JPH08279644A - Discharge circuit for pulse laser device - Google Patents

Abstract

PURPOSE: To provide a pulse laser device discharge circuit which is capable of dispensing with a direct current power supply and a timing circuit to reset by a method wherein a magnetic assist circuit is so structured as to be easily reset. CONSTITUTION: A discharge circuit is composed of a main capacitor 5 charged through the intermediary of a saturable reactor 4 included in a magnetic assist circuit 13 connected to a high-voltage power supply 1, a discharge gap 9 connected in parallel with a peaking capacitor 8 which is connected to the main capacitor 5 through the intermediary of a thyratron 3 and the saturable reactor 4 and charged by discharge of the main capacitor 5, a part of a discharge current of the peaking capacitor 8 is extracted through a diode 6, and the saturable reactor 4 is reset by the extracted current.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge circuit for a pulse laser device, and more particularly to resetting a saturable reactor of a magnetic assist circuit.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 2, a discharge circuit for a pulse laser device (hereinafter referred to as "pulse discharge circuit") has a high voltage power source 1 and a protective resistor 2 on the positive side of the high voltage power source 1. Connected to the saturable reactor 4 and the main capacitor 5 connected in series with the saturable reactor 4
And a charging reactor 7 connected in parallel to the main capacitor 5 and the other end connected to the negative side of the high-voltage power supply 1.
And a peaking capacitor 8 and a pair of main discharge electrodes 10.
a discharge gap 9 for generating a laser composed of a and 10b, and a thyratron 3 which is a high-speed switching element connected between the protective resistor 2 and the saturable reactor 4 on the negative side of the high-voltage power supply 1 are connected. There is.

The operation of the pulse discharge circuit having such a connection state is as follows. First, when the thyratron 3 is not turned on, the protective resistor 2, the saturable reactor 4, the main capacitor 5 and the charging capacitor are charged from the positive side of the high voltage power source 1. Reactor 7,
A closed loop is formed with the negative side of the high voltage power supply 1, and the main capacitor 5 is charged.

After the main capacitor 5 is charged, when a voltage is applied to the grid of the thyratron 3 to turn it on, the electric charge stored in the main capacitor 5 is passed through the thyratron 3 in the conductive state to a current in the direction of the peaking capacitor. I ₁ flows, and the electric charge stored in the main capacitor 5 moves to the peaking capacitor 8.

At this time, for the purpose of protecting the thyratron 3 and reducing the power loss, the saturable reactor 4 delays the current flow until the thyratron 3 settles in a conductive state. This is a well-known circuit operation called a magnetic assist circuit, in which the saturable reactor 4 saturates after a certain time has passed after the current has flowed in the saturable reactor 4, whereby the inductance drops sharply and the thyratron 3 is affected. It has a circuit configuration that utilizes the action of the saturable reactor 4 of flowing a large current.

As shown in FIG. 3, the hysteresis curve of the saturable reactor 4 constituting the magnetic assist circuit reaches the point b when a current gradually flows from the initial operating point a.
A large current flows due to a sudden decrease in inductance. After that, the current decreases to zero while tracing the hysteresis curve several times. At this time, the residual magnetic flux of the saturable reactor 4 is on any point of H = 0 in the hysteresis curve.

Therefore, in order to always stably and effectively use the high inductance state of the saturable reactor 4, the magnetic body is saturated in the direction opposite to the operating direction (point c),
It is necessary to perform a so-called reset operation.

FIG. 4 shows an essential part of a reset circuit in which the saturable reactor 4 is provided with a switch 12 for resetting. In order to saturate the saturable reactor 4 in a direction opposite to its operating direction. , The switch 12 is turned on to supply the DC power 11 and saturate in the opposite direction to stabilize the operation of the saturable reactor 4.

[0009]

However, in order to reset the saturable reactor in the conventional manner as described above, a separate DC power source is required to pass a current in the resetting direction of the saturable reactor, and the switch is required. There is also a problem in that a complicated timing circuit for synchronously operating the circuits is required, and a circuit for achieving resetting is large-scaled.

The present invention has been made in view of the above problems, and resets the magnetic assist circuit by a simple circuit.
An object of the present invention is to provide a discharge circuit for a pulse laser device which can omit a DC power supply for resetting and a timing circuit.

