JP2666149B2 - Ultraviolet preionization electrode for discharge-excited gas laser device. - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is generally called an excimer laser which generates ultraviolet light by arc discharge at a preionization electrode and uses the ultraviolet light for preionization of main discharge. The present invention relates to an ultraviolet pre-ionization electrode of a discharge excitation gas laser device.

[Conventional technology]

In a discharge type gas laser device such as an excimer laser, preliminary ionization is performed before a main discharge for performing laser oscillation. Examples of the preionization method include ultraviolet preionization, corona preionization, and X-ray preionization. However, corona and X-ray preionization are inefficient in energy, and have problems such as complicated equipment and high cost. Therefore, in many cases, an ultraviolet pre-ionization system, which has a simple and low-cost apparatus, is employed.

In this ultraviolet pre-ionization system, as shown in FIG. 7, arc discharge is performed by ultraviolet pre-ionization electrodes 2 disposed on both sides of a main discharge electrode 1 composed of an opposed anode 1a and a cathode 1b, and the arc discharge is performed therefrom. The laser medium gas between the main discharge electrodes 1 is pre-ionized by ultraviolet rays. In this figure, 3 is a line flow fan, 4 is a heat exchanger, and 5 is a laser beam.

The conventional ultraviolet preionization electrode is as shown in FIGS. 8 and 9.

That is, in the one shown in FIG. 8, the preionization electrodes 2a and 2b are opposed to each other with a predetermined gap, and both electrodes 2a and 2b are
The arc discharge is performed between b.
In the figure, arc discharge is performed between the preionization electrode 2a 'and one of the main discharge electrode pairs 1.

[Problems to be solved by the invention]

In the above-mentioned conventional ultraviolet preionization electrode, the electrode is consumed by arc discharge, and the interval between the electrodes is eventually widened.
If the distance between the electrodes is too wide, the discharge starting voltage of the arc discharge increases, and the discharge may not be performed, or the device of the device may be damaged due to the high discharge starting voltage.

For this reason, the life of the ultraviolet pre-ionization electrode is a factor that determines the life and maintenance interval of this type of gas laser device as a whole.

The present invention has been devised in consideration of the above, so that a stable arc discharge can be obtained for a long time,
The maintenance interval can be extended, and a stable main discharge can be obtained by obtaining a uniform spare electrode, and the reproducibility and stability of the pulse energy of the oscillated laser beam can be increased. It is an object of the present invention to provide an ultraviolet pre-ionization electrode in an excitation gas laser device.

[Means for solving the problem]

In order to achieve the above object, the ultraviolet pre-ionization electrode in the discharge excitation gas laser device according to the present invention generates ultraviolet light by arc discharge, and the ultraviolet pre-ionization electrode of the discharge excitation gas laser device using the ultraviolet light for pre-ionization. In, while making each discharge portion of the electrode pair of this ultraviolet pre-ionization electrode a planar shape, one of the two discharge portions constituting this electrode pair is formed in a right angle to the discharge direction, The other discharge portion is configured to be inclined with respect to the discharge direction such that the electrode pair interval becomes narrower on the main discharge electrode side.

(Operation)

When a voltage is applied to the electrode pair of the ultraviolet pre-ionization electrode having the above configuration, an arc discharge occurs on the main discharge electrode side having the shortest interval. The electrode pair is consumed by repeating this arc discharge, but the arc discharge always occurs on the main discharge electrode side, and the ultraviolet light generated at this time is efficiently irradiated on the main electrode side to perform uniform preliminary ionization. It is. Further, since one discharge portion of the opposed electrode pair is perpendicular to the discharge direction and the other discharge portion is inclined, even if the electrodes are consumed, the spread of the distance between the electrode pairs increases. Only the inclination of the inclined electrode is sufficient, and the spread of the distance between the electrode pairs at the time of the consumption is small.

〔Example〕

An embodiment of the present invention will be described with reference to FIGS. In this embodiment, the same members as those of the conventional example shown in FIGS. 7 to 9 are denoted by the same reference numerals, and description thereof will be omitted.

FIG. 1 shows a first embodiment of the present invention, in which an ultraviolet pre-ionization electrode 10 is disposed on each of the left and right sides of the main discharge electrode 1.
Comprises a pair of electrodes 10a and 10b facing each other, which are connected in series to the peaking capacitor 11 and the main discharge electrode 1. One of the ultraviolet preionization electrodes 10 (first
The electrode 10a (upper side in the figure) is fixed to a thin column 12, and has a flat plate shape. The other (lower in FIG. 1) electrode 10b is formed in a flat shape with the periphery of the discharge portion chamfered.

