JPH04192573A - Vertical electric-field discharge and stimulation laser apparatus of multiple electrode type - Google Patents

Abstract

PURPOSE:To be of a vertical electric-field simulation type and to reduce the inductance of a discharge region, i.e., of a plasma part, by a method wherein the electrode inner circumferential part of a laminated capacitor constituted in the following manner is used as a discharge part: a plurality of electrode plates and insulating plates as superconductors are laminated alternately in such a way that circular, oval or rectangular holes made in the electrode plates and holes in the insulating plates are concentric. CONSTITUTION:Doughnut-shaped electrode plates 10 in which circular, oval or rectangular holes 11 have been made in the central axis function as a positive pole. Doughnut-shaped electrode plates 14 in which circular holes 15 have been made function as a negative pole. A plurality of electrode plates 15, insulating plates 12 and electrode plates 10 are laminated alternately so as to be concentric; the electrode plates 10, 14 are arranged at outermost sides (alternatively, the electrode plates 14 are arranged on both outermost sides); bolts 17A are inserted into through holes 17 made in ear-shaped knobs 16 and fastened by using nuts 17B; the plates are assembled. As a result, a plurality of capacitors which use the insulating plates 12 inserted between the electrode plates 10, 14 as a dielectric are laminated and constituted. Thereby, the inductance of a plasma part is reduced as a transverse excitation type, and the stray inductance of a circuit is reduced.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention is an ASE (Amplified 5pon
This relates to a gas laser discharge excitation method (taneous emission) type, and is particularly used in the excitation discharge of short wavelength, high output pulsed lasers.

(Conventional technology) Gas lasers can be roughly divided into long-wavelength lasers with relatively long-life laser levels such as CO2 lasers, and long-wavelength lasers with relatively long-life laser levels such as N2 lasers and excimer lasers. There are short wavelength lasers with For example, in the case of N2 laser, the lifetime of the laser level is 40
It is about m5. Such short-lived lasers usually amplify spontaneously emitted light without constructing a resonator using a mirror (ASE type). Therefore, when pumping the laser, the short-time period corresponding to the lifetime of the spontaneously emitted light is required. In order to generate population inversion within a short period of time, an excited discharge with a fast current rise and a large input power is required.

The excitation and discharge methods of ASE-type pulsed gas lasers, which are the main object of the present invention, can be roughly divided into (1) transverse electric
(2) Longitudinal electric field excitation type
It can be classified as electric excjtation). In the former, the inductance of the plasma part can be made sufficiently small, so the output power of the discharge can be increased by lowering the impedance of the power supply, whereas in the latter, the inductance of the plasma is large, and the excitation power is, in principle, the same as that of the plasma. Limited by inductance. For this reason, horizontal discharge has mainly been used to excite high-output pulsed lasers such as N2 lasers and excimer lasers, and various methods have been adopted, such as Blumlein and reverse charging type discharge using capacitors. It has been.

In the vertical electric field excitation type conventional technology shown in Fig. 9, the discharge path and the current return path are coaxial, and usually anodes 1.
', the cathode 2 is provided in the middle.

The discharge occurs simultaneously between the anode 1 and the cathode 2 and between the anode 1° and the cathode 2 in the axial direction.

Note that 3 is a coaxial cable, 4 is a gap switch, and 5 is a discharge tube.

(Problems to be Solved by the Invention) Although the inductance of the discharge circuit is minimized to the extent possible in principle in the prior art shown in FIG. It does not eliminate the principle disadvantages of types.

In contrast, the present invention aims to reduce the inductance of the discharge region, that is, the plasma region, to the same level as that of the transverse electric field excitation type in the vertical electric field excitation type.

On the other hand, in the transverse electric field excitation type, the inductance of the plasma part is small, so if the impedance of the power source can be lowered, the input power can in principle be increased to a point commensurate with the inductance of the plasma part.

However, the input power is actually limited by the stray inductance of the power supply.

