JP2008192974A - Discharge circuit of discharge-excited gas laser - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve the high repeated operation of a magnetic pulse compressor by suppressing the excess heating of a core of a saturable reactor to be generated accompanied by an increase of a repeated frequency. <P>SOLUTION: A final magnetic switch 2 of a magnetic pulse compression circuit 10 is provided with a parallel circuit where two serial circuits configured by serially connecting a saturable reactor (reactor for compression) 21-n for magnetic compression and a saturable reactor (reactor for switching) 22-n for circuit switching are connected in parallel. A switching control part 3 controls switching so that magnetic reset quantities of the reactors 22-1 and 22-2 for switching can be turned to zero or maximum, that is, the rectors 22-1 and 22-2 for switching can be alternately turned on/off at each pulse oscillation. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a discharge circuit of a discharge excited gas laser that generates a main discharge between main discharge electrodes by performing a magnetic pulse compression operation of energy using a multi-stage capacitor and a magnetic switch, and more particularly, a saturable reactor with a high repetition frequency. It is intended to suppress the deterioration.

  With the miniaturization and high integration of semiconductor integrated circuits, improvement in resolving power is demanded in the projection exposure apparatus for production. For this reason, the wavelength of the exposure light emitted from the exposure light source is being shortened, and a KrF excimer laser device having a wavelength of 248 nm from a conventional mercury lamp is used as a light source for semiconductor exposure. Further, as a next-generation light source for semiconductor exposure, gas laser devices that emit ultraviolet rays, such as an ArF excimer laser device having a wavelength of 193 nm and a fluorine (F2) laser device having a wavelength of 157 nm, are promising.

  In the KrF excimer laser apparatus, a laser gas, that is, a mixed gas composed of a rare gas such as fluorine (F2) gas, krypton (Kr) gas, and neon (Ne) as a buffer gas is sealed in the laser chamber at several hundred KPa. A laser gas as a laser medium is excited by generating a discharge inside the laser chamber.

  In the ArF excimer laser device, a laser gas, that is, a mixed gas composed of a rare gas such as fluorine (F2) gas, argon (Ar) gas, and neon (Ne) as a buffer gas is sealed in the laser chamber at several hundred KPa. A laser gas as a laser medium is excited by generating a discharge inside the laser chamber.

  In the fluorine (F2) laser apparatus, a laser gas, that is, a mixed gas comprising fluorine (F2) gas and a rare gas such as helium (He) as a buffer gas is sealed in the laser chamber at several hundred KPa. A laser gas as a laser medium is excited by generating a discharge inside the laser.

  Inside the laser chamber, a pair of main discharge electrodes for exciting the laser gas are disposed facing each other at a predetermined distance in a direction perpendicular to the laser oscillation direction. A high voltage pulse is applied to the pair of main discharge electrodes, and when the voltage applied between the main discharge electrodes reaches a certain value (breakdown voltage), the laser gas between the main discharge electrodes breaks down and main discharge starts. The laser medium is excited by this main discharge. Such an exposure gas laser apparatus performs pulse oscillation by repeating main discharge, and the emitted laser light becomes pulse light. The laser pulse repetition frequency of laser devices used in recent exposure is about 4 KHz, but a repetition frequency of 6 KHz or more is required for an increase in throughput and a decrease in exposure variation, and a repetition frequency of 8 KHz. The above laser apparatus has been researched and developed.

  FIG. 5 shows an example of an apparatus (hereinafter referred to as a discharge circuit) for generating a discharge between main discharge electrodes in a laser chamber.

  The discharge circuit of FIG. 5 includes a high voltage power supply HV, a main capacitor C0 charged by the high voltage power supply HV, a magnetic assist SR1 to which the voltage of the main capacitor C0 is applied when the solid switch SW is turned on, Via a k-stage magnetic pulse compression circuit 10 having k transfer capacitors C1 and C2 and magnetic switches SR2 and SR3 (k is an integer of 2 or more) and a second-stage magnetic switch SR3 of the magnetic pulse compression circuit 10, respectively. A peaking capacitor Cp connected in parallel to the second-stage transfer capacitor C2 and a pair of main discharge electrodes E and E connected in parallel to the peaking capacitor Cp are provided.