The planes of the opposed discharge portions of the pair of electrodes 10a and 10b are not parallel, and the discharge portion of the lower electrode 10b is perpendicular to the discharge direction, and the upper electrode 10
The discharge part a is inclined with respect to the discharge direction such that the electrode pair interval becomes the narrowest on the main discharge electrode 1 side.

In the above configuration, both electrodes 10 of the ultraviolet preliminary ionization electrode 10
When a voltage is applied between a and 10b, an arc discharge 13 is generated at a point having the smallest interval, that is, a point closest to the main discharge electrode 1 (FIG. 2).

The main discharge electrode 1 is caused by the ultraviolet light generated by this arc discharge.
The laser medium gas between the quantity electrodes 1a and 1b is pre-ionized.

When the arc discharge is repeated at the ultraviolet pre-ionization electrode 10 in this manner, as shown in FIG. 3, of the two electrodes 10a and 10b constituting the electrode, the upper flat electrode 10a is consumed. The distance d between the narrowest portions between the electrodes 10a and 10b is increased to d '.

However, since the consumption of the electrode 10a gradually progresses from the side near the main discharge electrode 1, the arc discharge always occurs on the main discharge electrode 1 side even in the ultraviolet pre-ionization electrode 10 whose consumption has progressed.

Therefore, the generated ultraviolet light is not blocked by the ultraviolet preionization electrode 10 itself, but preliminarily ionizes the laser medium gas between the main discharge electrodes 1.

Further, when both discharge portions are consumed in accordance with the discharge of both electrodes 10a and 10b, the interval between the electrode pair is increased from the initial interval d to d ', but the interval in which the interval is increased by the exhaustion is consumed. As shown in FIG. 3, only the inclined electrode is used, and therefore, the spread of the distance between the electrode pairs due to the consumption of the electrode is only the inclination of the inclined electrode. Therefore, the spread amount is small, and the discharge starting voltage of the arc discharge does not increase.

FIG. 4 to FIG. 6 show another embodiment of the present invention, in which one electrode 10 constituting an ultraviolet pre-ionization electrode 10 ′ is shown.
a 'has a wide circular plane in the discharge part, and the other electrode 10b' is made by bending a flat plate. And the other electrode 10b '
Are inclined with respect to one electrode 10a ', and the main discharge electrode 1 side is the narrowest.

Also in this embodiment, when a voltage is applied between the electrodes 10a 'and 10b', an arc discharge 13 is generated from the main discharge electrode 1 having the shortest interval. As the arc discharge is repeated, both electrodes 10a 'and 10b' are consumed, and the initial interval d becomes d '. This d' is only slightly wider than d and has no significant effect.

〔The invention's effect〕

According to the present invention, each discharge portion of the electrode pair of the ultraviolet pre-ionization electrode is made flat, and one of the two discharge portions constituting the electrode pair is made perpendicular to the discharge direction. Further, since the other discharge portion is configured to be inclined with respect to the discharge direction so that the interval between the electrode pairs becomes narrower on the main discharge electrode side, even if the electrodes are consumed by the discharge between the electrode pairs. The spread of the distance between the electrode pairs is limited only by the inclination of the inclined electrode, so that the distance between the electrode pairs during the above consumption can be reduced.

Therefore, according to the present invention, a stable arc discharge can be obtained over a long period of time, a maintenance interval can be extended, and a stable main discharge can be obtained by obtaining uniform preliminary ionization, and oscillation can be achieved. The reproducibility and stability of the pulse energy of the laser beam can also be increased.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a configuration of a main part of a first embodiment of the present invention, FIGS. 2 and 3 are explanatory views of its operation, and FIG.
5, 6 and 7 are explanatory diagrams of the operation of the main part of the embodiment of the present invention, FIG. 7 is an explanatory diagram of the main portion of the discharge excitation gas laser device, and FIGS. 8 and 9 are conventional examples. FIG. 1 is a main discharge electrode, 10 and 10 'are ultraviolet pre-ionization electrodes.

Claims (1)

(57) [Claims] 1. An ultraviolet pre-ionization electrode of a discharge excitation gas laser device that generates ultraviolet light by arc discharge and uses the ultraviolet light for pre-ionization. At the same time, one of the two discharge portions constituting the electrode pair is formed so that one of the discharge portions is perpendicular to the discharge direction, and the other discharge portion is such that the electrode pair interval is narrower on the main discharge electrode side. An ultraviolet preionization electrode for a discharge excitation gas laser device, characterized in that the electrode is inclined with respect to the discharge direction.