JPH06104511A - Discharge electrode for pulsed gas laser - Google Patents

Abstract

PURPOSE:To allow long time operation by constituting discharge electrode for pulsed gas laser of an actual polar discharge electrode and an electrode for shaping the field distribution specifically. CONSTITUTION:The discharge electrode for pulse gas laser comprises a polar discharge electrode 1 having actually discharging surface profile forming a part of churn profile with screw gears being provided on the opposite sides thereof, a field shaping electrode 2 forming the surface churn profile along with the surface profile of the polar discharge electrode 1, and means for rotating the polar discharge electrode 1, i.e., a screw 5, having a screw gear at the tip thereof mating with screw gears provided on the opposite sides of the polar discharge electrode 1. Pulse current is transmitted from an external pumping circuit through a current introducing rod 3 and an electrode position adjusting screw 4 coupled therewith to the discharge electrode. The polar discharge electrode 1 has four discharging faces shifted by 90 deg. in angle and provides churn profile along with the discharge face of the field shaping electrode 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge electrode in a pulse gas laser.

[0002]

2. Description of the Related Art FIG. 3 shows an example of a conventional structure of a discharge electrode portion of an excimer laser which is a kind of pulse gas laser.
This pulse gas laser is described in detail in the May issue of the document "OPTRONICS" (1986). In this conventional example, it is composed of a discharge electrode 8 for generating a discharge for exciting a laser gas and a current introduction terminal 9 connected to the discharge electrode 8 and supplying a discharge current from an excitation circuit outside the laser container. It is fixed to a part of the wall of the laser vessel via a ring 6 and to an insulating base 7 for insulating the high voltage and holding the discharge electrode. Further, a discharge electrode 8 for causing discharge for laser excitation
The shape is a special shape called a chan profile in order to obtain a uniform glow discharge that efficiently excites the laser gas.

[0003]

In order to oscillate the laser beam in this conventional pulse gas laser, the laser gas is excited by the discharge between the discharge electrode pairs. For this reason, the metal of the discharge part on the surface of the discharge electrode is sputtered by the discharge, and the shape of the discharge electrode gradually becomes different from the chamber profile. As a result, it becomes difficult to maintain glow discharge between the pair of discharge electrodes, arc discharge frequently occurs, and laser output decreases. In order to suppress this decrease in laser output, it is necessary to open the inside of the laser container and replace the discharge electrodes frequently, and the stop time of the device and the startup time of the device to restore the inside of the laser container to the initial state. It had the drawback of being long.

It is an object of the present invention to provide a discharge electrode for a pulse gas laser which can be operated for a long time and whose frequency of replacement is low.

[0005]

DISCLOSURE OF THE INVENTION A discharge electrode for a pulse gas laser according to the present invention has a columnar electrode (hereinafter referred to as an electric field shaping electrode) in which at least a discharge portion where discharge occurs is hollowed out to the back surface, and a hollowed shape of the electric field shaping electrode. An electrode (hereinafter referred to as a discharge electrode column), which is disposed inside thereof and has the same plurality of surface shapes, and which rotates parallel to the central axis in the longitudinal direction of the electric field shaping electrode, and the discharge electrode column described above. It is characterized in that it is configured with a means for rotating.

[0006]

The discharge electrode for pulsed gas laser of the present invention is divided into the discharge electrode column where the discharge actually occurs and the electric field shaping electrode that shapes the electric field distribution into a predetermined shape as described above. The metal is sputtered only on the surface of the discharge electrode column. Therefore, it is only necessary to replace the discharge electrode column. Further, in order to reduce this exchange as much as possible, the discharge electrode column has a plurality of surfaces with the same surface shape. Therefore, the discharge electrode column should be rotated using a rotating means to make the new surface as a discharge surface. This reduces the number of times the discharge electrode is replaced.

[0007]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a structural diagram showing a discharge electrode and a portion in the vicinity of the discharge electrode according to the present invention in one embodiment using the present invention,
FIG. 2 is a structural view showing a cross section of the structure shown in FIG.

FIG. 1 shows a discharge electrode portion of a pulse gas laser using the present invention. Unlike the conventional discharge electrode part shown in FIG. 3, the surface shape of the discharge electrode where discharge actually occurs forms a part of the Chan profile, and the discharge electrode column 1 has screw gears on both sides, and the discharge electrode column 1 The electric field shaping electrode 2 having a chamfered surface shape in combination with the surface shape of the discharge electrode pillar 1 and a screw gear at the tip of the discharge electrode pillar 1 are provided.
And a screw 5 that meshes with the screw gears on both sides. Further, the pulse current from the excitation circuit outside the laser container is transmitted to the discharge electrode by using the current introducing rod 3 and the electrode position adjusting screw 4 connected thereto. Discharge electrode column 1
Has four discharge surfaces whose angles are different by 90 degrees, and the shape of the discharge surface is made so as to form a chan profile together with the surface of the electric field shaping electrode 2.

When a gas laser is operated using this discharge electrode to cause a discharge between the discharge electrodes, the surface of the discharge electrode column 1 is sputtered by the discharge, the surface shape deviates from the Chan profile, and the laser is gradually generated due to frequent arc discharge. A decrease in output occurs. In this case, the electrode position adjusting screw 4 is loosened so that the discharge electrode column 1 can be rotated in the groove of the electric field shaping electrode 2, and the discharge electrode column 1 is rotated by 90 degrees using the screw 5 to clean the solid surface. As the discharge surface, the position of the discharge electrode column 1 is adjusted by the electrode position adjusting screw 4 and fixed to the electric field shaping electrode 2. As a result, the electric field distribution between the discharge electrodes is returned to the initial state, so that frequent occurrence of arc discharge is suppressed and the laser output is also returned to the initial state. In the present embodiment, since the discharge electrode column has four discharge surfaces, the gas laser can be used for four times longer than when the conventional discharge electrode is used, without replacing the discharge electrode.

In the present embodiment, the discharge surface of the discharge electrode column is four, but it is not limited to this. Furthermore, although the shape of the discharge electrode is a chan profile, the shape is not limited to this.

[0012]

As described above, the pulse gas laser according to the present invention can be operated for a long period of time, and the replacement of the discharge electrode is small and the time for stopping the apparatus can be reduced.

[Brief description of drawings]

FIG. 1 is a structural diagram of a discharge electrode portion using an embodiment of the present invention.

2 is a cross-sectional view of the structure shown in FIG.

FIG. 3 is a structural diagram of a discharge electrode portion of a conventional excimer laser.

[Explanation of symbols]

 1 Discharge electrode column 2 Electric field shaping electrode 3 Current introduction rod 4 Electrode position adjusting screw 5 Screw 6 O-ring 7 Insulation stand 8 Discharge electrode 9 Current introduction terminal

Claims (1)

[Claims] 1. A columnar electrode (hereinafter referred to as an electric field shaping electrode) in which at least a discharge portion where discharge occurs is hollowed out to the back surface,
An electrode that is arranged inside the hollowed-out shape of the electric field shaping electrode, has the same plurality of surface shapes, and rotates about an axis parallel to the central axis of the electric field shaping electrode in the longitudinal direction ( Discharge electrode column) and a means for rotating the discharge electrode column as described above, a discharge electrode for pulsed gas laser.