In contrast, in the present invention, the inductance outside the discharge device can be easily reduced.

(Means for solving the problem) In the coaxial longitudinal electric field excitation type, the ratio of the diameter of the plasma to the diameter of the current return path only appears in the logarithm, so it does not affect the inductance of the plasma that much.

Therefore, the only parameter that can be varied is effectively the length. In consideration of this point, a multi-electrode type longitudinal electric field discharge excitation laser device is one in which the discharge path, that is, the electrode is divided in the length direction in order to reduce the plasma inductance. In this device, by increasing the number of electrode divisions, it is possible to make the inductance of the plasma part equal to or even smaller than that of the transverse electric field excitation type, and it is also possible to reduce stray inductance in areas other than the plasma part.

Furthermore, since these can be adjusted by adjusting the number of electrode divisions, etc., it is also possible to optimize the entire system.

In addition, in order to increase and stabilize the laser output, measures such as (a), (b), and (c), which will be described later, are added.

(Function) A multilayer capacitor is constructed by concentrically stacking multiple insulating plates and donut-shaped electrode plates with holes drilled on the central axis. Adjacent electrodes are charged so that they are alternately positive and negative. The circumference of the hole drilled in the center of the capacitor electrode is used as the discharge section, and discharge occurs between the inner circumferences of the holes of adjacent positive and negative electrodes.

(Example) Example 1 (Figures 1 to 5) Multi-electrode vertical electric field discharge excitation type (high gas pressure type) The electrode plate functions as a positive electrode.

Reference numeral 12 denotes an insulating plate having a hole 13 formed on its central axis, and 14 a donut-shaped electrode plate having a circular, oval, rectangular, etc. hole 15 formed on its central axis, which functions as a negative electrode.

The device of the present invention includes an electrode plate 14. A plurality of insulating plates 12 and electrode plates 10 are laminated concentrically and alternately so that the electrode plates 14 occupy the outermost sides of both, and a through hole 17 is bored in the ear-shaped handle 16.
Assemble by passing Porto 17A through the hole and tightening with 17B.

As a result, the insulating plate 1 inserted between the electrode plates (10, 14)
It has a structure in which a large number of capacitors with 2 as a dielectric are laminated.

If adjacent electrode plates of this multilayer capacitor are charged so that they become positive and negative alternately, each capacitor will be charged in parallel.

As shown in Fig. 4, the excited discharge occurs between the inner circumferences of the holes (11, 15) of the adjacent positive and negative electrodes, with the circumferential part of the hole made in the center of the capacitor electrode as the discharge part, in other words near the axis. occurs in the hole, and the laser is emitted along the axis.

18 and 19 are electrode fixing plates, and 20 is a trigger electrode.

Each of the capacitors described above is charged in a decoupled manner through an inductance or resistance so that each capacitor discharges independently.

The equivalent circuit at that time is shown in FIG.

In this circuit, each multilayer capacitor Cj (however, j=1, 2n-1) is pulse-charged from another main capacitor - CO through an inductance Lj (however, J=11"), and when the voltage becomes high enough, startup is performed. Excited discharge is generated between each divided electrode HD by discharge (or spontaneous discharge).

(a) The inductance of the multilayer capacitor and the discharge section is small, and high-speed discharge is possible.

However, in order to obtain large excitation energy, the multilayer capacitor must be able to be charged to a sufficiently high voltage. Therefore, the withstand voltage of the capacitor, the dielectric breakdown voltage near the axis between the electrodes, etc. must be made as high as necessary. Generally, the following methods are used.

(i) The outer diameter of the insulating plate 12 used as a dielectric is the electrode plate l
The inner diameter of the hole 13, which is sufficiently larger than O and is made in the center of the - man, is
A geometrical structure that increases the dielectric breakdown voltage is used, such as making the inner diameter smaller than the inner diameter of the hole 11 of the electrode plate IO (FIG. 3).

(ii) Atmospheric pressure or an airtight structure and use of high pressure gas.

