| 摘要 |
PROBLEM TO BE SOLVED: To provide a rare-gas discharge tube having a long life span. SOLUTION: The rare-gas discharge tube is provided with a glass bulb 2 whose interior diameter is 16 mm and under wherein Helium gas is enclosed from 400 to 1400 Pa, and air of electrodes 3, 3 disposed so as to oppose in the glass bulb and forced to open each of the opposed ends, on the other hand, end part in the opposite side in the axial direction closed to form in a closed end cylindrical shape, where a lamp current not less than 10 mmA is energized, and the current density per unit area of the inner surface of a cylinder is not more than 3.5 mA/cm2.
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