CN2463991Y

CN2463991Y - Pulse pre-ionization longitudinal discharge laser

Info

Publication number: CN2463991Y
Application number: CN01202113U
Authority: CN
Inventors: 万重怡; 于延宁
Original assignee: Institute of Electronics of CAS
Current assignee: Institute of Electronics of CAS
Priority date: 2001-02-14
Filing date: 2001-02-14
Publication date: 2001-12-05
Anticipated expiration: 2011-02-14

Abstract

The utility model relates to a pulse pre-ionization longitudinal discharge laser which comprises a discharge tube 21, an anode 23 and a cathode 24 of the discharge tube, a cooling jacket 25, a total reflection end mirror 26, and an output coupling mirror 27. The pulse pre-ionization longitudinal discharge laser is characterized in that the periphery of the discharge tube 21 is closely enclosed by a plurality of ring-shaped pre-ionization electrodes 22 which are connected, at intervals, with a high voltage terminal and a low voltage terminal of a pulse generator. The pulse discharge gas laser of the utility model has the advantages of low operating voltage, good discharge stability and high electro-optical conversion efficiency, is suitable for various gas lasers, such as CO2 lasers, etc., and has wide application in the fields, such as laser acquisition, laser processing, actinic chemistry, etc.

Description

Impulse preionization longitudinal discharge laser

The utility model belongs to laser, particularly a kind of longitudinal discharge pulsed gas laser that adopts the multistage impulse preionization.

The gas laser of longitudinal pulsed discharge is owing to its good beam quality, pulse recurrence rate advantages of higher are subject to people's attention.The impulse preionization technology is to improve a kind of effective means of pulsed discharge laser performance.Impulse preionization is exactly before the main pulse discharge or in the starting stage of main pulse discharge the laser discharge district to be carried out " preionization " pulsed discharge, the electro-optical efficiency that this will improve the stability of " main pulse " discharge greatly and improve laser.Technology in the document [1] (SPIE Vol.3092 (1997) P82-85) as shown in Figure 1, at the outer bread of discharge tube 11 with metallic sheath 12, this metallic sheath links to each other and ground connection with anode 13 in the discharge tube on electricity, when pulse high-voltage is added on the negative electrode 14 of discharge tube, negative electrode 14 and outside highfield between the metallic sheath 12 at first caused near the gas discharge the negative electrode, promptly near negative electrode, produced strong " preionization ", preionization has reduced the puncture voltage between the anode and negative electrode in the discharge tube, has formed discharge i.e. " main discharge " after therefore following preionization closely between anode and negative electrode.The major defect of this device be the preionization major limitation near the cathodic region, whole region of discharge (laser gain medium district) is not carried out preionization.

The purpose of this utility model is to propose a kind of new impulse preionization laser device---vertical multistage impulse preionization laser device.At the whole region of discharge (gain medium district) of longitudinal discharge laser thus carry out the operating voltage that the preionization pulsed discharge has reduced the laser discharge, improved the electro-optical efficiency of laser.

Main feature of the present utility model is anode 23, negative electrode 24, coolant jacket 25, total reflection end mirror 26 and the output coupling mirror 27 that comprises discharge tube 21, discharge tube, and a plurality of annular pre-ionization electrodes 22 closely are enclosed in discharge tube 21 peripheries, preionization round loop electrode 22 and respectively link to each other with low-pressure end with the high-pressure side of pulse generator;

The utility model pulsed discharge gas laser operating voltage is lower, and discharge stability is better, and electro-optical efficiency is higher, is applicable to CO ₂Laser, He-Xe laser, excimer laser, the multiple gases lasers such as chemical laser that discharge causes.In laser acquisition, laser processing, applications such as photochemistry have wide practical use.

For further specifying feature of the present utility model and structure, the utility model is described in detail below in conjunction with accompanying drawing.

Fig. 1 is the structural representation of existing longitudinal pulsed discharge gas laser.

Fig. 2 is a laser structure schematic diagram of the present utility model.

Fig. 3 is the laser schematic diagram of serial connection electric capacity between main electrode and pre-ionization electrode.

Fig. 4 is the laser schematic diagram of series resistor between main electrode and pre-ionization electrode.

