JP3907092B2 - Power supply for pulse laser - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pulse laser power supply device using a magnetic switch (saturable reactor) used for laser pulse discharge, and in particular to reduce the peak output of the pulse laser without reducing the energy per pulse of the laser pulse. Regarding improvements.
[0002]
[Background Art and Problems to be Solved by the Invention]
In recent years, high-power pulse lasers and pulse power supply devices for accelerators often use magnetic pulse compression circuits to improve the durability of main switches such as thyratrons and GTOs.
[0003]
FIG. 11 shows an equivalent circuit of a general capacity transfer type magnetic pulse compression device used for a pulse power source of a pulse laser, and FIG. 12 shows voltage and current waveform examples in each part of the circuit of FIG. .
[0004]
The discharge circuit shown in FIG. 11 is a two-stage magnetic pulse compression circuit that utilizes the saturation phenomenon of three magnetic switches AL0 to AL2 composed of saturable reactors.
[0005]
In FIG. 11, the capacitor C0 is first charged with a charge from the high voltage power supply HV via the magnetic switch AL0 and the coil L1.
[0006]
Thereafter, when a pulse oscillation synchronization signal (trigger signal) TR that is turned on in synchronization with the repetition frequency of the pulse laser oscillation is input, the main switch SW is turned on at this time (time t0 in FIG. 12). When the main switch SW is turned on, the potential VSW of the main switch SW suddenly drops to 0, and thereafter, the time product of the voltage difference VC0−VSW between the capacitor C0 and the main switch SW, which is the voltage across the magnetic switch AL0, and the voltage VC0. When the time integration value (S0) reaches a limit value determined by the setting characteristics of the magnetic switch AL0, the magnetic switch AL0 is saturated at this time t1, and the current pulse i0 flows into the loop of the capacitor C0, the magnetic switch AL0, the main switch SW, and the capacitor C1. Flows.
[0007]
The time δ0 from when the current pulse i0 starts to flow to 0 (time t2), that is, the charge transfer time δ0 until the charge is completely transferred from the capacitor C0 to the capacitor C1, ignores the loss due to the main switch SW and the like. In this case, it is determined by the saturation inductance of the magnetic switch AL0 and the capacitances of the capacitors C0 and C1.
[0008]
On the other hand, when the time product S1 of the voltage VC1 of the capacitor C1 reaches a limit value determined by the setting characteristics of the magnetic switch AL1, the magnetic switch AL1 is saturated at this time t3 and becomes a low inductance. As a result, the current pulse i1 flows through the loop of the capacitor C1, the capacitor C2, and the magnetic switch AL1. This current pulse i1 becomes zero at time t4 after passing through a predetermined transfer time δ1 determined by the capacitances of the capacitors C1 and C2 and the inductance after saturation of the magnetic switch AL1.
[0009]
Further, when the time product S2 of the voltage VC2 of the capacitor C2 reaches a limit value determined by the setting characteristics of the magnetic switch AL2, the magnetic switch AL2 is saturated at this time t5, whereby the capacitor C2, the peaking capacitor CP, and the magnetic switch AL2 are saturated. The current pulse i2 flows through the loop.
[0010]
Thereafter, the voltage VCp of the peaking capacitor Cp increases as the charging progresses. When this voltage VCp reaches a predetermined main discharge start voltage, the laser gas between the main electrodes 10 is broken down at time t6 to start main discharge. The The laser medium is excited by this main discharge, and laser light is generated after several nsec.
[0011]
Thereafter, the voltage of the peaking capacitor Cp rapidly decreases due to the main discharge, and returns to the state before the start of charging after a predetermined time.
[0012]
Such a discharge operation is repeatedly performed by the switching operation of the main switch SW synchronized with the trigger signal TR, whereby pulse laser oscillation at a predetermined repetition frequency (pulse oscillation frequency) is performed.
[0013]
Further, in this case, since the inductance of the charge transfer circuit at each stage constituted by the magnetic switch and the capacitor is set so as to decrease as it goes to the subsequent stage, the peak values of the current pulses i0 to i2 increase sequentially and A pulse compression operation is performed so that the energization width is also gradually reduced. As a result, a strong discharge is obtained in a short time between the main electrodes 6.
[0014]
By the way, if the pulse compression ratio is increased too much by the magnetic pulse compression as described above, a pulse laser beam having a short peak width and a large peak output can be obtained.
・ Durability of optical components installed in the laser resonator deteriorates
・ The number of round trips (number of laser beam reciprocations in the resonator) decreases.
・ By reducing the number of round trips, the number of incidents on the narrowband optical element is reduced.
Narrowband efficiency decreases
Various problems occur. Therefore, contrary to this, a pulsed laser beam whose pulse width is not too short and the peak output is not too large is often desired. Even if the peak output of the pulse laser beam is lowered, the pulse width is increased, so that the energy per pulse of the laser pulse is not reduced compared to the pulse laser beam having a short peak width and a large peak output.
[0015]
However, in the above prior art, all charges are transferred as a current pulse i2 from the capacitor C2 to the peaking capacitor Cp at a time, so that the emission intensity and emission time of the pulse laser beam are the charge transfer time of only the current pulse i2. And it is determined uniquely by the peak value, and it is difficult to fine-tune this. In the above prior art, most of the charge transferred from the capacitor C2 to the peaking capacitor Cp is consumed by the discharge, and the charge is not transferred to the peaking capacitor Cp even after the laser emission is started. In order to increase the pulse width of the laser pulse, there is a limit naturally in terms of the circuit.
[0016]
The present invention has been made in view of such circumstances, and provides a pulse laser power supply device that can obtain pulse laser light with a simple configuration that has a pulse width that is not too short and a peak output that is not too large. Objective.
[0017]
[Means for solving the problems and effects]
In the invention corresponding to claim 1, a pulse laser discharge electrode provided in a laser medium, a peaking capacitor connected in parallel to the discharge electrode, a saturable reactor connected in parallel to the peaking capacitor, and transfer A series circuit of original capacitors, and by performing pulse discharge between the discharge electrodes by transferring the electric charge charged in the transfer source capacitor to the peaking capacitor using the magnetic saturation phenomenon of the saturable reactor, In the pulse laser power source device that generates a pulse laser by exciting the plurality of saturable reactors and the transfer source capacitor in parallel with the peaking capacitor, the plurality of supersaturated reactors are magnetically coupled, At the start of transfer to each of the plurality of saturable reactors in series Characterized by being adapted to connect the saturable reactor for fine adjustment.