[0011]

The above object of the present invention is to connect a main capacitor, which is connected to a high-voltage power supply and is charged through a saturable reactor, and a main capacitor, which is connected to the main capacitor through a high-speed switching element and the saturable reactor. A discharge gap, in which a peaking capacitor that is charged by the discharge of the main capacitor is connected in parallel, and a reset circuit that saturates the saturable reactor in a direction opposite to the operating direction by a partial discharge current of the peaking capacitor are provided. And a discharge circuit for a pulse laser device.

[0012]

According to the above configuration of the present invention, a high speed switching element, for example, a thyratron is turned on, and after a certain period of time, the saturable reactor is saturated and the electric charge charged in the main capacitor is transferred to the peaking capacitor.
As a result, a discharge current flows in the discharge gap, and the peaking capacitor is repeatedly charged and discharged with the polarities reversed. The saturable reactor is reset by taking out a part of the discharge current of the peaking capacitor and supplying it to the saturable reactor. Therefore, it is not necessary to prepare a separate DC power supply or timing circuit for resetting the saturable reactor, and a simple discharge circuit for a pulse laser device can be obtained.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. The same parts are denoted by the same reference symbols throughout the drawings.

FIG. 1 is a diagram showing a discharge circuit for a pulse laser device according to an embodiment of the present invention. The discharge circuit for a pulse laser device (hereinafter referred to as "pulse discharge circuit") in this embodiment is, for example, a rare gas. This is a discharge circuit of an excimer laser device or the like that is generated by performing discharge and excitation in a mixed gas of a halogen gas and, and is basically the same as the circuit configuration of FIG. 2 described in the prior art.

That is, as shown in FIG. 1, the circuit configuration for forming the pulse discharge circuit includes a high-voltage power source 1 and a high-voltage power source 1.
The magnetic assist circuit 13 connected in series to the positive side of the magnetically assisted circuit via the protection resistor 2, the main capacitor 5 connected in series to the magnetic assist circuit 13, and the main capacitor 5 at one end.
The main capacitor 5 connected to the other end and the other end connected to the charging reactor 7 connected to the negative side of the high-voltage power supply 1.
Charging circuit.

The protective resistor 2 and the magnetic assist circuit 13 are also provided.
And a high-speed switching element (thyratron in this embodiment) 3 connected to the negative side of the high-voltage power supply 1 of the charging reactor 7, and the charging reactor 7 are connected in parallel to discharge in the discharge gap 9. A discharge circuit for the main capacitor 5 is constituted by a peaking capacitor 8 for supplying a discharge current to be generated and a pair of main discharge electrodes 10a, 10b connected in parallel to the peaking capacitor 8 and having a discharge gap 9 for generating a laser beam. I have it.

It comprises a magnetic assist circuit 13, a main capacitor 5 and a reset circuit 14 connected in parallel with the thyratron 3.

The thyratron 3 is, for example, a high-speed switching element that is turned on / off several thousand times per second, one end of which is connected to one end of the saturable reactor 4 and the other end of which is connected to the negative side of the high-voltage power supply 1. There is.

It should be noted that a switching drive unit for applying an electric pulse signal to the grid of the thyratron 3 to perform a switching operation and an electrode and a circuit for preliminary ionization discharge performed prior to the main discharge are omitted.

The magnetic assist circuit 13 is composed of the saturable reactor 4. The saturable reactor 4 is composed of a ring-shaped magnetic body 4a and a charging / discharging winding 4b wound around the magnetic body 4a. One end of the charging / discharging winding 4b is connected to one end of the thyratron 3 and The end is the main capacitor 5
Is connected to one end. In addition, this saturable reactor 4
The operating characteristics of are the same as those of the hysteresis curve shown in FIG.

The main capacitor 5 is for charging and discharging a high voltage from the high voltage power source 1, one end of which is connected to the other end of the charging / discharging winding 4b of the saturable reactor 4, and the other end is one of the main capacitors. It is connected to the discharge electrode 10a.

The reset circuit 14 includes the saturable reactor 4
Is wound in parallel with the charging / discharging winding 4b wound around the magnetic body 4a, and the reset winding 4c has a smaller number of turns than the charging / discharging winding 4b. The resetting high-voltage diode 6 is connected in series.

In order to effectively and stabilize the magnetic body 4a of the saturable reactor 4, the reset winding 4c causes a current to flow in a direction opposite to the operating direction of the saturable reactor 4 and saturates it in the opposite direction. High-voltage diode 6 at one end
Of the high voltage power supply 1 and the other end is connected to the negative side of the high voltage power supply 1.

