JPH05206553A - Pulsed laser electrode - Google Patents

Abstract

PURPOSE:To enable a pre-ionization electrode to be lessened in consumption and to generate sparks of light from its wide area. CONSTITUTION:Pre-ionization electrode pairs 12 composed of pin-shaped pre- ionization electrodes 10 and fan-shaped pre-ionization electrode 11 are provided on the lengthwise sides of a second main electrode confronting a first main electrode. The tip of the fan-shaped pre-ionization electrode 11 is stepped to enable its part 11a, which confronts the tip 10a of the pin-shaped pre-ionization electrode 10, to be the arc of a sector. The sector part 11a is provided adjacent to the primary electrode 2.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Generally, in order to obtain laser oscillation using a gas as a laser medium, it is necessary for the laser medium to generate a spatially uniform glow discharge between main discharge electrodes. _In a high-repetition pulse laser oscillator that generates short-pulse laser light such as a _two- laser or excimer laser, its operating pressure is higher than atmospheric pressure, so that the above-mentioned discharges converge and arc discharge easily occurs. In order to prevent this, it is usual to adjust the electric field distribution in the main discharge space or perform preionization to increase the electron density in the main discharge space in advance prior to the main discharge.

FIG. 6 shows an example of a conventional pulse laser electrode. That is, the second main electrode 2 is arranged at a position facing the first main electrode 1 arranged in the laser medium, and a plurality of pin-shaped preliminary electrodes are provided on both sides of the second main electrode 2 in the longitudinal direction. The ionization electrodes 3 are arranged at a certain interval. The pin-shaped preionization electrode 3 is composed of a pin-shaped metal 3a and an insulator 3b that covers an outer peripheral portion other than both ends thereof. Then, it is connected to the high-voltage pulse power supply 8 via the ballast inductance 6.

Outside the pin-shaped preionization electrode 3,
That is, the plate-shaped preionization electrode 4 is disposed at a position facing the second main electrode 2 with the pin-shaped preionization electrode 3 interposed therebetween so as to have the same potential as the second main electrode 2. Each tip of the pin-shaped preionization electrode 3 and the plate-shaped preionization electrode 4 are
The ends of are placed with a distance of about 1 mm,
Together, a pair of preionization electrode pairs is constructed.
The two main electrodes 1 and 2 are electrically connected via a peaking capacitor 5.

In the conventional pulse laser electrode thus constructed, when a high-voltage pulse is applied from the high-voltage pulse power supply 8, first, the high-voltage pulse power supply 8 → ballast inductance 6 → pin-shaped preionization electrode 3 → plate-shaped Pre-ionization electrode 4
→ Current flows in the circuit of the peaking capacitor 5 and the peaking capacitor 5 is charged. At this time, ultraviolet rays 7 are generated by the spark discharge that occurs in the small gap between the pin-shaped preionization electrode 3 and the plate-shaped preionization electrode 4. This ultraviolet light is photoionized to generate electrons, and the first main electrode 1
The space between and the second main electrode 2 is preionized.

Then, when the voltage applied to the peaking capacitor 5 that continues to be charged reaches the discharge breakdown voltage between the main electrodes 1 and 2, the main discharge starts and laser light is generated. At this time, the preliminary ionization is used to make the main discharge a glow-like uniform discharge.

[0007]

However, the conventional pulsed laser electrode having the above-mentioned structure has the following problems to be solved. That is, since a spark discharge for preionization is generated between the tip of the pin-shaped preionization electrode 3 and a part of the plate-shaped preionization electrode 4 which is the metal portion located closest to the tip-shaped preionization electrode 3, As the number of discharges increases, the electrode at the portion where the spark discharge occurs becomes more and more consumed. That is, when the number of shots is overlapped from the initial state of the preionization electrode as shown in FIG.
As shown in (B), the two preliminary ionization electrodes 3 and 4 are partly scooped around a point where the energy of the spark discharge is concentrated.

For this reason, the distance between the pin-shaped preionization electrode 3 and the plate-shaped preionization electrode 4 is increased, so that the initial preionization strength cannot be maintained for a long time.
Therefore, when the laser operation is performed for a long time, the main discharge is ignited in the state where the preliminary ionization is not sufficiently performed, and it is difficult to maintain a stable main discharge.

