Spectral Radiance of a Low Current Graphite Arc

Abstract

The spectral radiance of the anode of a low current graphite arc has been determined throughout most of the 850-210 nm region by utilizing a recently developed high accuracy spectroradiometer. The estimated standard deviation uncertainty varies from about 1.5% at the longer wavelengths to about 5% at the shorter. Results are given at twenty wavelength points in the region and also as a continuous function of wavelength throughout most of the region, excluding some areas of high molecular band radiation originating in the arc stream.

Calibration of the Spectral Radiance of a Low Current Carbon Arc between 185 nm and 340 nm

“…The spectral radiance of the carbon arc mainly utilized in the USA (current: ^ 12 amps) w r as investigated in the uv spectral region dow r n to the air cut-off [4,7,10] (A 185 nm), but the spectral radiance of the low r current carbon arc used here (current :i = 7.3 amps) is only known in the spectral region above 260 nm [5,8], with a relative uncertainty of + 5% at A = 260 nm and ±3% above A = 300nm. Differences of the spectral radiance values above 260 nm between both types of differently driven carbon arcs are only in the order of 3%, too, and will not be discussed in this paper.…”

Application of photographic pyrometry to ablation models

“…With a 6.4-mm-diam grade SPK graphite anode and a 3.2-mm-diam grade AGKS cathode, the spectral radiance of the anode center approximates a 3792° K blackbody over most of the wavelength range of the pyrometer. 11 Below 4200A, appreciable divergence from the blackbody curve occurs due to the addition of line and band radiation in the arc column. The arc is supplied with a set of five filters that simulate lower temperatures for calibration of brightness pyrometers operating at 6500A.…”

Excitation of He+ in a hollow cathode arc discharge

“…This lamp is reliable down to. 2700 ~' and has an inaccuracy of lp% [26,27]. As the temperature of the emitting surface is about 3800 K, the speetral distribution of the radietion is quite different from that of the tungsten ribbon lamp, which bas a temperature of at most 2700 K.…”

“…The speetral radiance was obtained from tables of Rattenburg [27] (2300 -8237 Î) and of Magdeburg [26] (9345-11626 R). These tables have an overlap between 2500 and 8500 i and are in excellent agreement in it.…”