JPH01215079A - Pulse laser oscillator - Google Patents

Abstract

PURPOSE:To reduce the residual inductance of a preionization circuit and then to shorten the charging time of a peaking capacitor for increasing a laser oscillation efficiency by connecting each preionization electrode to an inductance element, as well as to increase the preionization electron density and then to increase the stability of glow discharging for gaining a high output laser by making effective use of ultraviolet rays generated by spark discharging. CONSTITUTION:On the surface of one principal electrode 2 facing the other principal electrode 1, several holes 12 are made uniformly. Between the principal electrodes 1 and 2, a peaking capacitor 5 is connected. A high-speed high-voltage pulse generator and a preionization common electrode 10 are connected. Several preionization electrodes 3 are located at equal spaces 4, facing the common electrode 10. Each of the preionization electrodes 3 is connected to the capacitor 5 through a shunt inductance 6. Gas flow 9 circulates between the principal electrodes 1 and 2. On the inner area of the holes 12, high optical electron radiation efficiency material 13 is applied.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a pulsed laser oscillation device, and particularly to a pulsed laser oscillation device.

This relates to its electrode structure.

(Prior art) Generally, in order to obtain laser oscillation, it is necessary to generate a spatially uniform discharge in the laser medium, but TEACO□
In pulsed laser oscillation devices such as lasers and TEMACO□ lasers, the operating pressure is as high as the diffused pressure.
The above-mentioned discharge tends to focus and become arc discharge, and to prevent this, it is common to perform preliminary ionization prior to the main discharge.

FIG. 4 shows an example of a conventional pulsed laser oscillation device, and FIG. 5 shows a schematic diagram of its circuit configuration. As shown in FIG. The other main electrode 2 in the form of a net is arranged at a position opposite to the main electrode 1,
A plurality of pre-ionization electrodes 3 are arranged in series on the back surface of the main electrode 2 in the longitudinal direction of the main electrode with gaps 4 at appropriate intervals.

Further, a plurality of rows (two rows in FIG. 4) of the pre-ionization electrodes 3 are arranged in a direction perpendicular to the longitudinal direction of the main electrode. The row of pre-ionization electrodes 3 is connected to a high-speed, high-voltage pulse generation power source (not shown) via a shunt inductance 6, and the other end is connected to a peaking capacitor 5. Furthermore, the peaking capacitor 5 is connected between the main electrode 1 and the net-shaped main electrode 2. In the wind barrel of the Rade oscillator, there is a blower for circulating the laser gas, which generates a gas flow 9 that passes through the discharge space formed by the main electrodes 1 and 2. Furthermore, optical resonators (not shown) are disposed at both ends in the longitudinal direction of the two opposing main electrodes 1.2, and laser light is output.

The operation of the conventional pulsed laser oscillation device configured in this way will be explained with reference to FIG. When capacitor C1 is charged to a high voltage and switch 11 is closed, a high-speed pulse voltage (=
The 0-division inductance 6, in which the HV pulse) is generated and applied to the diversion inductance 6, is installed for the purpose of equally dividing the current when there are a plurality of pre-ionization electrode arrays.

The HV pulse current flows in the order of shunt inductance 6 → pre-ionization electrode 3 → gap 4 → peaking capacitor 5. In the process of charging the peaking capacitor 5, a spark discharge is ignited in the gap 4 between the pre-ionization electrodes 3 to generate ultraviolet rays 7, which irradiate the laser gas between the main electrodes 1 and 2. The laser gas is photoionized by this ultraviolet ray, electrons are generated, and the space between the main electrodes 1 and 2 is pre-ionized.The voltage of the peaking capacitor 5 increases during this process.
When the voltage between main electrodes 1 and 2 exceeds the discharge breakdown voltage of the laser gas, discharge breakdown occurs between main electrodes 1 and 2, and glow discharge 8
fires. This glow discharge 8 excites the laser gas and generates laser light.