[0018]
According to the first aspect of the present invention, the plurality of saturable reactors connected in parallel included in the final stage charge transfer circuit for transferring charges from the transfer source capacitor to the peaking capacitor are magnetically coupled. The saturation timings of the plurality of saturable reactors coincided. In other words, since a plurality of saturable reactors connected in parallel are magnetically coupled, it is assumed that there is some variation in changes in the current flowing through each saturable reactor before the saturable reactor is saturated due to various factors of variation. However, the saturation timings of the plurality of saturable reactors coincide with each other, and the start timing of charge transfer involving the plurality of saturable reactors can be made uniform. In the first aspect of the present invention, a saturable reactor for fine adjustment of transfer start time is connected in series to each of the plurality of saturable reactors that are magnetically coupled. A plurality of these saturable reactors for fine adjustment of transfer start time that are connected in series are not magnetically coupled.
[0019]
Therefore, according to the first aspect of the present invention, the charge transfer start timing in the plurality of circuit routes from the plurality of transfer source capacitors to the peaking capacitor can be finely adjusted and delayed by the saturable reactor for fine adjustment of the transfer start time. The inductance in each circuit route is increased by the plurality of saturable reactors for fine adjustment of the transfer start times, so that the charge transfer time in each circuit route can be finely adjusted.
[0020]
Thus, according to the first aspect of the present invention, the charge transfer start timing in the charge transfer from the plurality of transfer source capacitors to the peaking capacitor is delayed and the charge transfer time can be adjusted to be long. The light emission time can be extended, and the light emission intensity per unit time can be reduced. Therefore, in the present invention, a pulse laser beam whose pulse width is not too short and peak output is not too large can be obtained with a simple configuration. According to the first aspect of the present invention, a saturable reactor having a small inductance for fine adjustment is provided separately from a saturable reactor having a large inductance that is magnetically coupled, and transfer is started by the saturable reactor for fine adjustment. Since the timing and the charge transfer time are adjusted, the adjustment accuracy can be improved as compared with the case where the saturable reactor having a large inductance is adjusted.
[0021]
According to a second aspect of the present invention, in the first aspect of the invention, the assist times of the plurality of transfer start time fine saturable reactors are made different.
[0022]
In the second aspect of the invention, since the assist times of the plurality of fine-tunable saturable reactors are made different, the saturation timings of the plurality of fine-tunable saturable reactors become different. The start timing of charge transfer from the transfer source capacitor to the peaking capacitor is different. Accordingly, charge transfer to the peaking capacitor is performed at different start timings via a plurality of circuit routes, and thus the peaking capacitor is charged relatively slowly. Therefore, in the present invention, the emission time of the laser beam can be further extended as compared with the invention of the first aspect, and the emission intensity per unit time can be reduced. In this case, since the charge transfer of each circuit route is performed at a different start timing, the discharge is started by the charge transferred to the peaking capacitor and the peaking from the other circuit route is performed while the laser light is emitted. A phenomenon that charges are transferred to the capacitor occurs, and the emission time of laser light can be extended.
[0023]
According to a third aspect of the present invention, in the first aspect of the present invention, the saturation inductance of the plurality of magnetically coupled saturable reactors is made different.
[0024]
In the third aspect of the invention, since the inductance after saturation of the plurality of saturable reactors magnetically coupled is made different, the charge transfer start timing of the plurality of charge transfer routes from the plurality of transfer source capacitors to the peaking capacitor Are the same, but their charge transfer times are different. Therefore, in the present invention, the emission time of the laser beam can be further extended as compared with the invention of the first aspect, and the emission intensity per unit time can be reduced. In this case, since the charge transfer time of each circuit route becomes different, discharge is started by the charge transferred to the peaking capacitor and the peaking capacitor from other circuit routes is emitted while the laser beam is emitted. It is possible to extend the emission time of the laser beam by causing a phenomenon that charges are transferred to the laser beam.
[0025]
According to a fourth aspect of the invention, in the second aspect of the invention, the inductances after saturation of the plurality of magnetically coupled saturable reactors are made different.
[0026]
That is, in the invention of claim 4, the saturation inductances of the plurality of saturable reactors magnetically coupled are made different and the assist times of the plurality of saturable reactors for fine adjustment of the transfer start time are made different. The charge transfer start timings of the plurality of charge transfer routes from the plurality of transfer source capacitors to the peaking capacitor are different, and the charge transfer times are different. Therefore, in the present invention, the emission time of the laser beam can be further extended as compared with the invention of the first aspect, and the emission intensity per unit time can be reduced. In this case, since the charge transfer start timing and the charge transfer time of each circuit route are different, the discharge is started by the charge transferred to the peaking capacitor and the laser light is emitted while the other is being emitted. A phenomenon that charges are transferred from the circuit route to the peaking capacitor occurs, and the emission time of the laser light can be extended.
[0027]
According to the invention of claim 5, a pulse laser discharge electrode provided in a laser medium, a peaking capacitor connected in parallel to the discharge electrode, a saturable reactor and a transfer source capacitor connected in parallel to the peaking capacitor The laser medium is excited by performing pulse discharge between the discharge electrodes by transferring the charge charged in the transfer source capacitor to the peaking capacitor using the magnetic saturation phenomenon of the saturable reactor. In the pulse laser power source device for generating a pulse laser, the saturable reactor is divided into a plurality of magnetically coupled saturable reactors in parallel, and transfer start times are respectively serially connected to the plurality of saturable reactors. It is characterized by connecting a saturable reactor for fine adjustment. .
[0028]
According to the fifth aspect of the present invention, the saturable reactor in the series circuit of the saturable reactor and the transfer source capacitor included in the final charge transfer circuit in the magnetic pulse compression circuit is divided into a plurality of parallel circuits of saturable reactors. At the same time, the plurality of supersaturated reactors are magnetically coupled, and further, a saturable reactor for fine adjustment of transfer start time is connected in series to the plurality of magnetically coupled saturable reactors.
[0029]
In other words, in the case of claim 5, the number of transfer source capacitors is one.