(iii) Using another capacitor 〇〇 as the main power source, the multilayer capacitor is pulse-charged as an intermediate energy storage for impedance conversion (Figure 5).

(b) In order to increase the capacity of multilayer capacitors, it is useful not only to simply increase the outer diameter of the electrodes, but also to insert low-inductance capacitors CA in parallel to various layer capacitors (see Figure 1). e) It is necessary to increase the dielectric breakdown voltage between the electrodes and to reduce the discharge delay and jitter between adjacent multilayer capacitor electrodes. This request is somewhat contradictory to the above (&); for example, there is an upper limit to gas pressure. Furthermore, in order to obtain stable starting characteristics, it is useful to pre-ionize as necessary.

In the example shown in FIG. 1, a trigger electrode 20 that can control the start of discharge is provided near the axis at one end.

The multi-electrode type vertical electric field discharge excitation laser device as described above has the following features.

[a] Since the distance between each pair of electrodes can be made sufficiently narrow in principle, by making the electrodes airtight, discharge is possible even under considerably high gas pressure. Furthermore, the inductance of the plasma generation section can be further reduced.

[bl When the inductance of the main power supply is sufficiently small, the rise of the current pulse is generated by the multilayer capacitor,
It is possible to shape the waveform so that the latter half is generated by the main power supply.

[e] Controlling the discharge generation time in the axial direction (tra
It is possible to control the movement of the excitation region. As a method for this purpose, the charging voltage of each multilayer capacitor for 1 hour may be controlled by the values of Lj and Cj in diagram I85, or a trigger discharge may be generated on one side.

Example 2 (Figs. 6 to 8) Multi-electrode vertical electric field discharge excitation type (dilute gas type) with internal switch In this example, the same numbers are given to substantially the same parts as in Example 1. It is.

In the case of the first embodiment described above, it can be used for relatively high pressure gas by making it atmospheric pressure or airtight. However, when diluted gas is used, even if it is airtight, dielectric breakdown near the axis occurs at low voltages and discharge occurs, making it impossible to charge the multilayer capacitor sufficiently.To avoid this difficulty, each The high voltage side electrode of a multilayer capacitor may be separated into a capacitor electrode and a discharge electrode.

To this end, in this embodiment, an annular discharge electrode 21 is disposed concentrically in the hole 15 of the electrode plate 10 (positive electrode in this embodiment) as a capacitor electrode with a gap in between.

Therefore, a gap switch GS is provided between the electrode plate lO and the discharge electrode 21.

The potential of the discharge electrode 21 during charging is determined by connecting it to the negative voltage side electrode plate 14 through an appropriate resistance. For example, this can be achieved by providing an appropriate resistance value to the portion of the dielectric plate that is in contact with the discharge electrode 21.

FIG. 6 shows an example of a device in which charging and excitation discharging of a multilayer capacitor are made independent by changing the capacitor high voltage side electrode and dielectric plate in this way.

In FIG. 6, when the withstand voltage of the gap is appropriate, no voltage is applied to the discharge electrode 21 separated by the gap during charging of the multilayer capacitor, so no discharge occurs between the electrode plate 14 and the discharge electrode 21.

By short-circuiting the gap after charging, a voltage can be supplied to the discharge electrode 21, and a discharge can be generated near the axis as in FIG. 4.

By making the discharge region airtight and using such an electrode structure, it is possible to generate excited discharge at high voltage in the discharge region near the axis using any diluted gas.

The same as described in Example 1 is true except that the gap switch GS is provided between the capacitor electrode and the discharge electrode 21, and the airtightness is required.

When a diluted gas is used and the input power is the same, a higher temperature plasma can be generated and can be used for pulsed laser oscillation with a shorter wavelength.