Further, since the spark discharge is ignited only in a point shape, the light quantity of the spark light is small, and there is a drawback that a sufficient preionization intensity for preionizing the main discharge space cannot be obtained. Further, a preionization method using X-rays instead of ultraviolet rays is conceivable, but it has a drawback that it is not suitable for high repetition operation, the apparatus becomes large and the cost increases significantly.

The present invention has been proposed to solve the above-mentioned problems of the prior art, and its purpose is to suppress the consumption of the preionization electrode and to generate spark light from a wide surface. It is to provide a highly efficient pulsed laser electrode that can obtain a high-power laser beam while maintaining stable glow discharge.

[0011]

According to a first aspect of the present invention, there is provided a first main electrode and a second main electrode which are arranged to face each other, and prior to a main discharge occurring between the two main electrodes, In a pulsed laser electrode for preionizing the main discharge space, a preionization electrode for preionizing the main discharge space, a pin-shaped metal electrode and a fan-shaped metal electrode arranged around the metal electrode through an insulator. And a spark discharge is generated between the tip of the pin-shaped metal electrode and the end of the fan-shaped metal electrode, and the main discharge space is preionized by the ultraviolet light generated thereby. It is what

According to a second aspect of the present invention, in the same pulsed laser electrode, a preionization electrode for preionizing the main discharge space is arranged with a pin-shaped metal electrode and an insulator around the pin-shaped metal electrode. And a cylindrical metal electrode that has been formed, and spark discharge is generated between the tip of the pin-shaped metal electrode and the end of the cylindrical metal electrode, and the main discharge space is pre-ionized by the ultraviolet light generated thereby. It is characterized in that it is configured to.

[0013]

According to the invention described in claim 1, it is possible to irradiate the main discharge space with a wide ultraviolet ray generated between the pin-shaped metal electrode and the fan-shaped metal electrode, and to carry out the preliminary ionization. Since the consumption of the electrodes can be reduced, uniform preionization can be performed over a wide range of the main discharge space, and stable glow discharge with high excitation intensity can be ignited.

According to the second aspect of the invention, it is possible to irradiate the main discharge space with a wide ultraviolet ray generated between the pin-shaped metal electrode and the cylindrical metal electrode, and to carry out the preliminary ionization. Since the consumption of electrodes can be reduced, uniform preionization is possible over a wide area of the main discharge space.
It is possible to ignite a stable glow discharge with high excitation intensity.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be specifically described below with reference to FIGS. The same members as those of the conventional type shown in FIG. 6 are designated by the same reference numerals, and the description thereof will be omitted.

(A) First Embodiment In the present embodiment, as shown in FIG. 1, on both sides in the electrode longitudinal direction of a second main electrode arranged at a position facing the first main electrode 1. A plurality of pairs of preionization electrode pairs 12 each including one pin-shaped preionization electrode 10 and one fan-shaped preionization electrode 11 are arranged. Further, the fan-shaped preionization electrode 11 has a step at its tip,
Portion 11 of the pin-shaped preionization electrode facing the tip 10a
a is configured to draw a fan-shaped arc. The fan-shaped arc portion 11a is arranged so as to be close to the main electrode 2 side.

FIG. 2 shows the structure of the tip of the preionization electrode pair 12. That is, a fan-shaped preionization electrode 11 made of a hollow cylindrical metal is arranged around the pin-shaped preionization electrode 10 as a center. Further, between the pin-shaped preionization electrode 10 and the fan-shaped preionization electrode 11,
Insulator 1 for electrical insulation, excluding its tip
3 is filled.

Further, the pin-shaped preionization electrodes 10 are individually connected to the high-voltage pulse power source 8 via the ballast inductance 6 so that the wirings have the same inductance. On the other hand, the fan-shaped preionization electrode 11 is electrically connected to the second main electrode 2 and the peaking capacitor 5.

The operation and action of the pulsed laser electrode of this embodiment having such a structure will be described below. That is, when a high-voltage pulse is applied to the pin-shaped preionization electrode 10 from the high-voltage pulse power source 8, the ballast inductance 6 causes
Current is shunted equally to each pin-shaped preionization electrode 10.
Due to this current, the tip portion 10a of the pin-shaped preionization electrode 10
And the arc-shaped tip portion 11a of the fan-shaped preionization electrode 11 which is the closest metal end and is opposed thereto, a linear spark discharge is generated, and the ultraviolet ray 7 generated thereby causes the ultraviolet rays 7 of the second main electrode 2 to be generated. The main discharge space is irradiated from both sides in the longitudinal direction.

