JPS59214283A - Gas laser device - Google Patents

Abstract

PURPOSE:To lower the power loss at the starting of discharge by mounting an auxiliary anode between an anode and a cathode and generating seed discharge between the auxiliary anode and the cathode. CONSTITUTION:An anode 4 and a cathode 5 are mounted into a laser tube 1, and connected to a constant-current high-voltage pulse source 11 through a ballast resistor 10. An auxiliary anode 21 is set up between the anode 4 and the cathode 5, and a capacitor C and a resistor R are connected in series between the auxiliary anode and the anode 4. When pulses are transmitted from a pulse generator 12, output voltage from the constant-current light-voltage pulse power supply 11 begins to rise. The potential of the anode 4 and auxiliary anode 21 rises at the same value, seed discharge is formed between the auxiliary anode 21 and the cathode 5 first, and main discharge is generated between the anode 4 and the cathode 5 when output voltage from the power supply 11 further rises. Beakdown voltage can be lowered by mounting the auxiliary anode 21.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a gas laser device, and particularly to an improvement of a pulse output gas laser device whose output can be varied.

BACKGROUND OF THE INVENTION [0006] Hereinafter, a description will be given of a C02 gas laser device, which is one of the gas laser devices, as an example. In general, CO2 gas laser equipment has 1. (Glow discharge is performed in a mixed gas of e, N, Co□, etc., and the energy difference when CO8 molecules excited by the energy returns to the ground state is extracted as total laser light).

The configuration of a conventional gas laser device is shown in FIG.

In the figure, a ballast resistor 10 and a constant current high voltage pulse power source 11 are connected in series to an anode 4 and a cathode 5 provided in a laser tube 1. Further, the inside of the laser tube 1 is evacuated by a vacuum pump 8, and a laser medium gas 6 is introduced through a fixed diaphragm shift to maintain a constant gas pressure of several kP. Now, when a pulse is supplied from the pulse generator 12, the output voltage of the constant current high voltage pulse power supply 11 increases to several kilograms.
When the voltage increases from v to several tens of kV and reaches the discharge starting voltage between the anode 4 and the cande 5, a discharge occurs and a constant laser output 9 according to the discharge current is obtained until the supplied pulse falls. It will be done. The output voltage of the constant current high voltage pulse power supply 11 is required to be equal to or higher than the discharge starting voltage between the node 4 and the cathode 5 in order to start the discharge, and after the start of the discharge, the discharge sustaining voltage between the anode 4 and the cathode 50 is required. A voltage equal to the voltage drop across the ballast resistor IO is required. Ballast abrasive resistor 1O1l''ll: This is used to cancel the negative characteristics of the voltage and current of the laser tube 1 to obtain stable discharge.If the laser output 9 is made variable, the laser output 9 can be adjusted by lowering the discharge current ■. The lower the resistance value is, the higher the output voltage of the constant current high voltage pulse power supply 11 is required.
If the resistance value of the ballast resistor 10 is made large, the negative resistance of the laser tube 1 becomes small, so the resistance value of the ballast resistor 10 necessary for stabilizing the discharge can be made small. flows, causing an overshoot several times the set value at the rise of the pulse waveform of the discharge current.

In the conventional device, as described above, the anode 4 is
There is a problem that the withstand voltage between the 71i-9 and the mirror 2 is broken due to a high voltage higher than the discharge starting voltage, causing radiation and deterioration of the mirror.Also, when trying to vary the laser output, the ballast resistor 10 Due to the large size, power loss increases, power usage efficiency decreases, and the device becomes large.

[Purpose of the invention]

The object of the present invention is to
``The object of the present invention is to provide a small-sized, highly reliable laser output gas laser device with high power utilization efficiency.

[Summary of the invention]

In order to achieve this object, the present invention provides an auxiliary anode between the anode and the cathode, and forms a seed discharge between the auxiliary anode and the cathode, since the discharge starting voltage is proportional to the distance between the 7 node and the cathode. By letting
Reduces the output voltage of the high-voltage pulse power supply required to start discharge,
Moreover, the present invention is characterized in that the resistance value of the ballast resistor and the power loss are reduced without generating an excessive discharge current at the start of discharge.

