic field, and the ratio of the value of the charging voltage to the value of the initial current in the generator is chosen equal to
V ₀ / I ₀ = Z ₁ .