| 摘要 |
<p>A discharge arc lamp includes an arc tube (1) containing a dose, an electrode structure (4) sealed to each end of the arc tube, and an insert member (11; 23, 24) positioned between the arc tube wall and at least one said electrode structure(4). The insert member (11; 23, 24) is arranged to define a wick (12, 13, 15; 22, 22 min ; 25, 25 min ) which is effective, in operation of the lamp, to more liquid dose, by capillary action, from a relatively cold region (R1) of the arc tube (1) adjacent to said end into a reservoir (R2) in a relatively hot region of the arc tube (1), and to further define a passageway (16) allowing movement of dose, by vapour diffusion, to said relatively cold region (R1). The wick (12, 13, 15; 22, 22 min ; 25, 25 min ) is so configured as to accommodate a variable volume of liquid dose. The passageway is configured to enable attainment of a desired operating pressure in the arc tube (1). The distributions of vapour pressure and temperature along the passageway encourage condensation of vapour at said relatively cold region (R1) such that the wick (12, 13, 15; 22, 22 min ; 25, 25 min ) can maintain a substantially continuous supply of liquid dose at the reservoir (R2). Such a discharge arc lamp has an effective cool spot temperature, at the exposed surface of liquid in the reservoir (R2) supplied by the wick (12, 13, 15; 22, 22 min ; 25, 25 min ), which is higher than the temperature at the ends of the arc tube (1).</p> |