[Embodiments of the invention]

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 2 is a configuration diagram showing an embodiment of a gas laser device according to the present invention. In the figure, a ballast resistor lO and a constant current high voltage pulse power source 11 are connected in series to an anode 4 and a cathode 5 provided in a laser tube 1, and a constant current high voltage pulse power source 11 is connected from a pulse generator 12 to a constant current high voltage pulse power source 11 for a duration of 10 m, for example. (
8) Supply the pulse. An auxiliary anode 21 is provided between the anode 4 and the cathode 5, and a capacitor C and a resistor R are connected in series between the auxiliary anode 21 and the anode 4 as means for forming a seed discharge between the anode 4 and the cathode 5. The inside of the laser tube 1 is evacuated by the vacuum pump 8, and the laser medium gas 6 is introduced through the flow rate adjustment device 22, and the gas pressure inside the laser tube is adjusted to, for example, l.
Adjust in the range of /2 to several kP4.

In the above configuration, when a pulse is now supplied from the Noculus generator 12, the output voltage of the constant current high voltage Noculus generator 11 begins to rise at a rate of, for example, 20 kV/m5ec. At this time, the anode 4 and the auxiliary anode 21 rise at the same potential. Since the discharge start voltage between the auxiliary anode 21 and the cathode 50 is lower than the discharge start voltage between the anode 4 and the cathode 5, the output voltage of the constant current high voltage pulse power supply 11 is lower than the discharge start voltage between the auxiliary anode 21 and the cathode 50. When the voltage reaches, for example, more than ten kV, a seed discharge is formed between the auxiliary anode 21 and the cathode 5. Here, the discharge starting voltage is 2
For example, if the auxiliary anode 21 is provided at the center between the anode 4 and the cathode 5, the discharge starting voltage of the auxiliary anode 21 will be equal to the firing voltage of the anode 4, 1/2.

Next, when a seed discharge is formed, a current flows through the capacitor C and the resistance hole, causing a voltage drop, so that the potential of the auxiliary anode 21 begins to drop as viewed from the anode 4. However, the potential of anode 4 is ■.

continues to rise even after the seed discharge is formed, so by appropriately selecting the values of the capacitor C and the resistor R, the potential of the auxiliary anode 21, v,
can be kept constant, and the seed discharge can be stably maintained until the main discharge is formed between the anode 4 and cathode 5.

The value of capacitor C to satisfy this condition is expressed by the following equation.

■2 C=□ ・・・・・・・・・・・・・・・(
1) ∆V+/∆t Here, ∆ is the current value of the genus 'tortoise, and ∆■1/∆t is the rate of increase in the output voltage of the constant current high voltage pulse power supply 11.

Now, for example, select resistance f: l 00 to Ω and set I2=
If it is limited to lOmA, Δ■1/Δt=20kV
/m5ec, the capacitor C is 500 from formula (1).
1) Choose F.

Now, due to the formation of a seed discharge, the gas emitted from the cathode 5 ionizes gas molecules and creates plasma by the time it reaches the auxiliary anode 21. In addition to flowing as a current Plasma is also generated between the auxiliary anode 4 and the auxiliary anode 21.

