| 摘要 |
PURPOSE:To obtain a high efficiency lamp having stable arcing and a uniform luminous distribution along the axis of a luminescent tube by providing a visible light transmittable cylinder inside a luminescent tube and by shifting the vapor, which is generated through vaporization of an enclosed material transferred to the high temperature section of an electrode, to the upper section of the luminescent tube. CONSTITUTION:In a luminescent tube 1 which is lit up, the temperature in the center of an arc 7 is tens of hundreds degrees C., and the temperature in the space between the luminescent tube 1 and a cylinder 8 is on the order of a thousand degrees C. Accordingly, a convection takes place which flows up along the center of the arc 7 and flows down between the luminescent tube 1 and the cylinder 8. Therefore, the melted enclosed material is transferred from a reservoir 6 to the high temperature section of a lower electrode 4 by capillarity of a coil 3 and vaporized there, and the resultant vapor moves to the upper section of the luminescent tube 1. Also the vapor of the enclosed material, which rises from the high temperature section of the lower electrode 4, disperses in the radial direction and attaches on the inner wall surface of the cylinder 8. However, because of the high temperature in the cylinder 8, it is immediately vaporized and returns into the arc 7, and then, following the convection, moves up to the upper section of the luminescent tube 1.
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