JP3473244B2 - Corona generator - Google Patents

Description

BACKGROUND OF THE INVENTION [0001] [Technical Field of the Invention The present invention relates to a corona generating device, in particular, relates to Turkey Rona generator used <br/> for preionization of the laser device It is. 2. Description of the Related Art For example, in a discharge-excited excimer laser, in order to efficiently generate laser light, it is important to efficiently discharge energy into a discharge medium. For that purpose, it is important to sufficiently perform preliminary ionization and obtain a high electron number density. The preionization method includes an arc method, an X-ray method, and a corona method. The arc method has an advantage that the number density of generated electrons is high, but it is difficult to maintain a stable excitation discharge. The X-ray method has a high electron number density and is capable of stable excitation discharge, but the apparatus for radiation control becomes large. Corona method
Although stable excitation discharge is possible and there is no need for radiation control, there is a problem that the preliminary ionization effect is low and the generated electron number density is low. [0005] Referring to FIGS. 5 to 7, a conventional corona generating apparatus 1 that performs the above-described preionization by the corona method,
The dielectric ceramic substrate 2 is provided. On one surface of the dielectric ceramic substrate 2, as shown by hatching in FIG. As shown in FIG.
An electrode 5 having an electrode non-forming portion 4 extending in a slit shape is formed. Although not shown, the respective portions of the electrode 5 on each side of the electrode non-formed portion 4 are connected to each other and have the same potential. In another conventional corona generating apparatus 1a, FIG.
Instead of the electrode 5 formed on the other surface shown in FIG. 7, an electrode 5a having a plurality of circular island-shaped electrode non-formed portions 4a is formed as shown in FIG. As described above, in the corona method, the problem that the preliminary ionization effect is low and the number density of generated electrons is low is that the AC or AC between the electrode 3 and the electrode 5 or 5a of the corona generator 1 or 1a. When a pulse voltage is applied, the end of the electrode 5 or 5a, in other words, the boundary with the electrode non-formed portion 4 or 4a becomes a high electric field, and corona is generated. That is, the portion contributing to corona generation is limited to the end of the electrode 5 or 5a, and the other region of the electrode 5 or 5a does not contribute to corona generation. The current flowing outside the portion, that is, the current not involved in the preionization, increases, and as a result, the efficiency of the preionization decreases and the electron number density decreases. SUMMARY OF THE INVENTION An object of the present invention is to provide a corona generator capable of obtaining an electron number density comparable to that of the arc system while maintaining the advantages of the corona system. It is to be. SUMMARY OF THE INVENTION The present invention provides a laser device including a dielectric ceramic substrate and electrodes provided to face each other with the dielectric ceramic substrate interposed therebetween.
In order to solve the technical problem described above, one electrode is connected to a corona generator for preliminary ionization.
Consist of needle-like electrode, the needle electrode is characterized in that is pressed against such contact hand point of the dielectric ceramic substrate. According to the present invention , the needle as one of the electrodes is provided.
As the Jo electrode contacts hand point of the dielectric ceramic substrate
When an alternating current or a pulse voltage is applied, a high electric field is generated in the point contact portion of the needle electrode, and corona is generated. As a result, the current flowing in a portion that does not contribute to corona generation can be reduced, so that the ionization efficiency can be increased, and therefore, the electron number density can be increased. Therefore, if the corona generating device according to the present invention is applied for preliminary ionization in a laser device such as an excimer laser, it is possible to obtain a laser beam generation efficiency comparable to that of the arc method by the corona method. Become like FIG. 1 is a schematic perspective view showing a corona generator 11 according to an embodiment of the present invention, and FIG. 2 is a schematic diagram of the corona generator 11 shown in FIG. It is a side view. The corona generating device 11 includes a dielectric ceramic base material 12, and on one surface thereof, a planar electrode 13 extending in a plane is formed over the entire surface or almost the entire surface. On the other surface of the dielectric ceramic substrate 12, a needle electrode 14 is provided.
It is pressure contact to point contact. The needle electrode 14 is shown in FIG.
Although four are shown in the figure, the number may be simply one or another number. In such a corona generator 11,
If an alternating current or a pulse voltage is applied between the flat electrode 13 and the needle electrode 14 while the needle electrode 14 is connected to the ground, the needle electrode 14 becomes a dielectric ceramic substrate as shown in FIG. A high electric field is generated at the portion in contact with