[0030]
Therefore, in the fifth aspect of the invention, as in the first aspect of the invention, the charge transfer start timing in the plurality of circuit routes from the plurality of transfer source capacitors to the peaking capacitor by the saturable reactor for fine adjustment of the transfer start time. Since the inductance in each circuit route is increased by the saturable reactors for fine adjustment of the plurality of transfer start times, fine adjustment is made to increase the charge transfer time in each circuit route. Accordingly, in the present invention, the emission time of the laser beam can be extended, and the emission intensity per unit time can be reduced. In the present invention, since the transfer start timing and the charge transfer time are adjusted by the saturable reactor for fine adjustment, the adjustment accuracy can be improved as compared with the case of adjusting the saturable reactor having a large inductance. .
[0031]
In the invention of claim 6, in the invention of claim 5, the assist times of the plurality of fine-tunable saturable reactors are made different.
[0032]
In the invention of claim 6, since the assist times of the plurality of fine-tunable saturable reactors are made different, the saturation timings of the plurality of fine-tunable saturable reactors are different. The start timing of charge transfer from the transfer source capacitor to the peaking capacitor is different. Accordingly, charge transfer to the peaking capacitor is performed at different start timings via a plurality of circuit routes, and thus the peaking capacitor is charged relatively slowly. Therefore, in the present invention, the emission time of the laser beam can be further extended as compared with the invention of claim 5, and the emission intensity per unit time can be reduced. In addition, a phenomenon occurs in which charges are transferred from another circuit route to the peaking capacitor while the laser beam is emitted due to the start of discharge due to the charge transferred to the peaking capacitor. It is possible to extend the light emission time.
[0033]
According to a seventh aspect of the present invention, in the fifth aspect of the present invention, the plurality of magnetically coupled saturable reactors have different saturation inductances.
[0034]
In the seventh aspect of the invention, since the inductance after saturation of the plurality of saturable reactors magnetically coupled is made different, the charge transfer start timing of the plurality of charge transfer routes from the plurality of transfer source capacitors to the peaking capacitor Are the same, but their charge transfer times are different. Therefore, in the present invention, the emission time of the laser beam can be further extended as compared with the invention of claim 5, and the emission intensity per unit time can be reduced. In addition, a phenomenon occurs in which charges are transferred from another circuit route to the peaking capacitor while the laser beam is emitted due to the start of discharge due to the charge transferred to the peaking capacitor. It is also possible to extend the light emission time.
[0035]
The invention of claim 8 is characterized in that, in the invention of claim 6, the inductance after saturation of the plurality of saturable reactors coupled magnetically is made different.
[0036]
In the invention of claim 8, since the inductance after saturation of the plurality of saturable reactors magnetically coupled is made different and the assist time of the plurality of saturable reactors for fine adjustment of transfer start time is made different. The charge transfer start timings of the plurality of charge transfer routes from the transfer source capacitor to the peaking capacitor are different and the charge transfer times are different. Therefore, in the present invention, the emission time of the laser beam can be further extended as compared with the invention of claim 5, and the emission intensity per unit time can be reduced. In this case, since the charge transfer start timing and the charge transfer time of each circuit route are different, the discharge is started by the charge transferred to the peaking capacitor and the laser light is emitted while the other is being emitted. A phenomenon that charges are transferred from the circuit route to the peaking capacitor occurs, and the emission time of the laser light can be extended.
[0037]
According to the ninth aspect of the present invention, a pulse laser discharge electrode provided in the laser medium, a peaking capacitor connected in parallel to the discharge electrode, and a transfer start time fine adjustment connected in parallel to the peaking capacitor. A charge transfer circuit in the final stage having a series circuit of a saturable reactor and a first capacitor, and a plurality of series circuits of a saturable reactor and a second capacitor connected to each of the plurality of first capacitors A charge transfer circuit that is one stage prior to the final stage, and the charge charged in the plurality of second capacitors is transferred via the plurality of first capacitors using the magnetic saturation phenomenon of the saturable reactor. By transferring to a peaking capacitor, pulse discharge is performed between the discharge electrodes, thereby exciting the laser medium and generating a pulse laser. A power supply device for a laser, wherein a plurality of saturable reactors of a charge transfer circuit immediately preceding the final stage are magnetically coupled, and a plurality of transfer start times included in the charge transfer circuit of the final stage are finely adjusted. It is characterized in that the saturation timing of the saturable reactor is made different.
[0038]
According to the ninth aspect of the present invention, the charge transfer circuit one stage before the final stage connects a plurality of series circuits of a saturable reactor and a second capacitor in parallel, and magnetically couples the plurality of saturable reactors. In the final stage charge transfer circuit, a series circuit of a saturable reactor for fine adjustment of transfer start time and a first capacitor is connected in parallel to a plurality of peaking capacitors. The saturation timings of the saturable reactors for fine adjustment of transfer times included in the final stage charge transfer circuit are made different. That is, according to the ninth aspect of the invention, a plurality of series circuits of a saturable reactor for fine adjustment of transfer start time and a first capacitor are provided in order to make different charge transfer start timings of a plurality of charge transfer routes to the peaking capacitor. A plurality of charge transfer circuits connected in parallel are added to the final stage. In other words, the stage immediately before the final stage magnetically couples a plurality of saturable reactors so that the charge transfer start timings of the stage immediately before the final stage coincide with each other. The charge transfer start timing is varied.
[0039]
As described above, according to the present invention, charge transfer to the peaking capacitor is performed at different start timings through a plurality of circuit routes, so that the peaking capacitor is relatively slowly compared to the case where charges are transferred simultaneously at the same time. It will be charged. Therefore, the emission time of the laser beam can be extended, and the emission intensity per unit time can be reduced. It is also possible to extend the laser light emission time by causing a phenomenon that charges are transferred from other circuit routes to the peaking capacitor even during the start of discharge and laser light emission. Become.
[0040]
According to a tenth aspect of the present invention, in the ninth aspect of the invention, the inductances after saturation of the plurality of saturable reactors of the charge transfer circuit one stage before the final stage magnetically coupled are made different.
[0041]
In the invention of claim 10, since the inductances after saturation of the plurality of saturable reactors in the charge transfer circuit one stage before the magnetically coupled final stage are made different, the charge transfer one stage before the last stage is made. The charge transfer times of a plurality of charge transfer routes in the circuit are different. Therefore, in the present invention, charges having different charge transfer times are transferred to the peaking capacitor through different charge transfer routes at different charge transfer start timings, thereby further extending the laser light emission time. The emission intensity per unit time can also be reduced.
