JPH02106985A - Pulse laser device - Google Patents

Abstract

PURPOSE:To stabilize the operation of a magnetic pulse compression circuit, and to stabilize a laser output by using a battery as a power supply for resetting a saturable reactor and inserting impedance such as inductance between the saturable reactor and the battery of a reset circuit. CONSTITUTION:A reset device is composed of reset coils 19, 20, 21, batteries 25, 26, 27 as reset power supplies and additional impedance 22, 22', 23, 23', 24, 24'. The reset coils 19, 20, 21 are wound on the cores 6', 7', 8' of a saturable reactor. Reset currents 28, 29, 30 flow in the direction opposite to main currents 12, 13, 14 by the power supplies. When a magnetic pulse compression circuit is operated, high voltage pulses are generated among the terminals of saturable reactors 6, 7, 8, but the elements 22, 22', 23, 23', 24, 24' such as the inductance having impedance values sufficiently larger than the internal impedance of, the batteries 25, 26, 27 are inserted, thus preventing the generation of overvoltage on the battery side.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a pulse laser device, and in particular to a pulse laser device that stabilizes the operation of its magnetic pulse compression circuit and stabilizes the laser output. This invention relates to a laser device.

(Prior Art) In recent years, industrial use of various pulsed lasers such as high-output TEA and TEMA-CO2 lasers, excimer lasers, and copper vapor lasers has been studied. These lasers are now required to have high speed, large current, and repetitive pulse power. In such power supplies, the power burden of the switching elements that open and close large currents is extremely large, so the switching elements currently used, such as thyratrons and thyristors, are often unable to open and close, and pulsed lasers have a slow operation time. Since the switching time is required to be short (several tens of nanoseconds or less) and long life (about 10" shots or more), there are almost no switching elements that can be put to practical use.

Therefore, recently, by adding a pulse compression circuit to reduce the power burden on the switching element, high speed, large current,
Attempts have been made to realize a high-output pulse power source, and a magnetic pulse compression circuit is a typical example. This magnetic pulse compression circuit utilizes the saturation of magnetization of a ferromagnetic material such as an iron core. (For example, Japan
e Journal of Applied Physi
cs Vol, NO, 11, 1985, PPL855-
L857゜"Pulsed CO2La5er P
u1sed by an All 5olid
6(A) shows an example of such a magnetic pulse compression circuit.

In FIG. 6(A), full f! The power source l is connected to a first capacitor 3 via a charging resistor 2, and the first! Second and third capacitors 4.5 are connected in parallel to the capacitor 3. 1st. A first saturable reactor 6 is connected in series between the second capacitors 3 and 4; Third
A second saturable reactor 7 is connected in series between the capacitor 4.5. The third capacitor 5 has
A third saturable reactor 8 is connected in series, and a laser discharge section 9 is connected in parallel through this.

With the above configuration, the first capacitor 3
a first-stage loop that leads to the second capacitor 4 via the saturable reactor 6, and a second-stage loop that leads from the second capacitor 4 to the third capacitor 5 via the second saturable reactor 7. and a third stage loop extending from the third capacitor 5 to the laser discharge section 9 via the third saturable reactor 8 are formed. Further, the connection between the first capacitor 3 and the first saturable reactor 6 can be opened and closed by a switch 10. The operation of the circuit of FIG. 6(A) having such a configuration is as follows.

First, the first capacitor 3 is charged from the charging power source 1 via the charging resistor 2. When the switch 10 is turned on here, the voltage between the electrodes of the first capacitor 3 is applied to the series circuit of the first saturable reactor 6 and the second capacitor 4. At this time, no charge is stored in the second capacitor 4,
Since the voltage between the electrodes of the second capacitor 4 is almost zero, the voltage between the electrodes of the first capacitor 3 is almost entirely in front of the electrodes of the first saturable reactor 6, and as a result, the voltage between the electrodes of the first saturable reactor 6 A small current 12 flows between the poles of the reactor 6. This electrician 2 excites the first saturable reactor 6.

