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In 1980s, Quan-sheng Gao [1], a Chinese engineers had invented a new type of helium neon laser which possesses lower ignition voltage. This new laser has the advantage that only needs a power supply with 2 / 3 voltage of that of the traditional type. Its physical mechanism had encouraged several Chinese scholars to try to make interpretations. However, up to now, a satisfactory interpretation has not been obtained. From the viewpoint ofthe authors, this is because of lack ofexperimental details. Therefore, the authors have performed several experiments for this laser, mainly, from capillary discharges to the performances of the laser. In this paper, some experimental results of the capillary dischareges are reported. The results concerning the laser performances and related interpretations will be presented in the second paper [2] For performing experiments on capillary discharges a vacuum system called 630 1 type low vacuum calibrating system, was rearranged so that it can supply several kinds of gases with high accuracy pressure readings , see Fig. 1 . The breakdown characteristics of capillaries with various diameters have been investigated for six kinds of gases, i.e. H2, N2, He, Ne, Ar, and Kr, within a pressure range of 10~2000pa (10 -1~ 20 Torr approx.). For comparison, the characteristics of the parallel-electrode systems and of the minielectrode systems free from wall-effects were also performed. The following conclusions have been abtained: ( 1 ) The breakdown voltage of capillary tube is always higher than that of the ideal parallel electrode systems provided that the distances between electrodes are equal. (2) Paschen's law is no longer valid for the case of capillary discharges. A theoretical analysis is also presented. These results are useful in the interpretation of the mechanism of Gao's lasers.
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