JPH0276280A - Pulse laser oscillator - Google Patents

Abstract

PURPOSE:To improve energy utilization efficiency of a MPC circuit by dissipating residue charge of a capacitor of a magnetic pulse compression circuit(MPC circuit) into a reset circuit started by a trigger gap. CONSTITUTION:A reset coil winding 2 is wound around a donut-shaped core 1 of saturable reactors SI1 and SI2 of each stage and both edges of this reset coil winding 2 are connected to both edges of a capacitor C2 at the second stage through a trigger gap G and an impedance Z to constitute a reset circuit. Thus, residue charge of capacitor, generated when a MPC circuit operates is discharged through a reset coil winding, a trigger gap, and a series circuit of impedance, thus performing reset operation of saturable reactor automatically every time the operation of the MPC circuit is completed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a pulsed laser oscillation device,
In particular, the present invention relates to an improved technique for resetting a saturable reactor in a device equipped with a magnetic pulse compression circuit.

[Prior Art] Among pulse laser oscillation devices, in a pulse laser oscillation device such as a CO2 laser, one or more pairs of electrodes are provided in a closed container containing a laser medium, and a pulse voltage is applied between the pair of electrodes. The laser medium is excited by discharge. In this case, in a high-output pulsed laser oscillator,
It is necessary to apply a high voltage with an extremely narrow pulse width to the electrodes.

As a method of obtaining such a high pulse voltage with a narrow pulse width, there is a conventional method using a magnetic pulse compression circuit (hereinafter abbreviated as an MPC circuit). The operation of such an MPC circuit will be explained below with reference to FIG.

In Figure 3, three capacitors Co, C1, C2
and a load such as a laser electrode are connected in parallel, a switch So and a reactor Lo are connected between the capacitor Go and the capacitor C1 to form a resonant circuit, and a resonant circuit is formed between the capacitor C1 and the capacitor C2. A saturable reactor S11 is connected to form a first stage MPC circuit, and a saturable reactor Sh is connected between capacitors C2 and C3 to form a second stage MPC circuit. It is configured.

The operation of such an MPC circuit is as follows: First, capacitor Co is charged in advance, and when switch SO is turned on, a (long current Io) flows through a resonant circuit with a loop of reactor LO, capacitor C1, and capacitor CO. , discharges the charge on capacitor CO. At this point, the first
Saturable reactor S, which is a component of MPC opening in the stage
Since h is in an initial non-saturated state and has a high inductance, the resonant current IO hardly flows.

However, due to the resonant current IO, the first stage MPC
As the capacitor C1 of the circuit is charged, the current flowing through the first stage saturable reactor S11 gradually increases and becomes saturated. At this time, since the inductance of the first stage saturable reactor S11 is drastically reduced, when the voltage of the first stage capacitor C1 is at its peak, the charge of this capacitor C1 is changed from the capacitor C1 to the saturable reactor 5.
11-Discharge the circuit with the capacitor C2 as a loop and charge the capacitor C2 as in the previous step.

Similarly to the first stage, in the second stage, as the capacitor C2 is charged, the saturable reactor S
I2 becomes saturated, the inductance decreases sharply, and the second
The charge in the capacitor C2 in the second stage is transferred to a load such as a laser electrode.

In this way, in the process of transferring the charge of the capacitor Go to the load such as the laser electrode, the charge of the capacitor Go is transferred to the saturable reactor S1.
1. SI2 inductance and capacitors C1 and C2
By roughly matching the capacitances of , the resonant frequency is significantly increased and the voltage is shaped into a voltage with a progressively narrower pulse width.

By the way, the saturable reactor S11. used in the above MPC circuit. SI2 needs to be reset after performing magnetic pulse compression once.

This point will be explained below. That is, the MPC circuit has an unsaturated inductance of a saturable reactor,
A high pulse compression ratio is achieved by the difference between the inductance at saturation and the inductance at saturation. In this case, the change in inductance is determined by the change in relative magnetic permeability of the iron core of the saturable reactor, so in order to always perform pulse compression at a constant ratio in the MPC circuit, it is necessary to always keep the change in relative magnetic permeability the same. There is. Furthermore, in order to make the change in the relative magnetic permeability of the iron core of a saturable reactor the same, the direction of the residual magnetism of the iron core at the start of operation must always be in the same direction. As shown in the hysteresis curve of FIG. 4, the direction of the residual magnetism in the iron core shifts every - time, so it is necessary to magnetically reset the saturable reactor each time.