  The discharge circuit shown in FIG. 5 has a two-stage (k = 2) magnetic pulse compression circuit 10. In the magnetic pulse compression circuit 10, the second-stage transfer capacitor C2 is connected in parallel to the first-stage transfer capacitor C1 via the first-stage magnetic switch SR2, and the main pulse according to the magnetic saturation of the magnetic assist SR1. Charge is transferred from the capacitor C0 to the first-stage transfer capacitor C1, and the charge is sequentially transferred from the first-stage transfer capacitor C1 to the second-stage transfer capacitor C2 in accordance with the magnetic saturation of the first-stage magnetic switch SR2. Is done.

  In the discharge circuit shown in FIG. 5, a temporary winding Tr1 of a step-up transformer Tr is connected between the magnetic assist SR1 and the solid switch SW, and the main capacitor C0, the magnetic assist SR1, the primary winding Tr1, and the solid switch SW are connected. A loop is formed. Further, the first stage transfer capacitor C1 of the magnetic pulse compression circuit is connected to the secondary winding Tr2 of the step-up transformer Tr, and a loop of the secondary winding TC2 and the transfer capacitor C1 is formed.

The operation of the discharge circuit shown in FIG. 5 will be described with reference to FIG.
First, the solid switch SW is turned off, and the main capacitor C0 is charged by the high voltage power supply HV adjusted to the voltage value Vin. The charging voltage of the main capacitor at this time is assumed to be positive. When the solid switch SW is switched from OFF to ON, the charging voltage Vc1 of the main capacitor C0 is applied to the magnetic assist SR1. When the time integral value of the charging voltage Vc0 of the main capacitor C0 reaches a limit value determined by the characteristics of the magnetic assist SR1, the magnetic assist SR1 is saturated and the inductance of the magnetic assist SR1 is reduced. This timing is indicated by time t1 in FIG. Then, a current flows through the loop of the main capacitor C0, the magnetic assist SR1, the primary winding Tr1 of the step-up transformer Tr1, and the solid switch SW. At the same time, a current also flows through the loop of the secondary winding Tr2 of the step-up transformer Tr1 and the first-stage transfer capacitor C1, and the electric charge stored in the main capacitor C0 is transferred to the first-stage transfer capacitor C1, The first-stage transfer capacitor C1 is charged to the negative side.

  When the time integration value of the charging voltage Vc1 of the first-stage transfer capacitor C1 reaches a limit value determined by the characteristics of the magnetic switch SR2, the magnetic switch SR2 is saturated and the inductance of the magnetic switch SR2 decreases. This timing is indicated by time t2 in FIG. Then, a current flows through the loop of the first-stage transfer capacitor C1, the second-stage transfer capacitor C2, and the magnetic switch SR2, and the charge stored in the first-stage transfer capacitor C1 is transferred to the second-stage transfer capacitor C2. The second transfer capacitor C2 is charged to the negative side.

  Further, when the time integration value of the charging voltage Vc2 of the second-stage transfer capacitor C2 reaches a limit value determined by the characteristics of the magnetic switch SR3, the magnetic switch SR3 is saturated and the inductance of the magnetic switch SR3 is rapidly reduced. This timing is indicated by time t3 in FIG. Then, a current flows through the loop of the second-stage transfer capacitor C2, peaking capacitor Cp, and magnetic switch SR3, and the charge stored in the second-stage transfer capacitor C2 is transferred to the peaking capacitor Cp. Charged to the negative side.

  When the voltage Vcp of the peaking capacitor Cp reaches a certain value (breakdown voltage) Vb, the laser gas between the main discharge electrodes E and E breaks down and main discharge is started. This main discharge excites the laser medium to generate light.

  In order to generate a large discharge at the main discharge electrodes E, E, charge transfer from the first-stage transfer capacitor C1 to the second-stage transfer capacitor C2, and from the second-stage transfer capacitor C2 to the peaking capacitor Cp. Each element of the magnetic pulse compression circuit (C1, SR1, C2, SR2) is designed so that a so-called magnetic pulse compression operation for sequentially reducing the pulse width of the current pulse is performed during the charge transfer.

