JPH02184089A - Gas circulation type pulse laser - Google Patents

Abstract

PURPOSE:To prevent a discharging product generated in a preliminary ionization discharger from mixing in a main discharger through the opening of an opening electrode by isolating a gas passage including the main discharger and a gas passage including the preliminary ionization discharger, and independently circulating two gas flows. CONSTITUTION:Gas is circulated in a gas passage 9 by a fan 11. That is, laser gas raised at its temperature at a main discharger is fed to a heat exchanger 12 to be cooled, and newly supplied to a main discharger 4. Since a current density is relatively small in a glow discharge of the main discharge, a discharging product in the laser gas is very small, and does not substantially affect the influence to the stability of the discharge. Since an arc discharge having high current density is generated at gaps 5a and 5b in a gas passage 10, a large quantity of discharging product is generated. Since this product easily attracts electrons in a discharging plasma, it particularly makes the glow discharge of the main discharge unstable. The laser gas containing a large quantity of discharging product is circulated by a fan 13, passed through a gas reproducer 14, and newly supplied to a preliminary ionization arc discharger.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pulsed gas laser, and more particularly to gas circulation suitable for high repetition pulse operation.

[Conventional technology]

In the conventional device, as described in Japanese Patent Application Laid-Open No. 62-81078, the laser gas flow passes from the main discharge part through the opening of the aperture electrode, passes through the pre-ionization discharge part, and then goes to the main discharge part. It had a cyclical structure.

[Problem to be solved by the invention]

The above conventional technology does not take into consideration the fact that discharge products generated in the pre-ionization discharge section remain in the circulating gas flow, and the main discharge becomes unstable due to the residual discharge products during high repetition pulse operation. There was a problem.

An object of the present invention is to provide a high-output gas laser device that achieves stable main discharge even with high-repetition pulse operation.

(Means for solving I'll) The above purpose is to separate the gas flow path including the main discharge part and the gas flow path including the pre-ionization discharge part, and circulate the two gas flows independently of each other. This is achieved by

[Effect]

In the main discharge section, a negative pressure equal to the dynamic pressure ΔPl is generated due to the gas flow rate v1. Similarly, in the pre-ionization discharge section, a negative pressure equal to the dynamic pressure ΔPz is generated due to the gas flow rate v2. In the present invention, the gas flow rate vtt vz is set so that the magnitude of each negative pressure satisfies ΔPi≦ΔP2. by this,
It is possible to prevent discharge products generated in the pre-ionization discharge section from entering the main discharge section through the opening of the open electrode.

Further, since the two gas streams described above are circulated separately from each other, residual discharge products are not mixed into the gas flow path including the main discharge section.

〔Example〕

An embodiment of the present invention will be described below using an excimer laser device shown in FIG.

Inside the laser tube 1 is a 3 atm laser gas (HCfl).

A mixed gas of Xs, He, and Ne) is sealed. Main electrode 2a
, 2b is an aperture electrode 2b having circular apertures 3 of 1 m in number. A main discharge portion 4 is formed between the main electrodes 2a and 2b. A preliminary fi! A spark gap 5a as a releasing means,
5b is provided.

Peaking capacitors 6a, 6 are connected to one of the main electrodes 2a.
b are connected in parallel, and further connected to the high voltage pulse power supply 7.

On the other hand, the ducts 8a, 8b, and 8c form a gas flow path 9 including the main discharge portion 4 and a gas flow path 10 including the spark gap portions 5a and 5b. A gas circulation fan 11 and a heat exchanger 12 are arranged within the gas flow path 9. Furthermore, a gas circulation fan 13 and a gas regeneration device 14 are arranged within the gas flow path 10.

The operation of this embodiment is as follows. High voltage pulse power supply 7
A pulse voltage is applied between the main electrode 2a, the peaking capacitors 6a, 6b, and the spark gaps 5a, 5b. During application of pulse voltage, spark gaps 5a, 5
In b, arc discharge occurs and ultraviolet rays are produced. This ultraviolet light passes through the opening 3 of the aperture electrode 2b and pre-ionizes the laser gas in the main discharge section 4. When the applied voltage increases and reaches the main discharge starting voltage, a glow discharge, which is a main discharge, occurs between the main electrodes 2a and 2b, and the laser gas is excited by discharge.
Laser output is extracted from a laser resonator not shown in this figure.

