JPS5851582A - Lateral excitation type gas laser - Google Patents

Abstract

PURPOSE:To enhance the preliminary ionization effect of a gas laser by suitably disposing dielectric electrodes which generates a silent discharge between an anode and a cathode for producing a glow discharge. CONSTITUTION:When a high frequency voltage is applied from a high frequency power source 7 to between a dielectric electrode 3 and an earth installed at the upstream side of a main discharge gap between an anode 1 and a cathode 2, a silent discharge is produced between the dielectric electrode 3 and, the cathode 2, the anode 3. When a discharge power is applied from a DC high voltage power source 6 to between the anode 1 and the cathode 2 in the gap uniformly preliminarily ionized in the laser optical axial direction 13 by this voiceless discharge, uniform and high power density discharge exciting medium is produced. When a full reflection mirror 11 and a partial reflection mirror 12 having suitable reflectivity are disposed oppositely via the medium, a laser oscillation occurs.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a silent discharge auxiliary glow discharge excited gas laser device, and provides operating conditions under which preliminary ionization by silent discharge in the laser gas flow effectively increases the power density and homogenizes the glow discharge. Specifies the gas circulation type silent discharge auxiliary system.
The present invention relates to a discharge excited gas laser device. This laser device c.

This was newly developed by the inventor and others.

The laser device has been miniaturized and the beam mode has been improved, making it much more suitable than conventional devices as a continuous wave high-output (laser output 21 kV) laser for applications such as processing. .

Hereinafter, the silent discharge auxiliary glow discharge excitation co according to the present invention will be described.
2 laser device will be explained. FIG. 1 is a longitudinal cross-sectional view of one embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line I-1, where (1) is an anode.

(2) is a cathode, a dielectric electrode for +31 tl silent discharge.

(4) is a stabilizing resistor, (5) is an insulating cathode substrate, (6)
(7) is a high-frequency high-voltage power source for generating silent discharge; (8) is deionized water used for cooling the dielectric electrode; 91ij Laser gas flow n direction.

(Cross-sectional shape 1 of Ilj silent discharge auxiliary glow discharge excitation medium
(1'l) U Cross-sectional shape of glow discharge excitation medium when no silent discharge is generated, anFi total reflection mirror, u
is a partially reflecting mirror, (13II'i is a laser optical axis, and I is a laser beam.

Next, the operation will be explained. When a high frequency high voltage is applied by a high frequency power source (7) between the dielectric electrode (3) installed upstream of the main discharge gap between the anode (1) and the cathode (2) and the ground, the dielectric A silent discharge (hereinafter referred to as "silent discharge") occurs between the body electrode (3) and the cathode (2) and anode (1).

(abbreviated as SD) is generated. The laser gas (Co2-N2-He mixed gas) that has been pre-ionized on this day flows into the main discharge gap along the flow direction (9). When a discharge is applied between the anode (1) and the cathode (2) using the button DC high-voltage power supply (6) in a gas that has been pre-ionized uniformly in the laser optical axis direction 0 by the 8D auxiliary discharge, a homogeneous A high power density discharge excitation medium is deceived in the generation. When a total reflection mirror aυ and a partial reflection mirror a2 having an appropriate reflectance are placed facing each other with this discharge excitation medium in between, laser oscillation occurs and a laser beam I is emitted from the partial reflection mirror a2.

In order to operate the C02 laser continuously.

As is well known, it is essential to maintain the gas temperature of the discharge excitation medium low, so the cathode (2) is aligned with the laser optical axis, as shown in Figures 1 and 2. Multiple arrays irt in direction a1 and laser gas 1on76
Air is blown and circulated in the direction of the gas flow (9) at a speed of 6° or more.

The dielectric electrode body) is a cylindrical iron pipe with a circular cross section lined with 1' glass, or a metal silver II! for power supply inside the glass pipe. If a mourner is used, its interior is cooled by deionized water (8) K. The anode (11 is an integrated flat metal electrode, the material of which is copper), and the cathode (21Fi, a split electrode) is arranged in a row in the laser optical axis direction with a pitch of 10 degrees. Each of the n cathodes has a needle-like tip and is made of molybdenum, tungsten, or the like.