  By the way, a saturable reactor is used for each of the magnetic switches SR1 to SR3. Since the saturable reactors SR1 to SR3 generate heat when the magnetization curve changes, they are immersed in a refrigerant for the purpose of cooling. However, as the repetition frequency of the laser pulse increases, the amount of heat generated by the core of the saturable reactor SR3 arranged at the final stage of the magnetic pulse compression circuit 10 increases, and the amount of generated heat may exceed the rated value. Such saturable reactors have been a problem to be solved because of their severe deterioration. As the number of pulses per unit time increases, the amount of heat generated per unit time also increases, so the temperature rise of the core of the saturable reactor increases.

  In general, the cores of the saturable reactors SR1 to SR3 are formed by winding a plurality of ribbon-shaped magnetic alloys around a cylindrical core material, and a thin-film insulator (eg, silica) is formed on the front and back surfaces of the ribbon-shaped magnetic alloy. A thin film or the like) is formed. When such a core generates heat above the rated value, a crack occurs in the silica thin film due to the difference in thermal expansion coefficient between the magnetic material alloy and the silica thin film. Then, the leakage current increases at the cracked portion, and the amount of heat generation further increases. In the worst case, the characteristics of the circuit element are lost.

As a technique for solving such a problem, Patent Document 1 discloses a core in which a plurality of flat plate portions, each of which is a conventional core cut into a ring shape, are stacked at a predetermined interval. According to the invention according to the cited document 1, the surface area of the core per unit volume is increased, the contact area between the core and the refrigerant can be increased, and the core can be efficiently cooled.
JP 2003-115414 A

  However, with the further increase in the repetition frequency in recent years, it is expected that the conventional core cooling technology cannot suppress the heat generation of the core below an allowable value. Then, the saturable reactor is damaged. In addition, the life of the saturable reactor is shortened, and the number of replacements of the saturable reactor is increased, resulting in an increase in cost. In addition, since the replacement cycle of the saturable reactor is shortened and the number of maintenance is increased, the work man-hour may be increased.

  The present invention has been made in view of such a situation, and an object of the present invention is to suppress excessive heat generation of the core of the saturable reactor that occurs with an increase in the repetition frequency, and to enable a high repetition operation of the magnetic pulse compressor. It is what.

In order to achieve the above object, the first invention provides:
High voltage power supply (HV)
A main capacitor (C0) charged by the high voltage power supply (HV);
Magnetic assist (SR1) to which the voltage of the main capacitor (C0) is applied as the solid switch (SW) is turned on,
Each of the transfer capacitors (C1,..., Cn) and the magnetic switch portions (1,..., N) has k (k is an integer of 2 or more), and the transfer capacitors (Cn) in the n (n = 1 to k) stage. ) Is connected in parallel to the n-1 stage transfer capacitor (Cn-1) via the n-1 stage magnetic switch unit (n-1), and the magnetic saturation of the magnetic assist (SR1) is controlled. Accordingly, the charge is transferred from the main capacitor (C0) to the transfer capacitor (C1) at the first stage, and the n-1 stage at the n-1 stage according to the magnetic saturation of the magnetic switch unit (n-1). A magnetic pulse compression circuit (10) in which charges are sequentially transferred from the transfer capacitor (Cn-1) to the n-th transfer capacitor (Cn);
A peaking capacitor (Cp) connected in parallel to the k-th transfer capacitor (Ck) via the k-th magnetic switch section (k) of the magnetic pulse compression circuit (10);
A pair of main discharge electrodes (E, E) connected in parallel to the peaking capacitor (Cp);
In a discharge circuit of a discharge excitation gas laser comprising:
There are a plurality of series circuits of saturable reactors (21-1,..., 21-n) for magnetic compression and saturable reactors (22-1,..., 22-n) for circuit switching. The k-th magnetic switch unit (k) includes a parallel circuit in which circuits are connected in parallel to each other,
The magnetic reset amount of the saturable reactor (22-1,..., 22-n) for switching the circuit is changed for each pulse oscillation, and the saturable reactor (22-1,..., 22-n) for switching the circuit is changed. ), The magnetic reset amount of one or more saturable reactors is set to zero and turned on, and the magnetic reset amount of the remaining saturable reactor for circuit switching is maximized and turned off.