(Problem to be Solved by the Invention) However, in the conventional pulse laser oscillation device described above, the capacitor C1 and the peaking capacitor 5
In addition to the inductance 6 for the one-way shunt, the inductance between them increases due to the residual inductance of the three rows of pre-ionization electrodes connected in series and the residual inductance of the wiring, which limits the rise speed of the HV pulse that charges the peaking capacitor 5. If the rising speed of the HV pulse is slow, the time interval from when the gap 4 is destroyed by discharge and ultraviolet irradiation starts until the glow discharge 8 is ignited becomes long, and during this time, electrons generated by photoionization recombine. As a result, the electron density at the start of the main discharge was low, resulting in a low discharge current rise rate and a low discharge excitation intensity. Furthermore, the higher the porosity of the net-like main electrode 2, the more
Although the intensity of ultraviolet rays irradiated between the main electrodes 1 and 2 increases, the glow discharge current is greatly contracted on the surface of the main electrode 2, so the critical current value that causes the glow discharge to contract and become an arc discharge is low. There was a problem.

Further, in the process of charging the peaking capacitor 5, electrons near the cathode move due to the electric field between the main electrodes 1 and 2, causing a problem that electrons near the cathode become depleted.

Therefore, discharge instability was likely to occur near the cathode at the start of the main discharge.

For the reasons mentioned above, in the conventional method, not only is the laser oscillation efficiency low because the excitation intensity of the laser gas is low due to residual inductance, but also the injectable power is limited due to discharge instability, making it impossible to perform high-output laser oscillation. there were.

Therefore, the present invention was proposed to eliminate the above-mentioned drawbacks, and its purpose is to reduce the residual inductance of the preionization circuit, shorten the charging time of the peaking capacitor, and increase laser oscillation efficiency. Another object of the present invention is to provide a pulsed laser electrode that can effectively utilize ultraviolet rays generated by spark discharge to increase the density of pre-ionized electrons, improve the stability of glow discharge, and obtain high-output laser light.

(Structure of the Invention) (Means for Solving the Problems) A pulsed laser electrode of the present invention includes a main electrode having a plurality of openings disposed at a position facing one main electrode, and a pulse laser electrode of the present invention. A plurality of pre-ionization electrodes are provided near the back surface of the electrode, a shunt inductance is connected between each of the pre-ionization circuits and a high-speed high-voltage pulse generator, and photoelectrons are provided on the surface in the thickness direction of the main electrode having the opening. It is constructed to apply a material with high radioactivity.

(Function) According to the present invention having the above configuration, since the high-speed high-voltage pulse generator and the pre-ionization electrode are connected by a large number of shunt inductances, the residual inductance of the circuit can be reduced, and the main electrode Not only does the frequency of the pulse voltage applied between the electrodes become higher, which stabilizes the discharge, but also pre-ionization occurs in the gap between the electrodes due to the effect of the material with high photoelectron emission efficiency applied to the inner surface of the opening of the main electrode. A large amount of electrons are generated near the main electrode by ultraviolet rays, and in the process of applying voltage between the main electrodes, electron depletion near the electrodes is unlikely to occur, making stable high-power pulse discharge possible and generating high-output laser light. .

(Example) An example of the present invention will be specifically described below with reference to FIGS. 1, 2, and 3.

In this embodiment, as shown in FIG. 1, the other main electrode 2 is disposed at a position opposite to one main electrode 1, and a plurality of openings 12 are formed on the surface of the main electrode 2. It is evenly opened. A peaking capacitor 5 is connected between the main electrodes 1 and 2. A high-speed high-voltage pulse generator (not shown) and a pre-ionization common electrode 10 are connected, and the same gear as the pre-ionization common electrode 10 is connected. A plurality of preliminary ionization electrodes 3 are arranged facing each other at four intervals. The pre-ionization electrodes 3 are each connected to a peaking capacitor 5 via a shunt inductance 6. A gas stream 9 circulates between the main electrodes 1.2. Figure 2 shows the opening 1 of the main electrode 2.
The two neighborhoods are enlarged and shown in detail.

That is, on the inner surface of the plurality of openings 12 in the main electrode 2, a material 1 having high photoelectron radiation efficiency, such as Rb-Te, Cs1.
CsBr or the like is coated.