[0042]
The invention of claim 11 is characterized in that, in the invention of claim 9, the inductances after saturation of a plurality of saturable reactors for fine adjustment of transfer start times included in the charge transfer circuit at the final stage are made different. To do.
[0043]
In the eleventh aspect of the invention, since the saturation timing and the saturation inductance of the plurality of fine-tunable saturable reactors in the final stage charge transfer circuit are made different from each other, the plurality of charge transfers in the final stage charge transfer circuit. The charge transfer start timing of the route and the charge transfer time are different. Therefore, in the present invention, charges having different charge transfer times are transferred to the peaking capacitor through different charge transfer routes at different charge transfer start timings, thereby extending the laser light emission time. In addition, the emission intensity per unit time can be reduced.
[0044]
In the invention of claim 12, a pulse laser discharge electrode provided in the laser medium, a peaking capacitor connected in parallel to the discharge electrode, and a transfer start time fine adjustment connected in parallel to the peaking capacitor Last-stage charge transfer circuit having a series circuit of a saturable reactor for use and a first capacitor, a plurality of saturable reactors connected in series to each of the plurality of first capacitors, and the plurality of saturable reactors A charge transfer circuit which is one stage before the last stage having one second capacitor connected in parallel, and the charge charged in the second capacitor is converted into the plurality of charges using the magnetic saturation phenomenon of the saturable reactor. By performing pulse discharge between the discharge electrodes by transferring to the peaking capacitor via the first capacitor, the laser A power supply device for a pulse laser that generates a pulse laser by exciting the quality, and magnetically couples a plurality of saturable reactors in a charge transfer circuit one stage before the final stage, and in the charge transfer circuit in the final stage The saturation timings of the included saturable reactors for fine adjustment of a plurality of transfer start times are made different.
[0045]
According to the twelfth aspect of the present invention, the charge transfer circuit one stage before the final stage is composed of one second capacitor and a plurality of saturable reactors connected in parallel to the second capacitor. In the final stage charge transfer circuit, a series circuit of a saturable reactor for fine adjustment of transfer start time and a first capacitor is connected in parallel to a plurality of peaking capacitors. Then, the saturation timings of the saturable reactors for fine adjustment of transfer times included in the charge transfer circuit at the final stage are made different.
[0046]
In the twelfth aspect of the present invention, a plurality of series circuits of a saturable reactor for fine adjustment of the transfer start time and a first capacitor are arranged in parallel in order to vary the charge transfer start timing of the plurality of charge transfer routes to the peaking capacitor. A connected charge transfer circuit is added to the final stage. That is, the invention of claim 12 is different from the invention of claim 9 in that one capacitor is included in the charge transfer circuit one stage before the last stage.
[0047]
Therefore, also in the twelfth aspect of the present invention, the stage immediately preceding the final stage magnetically couples a plurality of saturable reactors so that the charge transfer start timings of the stage immediately preceding the final stage are matched. The charge transfer start timing of each charge transfer route is made different in the final stage.
[0048]
In the invention of claim 12, charge transfer to the peaking capacitor is performed at different start timings through a plurality of circuit routes, so that the peaking capacitor is compared with the case where the charge is transferred all at once. Will be charged slowly. Therefore, the emission time of the laser beam can be extended, and the emission intensity per unit time can be reduced. It is also possible to extend the laser light emission time by causing a phenomenon that charges are transferred from other circuit routes to the peaking capacitor even during the start of discharge and laser light emission. Become.
[0049]
In a thirteenth aspect of the invention, in the twelfth aspect of the invention, the inductances after saturation of the plurality of saturable reactors of the charge transfer circuit one stage before the magnetically coupled final stage are made different.
[0050]
In the invention of claim 13, since the inductances after saturation of the plurality of saturable reactors in the charge transfer circuit one stage before the magnetically coupled final stage are made different, the charge transfer one stage before the final stage is made. The charge transfer times of a plurality of charge transfer routes in the circuit are different. Therefore, in the present invention, charges having different charge transfer times are transferred to the peaking capacitor with different charge transfer start timings via a plurality of charge transfer routes, thereby further extending the laser light emission time. The emission intensity per unit time can also be reduced.
[0051]
According to a fourteenth aspect of the present invention, in the twelfth aspect of the invention, the saturation inductances of a plurality of saturable reactors for fine adjustment of transfer start times included in the final stage charge transfer circuit are made different.
[0052]
In the invention of claim 14, since the saturation timing and the saturation inductance of the plurality of fine-tunable saturable reactors in the final stage charge transfer circuit are made different, the plurality of charge transfers in the final stage charge transfer circuit. The charge transfer start timing of the route and the charge transfer time are different. Therefore, in the present invention, charges having different charge transfer times are transferred to the peaking capacitor through different charge transfer routes at different charge transfer start timings, thereby extending the laser light emission time. In addition, the emission intensity per unit time can be reduced.
[0053]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[0054]
FIG. 1 is an equivalent circuit diagram showing an embodiment of the present invention. In FIG. 1, only the final stage compression circuit portion of the magnetic pulse compression circuit is shown. This magnetic pulse compression circuit is used as a power supply circuit for applying a high voltage to a discharge electrode of a pulse gas laser such as an excimer laser.
[0055]
In this embodiment, a peaking capacitor Cp is connected in parallel to the discharge electrode 10. For this peaking capacitor Cp, a series circuit of a saturable reactor ALn1, a saturable reactor for fine adjustment of transfer time (hereinafter simply referred to as a saturable reactor for fine adjustment) BLn1, and a transfer source capacitor Cn1, and a saturable reactor ALn2 for fine adjustment A saturable reactor BLn2 and a series circuit of a transfer source capacitor Cn2 are connected in parallel. The two transfer source capacitors Cn1 and Cn2 transfer charges to the peaking capacitor Cp, and charge is simultaneously transferred to these capacitors Cn1 and Cn2 from a capacitor (not shown) in the preceding stage. That is, the voltages of the transfer source capacitors Cn1 and Cn2 change in exactly the same way. The capacitances of the transfer source capacitors Cn1 and Cn2 are the same.
[0056]
On the other hand, the two saturable reactors ALn1 and ALn2 connected in parallel are closely magnetically coupled, so that their saturation timings are simultaneous.
[0057]
As a magnetic coupling method, for example, as shown in FIG. 2, the windings 11 and 12 of the two saturable reactors ALn1 and ALn2 are wound around a common core 13.