The high voltage diode 6 has a higher impedance than the impedance on the discharge gap 9 side, for example, when a large current of several kiloamperes flows in the discharge gap 9,
It is a diode that flows from several amps to tens of amps.
The anode side is connected to the main discharge electrode 10a side, and the cathode side is connected to one end of the reset winding 4c.

The operation of the pulse laser device having such a connection state is as follows. First, when the thyratron 3 is not turned on, from the positive side of the high voltage power source 1, the protective resistor 2, the magnetic assist circuit 13 (saturable reactor 4), A closed loop is formed with the main capacitor 5, the charging reactor 7, and the negative side of the high-voltage power supply 1, and the main capacitor 5 is charged.

After the main capacitor 5 is charged, when a voltage consisting of an electric pulse signal is applied to the grid of the thyratron 3 to turn it on, the electric charge accumulated in the main capacitor 5 is passed through the thyratron 3 to the peaking capacitor 8 side. It is possible to set up a system in which a current I _{1 is} passed through. At this time, in order to stabilize the conduction state of the thyratron 3, after the saturable reactor 4 forming the magnetic assist circuit 13 is saturated, the electric charge stored in the main capacitor 5 is transferred to the peaking capacitor 8 with a delay.

When the voltage of the pair of main discharge electrodes 10a and 10b reaches the discharge start voltage by charging the peaking capacitor 8, the charge accumulated in the peaking capacitor 8 flows into the discharge gap 9 of the main discharge electrodes 10a and 10b (current I ₂ ) A pulse discharge is formed, the laser medium is excited, and laser oscillation occurs.

On the other hand, the charge stored in the peaking capacitor 8, the discharging current I2 flowing through the discharge gap 9 side, the current I ₃ of the part flows to the high-voltage diode 6 side of the reset circuit 14. A part of the current I ₃ flowing to the high voltage diode 6 side is generated by the magnetic substance 4 of the saturable reactor 4.
It flows through the reset winding 4c wound around a. That is, the saturable reactor 4 can be saturated in the direction opposite to the operating direction (point c in FIG. 3). The so-called saturable reactor 4 is automatically reset.

Since the impedance on the high voltage diode 6 side is considerably larger than that on the discharge gap 9 side, the current flows from only several amperes to several tens amperes (current I ₃ ) sufficient to reset the saturable reactor 4. A large current (current I ₂ ) of several kiloamperes flows on the discharge gap 9 side. Therefore, the discharge operation in the discharge gap 9 and the reset operation of the saturable reactor 4 are not hindered.

[0030]

As described above, according to the discharge circuit for a pulse laser device of the present invention, the saturable reactor forming the magnetic assist circuit is reset by utilizing a part of the current flowing in the discharge gap. Therefore, even if a DC power supply or a switch for resetting the saturable reactor forming the magnetic assist circuit is omitted, the reset can be performed easily and automatically, which is an extremely excellent effect.

[Brief description of drawings]

FIG. 1 is a discharge circuit diagram for a pulse laser device according to an embodiment of the present invention.

FIG. 2 is a discharge circuit diagram for a conventional pulse laser device.

FIG. 3 is a hysteresis curve diagram showing magnetic characteristics of a saturable reactor forming a magnetic assist circuit.

FIG. 4 is a reset circuit diagram of the saturable reactor shown in FIG.

[Explanation of symbols]

 1 High Voltage Power Supply 2 Protection Resistor 3 Thyratron 4 Saturable Reactor 4a Magnetic Material (Ring) 4b Charging / Discharging Winding 4c Reset Winding 5 Main Capacitor 6 High Voltage Diode 7 Charging Reactor 8 Peaking Capacitor 9 Discharge Gap 10a, 10b Main discharge electrode 13 Magnetic assist circuit 14 Reset circuit

Claims (1)

[Claims] 1. A main capacitor connected to a high-voltage power supply and charged through a saturable reactor, and peaking connected to the main capacitor through a high-speed switching element and the saturable reactor and charged by discharging the main capacitor. A discharge for a pulse laser device, comprising a discharge gap in which capacitors are connected in parallel, and a reset circuit for saturating the saturable reactor in a direction opposite to an operating direction by a partial discharge current of the peaking capacitor. circuit.