  The first invention will be described with reference to FIG.

  The magnetic switch unit 2 at the final stage of the magnetic pulse compression circuit 10 includes a magnetic compression saturable reactor (compression reactor) 21-1, 21-2 and a circuit switching saturable reactor (switching reactor) 22-1, 22. -2 includes a parallel circuit in which two series circuits connected in series are connected in parallel. The switching control unit 3 turns on the switching reactors 22-1 and 22-2 alternately so that the magnetic reset amount of the switching reactors 22-1 and 22-2 alternately becomes zero and maximum every pulse oscillation.・ Switch control to turn off.

  For example, at the time of pulse oscillation of 2m (m is an integer of 1 or more), the current supplied from the previous stage of the magnetic pulse compression circuit 10 is a series circuit of a compression reactor 21-1 and a switching reactor 22-1. And does not flow in the series circuit of the compression reactor 21-2 and the switching reactor 22-2. In the (2m-1) th pulse oscillation, the current supplied from the preceding stage of the magnetic pulse compression circuit 10 flows through the series circuit of the compression reactor 21-2 and the switching reactor 22-2, and is used for compression. It does not flow in the series circuit of the reactor 21-1 and the switching reactor 22-1.

The second invention is the first invention,
A plurality of series circuits of saturable reactors for magnetic compression (11-1,..., 11-n) and saturable reactors for circuit switching (12-1,..., 12-n) are provided. A parallel circuit in which circuits are connected in parallel to each other is provided in the magnetic switch unit (1) before the k-th stage,
The magnetic reset amount of the saturable reactor for switching the circuit (12-1,..., 12-n) is changed for each pulse oscillation, so that the saturable reactor for switching the circuit (12-1,..., 12-n) is changed. ), The magnetic reset amount of one or more saturable reactors is set to zero and turned on, and the magnetic reset amount of the remaining saturable reactor for circuit switching is maximized and turned off.

  In the second invention, in addition to the first invention, a plurality of series circuits of a compression reactor 21-n and a switching reactor 22-n are provided in parallel in a magnetic switch unit other than the final stage of the magnetic pulse compression circuit.

  According to the present invention, a plurality of saturable reactors used as magnetic switches are connected in parallel to each other, and the saturable reactor used for each pulse is switched. With such a configuration, the amount of heat generated in the saturable reactor per pulse is reduced. In addition, since the off interval of the saturable reactor can be increased, a sufficient cooling time for the saturable reactor can be ensured. Therefore, excessive heat generation of the saturable reactor can be suppressed, and high repetition operation of the magnetic pulse compressor is enabled.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a discharge circuit of the first embodiment. The difference between the discharge circuit shown in FIG. 1 and the conventional discharge circuit shown in FIG. 5 is the configuration of the magnetic switch provided at the final stage of the magnetic pulse compression circuit. The discharge circuit shown in FIG. 1 is a circuit that performs two-stage magnetic pulse compression similarly to the conventional discharge circuit shown in FIG.

  Both ends of the main capacitor C0 are connected to both ends of the DC high voltage power supply HV. One end of the magnetic switch SR1 is connected to one end of the main capacitor C0, one end of the primary winding Tr1 of the boosting transformer Tr is connected to the other end of the magnetic assist SR1, and the other end of the primary winding Tr1 is solid. One end of the switch SW is connected, and the other end of the main capacitor C0 is connected to the other end of the solid switch SW. The main capacitor C0, the magnetic assist SR1, the primary winding Tr1, and the solid switch SW form a loop.

  The magnetic assist SR1 is a magnetic switch composed of a saturable reactor. The solid state switch SW is a semiconductor switch such as an IGBT that performs a switching operation according to a signal transmitted from the outside.