[0058]
In a saturable reactor, even if a voltage is applied to the saturable reactor, the magnetic permeability of the core is extremely large at the beginning, so that the winding inductance is sufficiently large. Therefore, the current flowing through the winding increases very slowly. When the magnetic flux generated by the current exceeds the saturation magnetic flux density of the core, the core is saturated. As a result, the magnetic permeability of the core decreases rapidly, and the current flowing through the winding increases at a stretch. This time is the saturation time (on time) of the saturable reactor.
[0059]
In this embodiment, since the same core 13 is used to form a plurality of saturable reactors in the same stage, changes in the current flowing through the windings 11 and 12 before the core is saturated due to various variation factors. Even if there is some variation, the saturation timings of the plurality of saturable reactors in the same stage coincide with each other, and the start timing of charge transfer mediated by these saturable reactors ALn1 and ALn2 can be made uniform.
[0060]
As another method of magnetic coupling, there is also a method as shown in FIG.
[0061]
In the case of FIG. 3, four saturable reactors are magnetically coupled. That is, in this method, a plurality of (in this case, four) cores 20 to 23 are used, and the windings 25 to 28 of each saturable reactor are wound around the two cores. Of the arrows attached to FIG. 3, the arrows attached in parallel to the windings indicate the direction of the current, and the arrows shown in the cores 20 to 23 indicate the direction of the magnetic field created by each winding. Yes. Here, it is necessary to adjust the winding direction of the coil and the direction of the current so that the directions of these magnetic fields are reversed in units of one counterclockwise direction → clockwise direction → counterclockwise direction. In order to realize such a reverse magnetic field in units of one, the number of cores needs to be an even number.
[0062]
In FIG. 3, when a voltage is applied to each of the windings 25 to 28, a voltage is generated in the windings of each of the cores 20 to 23 so as to cancel the current flowing through each winding, and this suppresses an increase in current. . At first, since the magnetic permeability of each of the cores 20 to 23 is extremely large, the inductance of the winding is sufficiently large, so that the current flowing through the winding increases very slowly. As the current increases, the magnetic flux density of each of the cores 20 to 23 also increases, and approaches saturation as well. The core is saturated when the magnetic flux generated by the current exceeds the saturation magnetic flux density of the core.
[0063]
If one core 20 reaches saturation, the current flowing through the windings 25 and 28 wound around the core 20 increases rapidly. Due to these current increases, the magnetic flux densities of the cores 21 and 23 adjacent to the core 20 also rapidly increase, and thereby the cores 21 and 23 are immediately saturated.
[0064]
As a result, the current flowing through the windings 26 and 27 wound around the cores 21 and 23 increases rapidly.
[0065]
Then, the remaining core 22 is immediately saturated by these current increases.
[0066]
In this way, if any of the four cores saturates first, the remaining three cores will also saturate immediately, making it possible to match the saturation timing of these four saturable reactors. become.
[0067]
Next, in FIG. 1, saturable reactors BLn1 and BLn2 for fine adjustment are respectively connected in series to the two saturable reactors ALn1 and ALn2 magnetically coupled. These fine-tunable saturable reactors BLn1 and BLn2 are not magnetically coupled.
[0068]
That is, the saturation inductance of the fine-tunable saturable reactors BLn1 and BLn2 is smaller than the saturation saturation inductance of the two magnetically coupled saturable reactors ALn1 and ALn2, and these fine-tunable saturable reactors BLn1 and BLn2 Adjustment accuracy is improved by adjusting the inductance of BLn2. That is, rather than adjusting the inductance of the saturable reactors ALn1 and ALn2 having large inductances, the adjustment accuracy is improved by adjusting the inductances of the saturable reactors BLn1 and BLn2 for fine adjustment separately provided. I have to.
[0069]
(1) Here, as a first example in the circuit of FIG. 1, the two saturable reactors BLn1 and BLn2 have their assist times (that is, the saturable reactors start to apply a voltage to the saturable reactor after the start of voltage application). The time required for saturation is set differently. Further, the two saturable reactors ALn1 and ALn2 that are magnetically coupled have the same inductance after saturation.
[0070]
With this setting, charge transfer from the transfer source capacitors Cn1 and Cn2 to the peaking capacitor Cp is as shown in FIG. In FIG. 4, Vc1 is the voltage of the transfer source capacitor Cn1, Vc2 is the voltage of the transfer source capacitor Cn2, Vb1 is the terminal voltage of the saturable reactor BLn1 for fine adjustment, Vb2 is the terminal voltage of the saturable reactor BLn2 for fine adjustment, and Vcp is The voltage of the peaking capacitor CP, the current pulse I1 is the transfer current from the transfer source capacitor Cn1 to the peaking capacitor Cp, and the current pulse I2 is the transfer current from the transfer source capacitor Cn2 to the peaking capacitor Cp.
[0071]
In the initial state of the time axis of FIG. 4, the two magnetically coupled saturable reactors ALn1 and ALn2 are already saturated as can be seen from the states of the voltages Vc1 and Vc2. Although not shown in this waveform diagram, the saturable reactors ALn1 and ALn2 are magnetically coupled, so that their saturation timings coincide. Since the saturation inductances of the saturable reactors ALn1 and ALn2 are the same, the voltages Vc1 and Vc2 change in the same manner until the fine-tunable saturable reactors BLn1 and BLn2 are saturated.
[0072]
After the magnetically coupled saturable reactors ALn1 and ALn2 are saturated, the voltages Vb1 and Vb2 of the fine-tunable saturable reactors BLn1 and BLn2 change from 0V to -EV. In this case, the saturation characteristics of the saturable reactors BLn1 and BLn2 are set so that the assist time of the fine-tunable saturable reactor BLn1 is shorter than the assist time of the fine-tunable saturable reactor BLn2. Therefore, the fine-tunable saturable reactor BLn1 reaches saturation first, and at this time, the charge of the transfer source capacitor Cn1 is transferred to the peaking capacitor Cp as a current pulse I1.
[0073]
After that, when the voltage-time product applied to the fine-tunable saturable reactor BLn2 reaches the saturation limit of the saturable reactor BLn2, the saturable reactor BLn2 reaches saturation, and at this point, the charge of the transfer source capacitor Cn2 becomes a current pulse. It is transferred to the peaking capacitor Cp as I2.