Above a certain value, the iron core magnetic flux density of the first saturable reactor 6 exceeds the saturation magnetic flux density, and the first saturable reactor 6 becomes saturated. Then, since the inductance of the first saturable reactor 6 rapidly decreases, current 12 flows from the first capacitor 3 through the saturable reactor 6 of f51 in the saturated state, and charges the second capacitor 4. Here, the frequency of the current 12 flowing through the first stage loop is approximately determined by the capacitance value of the first capacitor 3, the inductance value of the first saturable reactor 6 at saturation, and the capacitance value of the second capacitor 4. It's decided. Subsequently, the voltage between the electrodes of the second capacitor 4 increases, and a voltage is applied between the electrodes of the second saturable reactor 7.

A current 13 flows through the second saturable reactor 7 and reaches saturation. At this time, the charge on the second capacitor 4 is transferred to the third capacitor 5. The operation of the third saturable reactor 8 is also similar.

Here, in order to increase the frequency of the [streams 12 to 14] of each stage flowing through each saturable reactor 6 to 7 in order, the first, second, and so on flows are sequentially increased. A method is adopted in which the inductances of the third saturable reactors 6 to 8 are sequentially reduced during unsaturated and saturated states. Furthermore, in order to efficiently transmit the energy transferred to each capacitor to the subsequent capacitor, a method is used in which the capacitances of the capacitors in each stage are made equal and the values of the saturable reactors 12 to I4 are successively reduced. In this method, the voltage of the loop at each stage is constant, and the peak values of the currents 12 to 14 flowing through the loop at each stage are sequentially amplified and one frequency is raised, as shown in Fig. 6 (B) or D). and,
The current 14 in the final stage loop compressed by the magnetic pulse flows into the laser discharge section 9, which is the load, and causes laser oscillation.The operation process of saturation and non-saturation of the saturable reactor described above is shown in Figure 7. This will be explained next using In addition, FIG. 7 is a graph showing the magnetization curve of the iron core that constitutes the saturable reactor.

First, when an exciting current flows from the capacitor at the front stage of the saturable reactor, the operating point of the iron core of the saturable reactor moves toward a point from the center 0 point in FIG. When the operating point reaches zero due to the excitation current, the magnetic flux density within the iron core of the saturable reactor becomes equal to or higher than the saturation magnetic flux density, and the saturable reactor enters a saturated state. At this time, the inductance of the saturable reactor decreases rapidly, so that the inductance of the saturable reactor is transferred from the previous stage capacitor to the saturable reactor that is in the saturated state.

Current flows into the subsequent capacitor and charges it. In this way, when the saturable reactor is saturated, the operating point of the iron core is at a point where the magnetizing force H is much larger than the zero point, but as the flow decreases, it moves to the side where the magnetizing force H is smaller. At this point, the core goes from saturated to unsaturated. At this time, since the inductance of the saturable reactor increases rapidly, the current flowing through the saturable reactor decreases rapidly. When the half-cycle post-current becomes zero, the operating point becomes point ■, where it stops and residual magnetism remains.

By the way, if the switch 10 is turned on again with the operating point of the iron core at point ■, the operating point of the iron core moves in the direction from ■ to ■, but since the amount of change in magnetic flux in this case is small, The inductance of the saturation reactor cannot be sufficiently large, and magnetic pulse compression can hardly be performed. Therefore, after performing the magnetic pulse compression once, the operating point of the iron core is returned to the center 0 point via the 0 point in Fig. 7.
A so-called magnetic reset is performed so that the same level of magnetic pulse compression can be performed again. That is, the conventional circuit is provided with a reset device for performing the magnetic reset as described above, as shown at 16 to 18 in FIG. 6(A). There are several methods for magnetic reset, but the simplest one is to flow a direct current in the opposite direction so that the operating point of the iron core becomes zero. According to this method of flowing direct current, after magnetic pulse compression operation is performed, the operating point of the iron core is
However, if the next magnetic pulse compression operation is performed in this state, the magnetic flux change can be larger than that performed from zero point, and the compression ratio can be increased, so this method is considered to be highly practical.