A two-stage magnetic pulse compression circuit 10 is connected to the secondary winding Tr2 of the step-up transformer Tr.
The both ends of the first stage transfer capacitor C1 of the magnetic pulse compression circuit 10 are connected to both ends of the secondary winding Tr2 of the step-up transformer Tr. The secondary winding Tr2 and the first stage transfer capacitor C1 form a loop.

  One end of the first stage magnetic switch unit 1, here a saturable reactor SR2, is connected to one end of the first stage transfer capacitor C1, and the other end of the first stage magnetic switch unit 1 is connected to the second stage. One end of the transfer capacitor C2 is connected, and the other end of the second-stage transfer capacitor C2 is connected to the other end of the first-stage transfer capacitor C1. The first-stage transfer capacitor C1, the first-stage magnetic switch unit 1, and the second-stage transfer capacitor C2 form a loop.

  One end of the second-stage magnetic switch unit 2 is connected to one end of the second-stage transfer capacitor C2, and one end of the peaking capacitor Cp is connected to the other end of the second-stage magnetic switch unit 2. The other end of the transfer capacitor C2 at the second stage is connected to the other end. The second-stage transfer capacitor C2, the second-stage magnetic switch unit 10, and the peaking capacitor Cp form a loop. Details of the second-stage magnetic switch unit 2 will be described later.

  The magnetic compression operation of the discharge circuit shown in FIG. 1 is basically the same as the magnetic compression operation of the discharge circuit shown in FIG. 5 described with reference to FIG.

  The second-stage magnetic switch unit 2 includes a magnetic compression saturable reactor 21-n (hereinafter simply referred to as “compression reactor”) and a circuit switching saturable reactor 22-n (hereinafter simply referred to as “switching reactor”). Is a parallel circuit in which n series circuits are connected in series, and n series circuits are connected in parallel to each other. In the magnetic switch unit 2 shown in FIG. 1, two series circuits, that is, a series circuit including a compression reactor 21-1 and a switching reactor 22-1, a compression reactor 21-2, and a switching reactor 22-2 are included. Are connected in parallel with each other. The end of each magnetic compression saturable reactor 21-n is connected to one end of the second-stage transfer capacitor C2, and the end of the circuit switching saturable reactor 22-n is connected to one end of the peaking capacitor Cp. .

  The switching control unit 3 includes an excitation circuit 31-n provided for each switching reactor 22-n. Each excitation circuit 31-n includes a current source 33-n and a winding 34-n. As shown in FIG. 2, the winding 34-n is wound around the core CR of the switching reactor 22-n. Therefore, by appropriately adjusting the current flowing through the winding 34-n, the magnetic reset amount of the switching reactor 22-n can be switched between the maximum and zero. The switching control unit 3 switches the magnetic reset amount of the switching reactor 22-n between the maximum and zero for each pulse oscillation.

  At the time of this switching, one of the switching reactor 22-1 and the switching reactor 22-2 is set to the maximum magnetic reset amount and the other is set to the magnetic reset amount zero. Avoid continuous magnetic saturation. For example, as shown in FIG. 1, when switching control of the two switching reactors 22-1 and 22-2 is performed, the excitation circuit 31-2 with respect to the cycle of the current source 33-1 included in the excitation circuit 31-1. When the cycle of the current source 33-2 included in is shifted by a half cycle, the switching reactor 22-1 and the switching reactor 22-2 alternately have a maximum magnetic reset amount (or zero magnetic reset amount) at a constant cycle.

  In the series circuit in which the magnetic reset amount of the switching reactor 22-n is maximized, the voltage applied to the series circuit is divided between the core of the switching reactor 22-n and the core of the compressible saturable reactor 21-n. A half voltage is applied to each core. On the other hand, in the series circuit in which the magnetic reset amount of the switching reactor 22-n is zero, the voltage applied to the series circuit is applied to the core of the compressible saturable reactor 21-n. For this reason, the core of the reactor for compression 22-n connected to the series circuit in which the magnetic reset amount of the reactor for switching 22-n becomes zero first saturates and current flows.