That is, in the hysteresis curve diagram of FIG. 4, when a voltage V is applied with point a having residual magnetism as the operating point,
A current I flows through the winding of the saturable reactor, and the operating point is a
Move from point to point b. When the magnetic flux generated by this current I reaches the saturation magnetic flux (point B → point C), the value of magnetic permeability μ, which indicates the slope of the hysteresis curve, decreases rapidly, and the inductance of the saturable reactor decreases rapidly. , a large current flows through the circuit. After this, the operating point returns from point 0 to point b again as the current decreases, and when the value of magnetic permeability μ increases rapidly, the inductance of the saturable reactor increases rapidly, so the current flowing through the saturable reactor decreases rapidly. Then, after half a cycle, when the current becomes zero, it stops at point d, which has residual magnetism in the opposite direction to that at the beginning of the operation. If the next magnetic pulse compression operation is performed by applying voltage V again from point d, the operating point will move from point d to point 0, but the amount of magnetic flux change in this case will change from point a to point d. Since it is much smaller than the magnetic flux change amount ΔB when the magnetic flux is moved, the inductance of the saturable reactor during non-saturation is not sufficiently large, and magnetic pulse compression is hardly performed.

Therefore, after performing magnetic pulse compression, the iron core of the saturable reactor is excited in the opposite direction to change the operating point of the iron core to the fourth
It is necessary to perform a so-called magnetic reset from point d in the figure to point e and back again to point a, and only by performing this reset can the next magnetic pulse compression be performed at the same pulse compression ratio.

(Problem to be solved by the invention) By the way, as a method for performing the above reset,
For example, there is a technique as disclosed in Japanese Patent Application Laid-Open No. 60-96182.

In this publication, as shown in Fig. 5, the ratio of the series configuration of capacitors C1 and C2 and the value of capacitor C3 is adjusted so that the energy is uniform when charges are transferred from capacitors C1 and C2 in the direction of C3. The residual charge is not absorbed by the load R1 but is reflected, and the residual charge is exchanged between the series configuration of capacitors C1 and C2 and the capacitor C3, thereby photographing the charge. Then, this charge imaging is used to generate a current in the opposite direction in the saturable reactor SI, thereby performing automatic reset.

However, in such a reset method, a part of the charge in the capacitor is not transferred to the load side, but is returned to the load side, which basically has the disadvantage that the energy utilization efficiency of the MPC circuit itself deteriorates. Another drawback is that the reset operation becomes unstable when an abnormal operation such as arc discharge occurs.

Further, as another reset method, a method of winding a reset winding around a saturable reactor and flowing a direct current can be considered.

As such a method, for example, a reset circuit RE as shown additionally within the dotted line in FIG. 3 can be considered. This reset circuit RE includes a reactor L1, a battery Ba
This is a circuit in which reset is performed by flowing direct current through the windings via the switch S1. Here, reactor L
z is used to prevent the surge voltage induced by the saturable reactors Sll and SI2 from entering the DC circuit and to adjust the reset current.

However, this method has the following drawbacks because it uses a battery Ba. That is,
Battery Ba generally takes a long time to charge, but its current consumption time is short. For applications that require a large reset current, such as iron cores with poor hysteresis characteristics, short life is a major drawback.

The present invention was proposed in order to solve the problems of the prior art as described above, and its purpose is to provide a pulsed laser oscillation device having an MPC circuit without reducing the energy utilization efficiency of the MPC circuit. An object of the present invention is to provide a pulsed laser oscillation device having excellent reset performance and capable of performing a stable reset operation.

[Structure of the Invention] (Means for Solving the Problems) The pulsed laser oscillation device of the present invention includes a reset winding wound one or more times around the iron core of a saturable reactor of an MPC circuit, and a trigger gap and a trigger gap between the reset winding and the trigger gap. The structure is characterized by connecting impedances in series and connecting both ends of this series circuit to both ends of the capacitor.

(Function) In the pulsed laser oscillation device of the present invention having the above configuration, the residual charge of the capacitor generated during the operation of the MPC circuit is discharged through the series circuit of the reset g6, the trigger gap, and the impedance.
The saturable reactor can be reset automatically every time the PC circuit ends its operation. Furthermore, since the configuration utilizes residual charges rather than forcefully returning charges, energy utilization efficiency does not decrease.

(Example) Hereinafter, an example of a pulse laser oscillation device according to the present invention will be specifically described with reference to the drawings.

FIG. 1 is a diagram showing an embodiment in which the present invention is applied to the MPC circuit of FIG. 3. FIG. 1 shows only the periphery of the reset circuit section which is different from the conventional technique shown in FIG. 3, and the drawing is omitted for the same parts as the conventional technique shown in FIG.

In FIG. 1, saturable reactors S11, S
A reset winding 2 is wound around each donut-shaped core 1 of I2, and both ends of the reset winding 2 are connected to both ends of the second stage capacitor C2 via the trigger gap G1 impedance Z. The reset circuit is configured with: Note that ST in the figure is a trigger gap starter.

The operation of this embodiment having the above configuration is as follows.

First, due to the operation of each stage of the MPC circuit, the capacitor Cz
, C2 are transferred to the load side via resonance currents It and I2. Here, the second stage capacitor C
Focusing on the polarity of the charge in 2, when the resonant current 1z flows in the direction shown in the figure due to the operation of the saturable reactor SIz in the first stage, the polarity of the capacitor C2 becomes positive on the upper side and negative on the lower side. 2nd stage saturable reactor SI
When the resonant current I2 flows due to the operation of step 2, the capacitor C
The polarity of 2 is reversed. In this case, since most of the energy is consumed for loading, only the remaining energy remains as charges with reversed polarity.