[0074]
Thereafter, the voltage VCp of the peaking capacitor Cp rises, and when this voltage VCp reaches a predetermined discharge start voltage, the laser gas between the main electrodes 10 is broken down at this point in time and discharge is started. The laser medium is excited by this discharge, and laser light is generated.
[0075]
As described above, in the first example, the assist times of the plurality of fine-tunable saturable reactors BLn1 and BLn2 are made different, so the saturation timings of the plurality of fine-tunable saturable reactors are different. As a result, the charge transfer start timing from the transfer source capacitors Cn1 and Cn2 to the peaking capacitor Cp becomes different. Therefore, charge transfer to the peaking capacitor Cp is performed at different start timings through a plurality of circuit routes, and as a result, the peaking capacitor Cp is charged for a relatively long time as shown in FIG. Will be.
[0076]
Therefore, a phenomenon occurs in which electric charge is further transferred to the peaking capacitor even while the laser beam is emitted after the discharge is started, and the emission time of the laser beam can be extended. The emission intensity of can be reduced.
[0077]
(2) Next, as a second example in the circuit of FIG. 1, the saturation inductances La1 and La2 of the two saturable reactors ALn1 and ALn2 magnetically coupled are made different. For example, La1 <La2. However, the two fine-tunable saturable reactors BLn1 and BLn2 are set to have the same assist time. That is, the saturation timing of the fine-tunable saturable reactors BLn1 and BLn2 is the same.
[0078]
With this setting, charge transfer from the transfer source capacitors Cn1 and Cn2 to the peaking capacitor Cp is as shown in FIG.
[0079]
In this second example, the fine-tunable saturable reactors BLn1 and BLn2 are set to have the same assist time, so the saturation timings of the fine-tunable saturable reactors BLn1 and BLn2 are the same. When the saturable reactors BLn1 and BLn2 for fine adjustment are saturated, charge transfer (I1) from the transfer source capacitor Cn1 to the peaking capacitor Cp and charge transfer (I2) from the transfer source capacitor Cn2 to the peaking capacitor Cp are performed. Started at the same time.
[0080]
However, in this second example, the saturation inductances La1 and La of the two saturable reactors ALn1 and ALn2 that are magnetically coupled are such that La1 <La2, and therefore, as shown in FIG. I2 has a longer charge transfer time.
[0081]
As described above, in the second example, since the saturable reactors BLn1 and BLn2 for fine adjustment are respectively connected to the magnetically coupled saturable reactors ALn1 and ALn2, the start timing of the charge transfer at the final stage is set. Can be delayed. Further, the saturation inductances La1 and La2 of the saturable reactors ALn1 and ALn2 that are magnetically coupled are made different. Therefore, the start timings of the charge transfer (I1) from the transfer source capacitor Cn1 to the peaking capacitor Cp and the charge transfer (I2) from the transfer source capacitor Cn2 to the peaking capacitor Cp match, but these charge transfer times are different. It becomes like this. Accordingly, the peaking capacitor Cp is charged for a relatively long time as shown in FIG. Therefore, a phenomenon occurs in which electric charge is further transferred to the peaking capacitor even while the laser beam is emitted after the discharge is started, and the emission time of the laser beam can be extended. The emission intensity of can be reduced.
[0082]
(3) Next, as a third example in the circuit of FIG. 1, the saturation inductances La1 and La2 of the two saturable reactors ALn1 and ALn2 that are magnetically coupled are made different (for example, La1 <La2). The assist times of the two fine-tunable saturable reactors BLn1 and BLn2 are made different.
[0083]
With this setting, charge transfer from the transfer source capacitors Cn1 and Cn2 to the peaking capacitor Cp is as shown in FIG.
[0084]
In this third example, since the saturable inductances La1 and La2 of the two saturable reactors ALn1 and ALn2 that are magnetically coupled are different (La1 <La2), the current from the current pulse I1 as shown in FIG. The pulse I2 has a longer charge transfer time. Also, since the assist times of the two fine-tunable saturable reactors BLn1 and BLn2 are made different (in the case of FIG. 6, the assist time of the reactor BLn1 is shorter than the reactor BLn2), the charge transfer start timing of the current pulse I1 Is earlier than the charge transfer start timing of the current pulse I2.
[0085]
Thus, in the third example, the start timing and charge transfer time of the charge transfer (I1) from the transfer source capacitor Cn1 to the peaking capacitor Cp and the charge transfer (I2) from the transfer source capacitor Cn2 to the peaking capacitor Cp. Therefore, the peaking capacitor Cp is charged for a relatively long time as shown in FIG. Therefore, a phenomenon occurs in which electric charge is further transferred to the peaking capacitor even while the laser beam is emitted after the discharge is started, and the emission time of the laser beam can be extended. The emission intensity of can be reduced.
[0086]
(4) Next, as a fourth example in the circuit of FIG. 1, the two saturable reactors ALn1 and ALn2 that are magnetically coupled have the same post-saturation inductance, and the two fine-tunable saturable reactors BLn1, The assist time for BLn2 is the same.
[0087]
With this setting, charge transfer from the transfer source capacitors Cn1 and Cn2 to the peaking capacitor Cp is as shown in FIG.
[0088]
That is, in this case, since the assist times of the fine-tunable saturable reactors BLn1 and BLn2 are the same, the transfer start times of the current pulses I1 and I2 are not different, but these fine-tunable saturable reactors BLn1 and BLn2 The charge transfer start timing of the current pulses I1 and I2 is delayed as compared with the case where the current is not inserted. Further, the saturation reactance of each circuit is increased by the amount of the saturable reactors BLn1 and BLn2 for fine adjustment, and the charge transfer time of the current pulses I1 and I2 is increased.
[0089]
As described above, in the fourth example, the fine-tunable saturable reactors BLn1 and BLn2 delay the charge transfer start timing in the charge transfer from the plurality of transfer source capacitors Cn1 and Cn2 to the peaking capacitor Cp. Since the charge transfer time can be adjusted to be long, the light emission time of the laser light can be extended, and the light emission intensity per unit time can be reduced.
[0090]
FIG. 8 is an equivalent circuit diagram showing another embodiment of the present invention.
[0091]
In this embodiment, two magnetically-coupled saturable reactors ALn1 and ALn2 in the final-stage charge transfer circuit and only two fine-tunable saturable reactors BLn1 and BLn2 connected in series to the peaking capacitor Cp are provided. They are connected in parallel, and the transfer source capacitor Cn remains one as before. That is, the circuit of FIG. 8 differs from the circuit of FIG. 1 only in that the number of transfer source capacitors Cn is kept as usual.