  According to the control of the switching control unit 3, the switching reactors 22-1 and 22-2 alternately become the maximum magnetic reset amount every time the pulse is oscillated, and become the magnetic reset amount zero. That is, each switching reactor 22-n is switched on and off every pulse oscillation. When the switching reactor 22-n is off, no current flows through the series circuit. That is, the switching reactor 22-n and the compression reactor 21-n are not magnetically saturated at a rate of once per two pulse oscillations. For example, in the case of a laser device that oscillates at 8 KHz, the magnetic saturation does not occur for 4 KHz.

  For example, at the time of pulse oscillation of 2m (m is an integer of 1 or more), the current supplied from the previous stage of the magnetic pulse compression circuit 10 is a series circuit of a compression reactor 21-1 and a switching reactor 22-1. And does not flow in the series circuit of the compression reactor 21-2 and the switching reactor 22-2. In the (2m-1) th pulse oscillation, the current supplied from the preceding stage of the magnetic pulse compression circuit 10 flows through the series circuit of the compression reactor 21-2 and the switching reactor 22-2, and is used for compression. It does not flow in the series circuit of the reactor 21-1 and the switching reactor 22-1.

Next, the function and effect of the present invention will be specifically described.
In the following, it is assumed that the discharge circuit shown in FIG. 1 is operated at the same frequency as that of the discharge circuit shown in FIG. 5, and the heat quantity P generated during one pulse oscillation in the single saturable reactor SR3 shown in FIG. The amounts of heat P21 and P22 generated in the saturable reactors 21-n and 22-n of the magnetic switch unit 2 shown in FIG. 1 are calculated. For convenience of explanation, it is assumed that the Vt product of the compression reactor 21-n and the switching reactor 22-n are the same, and the inductance at the time of non-saturation is also the same. It is assumed that the voltage of the transfer capacitor C2 provided in the previous stage of the magnetic switch unit 2 is E.

  First, it is assumed that the magnetic reset amount of the switching reactor 22-1 is maximum (off) and the magnetic reset amount of the switching reactor 22-2 is zero (on) during pulse oscillation.

In this case, the voltage applied to the series circuit is divided by the reactors 21-1, 22-1. Therefore, the voltage Eoff applied to the compression reactor 21-1 is the voltage applied to the capacitor in the previous stage. E
Eoff = (1/2) E
Thus, the voltage Ecoff applied to the switching reactor 22-1 is Ecoff = (1/2) E
It becomes.
The voltage Eon applied to the compression reactor 21-2 is Eon = E
And the voltage Econ applied to the switching reactor 22-2 is Econ = 0
It becomes. The voltage Econ becomes 0 because the magnetic reset amount of the switching reactor 22-2 is zero, that is, the magnetic saturation state. The amount of heat generated by each reactor under these conditions is calculated as follows.

The amount of heat generated by the core increases with the square of the amount of change in magnetic flux density. Therefore, the heat generation amount Poff of the compression reactor 21-1 is Poff = (1/4) P (1)
Thus, the heat generation amount Pcoff of the switching reactor 22-1 is Pcoff = (1/4) P (2)
It becomes.
Further, the heat generation amount Pon of the compression reactor 21-2 is Pon = P (3)
Therefore, the heat generation amount Pcon of the switching reactor 22-2 is Pcon = 0 (4)
It becomes.

  What has been described so far is “when the magnetic reset amount of the switching reactor 22-1 is maximum (off) and the magnetic reset amount of the switching reactor 22-2 is zero (on) during pulse oscillation”. The amount of heat generated by each reactor 21-n, 22-n. In the opposite case, that is, “when the pulse reset oscillates, the magnetic reset amount of the switching reactor 22-1 is zero (on) and the magnetic reset amount of the switching reactor 22-2 is maximum (off)”. The heating values Poff and Pon of the reactor 21-n are switched, and the heating values Pcoff and Pcon of the switching reactor 22-n are switched. In the magnetic switch unit 2 shown in FIG. 1, each series circuit is alternately turned on and off, so that the amount of heat generated by each of the saturable reactors 21 -n and 22 -n changes alternately every pulse oscillation. Therefore, an average value is calculated as the heat generation amounts P21 and P22 per pulse.

