JPS6017975A - Silent discharge gas laser device - Google Patents

Abstract

PURPOSE:To emit a stable laser output by cooling a dielectric electrode by separately using evaporated heat based on the phase change of coolant having low specific dielectric constant, thereby reducing the induced current flowed through the coolant and simplifying a silent discharge gas laser device. CONSTITUTION:Specific dielectric constant of coolant 17 formed of insulating solution such as ammonia or halogenated fluoride carbon sealed in a dielectric electrode is approx. 2-5, thereby remarkably reducing the induced current flowed in the coolant 17. When the discharging power is approx. 20kW, in case of halogenated fluoride carbon as the coolant 1, its evaporation latent heat is 43.5cal/g (182.7J/g). Accordingly, the coolant 17 is evaporated at the ratio of approx. 328g. per minute to apply heat to the outer cylinder for forming a dielectric electrode 3, thereby liquefying it to return to the original. The heat applied to the outer cylinder is effectively dispersed to the exterior through heat sink fins 18. At this time, when the fins 18 are exposed with the circulating flow of the gas laser medium, its heat sink effect can be remarkably improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in an electrode cooling means in a silent discharge gas laser device.

Conventionally, as this type of silent discharge gas laser device, the first
There was something shown in the figure. FIG. 1 is a schematic configuration diagram showing a three-axis orthogonal CO laser device as an example of a conventional silent discharge type gas laser device, and FIG. 2 is an enlarged sectional view showing a dielectric electrode in FIG. 1. In FIG. 1, inside a laser oscillator 1, a grounded metal electrode 2 and a dielectric electrode 3 to which a high frequency and high voltage is applied are arranged facing each other. A discharge space 4 is formed between the metal electrode 2 and the dielectric electrode 3, and carbon dioxide gas (COt) is present in the discharge space 4.

A gas laser medium consisting of a mixed gas of helium gas (1-Ie), nitrogen gas (N2), etc. is cooled by a heat exchanger 6, and is blown at a high speed of about 30 meters per second by a blower 7. It is designed to be supplied in circulation.

A total reflection mirror 8 and a partial reflection mirror 9 are arranged at both ends of the discharge space 4 to form an optical resonator. The dielectric electrode 3 is
As shown in FIG. 2, a dielectric material 12 is placed on the surface of the metal pipe 110.
It has a structure in which deionized water 10 for cooling the electrode flows into the inside thereof. Approximately 1.0 mm is supplied to the dielectric electrode 3 from the AC power source 13. OQKHz,
A high frequency high voltage of about 10 KV (effective value) is applied, and a stable glow-like discharge known as a silent discharge and I~ is generated in the discharge space 4. In the discharge space 4, a circulating flow of the gas laser medium by the blower 7 and each of the metal electrodes 2. When the silent discharge between the dielectric electrodes 3 is in a perpendicular state, the discharge energy at this time is applied to the gas laser medium. In this example, carbon dioxide (CO□) molecules are excited by the laser, and the aforementioned circular flow of the gas laser medium and silent discharge are orthogonal to each other. That is, the laser beam 5 is directed toward the optical axis of the optical resonator formed by the discharge space 4 and the total reflection mirror 8 and partial reflection mirror 9 fixedly arranged at both ends of the discharge space 4.
Excitation is performed, and after resonance amplification is performed by this optical resonator, a part of the excitation is emitted from the partial reflection mirror 9 to the outside as a laser beam 5. An increase in the temperature of the gas laser medium due to the discharge energy in the discharge space 4 causes a decrease in the energy efficiency of laser oscillation, so the circulating flow of the gas laser medium in the discharge space 4 is cooled by a heat exchanger 6, By forced circulation at high speed, the temperature rise of the gas laser medium is suppressed. In addition, the temperature of the dielectric electrode 3 may increase due to the temperature rise of the dielectric electrode 3.
In order to prevent damage to the dielectric 12 constituting the dielectric electrode 3, a pump (P) 14 to a cooler (
(E) 15 and a water deionizer (DI) 16 to be cooled;
and deionized water 10 for electrode cooling with increased electrical resistance.
is supplied, and the heat generated by the dielectric electrode 30 is directly cooled by cooling water made of deionized water 10.