[0092]
In the circuit of FIG. 8, there is one transfer source capacitor Cn, but the charge transfer route to the peaking capacitor Cp has a plurality of routes as in the circuit of FIG. 1, and charge transfer is performed via these multiple routes. By doing so, substantially the same effect as the circuit of FIG. 1 can be obtained. However, in the case of the circuit of FIG. 8, when the charge transfer of one of the two charge transfer routes is started, the voltage of the transfer source capacitor Cn drops, and therefore the charge transfer of the other route is started. In some cases, charge transfer must be performed in a state where the transfer charge amount of the transfer source capacitor Cn is reduced, and various circuit adjustment operations are more complicated than the circuit of FIG.
[0093]
Thus, also in the circuit configuration of FIG. 8, the adjustment of the charge transfer start timing or the charge transfer time shown in the first to fourth examples in the circuit of FIG. 1 can be applied.
[0094]
That is, in the first example in the circuit of FIG. 8, the assist times of the two fine-tunable saturable reactors BLn1 and BLn2 are set to be different.
[0095]
Further, in the second example in the circuit of FIG. 8, the two saturable reactors ALn1 and ALn2 that are magnetically coupled have different saturation inductances La1 and La2 and assist the two fine-tunable saturable reactors BLn1 and BLn2. Set the time to be the same.
[0096]
In the third example of the circuit of FIG. 8, the two saturable reactors ALn1 and ALn2 that are magnetically coupled differ from each other in saturation inductances La1 and La2, and the two fine-tunable saturable reactors BLn1 and BLn2 are assisted. Try to make the time different.
[0097]
In the fourth example in the circuit of FIG. 8, the two saturable reactors ALn1 and ALn2 that are magnetically coupled have the same inductance after saturation, and the assist times of the two fine-tunable saturable reactors BLn1 and BLn2 are also the same. The same.
[0098]
In the embodiment of FIG. 8, the same charge transfer state as that shown in FIG. 1 can be generated, and the emission time of the laser beam can be extended, and the emission intensity per unit time can be increased. Can be reduced.
[0099]
FIG. 9 shows still another embodiment of the present invention.
[0100]
In the embodiment of FIG. 9, the fine-tunable saturable reactors BLn1 and BLn2 are not inserted into the final stage charge transfer circuit as in the embodiments of FIGS. One stage of charge transfer circuit composed of the saturable reactors BLn1 and BLn2 and transfer source capacitors C (n + 1) 1 and C (n + 1) 2 is added to the final stage.
[0101]
In FIG. 9, the charge transfer circuit one stage before the final stage includes capacitors Cn1 and Cn2 and saturable reactors ALn1 and ALn2 connected in series to these capacitors, respectively. Saturable reactors ALn1 and ALn2 are magnetically coupled.
[0102]
The charge transfer circuit at the final stage includes capacitors C (n + 1) 1, C (n + 1) 2, and fine-tunable saturable reactors BLn1, BLn2 connected in series to these capacitors, respectively. The fine-tunable saturable reactors BLn1 and BLn2 are not magnetically coupled. These fine-tunable saturable reactors BLn1 and BLn have different saturation times with different assist times.
[0103]
In the circuit of FIG. 9, basically, the saturable reactors ALn1 and ALn2 of the charge transfer circuit in the previous stage are magnetically coupled to form capacitors C (n + 1) 1 and C (n + 1) from the capacitors Cn1 and Cn2. The charge transfer start timings of a plurality of charge transfer routes to 2 are aligned, and capacitors C (n + 1) 1, C (n + 1) 2 are adjusted by saturable reactors BLn1, BLn2 for fine adjustment of the charge transfer circuit in the final stage. The charge transfer start timings of the plurality of charge transfer routes from the peaking capacitor Cp to the peaking capacitor Cp are varied to obtain the same effect as in the previous embodiment. In other words, if the saturation inductances of the saturable reactors ALn1 and ALn2 that are magnetically coupled are made the same, it is possible to obtain substantially the same effect as the first example.
[0104]
As described above, the saturation inductance of each saturable reactor can be variously set.
[0105]
For example, in the circuit of FIG. 9, if the saturation inductances of the magnetically coupled saturable reactors ALn1 and ALn2 are made different from each other, the capacitors C (n + 1) 1, C (n + 1) are changed from the capacitors Cn1, Cn2. The charge transfer times of a plurality of charge transfer routes to 2 can be made different. Therefore, in this case, the charge transfer start timing of a plurality of charge transfer routes from the capacitors C (n + 1) 1, C (n + 1) 2 to the peaking capacitor Cp and the capacitors Cn1, Cn2 to the capacitor C (n +1) 1 and C (n + 1) 2 have different charge transfer times for a plurality of charge transfer routes, so that when transferring charges to the peaking capacitor Cp, transfer starts for each transfer route Timing and charge transfer time can be made different.
[0106]
Further, in the circuit of FIG. 9, the saturation inductances of fine-tunable saturable reactors BLn1 and BLn2 that are not magnetically coupled may be made different. In this way, the charge transfer start timing and the charge transfer time of a plurality of charge transfer routes from the capacitors C (n + 1) 1, C (n + 1) 2 to the peaking capacitor Cp can be made different. .
[0107]
With the circuit configuration shown in FIG. 9 as well, the light emission time of the laser light can be extended, and the light emission intensity per unit time can be reduced.
[0108]
FIG. 10 is an equivalent circuit diagram showing still another embodiment of the present invention.
[0109]
In this embodiment, the number of capacitors Cn included in the charge transfer circuit one stage before the last stage is kept as usual. The other points are the same as the circuit shown in FIG.
[0110]
That is, also in the embodiment of FIG. 10, the saturable reactors ALn1 and ALn2 of the previous stage charge transfer circuit are magnetically coupled, and the saturation timings of the fine adjustment saturable reactors BLn1 and BLn of the final stage charge transfer circuit are varied. ing.
[0111]
Also in this case, the saturation inductances of the saturable reactors ALn1 and ALn2 that are magnetically coupled may be made different, or the saturation inductances of the saturable reactors BLn1 and BLn for fine adjustment may be made different. Good.
[0112]
With the circuit configuration shown in FIG. 10 as well, the emission time of the laser light can be extended, and the emission intensity per unit time can be reduced.