From the results of the above equations (1) and (3), the average value P21 of the heat generation amount per pulse of each compression reactor 21-n is P21 = (1/2) × Poff + (1/2) × Pon = (5/8) P
From the results of the above equations (2) and (4), the average value P22 of the heat generation amount per pulse of each switching reactor 22-n is P22 = (1/2) × Pcoff + (1/2) × Pcon = (1/8) P
It becomes.

  Thus, the heat generation amount P21 of each compression reactor 21-1 of the magnetic switch unit 2 is (5/8) P, and the heat generation amount P22 of each switching reactor 22-1 is (1/8) P. These calorific values P21 and P22 are lower than the calorific value P of the conventional saturable reactor SR3 shown in FIG. Therefore, even if the repetition frequency of the laser device is increased, the temperature rise of the core of the saturable reactor can be kept low, and the repetition frequency of the laser device can be increased.

  Up to this point, the embodiment has been described in which two series circuits are provided in the magnetic switch unit 2, but two or more series circuits may be provided. Hereinafter, a case where there are three series circuits will be described as an example of the second embodiment.

  FIG. 3 shows a discharge circuit of the second embodiment. The discharge circuit shown in FIG. 3 has three series circuits in the magnetic switch unit 2.

  In the magnetic switch unit 2 shown in FIG. 3, three series circuits, that is, a series circuit including a compression reactor 21-1 and a switching reactor 22-1, a compression reactor 21-2, and a switching reactor 22-2 are included. Are connected in parallel with each other, and a series circuit including a compression reactor 21-3 and a switching reactor 22-3.

  The switching control unit 3 includes an excitation circuit 31-n provided for each switching reactor 12-n. Each excitation circuit 31-n includes a current source 33-n and a winding 34-n. Therefore, by appropriately adjusting the current flowing through the winding 34-n, the magnetic reset amount of the switching reactor 22-n can be switched between the maximum and zero. The switching control unit 3 switches the magnetic reset amount of the switching reactor 22-n between the maximum and zero for each pulse oscillation.

  In the present embodiment, one of the switching reactors 22-n has a magnetic reset amount of zero and the rest has a maximum magnetic reset amount.

  Here, average values P21 and P22 of the calorific values of the respective compression reactors 21-n and the respective switching reactors 22-n are calculated.

From the results of the above formulas (1) and (3), the average value P21 of the calorific value per pulse of each compression reactor 21-n is P21 = (2/3) × Poff + (1/3) × Pon = (1/4) P
From the results of the above equations (2) and (4), the average value P22 of the heat generation amount per pulse of each switching reactor 22-n is P22 = (2/3) × Pcoff + (1/3) × Pcon = (1/6) P
It becomes.

  Thus, the heat generation amount P21 of each compression reactor 21-1 of the magnetic switch unit 2 is (1/4) P, and the heat generation amount P22 of each switching reactor 22-1 is (1/6) P. These calorific values P21 and P22 are lower than the calorific value P of the conventional saturable reactor SR3 shown in FIG. Therefore, even if the repetition frequency of the laser device is increased, the temperature rise of the core of the saturable reactor can be kept low, and the repetition frequency of the laser device can be increased.

  FIG. 4 shows a discharge circuit of the third embodiment. The discharge circuit shown in FIG. 4 has two series circuits in the magnetic switch unit 2 in the final stage, and also has two series circuits in the magnetic switch unit 1 in the first stage.

  The first-stage magnetic switch unit 1 has n series circuits in which a compression reactor 11-n and a switching reactor 12-n are connected in series, and the n series circuits are connected in parallel to each other. Circuit. In the magnetic switch unit 1 shown in FIG. 4, two series circuits, that is, a series circuit including a compression reactor 11-1 and a switching reactor 12-1, a compression reactor 11-2, and a switching reactor 12-2. Are connected in parallel with each other.

  The switching control unit 4 includes an excitation circuit 41-n provided for each switching reactor 12-n. Each excitation circuit 41-n has a current source 43-n and a winding 44-n. Accordingly, the magnetic reset amount of the switching reactor 12-n can be switched between the maximum and zero by appropriately adjusting the current flowing through the winding 44-n. The switching control unit 4 switches the magnetic reset amount of the switching reactor 12-n between the maximum and zero for each pulse oscillation.