Corona 15 is generated. The dielectric ceramic substrate 12 described above is made of, for example, but not limited to, a dielectric ceramic such as barium titanate, strontium titanate, and lead titanate. The flat electrode 13 is made of, for example, nickel, but is not limited to this. One that is not attacked by a gas in the laser chamber, for example, a gas containing fluorine or chlorine, and one that does not attack these gases, For example, copper,
It may be made of brass, stainless steel, gold, or those whose surfaces are plated with them. In addition, the needle electrode 14
Is made of, for example, stainless steel, but is not limited to this, as in the case of the flat electrode 13, one that is not affected by the gas in the laser chamber, for example, a gas containing fluorine or chlorine, and one that does not attack these gases. , For example, copper,
It may be made of brass, nickel, gold, or those whose surfaces are plated with them. In the illustrated embodiment, the needle-like electrode 14 is gradually narrowed from its root to its tip,
Although it has a pointed shape at the tip, it may have a thin pointed shape only at the tip or a shape that remains thin from the root to the tip. Experimental Example Referring to FIGS. 1 and 2, the relative dielectric constant is 68.
A flat electrode 13 made of nickel and a needle-shaped electrode 14 made of stainless steel were provided on a dielectric ceramic base material 12 made of a barium titanate-based dielectric ceramic of No. 00, and a corona generator 11 was obtained. The corona generating device 11 was incorporated in a corona generating circuit 16 shown in FIG. 3 to generate a corona. In the corona generating circuit 16, the corona generating device 11 is connected in series with the capacitor 17 and the circuit inductance 18, and the charging inductance 19 is connected in parallel with the corona generating device 11. Further, the pulse voltage obtained based on the charging voltage of the capacitor 17 is converted to a corona generator 11.
, A switch 20 is provided. In such a corona generation circuit 16, when the switch 20 is closed after the capacitor 17 is charged, a pulse voltage is applied to the corona generation device 11, and as shown in FIG.
Corona 15 is generated. In the experiment, two capacitors 17 were used.
nF of 300 n as the circuit inductance 18
H and 30 μH as the charging inductance 19 were used. Corona 1 as described above
The two corona generating devices 11 that generate 5 were arranged on both sides of the parallel plate electrode 22 of the electron number density measuring circuit 21 at an interval of 10 mm, respectively, and the electron number density was measured. The result is shown in FIG. FIG. 4 also shows the electron number density by an arc method using a stainless needle in place of the corona generating device 11 using the corona generating circuit 16 of FIG. 3 as a pulse voltage applying circuit. From FIG. 4, it can be seen that, according to this experimental example, the corona system has a higher electron number density than the arc system, but has a higher electron density than the arc system. In particular, it can be seen that the higher the charging voltage of the capacitor 17 is, the more excellent the corona method is. In the above-described experimental example, the dielectric ceramic substrate 12 was made of a dielectric ceramic having a relative dielectric constant of 6800.
Having a relative permittivity of less than 10500, 1
It has been confirmed that even when a dielectric ceramic of 6000 or more is used, substantially the same electron number density is exhibited. The relative dielectric constant is desirably 1000 or more.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a corona generator 1 according to an embodiment of the present invention.
1 is a perspective view schematically showing 1. FIG. 2 is a side view schematically showing the corona generating device 11 shown in FIG. FIG. 3 is a diagram showing a corona generation circuit 16 and an electron number density measurement circuit 21 used in an experimental example to measure an electron number density by the corona generation device 11 shown in FIG. FIG. 4 is a diagram showing the electron number density obtained by the corona generator 11 obtained in an experimental example implemented according to the present invention, in comparison with the electron number density obtained by an arc method. FIG. 5 is a perspective view schematically showing a conventional corona generating device 1. 6 is a perspective view schematically showing a surface on the opposite side of the corona generating device 1 shown in FIG. FIG. 7 is a diagram corresponding to FIG. 6, schematically illustrating another conventional corona generating device 1a. [Description of Signs] 11 Corona generator 12 Dielectric ceramic substrate 13 Planar electrode 14 Needle electrode 15 Corona

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Osamu Yamaoka 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto, Japan Murata Manufacturing Co., Ltd. (56) References JP-A-7-313833 (JP, A) 8-151201 (JP, A) JP-A-5-89942 (JP, A) Japanese Utility Model Application Sho 62-166230 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01T 19/00 -23/00 H01S 3/00

Claims (1)

(57) Claims 1. A pre-ionization corona generation for a laser device, comprising: a dielectric ceramic substrate; and electrodes provided to face each other with the dielectric ceramic substrate interposed therebetween. in the device, one of said electrodes is made of needle-like electrodes, characterized in that it pressed to contact the dielectric hand points to a ceramic substrate, a corona generating device.