[Brief description of the drawings]
FIG. 1 is an equivalent circuit diagram showing an embodiment of the present invention.
FIG. 2 is a diagram showing one method of magnetic coupling.
FIG. 3 is a diagram showing another method of magnetic coupling.
4 is a current voltage time chart of the first example of the embodiment of FIG. 1; FIG.
FIG. 5 is a current voltage time chart of a second example of the embodiment of FIG. 1;
6 is a current-voltage time chart of the third example of the embodiment of FIG. 1; FIG.
7 is a current-voltage time chart of the fourth example of the embodiment of FIG. 1; FIG.
FIG. 8 is an equivalent circuit diagram showing another embodiment of the present invention.
FIG. 9 is an equivalent circuit diagram showing another embodiment of the present invention.
FIG. 10 is an equivalent circuit diagram showing another embodiment of the present invention.
FIG. 11 is an equivalent circuit diagram showing a conventional technique.
FIG. 12 is a time chart of current, voltage, etc. in the prior art.
[Explanation of symbols]
C1 to C2, Cn, Cn1 to Cn2 ... capacitors
Cp ... Peaking capacitor
HV ... Charging power supply
SW ... Main switch
AL1, AL2, ALn1, ALn2 ... Saturable reactor
BLn1, BLn2 ... Saturable reactor for fine adjustment
10 ... Discharge electrode
11, 12, 25-28 ... winding
13, 20-23 ... Core

Claims (14)

A pulse laser discharge electrode provided in a laser medium, a peaking capacitor connected in parallel to the discharge electrode, a series circuit of a saturable reactor and a transfer source capacitor connected in parallel to the peaking capacitor, By transferring the electric charge charged in the transfer source capacitor to the peaking capacitor using the magnetic saturation phenomenon of the saturable reactor, pulse discharge is performed between the discharge electrodes to excite the laser medium and generate a pulse laser. In the power supply for pulse laser,
A plurality of series circuits of the saturable reactor and the transfer source capacitor are connected in parallel to the peaking capacitor,
A pulsed laser power supply apparatus, wherein the plurality of supersaturated reactors are magnetically coupled, and a saturable reactor for fine adjustment of transfer start time is connected to each of the plurality of saturable reactors in series. 2. The pulse laser power supply device according to claim 1, wherein the plurality of transfer start time fine saturable reactors have different assist times. 2. The pulse laser power supply device according to claim 1, wherein inductances after saturation of the plurality of magnetically coupled saturable reactors are made different from each other. 3. The pulse laser power supply device according to claim 2, wherein inductances after saturation of the plurality of magnetically coupled saturable reactors are made different from each other. A pulse laser discharge electrode provided in a laser medium, a peaking capacitor connected in parallel to the discharge electrode, a series circuit of a saturable reactor and a transfer source capacitor connected in parallel to the peaking capacitor, By transferring the electric charge charged in the transfer source capacitor to the peaking capacitor using the magnetic saturation phenomenon of the saturable reactor, pulse discharge is performed between the discharge electrodes to excite the laser medium and generate a pulse laser. In the power supply for pulse laser,
The saturable reactor is divided into a plurality of magnetically coupled saturable reactor parallel circuits, and a saturable reactor for fine adjustment of transfer start time is connected to each of the plurality of saturable reactors in series. A power supply device for a pulsed laser. 6. The pulse laser power supply device according to claim 5, wherein the plurality of saturable reactors for fine adjustment of transfer start time are made different in assist time. 6. The pulse laser power supply device according to claim 5, wherein the plurality of magnetically coupled saturable reactors have different post-saturation inductances. 7. The pulse laser power supply device according to claim 6, wherein the plurality of magnetically coupled saturable reactors have different post-saturation inductances. A pulsed laser discharge electrode provided in the laser medium;
A peaking capacitor connected in parallel to the discharge electrode;
A charge transfer circuit in the final stage having a series circuit of a saturable reactor for fine adjustment of transfer start time and a first capacitor connected in parallel to the peaking capacitor;
A charge transfer circuit one stage prior to the last stage having a saturable reactor connected to each of the plurality of first capacitors and a plurality of series circuits of second capacitors;
And transferring the charges charged in the plurality of second capacitors to the peaking capacitor through the plurality of first capacitors using the magnetic saturation phenomenon of the saturable reactor, thereby performing pulse discharge between the discharge electrodes. A power source device for a pulse laser that generates a pulsed laser by exciting a laser medium,
Magnetically coupling a plurality of saturable reactors in the charge transfer circuit one stage before the last stage,
A pulse laser power supply device characterized in that the saturation timings of a plurality of saturable reactors for fine adjustment of transfer start time included in the final stage charge transfer circuit are made different. 10. The pulse laser power supply device according to claim 9, wherein the saturation inductance of the plurality of saturable reactors in the charge transfer circuit immediately preceding the magnetically coupled final stage is made different. 10. The pulse laser power supply device according to claim 9, wherein the saturation inductances of a plurality of saturable reactors for fine adjustment of transfer start time included in the final stage charge transfer circuit are made different. A pulsed laser discharge electrode provided in the laser medium;
A peaking capacitor connected in parallel to the discharge electrode;
A charge transfer circuit in the final stage having a series circuit of a saturable reactor for fine adjustment of transfer start time and a first capacitor connected in parallel to the peaking capacitor;
A charge transfer circuit one stage prior to the last stage having a plurality of saturable reactors connected in series to each of the plurality of first capacitors and a second capacitor connecting the plurality of saturable reactors in parallel; ,
And the electric charge charged in the second capacitor is transferred to the peaking capacitor through the plurality of first capacitors using the magnetic saturation phenomenon of the saturable reactor, thereby performing pulse discharge between the discharge electrodes. Thus, a power source device for a pulse laser that generates a pulse laser by exciting a laser medium,
Magnetically coupling a plurality of saturable reactors in the charge transfer circuit one stage before the last stage,
A pulse laser power supply device characterized in that the saturation timings of a plurality of saturable reactors for fine adjustment of transfer start time included in the final stage charge transfer circuit are made different. 13. The pulse laser power supply device according to claim 12, wherein the saturation inductances of the plurality of saturable reactors in the charge transfer circuit one stage before the magnetically coupled final stage are made different. 13. The pulse laser power supply device according to claim 12, wherein the saturation inductance of a plurality of saturable reactors for fine adjustment of transfer start time included in the final stage charge transfer circuit is made different.

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