Gas circulation is performed within the gas flow path 9 by a fan 11 . That is, the laser gas whose temperature has increased due to the main discharge is sent to the heat exchanger 12 to be cooled, and is then newly supplied to the main discharge section 4. Here, in glow discharge, which is the main discharge, the current density is relatively low, so the discharge products in the laser gas are extremely small and do not substantially affect the stability of the discharge.

On the other hand, arc discharge with a large current density occurs in the gaps 5a and 5b in the gas flow path 10, so a large amount of discharge products are generated. This product tends to adsorb electrons in the discharge plasma, making glow discharge, which is the main discharge, particularly unstable. The laser gas containing a large amount of discharge products is circulated by a fan 13.

The gas passes through the gas regeneration device 14 and is newly supplied to the preliminary ionization arc discharge section.

In this embodiment, the gas flow velocity v1 of the main discharge section and the gas flow velocity v2 of the preliminary ionization arc discharge section are set to be substantially equal.

Gas flow rate 1/l, dynamic pressure ΔPl generated by V2,
Since ΔP2 is equal, no pressure difference occurs on both sides of the open electrode 2b. Therefore, the laser gas containing discharge products does not enter the main discharge section 4 through the opening 3.

In this embodiment, the discharge products generated by the pre-ionizing arc discharge do not enter the main discharge section 4, so that the glow discharge, which is the main discharge, is stabilized and high repetition pulse operation is achieved. be.

A second embodiment of the invention is shown in FIG. This embodiment differs from FIG. 1 in that the gas channels 9 and 10 are connected by a new gas channel 15, and a gas regenerator 16 and a fan 17 are arranged in the gas channel 15. . The fan 17 creates a differential pressure Δ between the inlet 15a and outlet 15b of the gas flow path 15.
P occurs.

Therefore, the pressure in the gas flow path 9 is greater than the pressure in the gas flow path 10 by ΔP. In another embodiment, even if the gas pressure in the preliminary ionization arc discharge section increases locally due to a rise in the temperature of the laser gas, the differential pressure ΔP caused by the fan 17 causes the laser gas in the arc discharge section to
This has the effect of reliably preventing contamination.

Furthermore, a third embodiment of the present invention is shown in FIG. 3, a laser tube 1.
A removable mounting plate 1a is installed which forms a part of the.

The gas flow path 10 formed by the ducts 8a and 8d is connected to the mounting plate 1.
The gas regeneration device 14 is disposed opposite to the mounting plate 1a, and is installed at a position corresponding to the mounting plate 1a. According to this configuration, maintenance and inspection of the gas regeneration device 14 is facilitated by the simple operation of removing the mounting plate 1a.

〔Effect of the invention〕

According to the present invention, since the discharge products generated by the pre-ionizing arc discharge are not mixed into the main discharge part, a stable main discharge can be obtained and a high repetition pulse operation can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an excimer laser device according to one embodiment of the invention, and FIGS. 2 and 3 are sectional views of other embodiments of the invention.

Claims (1)

[Scope of Claims] 1. At least one of the main electrodes forming the main discharge part for discharge excitation of the laser gas sealed in the laser tube is an open electrode having an opening, and the main discharge part and the main discharge part are connected to the open electrode. 1. A gas circulation type pulsed laser having a laser gas pre-ionization means section on the opposite side, characterized in that the gas flow path including the main discharge section and the gas flow path containing the pre-ionization means are separated. 2. The gas circulation type pulsed laser according to claim 1, wherein the gas flow velocity in the main discharge section and the gas flow velocity in the preliminary ionization section are made substantially equal. 3. The gas circulation type pulse laser according to claim 1, wherein the gas pressure in the pre-ionization means section is set to be a negative pressure with respect to the gas pressure in the main discharge section. 4. The gas circulation type pulsed laser according to claim 1, wherein the gas flow path including the pre-ionization means is arranged to face a tube wall forming the laser tube.