At the same time, the current flowing by the spark discharge flows to the ground via the fan-shaped preionization electrode 11 while charging the peaking capacitor 5 from the main electrode 2.
When the voltage of the peaking capacitor 5 rises and reaches the discharge breakdown voltage of the laser medium gas filled between the main electrodes 1 and 2, the main discharge is ignited between the main electrodes 1 and 2. Then, laser light is generated in the electrode longitudinal direction by the action of the optical resonator (not shown).

As described above, when the pulsed laser electrode of this embodiment is used, the spark discharge for preionization, which has conventionally been concentrated at one point, is generated in the arc of the tip of the fan-shaped preionization electrode 11. Since they are generated linearly, the electric load locally applied to only a small part of the tip of each preionization electrode is significantly reduced. As a result, consumption of the preionization electrode due to metal sputtering or the like is reduced, so that the change in the shape of the preionization electrode is suppressed.

Thus, the preionization conditions such as the preionization intensity, the preionization space, and the uniformity of the preionization are kept constant for a long time, so that the stability and the uniformity of the laser main discharge can be maintained for a long time. Guaranteed. Further, it is possible to prevent the contamination of the laser window for taking out the laser oscillation light to the outside due to the metal fine particles generated by sputtering or the like.

Furthermore, since the preionization occurs linearly along the arc of the fan-shaped preionization electrode, the pair of preionization electrode pairs 1
The space where 2 can be pre-ionized becomes wider. Further, since it is concentratedly generated in the space close to the main electrode, sufficient preionization can be performed by irradiating the main discharge space with intense preionization light. As a result, it is possible to realize stable preionization that is spatially homogeneous and has little unevenness, so that the laser excitation intensity is increased and the oscillation efficiency is also greatly improved.

The present invention is not limited to the above-described embodiments. For example, in the fan-shaped preionization electrode, only the tip portion facing the pin-shaped preionization electrode has the pin-shaped preionization electrode as the center. It is sufficient to draw a fan-shaped arc, as shown in FIG.
As shown in (A), the fan-shaped preionization electrode 14 may be formed in a semi-cylindrical shape. Further, as shown in FIG. 3 (B), except for the tip end facing the pin-shaped preionization electrode, it may be formed in a narrow rod shape, and according to the surrounding discharge part structure, discharge circuit, etc., It is possible to take the optimum shape in each case.

(B) Second Embodiment In this embodiment, as shown in FIG. 4, both sides in the electrode longitudinal direction of the second main electrode 2 arranged at a position facing the first main electrode 1. In addition, a plurality of pairs of preionization electrodes 22 each including one pin-shaped preionization electrode 20 and one hollow cylindrical preionization electrode 21 are arranged.

5 (A) and 5 (B) show the structure of the tip of the preionization electrode pair 22. That is, a hollow cylindrical preionization electrode 21 is arranged around the pin-shaped preionization electrode 20 and an insulator 23 for electrical insulation is provided between the two except for the tip. Is filled.

The pin-shaped preionization electrodes 20 are individually connected to the high-voltage pulse power source 8 via the ballast inductance 6 so that the inductances of the wirings become equal. On the other hand, the cylindrical preionization electrode 21 is electrically connected to the second main electrode 2 and the peaking capacitor 5.

The operation and action of the pulse laser electrode of this embodiment having such a structure will be described below. That is, when a high-voltage pulse is applied to the pin-shaped preionization electrode 20 from the high-voltage pulse power source 8, the ballast inductance 6 causes
The current is shunted equally to each pin-shaped preionization electrode 20.
This current causes a linear spark discharge between the tip portion of the pin-shaped preionization electrode 20 and the tip circumferential portion of the opposing cylindrical preionization electrode 21, which is the metal end closest to the pin-shaped preionization electrode 20. The generated ultraviolet rays 7 are applied to the main discharge space from both sides in the longitudinal direction of the second main electrode 2.

At the same time, the current flowing by this spark discharge flows from the main electrode to the ground while charging the peaking capacitor 5 from the main electrode 2 via the cylindrical preionization electrode 21. When the voltage of the peaking capacitor 5 rises and reaches the discharge breakdown voltage of the laser medium gas filled between the main electrodes 1 and 2, the main discharge is ignited between the main electrodes 1 and 2. Then, laser light is generated in the electrode longitudinal direction by the action of the optical resonator (not shown).