As shown in Figure 2, preionization and main discharge share a high-voltage pulse generator. Work as Pulse Electric When pressure is added on the high-pressure side electrode, at first cause in advance electricity of pulse in the gas between pre-ionization electrode From discharge (pre-ionization electrode that is positioned at the discharge tube both sides then discharges with corresponding main discharge electrode), Preionized discharge has been full of the whole discharge tubes zone between negative electrode and the anode. Strong preionization is led Cause breakdown voltage decline between negative electrode and the anode, after the preionization, following hard on is main discharge.

If the distance between negative electrode and the anode is L, preionization round loop electrode number is that (N is idol to N Number), then the electric-field intensity between the pre-ionization electrode should be much larger than the electric-field strength between the main discharge electrode Degree. The ratio of its electric-field intensity in theory maximum can reach N+1. The voltage height of preionization pulsed discharge Frequency component is coupled in the discharge tube by discharge vessel wall, before its coupling efficiency and potential pulse rise The size of the coupling capacitance between the steepness on edge and round loop electrode and the discharge tube is relevant. Because coupling electricity Have inevitably voltage drop on the appearance, therefore above-mentioned ratio should be less than N+1. Preionization annulus electricity Coupling capacitance numerical value between the utmost point and the discharge tube is very little, and preionized discharge is only at the pulse voltage rising edge Be that main discharge took place in very short time before, so preionized discharge only consume in total discharge energy A very little part. Area by changing round loop electrode, the material of discharge tube, discharge vessel wall Thickness can change the numerical value of coupling capacitance. As shown in Figure 3 and Figure 4, in main electrode and preionization Serial connection electric capacity or resistance also can be regulated the energy that is coupled in the preionization between the electrode. Pulse is electricity in advance From two aspect effects are arranged: the first has reduced the breakdown voltage of main discharge, makes the easier puncture of discharge. It two is the E/P values (ratio of electric-field intensity and air pressure) that reduced main discharge. Lower E/P value Corresponding to lower Electron energy distribution. In many cases, for example at CO₂In the laser instrument, low The E/P value is conducive to the pumped gas molecule to excitation state, thereby the electric light that is conducive to improve laser instrument turns to Change efficient; E/P value higher in the preionization process then is conducive to γ-ray emission ionization, for thereafter Main discharge enough initiating electron concentration is provided, thereby realize stable main discharge, increase discharge Electric current and the energy that is injected in the gaseous medium.

Provide an embodiment of the present utility model below.Laser is pulse CO ₂Laser, discharge tube are 11 flint glass Fs of internal diameter 8mm, and the preionization round loop electrode is counted N=12, and laser resonant cavity is that concave spherical mirror and the uncoated germanium plane parallel output coupling mirror of 4m formed by gold-plated radius of curvature, and the chamber is long to be 1.04m to fill with CO in the pipe ₂, N ₂The He mist, the air pressure ratio is 1: 1: 4, and total gas pressure is 2000Pa, when pulse voltage is 14KV, when pulse duration is 4 μ s, laser output pulse energy 14.2mJ, pulse peak power is 3.5kW, the situation when contrasting no preionization, its operating voltage has descended 18%, and electro-optical efficiency has improved 52%.

Claims

1. multistage impulse preionization laser device, the anode (23) and negative electrode (24), coolant jacket (25), total reflection end mirror (26) and the output coupling mirror (27) that comprise discharge tube (21), discharge tube is characterized in that a plurality of annular pre-ionization electrodes (22) closely are enclosed in discharge tube (21) periphery, preionization round loop electrode (22) respectively links to each other with low-pressure end with the high-pressure side of pulse generator;

2. by the described laser of claim 1, it is a pair of to it is characterized in that the preionization round loop electrode is at least.

3. by the described laser of claim 1, the material that it is characterized in that discharge tube is glass, quartz or ceramic;

4. by the described laser of claim 1, it is characterized in that main discharge and preionized discharge adopt the same pulse power.

5. by the described laser of claim 1, it is characterized in that main discharge and preionized discharge adopt the pulse power separately respectively.

6. by the described laser of claim 1, it is characterized in that being connected in series electric capacity between main electrode and the preionization round loop electrode.

7. by the described laser of claim 1, it is characterized in that series resistor between main electrode and the preionization round loop electrode.