Before describing the various conditions for realizing the 8D preionization effect significantly, the general specifications of the laser as an example shown in FIGS. 1 and 2 will be described.

The main discharge gap length (distance between anode (1) and cathode (2)) is 75 m, discharge length Fi1 ml, number of cathodes 11,100.

Stabilizing resistance +4) Fis Okm. Diameter DFi of dielectric electrode (3)? -30mφ, the thickness of the glass as a dielectric is about 1cm, the frequency of the high frequency high voltage power supply (7) is 1
kHz-IMHg, voltage (O-peak value) is 3-1kV
It is. The laser gas was a mixed gas of CO2-Co-N2-''8, the gas pressure was 3O-300), and the gas flow rate was 20-109 m/.

Figure 3 shows typical discharge characteristics (support) of 8D auxiliary glow discharge.
Characteristics of normal glow discharge (→ and n-0) The difference between the two characteristics is 8D.
It is 6c. Figure 3: Due to the pre-ionization effect of ρ Shima et al.*BD, the discharge pressure decreases significantly.1. It can be seen that the maximum input power increases approximately three times. Furthermore, as shown in Fig. 2, the cross-sectional shape a (I
Its cross-sectional shape (101) when 8D assistance is not added (
(the shaded area in the figure) is larger and more diffused. In this way, in order to realize the pre-ionization effect of SD significantly, 1. The location and diameter of the dielectric electrode (3), the 8D power and power frequency, and the gas pressure.

It is necessary to optimize the gas flow rate, etc.・In Figure 4,
The relationship between the placement position of the lI dielectric electrode 3) and the maximum glow discharge force is shown. In the figure, d is the discharge gap length, ! , is the distance w12 between the cathode (21-dielectric electrode (3)) in the gas flow direction
This is the distance between the ri anode (1) and the dielectric electrode (3). d
The isochoric melting of the maximum glow discharge force for -15+w is depicted. Completed with maximum power of 40 kW! 40
m≦11≦6. Om, @xtsu251m1lI≦12≦6
It is within the range of 11. This region is affected by changes in gear length d, gas flow rate, etc. Figure 5 shows the maximum glow discharge and S with 12 set as a parameter and 56 days.
It is a characteristic diagram which shows the relationship with D electric power. From this diagram! When , becomes as large as 65■, a larger 8D power is required to exhibit the same pre-ionization effect as in the case of l, -50s+a. l is 150m or 2d
In the case of
This method requires more than twice the sn power as compared to the case of 50 m, which is not practical. From these experimental results, the placement position of the dielectric electrode (3) is approximately O≦1. ≦2(!,
Tell them that it is appropriate to select within the range 0≦12≦d. If you set tl and t2' within the above range,
The pre-ionization effect of 8D works effectively. Note that the dielectric electrode (
3) is installed downstream of the cathode (2) (indicated by diagonal lines in FIG. 4), the maximum glow discharge force is significantly reduced compared to the case without the dielectric electrode. That is, in this case, ti8Dti adversely affects glow discharge.

Next, the relationship between the cross-sectional diameter of the dielectric electrode (3) and the maximum glow discharge force will be described. When the diameter is increased to the same extent as the gap length d, the gas flow is strongly disturbed by the dielectric electrode, and the maximum glow discharge force is reduced. Also,
If D is set in a small range of degrees, the preionization effect of SD can be effectively exerted.

Figure 6 1i, t, -t2-so- 81
This is a characteristic diagram showing the change in the maximum glow discharge force per power.The maximum glow discharge power increases as the 8D power increases.The 8D power has a remarkable pre-ionization effect with just a few inches of the glow discharge power. is expressed n.

In the increasing function, f is the power supply frequency and C is the capacitance of the dielectric electrode. Parameter governing 8D power W Ma5
Maximum glow discharge power and 8D by varying fsc.
As a result of investigating the relationship between 1 and force, 1m59 shown in Figure 5
It was found that all measurement points were lined up on the wa characteristic curve.

In other words.