As described above, when the pulsed laser electrode of the present embodiment is used, spark discharge for preionization, which has conventionally been concentrated at one point, is generated in the circumference of the tip portion of the cylindrical preionization electrode 21. Since it is generated linearly along the line, the electrical load locally applied to only a small part of the tip of each preionization electrode is significantly reduced. As a result, consumption of the preionization electrode due to metal sputtering or the like is reduced, so that the change in the shape of the preionization electrode is suppressed.

Therefore, the preionization conditions such as the preionization intensity, the preionization space, and the uniformity of the preionization are kept constant for a long time, so that the stability and uniformity of the laser main discharge are guaranteed for a long time. To be done. Further, it is possible to prevent the contamination of the laser window for taking out the laser oscillation light to the outside due to the metal fine particles generated by sputtering or the like.

Further, since the preionization occurs linearly along the circumference of the cylindrical preionization electrode, it is possible to irradiate the preionization light over a wider range. As a result, it is possible to realize stable preionization that is spatially homogeneous and has little unevenness, so that the laser excitation intensity is increased and the oscillation efficiency is also greatly improved.

[0033]

As described above, according to the present invention, a fan-shaped metal electrode or a cylindrical metal electrode in which the preionization electrode is provided with a pin-shaped metal electrode and its periphery with an insulator interposed therebetween. A spark discharge is generated between the tip of the pin-shaped metal electrode and the end of the fan-shaped metal electrode or the end of the cylindrical metal electrode, and the main discharge space is pre-ionized by the ultraviolet light generated by the spark discharge. With such a configuration, it is possible to suppress the consumption of the preionization electrode, generate spark light from a wide surface, maintain stable glow discharge, and obtain high-output laser light, high efficiency. Pulsed laser electrodes can be provided.

[Brief description of drawings]

FIG. 1 is a perspective view showing a first embodiment of a pulse laser electrode of the present invention.

2 (A) is an enlarged perspective view of a tip portion of the preionization electrode pair of the embodiment shown in FIG. 1, and FIG. 2 (B) is a sectional view thereof.

3A and 3B are perspective views showing another configuration example of the first embodiment shown in FIG.

FIG. 4 is a perspective view showing a second embodiment of the pulsed laser electrode of the present invention.

5A is an enlarged perspective view of a tip portion of the preionization electrode pair of the embodiment shown in FIG. 2, and FIG. 5B is a sectional view thereof.

FIG. 6 is a perspective view of a conventional pulse laser electrode.

FIG. 7A is a perspective view of a main part of a conventional preionization electrode pair of a pulse laser electrode, and FIG. 7B is a perspective view showing how it is consumed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... 1st main electrode 2 ... 2nd main electrode 3 ... Pin-shaped preionization electrode 4 ... Plate-shaped preionization electrode 5 ... Peaking capacitor 6 ... Ballast inductance 7 ... Ultraviolet 8 ... High-voltage pulse power supply 10 ... Pin-shaped preionization Electrode 11 ... Fan type preionization electrode 12 ... Preionization electrode pair 13 ... Insulator 14, 15 ... Fan type preionization electrode 20 ... Pin-shaped preionization electrode 21 ... Cylindrical preionization electrode 22 ... Preionization electrode pair 23 ... Insulation object

Claims (2)

[Claims] 1. A first main electrode and a second electrode which are arranged to face each other.
In the pulsed laser electrode for preionizing the main discharge space prior to the main discharge generated between the main electrodes, a preionization electrode for preionizing the main discharge space,
It is composed of a pin-shaped metal electrode and a fan-shaped metal electrode that is arranged around the pin-shaped metal electrode, and spark discharge is generated between the tip of the pin-shaped metal electrode and the end of the fan-shaped metal electrode. The pulsed laser electrode is characterized in that the main discharge space is preionized by the ultraviolet light generated thereby. 2. A first main electrode and a second electrode which are arranged to face each other.
In the pulsed laser electrode for preionizing the main discharge space prior to the main discharge generated between the main electrodes, a preionization electrode for preionizing the main discharge space,
It is composed of a pin-shaped metal electrode and a cylindrical metal electrode arranged around the pin-shaped metal electrode via an insulator, and a spark discharge is generated between the tip of the pin-shaped metal electrode and the end of the cylindrical metal electrode. A pulsed laser electrode characterized in that it is constructed so that the main discharge space is preionized by the ultraviolet light generated thereby.