JPH02105479A - Pulsed laser power source - Google Patents

Abstract

PURPOSE:To prevent current from flowing from a laser device to a magnetic compression circuit by providing a device to prevent reverse current between a saturable reactor of a final stage of the magnetic compression circuit and the laser device. CONSTITUTION:A diode 23 is provided between a saturable reactor 21 of a final stage and a laser device 22. An electric charge stored in capacitors 8, 9, 10 of a charge power source is charged to a capacitor of a first stage of a magnetic compression circuit through a pulse transformer 11 at a fixed frequency. A voltage rises to the capacitor 16 of the first stage of the magnetic compression circuit at the frequency. When it attains to a saturated voltage of the saturable reactor 19 of the first stage, an electric charge is transferred to a capacitor of the next stage through the saturable reactor 19. Similarly, electric charge is transferred to a capacitor 18 of a third stage through a saturable creator 20. Finally, an electric charge is input to a discharge section through the saturable reactor 21 and the diode 23.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a pulsed laser power supply for realizing a stable pulsed laser power supply.

(Prior Art) Various lasers such as TEA and TEMACO2 lasers, excimer lasers, and copper vapor lasers are being considered for use in industry, and at the same time, excellent pulse power sources for these lasers are required. It has become. A similar power supply is also required for Fast Pulsad% agnats in accelerators.

This type of pulse power supply has a fast current rise (100k).
A/μ5ec), large m (~10kA), high voltage (
~150kV), saturable reactor with low impedance and high reactance ratio, responds well with C number M& or higher, and has a large inductance ratio between saturated and non-saturated), very narrow pulse width (100nsec)
), jitter time (number + n5ac or less).

Conditions such as long life (about 101 to 11 or more) are required.

The electric circuit shown in FIG. 3 was devised for the above purpose. In the electric circuit shown in FIG. 3, the low voltage side of the pulse transformer 11 is a switch circuit for generating pulse current, and the high voltage side is a magnetic pulse compression circuit (Magnetic pulse compression circuit).
Pulse Compression=NPC circuit)
It is an electrical circuit called.

In the switch circuit formed on the low voltage side of the pulse transformer 1 shown in FIG.
4 and rectifiers 5 to 7, and three capacitors 8 to 10 are connected in parallel to the low voltage side of the pulse transformer 11. In addition, thyristors 12 to 1, which are switching elements,
4 is adapted to be ignited by a driver 15.

The operation of such a switch circuit is as follows: First, the charging power supply 1
According to charging reactor 2.3.4 and rectifier 5.
6.7, the capacitor 8.9.10 is always charged to a constant voltage. Here, by firing the thyristors 12 to 14 one after another by the driver 15 so that the frequency required for the entire power supply is reached, a pulse current is generated on the low voltage side of the pulse transformer 11 at the required number of repetitions. do.

In the example shown in Figure 3, the number of thyristors is three, that is, the circuit connected to the low voltage side of the pulse transformer is connected in three parallels, but this depends on the number of repeated pulses required as a power source and the capacity of the thyristor. In response to the.

You will choose an appropriate number. For example, the limit for general Cyrisk is that it can be used at several hundred meters and at a repetition frequency of about 1 kHz. Therefore, for example, if the repetition frequency is 5kHz
In the case of z, the number of parallel thyristors is 7 to 10 or more.

In addition, in Fig. 3, the switching element for generating a repetitive pulse current is not limited to a thyristor, but a mechanical switch is used as the switching element under severe conditions as described above. However, there are problems in terms of lifespan and jitter, and in the end thyristors are the most suitable.

The switch element used in such a switch circuit plays the role of transmitting energy from the charging power source to the NPC circuit side with a constant pulse width, and a thyratron or a semiconductor is considered to be optimal for this switch element, but the above-mentioned In high voltage power supply circuits such as
Therefore, a large switch must be used.

On the other hand, the MPCI'l path on the high voltage side of the pulse transformer 11 is connected to capacitors 16 to 18 of appropriate values and a saturable reactor 19.
21 are combined in three stages, and each stage of circuits is configured to sequentially compress the time width of the current input from the low voltage side of the pulse transformer 11. With such a configuration, by reducing the time width of the current input from the low voltage side of the pulse transformer to about one hundredth, the rate of increase in current can be increased to the above-mentioned 100 kA/μsec or more.

To describe the operation of the high voltage side of the pulse transformer 11 in detail, when a voltage is induced on the high voltage side of the pulse transformer 11,
The interelectrode voltage of the first stage capacitor 16 increases in proportion to this voltage. As a result, a small amount of current flows into the first stage saturable reactor 19 in proportion to the voltage between the poles of the capacitor 16, but when this current reaches a certain value, the number of magnetic fluxes in the iron core of the saturable reactor 19 becomes saturated. When the magnetic flux density exceeds the saturable reactor 19, the saturable reactor 19 becomes saturated, the inductance rapidly decreases, and the energy stored in the capacitor 16 is transferred to the second stage capacitor 17 through the saturable reactor 19. In this case, by sequentially decreasing the inductance of the saturable reactors 19, 20, and 21 in each stage when they are not saturated and when they are saturated, the frequency of the current flowing through each stage can be made successively higher.