The operation of the pulsed laser electrode of this embodiment having such a configuration will be explained with reference to FIGS. 2 and 3. In Figure 3,
Charge the capacitor C to a high voltage and switch 11.
When closed, a fast high voltage pulse is applied to the main electrode 1 and the pre-ionization common electrode 10. Lo represents the residual inductance of the circuit. When a fast high voltage pulse is applied, a spark discharge occurs in the gap 4 between the pre-ionization common electrode lO and the pre-ionization electrode 3 and ultraviolet light 7 is generated. By the action of the shunt inductance connected to each preionization electrode 3, each gap 4
A current equal to 2 flows, and the main discharge space is uniformly irradiated in the longitudinal direction of the main electrode by ultraviolet rays that have passed through the apertures 12 on the main electrode 2. The current flowing through the gap 4 charges the peaking capacitor 5, and a voltage is applied between the main electrodes 1 and 2. When the voltage between the main electrodes 1 and 2 becomes equal to or higher than the discharge starting voltage, discharge starts.

A glow discharge 8 occurs. By using a large number of pre-ionization electrodes 3, the parallel impedance of the shunt inductance becomes extremely small, and the voltage rise speed of the peaking capacitor 5 becomes faster.

Therefore, the time interval from ultraviolet irradiation to the start of main discharge is shortened, the number of electrons lost due to recombination is small, and the number of electrons at the start of main discharge is kept high. In addition, as shown in FIG. 2, the ultraviolet rays 7 generated in the gap 4 are
2 and irradiates the laser gas in the main discharge space to not only perform preliminary ionization, but also irradiate the inner surface 13 of the aperture to generate electrons e by the effect of the material 13 with high photoelectron radiation efficiency. A large number of them are generated on the surface of 12. If the polarity of the porous main electrode 2 is set to cathode, the electrons e generated in the opening 12 are attracted by the electric field between the main electrodes 1 and 2 and enter the main discharge space. In the process of charging the peaking capacitor '5, electrons near the cathode move due to the electric field between the main electrodes 1 and 2, and electrons near the cathode become depleted in the conventional electrode structure, but in the present invention, this occurs. Materials with high photoelectron radioactivity 1
Due to the effect of 3, electron deficiency in the vicinity of the cathode is less likely to occur, and discharge instability does not occur at the start of the main discharge.In addition, if the photoelectron emitting material is optimally selected, not only the ultraviolet rays 7 generated from the spark discharge in the gap 4, but also the Since electrons can be generated even with low-energy, long-wavelength light, the number of pre-ionized electrons increases by one order of magnitude or more compared to the conventional method in which the laser gas is photoionized and pre-ionized using only ultraviolet rays. Therefore, discharge stability is high and high power density discharge is possible.

〔Effect of the invention〕

As described above, according to the pulsed laser oscillation device of the present invention, since a large number of pre-ionization electrodes are connected in parallel, the inductance of the pre-ionization circuit is reduced, and the charging time of the peaking capacitor is shortened, so that laser oscillation is possible. Efficiency is increased, and the electron density near the cathode is increased by effectively utilizing ultraviolet rays and longer wavelength light rays generated by spark discharge, increasing discharge stability at the start of glow discharge and efficiently obtaining large-scale laser light. It is possible to provide a pulsed laser oscillation device that can perform

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an embodiment of the pulsed laser oscillation device of the present invention, FIG. 2 is a perspective view showing details of the main parts of the pulsed laser oscillation device of the present invention, and FIG. 3 is a schematic configuration diagram of the same, FIG. 4 is a perspective view showing a conventional pulse laser oscillation device, and FIG. 5 is a schematic configuration diagram thereof. 1.2... Main electrode 3... Pre-ionization electrode 4...
・Gap 5...Peaking capacitor 6...
Diversion inductance 7... Ultraviolet light 8... Glow discharge 9... Gas flow lO... Pre-ionization common electrode 11... Switch 12... Opening part
13...Photoelectron emission material agent Patent attorney Nori Ken Yudo Chika Ken Daishimaru Figure 1 Figure 2. Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] One main electrode, the other main electrode having a plurality of openings arranged opposite to the one main electrode, and a plurality of pre-ionization electrodes provided near the back surface of the other main electrode. , a pulsed laser oscillation device in which an inductance element is connected to each of the pre-ionization electrodes.