By employing the filter-thermopile method of making radiation analyses, the energy distributions of the radiation emitted by a number of special quartz mercury arcs have been determined over wide ranges of arc voltage at several constant current densities. The results indicate that high voltage, high current density and large tube diameter arc favorable for high percentage of ultraviolet radiation. For any given tube diameter and current density, there exists an arc voltage at which the infrared percentage reaches a maximum. The visible and near and far ultraviolet percentages exhibit corresponding minima. The infrared maximum appears at lower voltages as the current density or tube diameter is increased.
It is shown that intensity is a function of current and arc voltage treated as separate variables, rather than of the product of these two. The intensity of a spectral group may increase, remain constant or decrease with increasing input to the burner.
The total efficiency expressed as the ratio of radiant power to electrical input increases with increasing arc voltage, current density and tube diameter. Under given electrical conditions the efficiency can be increased by heating the luminous tube.
© 1927 Optical Society of AmericaFull Article | PDF Article