(Effects of the Invention) (1) In the invention of claim 1, (a) compared to conventional longitudinal discharge excitation, greater power can be input into the discharge region. As a guideline, when the size of the excited discharge section is fixed and the inductance of the plasma section is compared, when the number of electrode divisions is N, it is N-2 compared to the conventional type. It is not so difficult to set N = 50 to 100, and this point alone can increase the current increase rate by 10
It can be multiplied by 3 to 104 times.

(b) Similarly, compared to the transverse electric field excitation type, the invention according to claim 1 can input large power to the discharge region. In the present invention, a pair of electrodes forming adjacent capacitors each correspond to a conventional transverse electric field excitation type Blumlein discharge. Therefore,
By increasing the outer diameter of the electrode, the input energy is
The number of divisions can be increased to about N times. In the lateral excitation type, the inductance of the plasma part is small, and it is difficult to reduce the stray inductance of the circuit accordingly.

In the present invention, first, the stray inductance can be made much smaller than that of the conventional transverse electric field excitation type. Further, when the length L of the excited discharge section is the same and the electrode spacing is about the same L/N, the inductance of the plasma section is about the same.

When N is larger than this, the inductance of the plasma section decreases accordingly. The rise of the current can be increased by the amount of inductance reduction caused by these. Furthermore, when the width of the current pulse and the lifetime of the laser level are approximately the same, an increase in input energy can be expected due to an increase in capacitance.

(2) The invention according to claim 2 is adapted to be used in a dilute gas.

(3) According to the invention set forth in claim 3, the capacity of each multilayer capacitor can be increased.

(4) According to the invention set forth in claim 4, the device can be simplified in terms of withstand voltage, and the charging energy of the multilayer capacitor can be increased with the same device.

(5) The invention described in claim II has the effect of stabilizing its operation.

[Brief explanation of drawings]

1 to 5 show Embodiment 1 of the present invention, FIG. 1 is a partially longitudinal front view of the apparatus of the present invention, FIG. 2 is a partially longitudinal right side view of FIG. 1, and FIG. Figure 4 is an exploded perspective view of the main parts showing the laminated relationship between electrode plates and insulating plates, Figure 4 is an enlarged longitudinal sectional front view of the main parts with electrode plates and insulation plates stacked alternately, and Figure 5 is an exploded perspective view of the main parts of a multilayer capacitor. This shows an equivalent circuit during charging. 6 to 8 show Example 2, FIG. 6 is a partially longitudinal front view of the device, FIG. 7 is a partially longitudinal right side view, and FIG. 8 is a front view of an electrode plate having discharge electrodes. It is. FIG. 9 shows the prior art.

Claims (5)

[Claims] (1) The inner periphery of the electrode of a multilayer capacitor is constructed by concentrically stacking multiple electrode plates with circular, elliptical, rectangular, etc. holes drilled on the central axis and insulating plates as dielectric bodies. A multi-electrode vertical electric field discharge excitation laser device characterized by a discharge section. (2) One side of a multilayer capacitor that has a high potential is constructed by concentrically stacking multiple electrode plates with circular, elliptical, rectangular, etc. holes drilled on the central axis and insulating plates as dielectric bodies. The electrodes are separated into a capacitor electrode and a discharge electrode, and a gap is provided between them, making charging of a multilayer capacitor and discharging between the discharge electrodes independent, and can be used even when the charging voltage is high and the filling gas in the discharge section is dilute. Multi-electrode vertical field discharge excitation laser device with an electrode structure that enables (3) The multi-electrode type longitudinal electric field discharge excitation laser device according to claim 1 or claim 2, wherein a low inductance capacitor CA is connected in parallel to each multilayer capacitor to increase the capacity of each multilayer capacitor. (4) The multi-electrode longitudinal field discharge excitation laser device according to claim 1, 2 or 3, wherein a separate capacitor is used as a main power source, and the multilayer capacitor is an intermediate energy storage capacitor. (5) The multi-electrode longitudinal electric field discharge excitation laser according to claim 1 or 2 or 3 or 4, which has a trigger mechanism such as pre-ionization by ultraviolet rays or trigger discharge to control the start of discharge. Device