Coherent light generators – Particular pumping means – Electrical
Patent
1997-01-22
1999-02-23
Scott, Jr., Leon
Coherent light generators
Particular pumping means
Electrical
372 87, H01S 3097
Patent
active
058752072
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a discharge arrangement for pulsed gas lasers, wherein laser electrodes are disposed and a pre-ionization of the gaps between the laser electrodes is produced by means of an at least one-sided system for producing discharges of intense UV emission.
The effectiveness of gas lasers, especially TEA lasers, which operate at a pressure of >1 bar, depends on the pre-ionization of the gaseous medium, i.e., on the initial electron concentration in the discharge volume, the initial stage of the development of the discharge. For the pre-ionization of the gaps between the laser electrodes it is already known to operate with spark discharges. Such a discharge arrangement is described, for example, in the inventor's older, not previously published patent application P 43 15 973.7.
One special method of pre-ionization of a gaseous medium is the sliding discharge which has in recent years been applied as an intense UV and VUV light source (A. Baschkin, Kvantowaja Eleektronika 1976, vol. 3, No. 8, pp. 1824-26). The sliding discharge assures radiation in the UV and VUV spectral ranges up to a wavelength of .lambda.=2 nm at a plasma temperature in the discharge of up to -3.multidot.10.sup.4 K (Bagen B. et al., Ins. Plasma Phys. Julich, 1963, pp. 631-34).
The sliding discharge is formed between the cathode and anode electrodes which are on the surface of the dielectric on the back of which the anode electrode is also disposed. The voltage pulse results in the development of large gradients of the voltage in the electrical field of the cathode, due to a capacity present between the electrodes. On this account a pre-ionization wave forms, which is accompanied by a glow and moves away from the cathode and permits a flashover onto the surface of the dielectric. The sliding discharge is basically far more suitable as a light source than a free spark discharge (Daniel E., Zeitschr. Techn. Phys. (Russian) 1979, vol. 49, No. 6, pp 1241-1244).
Since the plasma temperature of the sliding discharge is significantly higher than the temperature of the free spark, an optical yield approximately 10 times greater is produced. The spectrum contains more lines at the expense of the dielectric material. Moreover, in the sliding discharge the electrodes undergo a very slight erosion, which is greatly to the advantage of gas lasers operating with a high repetition at a higher repetition rate. Appropriate materials with a dielectric surface are in this case a variety of types of ceramic. Ceramics have chemical, thermal and mechanical stability as well as high breakdown resistance.
The invention is addressed to the task of creating a discharge arrangement which will permit a definitely greater effectiveness of the laser beam production and will lengthen the life of the components and of the gas filling the laser.
This task is accomplished by the invention through the features of claim 1. Since the arrangement is formed of at least one rod-like electrode which is enveloped by an insulating, preferably ceramic material, and which has a conductive contact with the surface of the insulating ceramic material, and since on this surface at least one counter-electrode is disposed at a distance from the rod-like electrode and is conductively connected to one of the laser electrodes, sliding discharges are formed between the rod-like electrode and the counter-electrode. On account of this arrangement it has become possible to utilize the advantages of a sliding discharge for the pre-ionization of the gap between the laser electrodes.
According to a preferred embodiment of the invention provision is made for making one external surface of the rod-like electrode rounded. Thus the formation of peak voltages is prevented, so that overall the rod-like electrodes can extend very effectively far into the gap between the laser electrodes without the occurrence of flashovers to the other laser electrode. Preferably, therefore, the rod-like electrode is provided with a mushroomed head.
It is furthermore advantageous if a plurality of rod-l
REFERENCES:
patent: 5042047 (1991-08-01), Ono et al.
patent: 5377215 (1994-12-01), Das et al.
ATL Lasertechnik & Accessories GmbH
Jr. Leon Scott
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