(1111 problems to be solved by the invention) In order to set the operating point of the saturable reactor in the magnetic pulse compression circuit to an appropriate position, a reset current is passed as described above, but this reset circuit generally uses a saturable reactor. It consists of a coil winding wound around an iron core separately from the main circuit winding.

The DC ffi current described above is passed through this winding, but since the reset winding is electromagnetically coupled to the main circuit winding, the voltage generated in the main circuit corresponds to the turns ratio of these windings. There is a possibility that this problem may occur in the reset winding as well.

An object of the present invention is to provide a magnetic pulse compression circuit that does not cause the problems that may occur in magnetic pulse compression circuits as described above, and to provide a highly stable pulse laser device.

[Structure of the invention]

(Means and effects for solving the problems) As a result of analyzing the technical problems described above, in order to solve these problems, it is necessary to use a power supply with a structure or method that can be isolated from the outside as the reset power supply of the magnetic pulse compression circuit. It was found that an appropriate value of impedance should be inserted to prevent the voltage corresponding to the turns ratio between the main circuit winding and the set circuit winding.

Next, the effects of configuration 1 of the present invention will be explained based on specific embodiments of the present invention.

(Embodiment) An embodiment of the present invention is shown in FIG. 1. Since most of the drawings are the same as those used in the explanation of the prior art, a detailed explanation will be omitted. It corresponds to In this figure, the reset device is reset coil 19.20.2
1. Power storage area 25, 26, 27. and additional impedance 22.22'23, 23', 24.
It consists of 24'. Reset coil 19.20.
21 is wound around the iron cores 6'7' and 8' of the saturable reactor. This power supply generates a reset current of 28.29.
30 flows in the opposite direction to the main current 12, 13, 14.

When the magnetic pulse compression circuit operates, a saturable reactor6.
7. A high voltage pulse occurs between the terminals of 8, but the
5.22 Element 22 such as an inductance with an impedance value sufficiently larger than the internal impedance of 27
．． 22', 23.23', and 24.24' are inserted, and no excessive voltage occurs on the side of the power storage area.

By configuring the magnetic pulse compression circuit in this manner, a sufficient reset current can flow through the saturable reactor, and an excessive voltage generated during operation of the magnetic pulse compression circuit will not appear on the power supply side. Furthermore, since the reset can be performed using a direct current, the point at which the saturable reactor starts operating can be placed at a point corresponding to (■) in FIG. 7, so that a sufficient magnetic compression effect can be obtained.

Therefore, it can be seen that the operating condition of the laser is always constant and stable laser oscillation can be obtained.

Next, FIG. 2(A) is a circuit diagram of another embodiment, and FIG. 2(B) is a circuit diagram of another embodiment.
shows the operation timing of the switch and magnetic pulse compression circuit in the same embodiment.The operation of one circuit itself is basically the same as that described in the explanation of the prior art, so the details will be omitted here. Identical numbers indicate identical component parts.

In this embodiment, the reset device is a reset coil 19°20
, 21, Reset power source with storage battery 25.26.27. and additional impedance 22.22', 23.23'
, 24.24' and 31.32.33. The reset coils 19, 20, 21 are wound around the iron cores 6', 7', 8' of the saturable reactor. Switches 34° 34', 35, 35', 36.
36' is provided, and this switch is closed only when performing the magnetic pulse compression operation as shown in FIG. 2(B), and a reset current of 2 g, 29°30 flows.

