Optimum Performance of High-Brightness Carbon Arcs

The effects of positive-crater cooling are described, and a suitable apparatus for this purpose is illustrated. The combination of specially made high-brightness carbons with water-cooled operation permits the use of higher currents without unsteadiness, and so gives a higher brightness than has been achieved in conventional air-cooled operation. This is attributed to the fact that effective cooling of the positive carbon removes energy which would otherwise be dissipated in turbulent volatilization, so that a higher current density can be achieved in the light-producing gas ball before overload turbulence occurs. A considerable part of the more efficient crater cooling is attributable to the carbons themselves, since they will operate without water cooling at higher currents and brightnesses than other types of equal size. — Within the limit of satisfactory air-cooled operation with a given carbon, efficient water cooling always reduced the light produced at a given current; the ability to operate with higher brightness at higher currents was thus gained at the expense of a lower current efficiency. Carbons designed for efficient air-cooled operation gave no better result with water cooling; the current efficiency was sacrificed with no gain in maximum brightness.

Print ISSN

0097-5834

Published

1949-04

Content type

Original Research

DOI

10.5594/J12506