The electric field strength between the 7 node 4 and the cathode 50 due to the potential V, which continued to rise, is now equal to the electric field strength between the 7 auxiliary node 4 and the cathode 50 due to the potential 2, which is kept constant throughout the genus . When the current ■1 begins to flow, node 4 becomes 7.
A main discharge between the cathode 5 and the cathode 5 starts. That is, after the seed discharge is formed, the main discharge starts when the potential 1 reaches the discharge sustaining voltage between the anode 4 and the cathode 5, and this discharge sustaining voltage is equal to the discharge starting voltage when the auxiliary anode 21 is not present. For example, the value is about 7056. Once the main discharge starts, a preset current, for example 30 mA, flows from the output of the constant current high voltage pulse power supply 11, and as the potential 1, which had been rising until then, becomes one foot, the seed discharge current I begins to decrease. It becomes zero in a short time, for example, 0.1 m5ec. After that, only the main discharge current 1 flows, and the auxiliary anode 21 does not affect the main discharge. Here, in order to reduce the resistance value of the ballast resistor 10, the discharge current is kept constant.
For example, the laser output 9 may be adjusted to 30 mA using a manual flow control valve or an electric flow control valve as the flow rate control device 22, and the gas flow rate may be adjusted from several A/hr to several tens of tons/hour.
The gas pressure inside the laser tube 1 is varied from 1/2 to several kP, for example. For example l/2k
When P, the laser output is 5W, 5kP, and @50W. At this time, the resistance value of the ballast resistor lO is approximately 172~l compared to the case where the laser output is adjusted by the discharge current.
/3, and the power loss of the ballast resistor is approximately 1/4
-1/9, and as mentioned above, no excessive current occurs even at the start of discharge.

Note that the shape of the auxiliary anode 21 may be exactly the same as the anode 4, and conventional laser tube manufacturing techniques can be used as is. Furthermore, when the auxiliary anode 21 is installed closer to the anode 4, it becomes easier to spatially transition from polar discharge to main discharge, but the duration of the seed discharge is short (none), and when it is closer to the cathode 5, the opposite occurs. From, 7 nodes 4 and cathodes 5
It is preferable to provide the cathode 50 in a range between the center of the cathode 50 and the center of the cathode 50 .

Therefore, according to the embodiment of the present invention, it is possible to reduce the output voltage of the constant current high voltage pulse power supply required to start discharge, and also to reduce the resistance value of the ballast resistor and power loss without generating an excessive discharge current at the start of discharge. Therefore, power usage efficiency is improved, the device can be made smaller and cheaper, and stability and reliability can be improved.

Figure 3 is a book! The difference from FIG. 2 is that auxiliary anodes 21 . 21' is provided. This embodiment has a constant current high voltage pulse power supply 11 compared to the embodiment shown in FIG.
Although the output current is doubled, the output voltage is only 1/2, which makes the device even more compact.The voltage drop across the ballast resistors io and io' can be lowered, so mirror 2 and cathode 5 and mirror 3 and cathode 5' It is easy to prevent abnormal discharge during Furthermore, by providing the resistors R, R' and the capacitor C2C' for each of the two auxiliary anodes 21, 21', the discharge initiation of each of the two discharge paths becomes less likely to affect each other. The number of discharge paths is 2 compared to the case
There is a high probability that discharge will start in both systems. In addition, a DC high-voltage power supply is used instead of the constant-current high-voltage source 11, a constant-current circuit such as a high-voltage vacuum tube is used instead of the ballast resistor 10, 10', and the pulse generator 12 supplies pulses to the constant-current circuit. may also be supplied.

〔Effect of the invention〕

As explained above, according to the present invention, in a pulse output gas laser device, it is possible to reduce the output voltage of the high-voltage power supply required to start discharge, and to reduce the ballast resistance without causing an excessive sleep current at the start of discharge. Since resistance value and power loss can be reduced, power usage efficiency is improved and equipment can be made smaller and smaller.
It can be made at low cost and has improved safety and reliability.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional gas laser device, FIG. 2 is a block diagram showing an embodiment of a gas laser device according to the present invention, and FIG.
The figure is a block diagram showing another embodiment of the gas laser device according to the present invention.

Claims (1)

[Claims] 1. In a gas laser device that obtains a pulsed laser output by passing a laser medium gas through a discharge path formed by applying a high voltage pulse between an anode and a cathode of a laser tube, the anode and cathode are connected to each other. An auxiliary anode is provided between the
A gas laser device comprising means for forming a seed discharge between the auxiliary anode and the cathode at the time of starting discharge. 2. The gas laser device according to claim 1, wherein the means for forming a seed discharge between the auxiliary anode and the cathode comprises a capacitor and a resistor connected in series to the anode and the auxiliary anode. 3. The gas laser device according to claim 1, wherein the discharge path is composed of a plurality of discharge paths, and an auxiliary anode is provided for each discharge path.