  As in this embodiment, a plurality of series circuits of the compression reactor 21-n and the switching reactor 22-n may be provided in parallel in the magnetic switch unit other than the final stage. In the future, since the repetition frequency of the laser device is expected to increase further, the heat generation amount of the magnetic switches other than the final stage is also expected to increase. According to this embodiment, it is possible to suppress an increase in the amount of heat generated by the magnetic switch units other than the final stage.

The figure which shows the discharge circuit of 1st Embodiment. The figure which shows the structure of a switching control part. The figure which shows the discharge circuit of 2nd Embodiment. The figure which shows the discharge circuit of 3rd Embodiment. The figure which shows an example of the discharge circuit which generate | occur | produces discharge between the main discharge electrodes in a laser chamber. The figure for demonstrating operation | movement of a discharge circuit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 ... Magnetic switch part 3 ... Switching control part 10 ... Magnetic pulse compression circuit 21-1, 21-2 ... Saturable reactor for magnetic compression (reactor for compression)
22-1, 22-2 ... Saturable reactor for circuit switching (reactor for switching)
31-1, 31-2: Excitation circuit 33-1, 33-2 ... Current source 34-1, 34-2 ... Winding HV ... High voltage power supply SV ... Solid switch C0 ... Main capacitor C-1, C-2 ... Transfer capacitor SR-1 ... Magnetic assist E, E ... Main discharge electrode

Claims (2)

High voltage power supply (HV)
A main capacitor (C0) charged by the high voltage power supply (HV);
Magnetic assist (SR1) to which the voltage of the main capacitor (C0) is applied as the solid switch (SW) is turned on,
Each of the transfer capacitors (C1,..., Cn) and the magnetic switch portions (1,..., N) has k (k is an integer of 2 or more), and the transfer capacitors (Cn) in the n (n = 1 to k) stage. ) Is connected in parallel to the n-1 stage transfer capacitor (Cn-1) via the n-1 stage magnetic switch unit (n-1), and the magnetic saturation of the magnetic assist (SR1) is reduced. In response, the charge is transferred from the main capacitor (C0) to the first-stage transfer capacitor (C1), and the n-1st stage according to the magnetic saturation of the n-1st stage magnetic switch unit (n-1). A magnetic pulse compression circuit (10) in which charges are sequentially transferred from the transfer capacitor (Cn-1) to the n-th transfer capacitor (Cn);
A peaking capacitor (Cp) connected in parallel to the k-th transfer capacitor (Ck) via the k-th magnetic switch unit (k) of the magnetic pulse compression circuit (10);
A pair of main discharge electrodes (E, E) connected in parallel to the peaking capacitor (Cp);
In a discharge circuit of a discharge excitation gas laser comprising:
There are a plurality of series circuits of saturable reactors (21-1,..., 21-n) for magnetic compression and saturable reactors (22-1,..., 22-n) for circuit switching. The k-th magnetic switch unit (k) includes a parallel circuit in which circuits are connected in parallel to each other,
The magnetic reset amount of the saturable reactor (22-1,..., 22-n) for switching the circuit is changed for each pulse oscillation, and the saturable reactor (22-1, ..., 22-n) for switching the circuit is changed. ), The magnetic reset amount of one or more saturable reactors is set to zero and turned on, and the magnetic reset amount of the remaining saturable reactor for circuit switching is maximized and turned off. Discharge circuit. A plurality of series circuits of saturable reactors for magnetic compression (11-1,..., 11-n) and saturable reactors for circuit switching (12-1,..., 12-n) are provided. A parallel circuit in which circuits are connected in parallel to each other is provided in the magnetic switch unit (1) before the k-th stage,
The magnetic reset amount of the saturable reactor for switching the circuit (12-1,..., 12-n) is changed for each pulse oscillation, so that the saturable reactor for switching the circuit (12-1,..., 12-n) is changed. The magnetic reset amount of one or more saturable reactors is set to zero and turned on, and the magnetic reset amount of the remaining saturable reactor for circuit switching is maximized and turned off. Discharge excitation gas laser discharge circuit.

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