By the way, the relationship between the first-stage capacitor 16, the first-stage saturable reactor 19, and the second-stage capacitor 17 is such that when the saturable reactor 19 is non-saturated, the frequency of the current flowing through this loop is single stage capacitor 16
By setting the impedance of the first stage saturable reactor 19 and the non-saturated impedance of the first stage saturable reactor 19 to appropriate values, the first stage capacitor 16 to the second stage capacitor 17
To be able to adjust the timing at which energy is transferred to the saturable reactor 19, and to make the impedance of the saturable reactor 19 at saturation sufficiently larger than the impedance of the second stage capacitor 17 at the current frequency flowing when the saturable reactor 19 is saturated. Accordingly, almost all the energy of the first stage capacitor 16 can be transferred to the capacitor 17.

Similarly, the operation of the saturable reactors 20, 21 transfers energy to the laser device 22. Repeat this operation and operate.

(Problems to be Solved by the Invention) Regarding the conventional power supply for pulsed lasers as described above, stable operation of the magnetic compression circuit depends on whether the energy transfer of the capacitor can be carried out smoothly. If the laser device does not discharge and voltage remains in the laser device, the charge will flow back from the laser device to the magnetic compression circuit side, making it impossible to perform stable operation.

Therefore, the present invention was proposed in order to eliminate the above-mentioned drawbacks, and its purpose is to provide a power source for a pulsed laser that can obtain stable output by stably operating a magnetic compression circuit. .

[Structure of the invention]

(Means for Solving the Problems) The pulsed laser power supply of the present invention has a device for preventing current backflow between the saturable reactor at the final stage of the magnetic compression circuit and the laser device, so that magnetic It is constructed to prevent current from flowing into the compression circuit.

(Function) According to the present invention having such a configuration, the magnetic compression circuit can be operated with stable operation, and stable output can be obtained.

(Example) An example of the present invention will be specifically described below with reference to FIG. Incidentally, the same members as those of the conventional type shown in FIG. 3 are denoted by the same reference numerals, and the description thereof will be omitted.

In this embodiment, as shown in the circuit diagram of FIG.
A diode 23 is provided between the final stage saturable reactor 21 and the laser device 22. The charges stored in the capacitors 8, 9, and 10 of the charging power source are charged at a certain frequency to the capacitor 16 of the first stage of the magnetic compression circuit via the pulse transformer 11. When the voltage rises in the capacitor 16 of the first stage of the magnetic compression circuit at that frequency and reaches the saturation voltage of the saturable reactor 19 of the first stage, the charge is transferred to the capacitor 17 of the next stage via the saturable reactor 19. .

Similarly, charges are transferred to the third stage capacitor 18 via the saturable reactor 2o. Finally, the charge is input to the discharge section via the positive saturation reactor 21 and the diode 23.

What is shown in FIG. 2 is another embodiment of the present invention, in which a gap 25 consisting of a parallel electrode 23 and a needle-shaped electrode 24 is provided between the saturable reactor at the final stage and the laser device. When the voltage rises, the gap 25 does not discharge, and when the charge remains in the laser device, the gap 25
By discharging, the current flows and prevents it from flowing into the magnetic compression circuit side, eliminating instability in the operation of the magnetic compression circuit, and preventing damage to the laser device and charging power supply when performing repeated operations. Can perform actions.

In the pulsed laser power supply of this embodiment having such a configuration, if there is no glow discharge in the discharge section of the laser device 22 shown in FIG. This prevents charges from flowing backward into the final stage capacitor 18 of the magnetic compression circuit when a reverse voltage is applied.

It is possible to prevent the operation of the magnetic compression circuit from becoming unstable. Furthermore, when performing repeated operations, damage to the laser device and the charging power source can be prevented and stable operations can be performed.

In this way, by using the pulsed laser power supply of this embodiment, it is possible to block the flow of current from the laser device to the magnetic compression circuit and stabilize the operation of the magnetic compression circuit, resulting in a pulsed laser that provides stable output. You can get power for

〔Effect of the invention〕

As described above, according to the present invention, since the magnetic compression circuit can operate stably, a stable output can be obtained, and a stable power source for a pulsed laser can be provided.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing one embodiment of the power supply for a pulsed laser according to the present invention, FIG. 2 is a circuit diagram showing another embodiment, and FIG. 3 is a circuit diagram showing an example of a conventional power supply for a pulsed laser. be. DESCRIPTION OF SYMBOLS 1... Charging power supply of switch circuit, 8-10... Capacitor, 12-14... Switch element (thyristor), 15.
...Driver, 11...Pulse transformer. 18-21... Saturable reactor, 22... Laser discharge section 523... Diode, 24
... Peaking capacitor, 23 ... Flat plate electrode, 24 ... Needle electrode, 25
...discharge gap.

Claims (1)

[Claims] In a pulsed laser power supply having a switch circuit in which a switch element is connected to a capacitor connected to a charging power supply, and a magnetic pulse compression circuit in which a saturable reactor and a capacitor are connected to a laser discharge section, the final stage in the magnetic pulse compression circuit is A power source for a pulsed laser, characterized in that a device for preventing backflow is connected between the saturable reactor and the laser device.