By configuring the magnetic pulse compression circuit in this way, it is possible to perform a reliable reset operation with less consumption of the battery by supplying the reset current only for the necessary time. Also, in the unlikely event that one of the switches fails and does not close, the additional impedance 31, 32.
33 is sufficiently smaller than the impedances 22 to 24', so no excessive voltage is generated on the power supply side. As a result, the magnetic pulse compression circuit remains at the initial setting value without changing and always operates in the same state. It becomes possible to do so.

Therefore, it is possible to ensure that the operating conditions of the laser are always constant and stable laser oscillation can be obtained.

Next, FIG. 3(^) shows only one set of the reset device part of the circuit diagram of still another embodiment. FIG. 3(B) shows the circuit operation of the embodiment.

The basic configuration is almost the same, so a detailed explanation will be omitted, but the same numbers represent the same components as before. The operating point of the saturable reactor can be determined by closing the switches 34, 34' and allowing the charge on the capacitor to flow into the reset circuit. This is also sufficient only for a limited time before and after the operation of the magnetic pulse compression circuit, and during other times the switches 34 and 34' are shut off, and furthermore, while this is shut off, the switches 40 and 40 are closed.
' is closed and the capacitor 41 is charged.

FIG. 4(A) shows an attempt to charge the capacitor 41 with the overvoltage generated when the saturable reactor operates by making the additional impedance smaller than the conventional one. When the capacitor 41 is charged, first.

- once disconnected from the circuit, and after an appropriate period of time switch 3
4.34' is applied, the capacitor 411 is discharged, and a reset current is supplied. The timing of the operation is shown in FIG. 4(B).

FIG. 5(A) shows the timing of the operation of operating the switches 34, 24', 40, etc. so that when the capacitor 41, 41' is charged, it is connected in series and discharged to supply a reset current. It is shown in FIG. 5 (El).

According to the present invention, when the magnetic pulse compression circuit is in operation, there are no active circuit elements in the reset circuit, but only passive elements, which increases reliability and allows stable operation.

Therefore, it can be seen that the operating condition of the laser is always constant and stable laser oscillation can be obtained.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to obtain a pulsed laser device that stabilizes the operation of the magnetic pulse compression circuit and stabilizes the laser output in a repetitive pulsed laser.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing an embodiment of the present invention, Fig. 2 (A) is a circuit diagram of another embodiment, and Fig. 2 (B) is an operation of a switch used in the embodiment of Fig. 2 (^). A diagram showing the timing, FIG. 3(A) is a circuit diagram of another embodiment, FIG. 3(B)
) is a diagram showing the operation timing of the switch used in the embodiment of FIG. 3(^), FIG. 4(^) is a circuit diagram of still another embodiment, and FIG. 4(0) is a diagram of FIG. 4(A). FIG. 5 is a diagram showing the operation timing of the switch used in the embodiment.
A) is a circuit diagram of yet another embodiment, FIG. 5(B) is a diagram showing the operation timing of the switch used in the embodiment of FIG. 5(A), and FIG. 6(A) is a diagram of the magnetic pulse compression circuit. FIGS. 6(B), 6(C), and 6(D) are diagrams showing the operation of the magnetic pulse compression circuit, and FIG. 7 is a graph showing the magnetization curve of the iron core constituting the saturable reactor. 1.2... Charging 'a source 3,4.5...
・Capacitor 6.7.8...Saturable reactor 1
9,20.21...Reset coil 22.23.24
...Additional impedance 25.26.27...Electricity storage area agent Patent attorney Nori Ken Chika Ken 3σ Figure (B) Figure (A) (A) (B) Figure (A) Figure (8) Figure (A) C,C) Figure (A') Figure CB) Figure

Claims (1)

[Claims] In a pulse laser device having a magnetic pulse compression circuit consisting of a capacitor and a saturable reactor that compresses the time width of the current input from the capacitor and outputs the current, an electric storage ground is used as a power source for resetting the saturable reactor. A pulse laser device characterized in that an impedance such as an inductance is inserted between a saturable reactor of a reset circuit and a power storage ground.