The configuration of the conventional three-axis orthogonal CO laser device is as described above, and each metal electrode 2. The laser excitation effect by silent discharge based on the high frequency and high voltage applied between the dielectric electrodes 3 will be explained. Silent discharge is caused by each metal electrode 2,
High frequency high voltage (approximately 10KV) applied between the dielectric electrodes 3
), it is an alternating current discharge that occurs in the discharge space 4 through the dielectric 12, and in the rising process of each application period of the power supply voltage, when the discharge starting voltage (approximately sKV') is reached, a pulse is generated.
3- Target discharge occurs. Due to this discharge, charges due to the discharge current are accumulated on the surface of the dielectric 120, and as a result, the discharge space 4
voltage decreases, and the pulse discharge (I) disappears. The above pulse discharge is repeated during the rising process of each cycle of the power supply voltage, and in normal cases, it occurs several times to several times during a half cycle of the AC power supply voltage. A 17-pulse discharge is obtained ten times. In the next half cycle, when the polarity is reversed, a similar pulse discharge with the opposite polarity is repeated. Therefore, the discharge space 4
The discharge power is supplied repeatedly over time, but the laser excitation and 1/- laser oscillation outputs are almost uniform over time because nitrogen in the gas laser medium acts as an energy boule. , you can get it.

Since the structure of the dielectric electrode 3 in the conventional three-axis orthogonal CO□ laser device is configured as described above, a water deionization device that generates deionized water 10 for cooling the dielectric electrode 3 is required. , and its circulation pump (P) 14
In addition, even deionized water has a relative permittivity of about 80, and this value is higher than the relative permittivity of about 5 of the dielectric material 4-12 covered in the dielectric electrode 3. Since this is very large, a huge induced current proportional to this flows through the deionized water 10 to the grounded part, for example, the wall of the housing of the laser oscillator 1. To compensate for this, the power supply capacity used must be sufficiently large. There were drawbacks such as the need to

This invention was made in order to eliminate the drawbacks of the conventional ones as described above, and in a silent discharge type gas laser device, a refrigerant with a low dielectric constant is sealed in one dielectric electrode, and the phase change of this refrigerant is It has a configuration in which the dielectric electrode is cooled using the heat of vaporization based on the cooling medium, which reduces the induced current flowing in the coolant, simplifies the device to make it compact, and emits stable laser output. The purpose is to provide a silent discharge type gas laser device.

An embodiment of the present invention will be described below with reference to the drawings. Third
The figure is a schematic configuration diagram showing a silent discharge type gas laser device which is an embodiment of the present invention, and FIG. 4 is an enlarged sectional view showing the dielectric electrode in FIG. 3, showing the same parts as FIGS. 1 and 2. are indicated using the same reference numerals, and detailed explanation thereof will be omitted. In FIGS. 3 and 4, 17 is a refrigerant made of an insulating liquid such as ammonia or fluorohalogenated carbon, and 18 is a heat dissipation fin provided on the outer periphery of the dielectric 12 of the dielectric electrode 3. . The dielectric constant of the refrigerant 17 is approximately 2
~5, and this value is sufficiently smaller than the dielectric constant of about 80 of the deionized water 10 in the conventional example, and therefore the induced current flowing in the refrigerant 17 can be drastically reduced.

Regarding the cooling effect of the refrigerant 17, in the conventional example described above, at a discharge power of approximately 20 KW, the deionized water 10 carried away approximately IKW of heat, but in the example of the present invention, the deionized water 10 removed approximately IKW of heat. For example, the latent heat of vaporization of fluorinated halogenated hydrocarbon is 43.5 cg/9 (1B
2.7 J/liter), the refrigerant 17 evaporates at a rate of about 3282 per minute, transfers heat to the outer cylinder constituting the dielectric electrode 3, liquefies and returns to its original state. The heat transferred to the outer cylinder passes through the heat dissipation fins 18 that are not exposed to electric discharge.
It will be effectively dissipated to the outside. At this time, if the heat dissipation fins 18 are exposed to the circulating flow of the gas laser medium, the dissipation effect will be even more remarkable. The other structure and operation of the silent discharge gas laser device which is an embodiment of the present invention shown in FIGS. 3 and 4 are the same as those of the conventional example shown in FIGS. 1 and 2 described above. I'll omit that explanation.