The 8D pre-ionization effect is defined only by the 8D power. The range of the power supply frequency f actually tested was 1
keg-I MHz.

FIG. 1 shows the gas pressure dependence of the maximum glow discharge force when 8D assistance is added. 30- Yes.

FIG. 8 shows the dependence of the maximum glow discharge force on the gas flow rate. Gas flow velocity is 20-100 m/s+s. In the range of , the maximum glow discharge force increases monotonically.

This is not because the pre-ionization effect of EID is increased by changing the gas flow rate, but because the glow discharge itself without 8D assistance increases the gas flow rate, which increases the maximum input power.

As described in detail above, in order for 8D pre-ionization to effectively increase the power density and homogenize glow discharge, it is necessary to
Setting position of dielectric electrode and its diameter, 8D power, S
I) Frequency, gas pressure.

1. The preionization effect is clearly realized, and an excitation medium suitable for laser operation can be easily obtained.

This invention comprises an anode and a cathode which are arranged to face each other across the laser gas airflow, and to which a DC high voltage is applied to generate a glow discharge. A dielectric electrode is arranged to generate a silent discharge between the two electrodes when a high-frequency high voltage is applied thereto, and the discharge gap length ff1a between the two electrodes and the dielectric electrode are Distance from the cathode in the gas flow direction! 1. Distance from the anode 12. Diameter f of the above dielectric electrode
If D, the dielectric electrode laser device described above can be realized.

[Brief explanation of drawings]

Fig. 1 is a longitudinal cross-sectional view of a silent discharge auxiliary glow discharge excited gas laser device according to the present invention, Fig. 2 is a cross-sectional view thereof taken along line 1-1, and Fig. 3 is a diagram showing voltage-current characteristics of glow discharge. , Fig. 4 is a diagram for explaining the relationship between the position of the dielectric electrode and the maximum discharge force, and Fig. 5 shows the change in discharge characteristics depending on the position of the dielectric electrode in the gas flow direction. Figure 6 is a characteristic diagram showing the relationship between maximum glow discharge force, infinite glow discharge force and gas pressure, and Figure 8 is a characteristic diagram showing the relationship between maximum glow discharge force and gas flow velocity. It is. In the figure, (IIFi anode, (2) is a cathode, (2) is a negative electrode, (4) is a stabilizing resistor, (5) is an insulating cathode substrate, (6) is a DC high voltage power supply, (7) is a high frequency High voltage power supply, (8
) is deionized water, (91 is an arrow indicating the n direction of laser gas flow, (1(l) is the cross-sectional shape of the silent discharge auxiliary glow discharge excitation medium, (101) is the cross-sectional shape of the glow discharge excitation medium,
611 is total reflection zlar, and az is partial reflection ilar. α3 is the laser optical axis, and 04) i is the laser beam. Note that the same reference numerals in each figure indicate the same or corresponding parts. Applicant Makoto Ishizaka, Director General of the Agency of Industrial Science and Technology -@3FgJ Figure 4 Figure 5 o/z
SDt force (KW) Fig. 6 SDv force (KW) Fig. 7 Fig. 8 Gas i speed (m/sec)

Claims (2)

[Claims] (1) An anode and a cathode arranged to face each other across the laser gas airflow, to which a DC high voltage is applied to generate a glow discharge, and an anode and a cathode that are in the laser gas airflow and are on the upstream side of the two electrodes. A high frequency high voltage is applied to the
and a dielectric electrode that generates a silent discharge between the two electrodes, the discharge gap length between the two electrodes is d.
, the distance between the dielectric electrode and the cathode in the gas flow direction! ,
If the distance from the anode is 12° and the diameter of the dielectric electrode is fD, then the diameter of the dielectric electrode is within the range of 3<D<-, and the dielectric electrode is O≦j1≦2d and 0≦l
A lateral excitation type gas laser device characterized in that the structure is closed so that the device can be disposed within a range of ,≦cover. (2) A patent claim characterized in that the frequency of the high-frequency voltage applied to the dielectric electrode is within the range of 1 kHz to IMEg, and the silent discharge force is 10 − or less of the laser-excited discharge force. The lateral excitation type gas laser device according to scope 1.