When this residual charge is flattened to an inverted polarity, the starter ST sends a trigger signal voltage to the trigger gap G, and the trigger gap G starts. As a result, charges of inverted polarity are discharged through the reset winding 2. In this case, the reset current is adjusted to an appropriate current by impedance Z.

Also, in this reset, the second stage capacitor C2
The operating special voltage is on the order of several tens of kilovolts, but in this example,
Since the trigger gap G is used, the reset circuit is separated from the MPC main circuit during this operation, and the
Can withstand KV high pressure.

Therefore, in this embodiment, each stage of saturable reactor S11. The SI2 reset operation can be performed automatically.

In this case, there are no disadvantages as in the prior art using batteries.

Further, unlike the conventional technique in which a portion of the charge of the capacitor is forcibly returned, this embodiment uses only the naturally remaining charge, so there is an advantage that the energy utilization efficiency of the MPC circuit can be increased.

By the way, as a specific structure of the starter ST of the trigger gap G used in the above embodiment, for example, a structure as shown in FIG. 2 can be considered.

The starter ST in FIG. 2 is a series circuit of a reactor LST, a capacitor C3T, a resistor R3□, and a diode D. In the starter ST having such a configuration, the voltage that charges the capacitor C3T generates the trigger signal voltage V, by combining with the induced magnetic flux φ8 and generating the induced electromotive force in the reactor L3□, which starts the trigger gap G. do. Here, the induced magnetic flux φ is the resonant current I of the MPC circuit
This noise is typified by high-energy electromagnetic induction magnetic flux generated by O to ■2. The magnetic field caused by this surge current has a high frequency of several 100 KHz to MH2.

In addition, as the starting timing of the trigger gap G, instead of detecting the residual charge after the polarity of the capacitor C2 is reversed, the time until immediately after the detection of the magnetic flux φN induced by the surge current and the polarity is reversed is determined by the integral shown in FIG. Circuit time constant <C8
It is also possible to adjust the time to match the sum of the start delay time of the trigger gap G and the start delay time of the trigger gap G. In this case, the time from detection of the induced magnetic flux φN to starting the trigger gap is on the order of several μs.

Note that another method for obtaining the trigger signal is to use GTo or thyratron gate signals, but since these pulse power supplies and the MPC circuit are placed apart, wiring problems and Malfunctions and other problems are predicted, making it less practical.

In addition to the above, modifications of the starter ST include:
For example, it is possible to omit the diode D in FIG. 2 and to take the trigger signal voltage V from both ends of the resistor R8T. In this case, it is possible to change the integrating circuit to an LCC common circuit to advance the starting timing. Also, instead of setting the trigger signal voltage V to alternating current, the diode D
It is also possible to create a configuration in which the arrangement is changed to create a pulsating flow.

Roughly speaking, it is also conceivable to replace the resistor R8 with a small superconducting current limiter in such a modified circuit. In this case, the peak current above the current level is quenched and becomes normal conduction, and as a result, a pulse voltage is generated and a trigger signal can be supplied.

In addition, modifications can be made by changing the shape and configuration of the eight reactors.

[Effects of the Invention] As explained above, the present invention has a simple configuration in which the residual charge in the capacitor of the MPC circuit is discharged to a reset circuit that is started by a single torque gap, which makes the MPC circuit more efficient than the conventional one. We can provide a high-efficiency pulsed laser generation (film device) that can automatically perform a stable reset operation while enjoying the energy utilization efficiency of

[Brief explanation of the drawing]

FIG. 1 shows an example of an MPC circuit according to an embodiment of the present invention.
FIG. 2 is a circuit diagram showing details of the trigger gap starter used in the embodiment of FIG. 1; FIG. 3 is a circuit diagram showing a conventional MPC circuit; FIG.
The figure is a curve diagram showing the hysteresis curve of the iron core of the saturable reactor together with the corresponding voltage and current curves, and FIG. 5 is a circuit diagram showing a conventional MPC circuit different from that of FIG. 3. 1... Iron core of saturable reactor, 2... Reset winding, G... Trigger gap, Z... Impedance 1, ST... Starter of trigger gap, Ct, C
2... Capacitor, Sit, 812... Saturable reactor.

Claims (1)

[Scope of Claims] One or more pairs of electrodes are provided in a closed container enclosing a laser medium, and a pulse voltage is applied between the pairs of electrodes to discharge and excite the laser medium, and as a power source, In a pulsed laser oscillation device using a magnetic pulse compression circuit including a capacitor and a saturable reactor, a reset winding is wound one or more times around the iron core of the saturable reactor of the magnetic pulse compression circuit, and the reset winding and a trigger are connected to each other. A pulsed laser oscillation device characterized in that a gap and an impedance are connected in series, and both ends of this series circuit are connected to both ends of a capacitor.