In the above embodiment, the case where the heat dissipation fins 18 were provided inside the housing of the laser oscillator 1 was explained, but the portion corresponding to the heat dissipation fins 18 was taken out of the housing and Natural cooling, wind blowing cooling,
Even if water cooling or the like is performed, the same effects as in the above embodiments can be obtained.

As described above, according to the silent discharge gas laser device of the present invention, a coolant with a low relative dielectric constant is sealed in the dielectric electrode,
Since the dielectric electrode is cooled by using the heat of vaporization caused by the phase change of the refrigerant, the induced current flowing into the refrigerant is significantly reduced, which reduces the power supply capacity used. The device can be made smaller by removing external equipment such as the deionization device or the pump for circulation of deionized water.This has the effect of greatly simplifying the device and making it more compact. Furthermore, because it utilizes the heat of vaporization based on the phase change of a refrigerant with a low dielectric constant, the heat transfer rate is extremely high, ranging from several thousand to 1,000 KCat/ze・hr・℃, and as a result, it is resistant to thermal fluctuations. This has excellent effects such as very quick control.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing a three-axis orthogonal CQ laser device as an example of a conventional silent discharge type gas laser device;
The figures are an enlarged sectional view showing the dielectric electrode in Fig. 1, Fig. 3 is a schematic configuration diagram showing a silent discharge gas laser device as an embodiment of the present invention, and Fig. 4 is an enlarged sectional view showing the dielectric electrode in Fig. 3. FIG. 3 is an enlarged cross-sectional view showing an electrode. In the figure, 1--Laser oscillator, 2--Metal electrode, 3--Dielectric electrode, 4--Discharge space, 5--Laser beam, 6--Heat exchanger, 7-- Air blower, 8
- Total reflection mirror, 9... Partial reflection mirror, lO... Deionized water, 11... Metal pipe, 12... Dielectric, 13
... AC power supply, 148- ... Pump (P), 15 ... Cooler (HE), 16
... Deionizer (DI), 17... Refrigerant, 18... - Heat dissipation fin. In addition, in the figures, the same reference numerals indicate the same or corresponding parts. Agent Masuo Oiwa Figure 1 Figure 2 Figure 3 Figure 3 6 4th Problem 1 8 Procedural Amendment (Voluntary) 1. Display of the incident! l,'li Gansho 58-122570
No. 3 No. 2, Title of the invention Silent discharge gas laser device 3, Relationship to the case of the person making the amendment 1 “I”:! 'l-out IQ (i person representative piece 111 jin 8 part 4, agent (, book J1i7Q O: 1 (2] 3) 3121i &, +
Section 'l') 5. Subject of amendment: "Claims" and "Detailed Description of the Invention" columns of the specification. 6. Contents of the amendment (1) The "Claims" of the specification will be amended to include multiple attachments. (2) "Silent discharge method" on page 6, line 8 of the Ministry of Education is corrected to "lateral excitation silent discharge method." Attachment 2, Claims (1) An AC high voltage is applied between a pair of electrodes, at least one of which has a dielectric electrode whose surface is coated with a dielectric, and a silent discharge is generated between the pair of electrodes. A silent discharge type characterized in that the silent discharge is filled with a coolant having low laser excitation, and the dielectric electrode is cooled using the heat of vaporization based on the phase change of the coolant. Gas laser equipment. (2) The silent discharge type gas laser device according to claim 1, wherein either ammonia, fluorohalogenated carbon, or a mixture of both is used as the refrigerant. 2-

Claims (2)

[Claims] (1) A high AC voltage is applied between a pair of electrodes, one of which has a dielectric electrode whose surface is coated with a dielectric, and a fish meat discharge is generated between the pair of electrodes. In a silent discharge gas laser device used for discharge laser excitation, a refrigerant with a low specific inductivity is sealed in the dielectric electrode, and the dielectric electrode is heated using the heat of vaporization based on the phase change of the refrigerant. A silent discharge gas laser device characterized in that it is cooled. (2) The silent discharge gas laser device according to claim 1, wherein either ammonia, fluorohalogenated carbon, or a mixture of both is used as the refrigerant.