Radiance of a Pt/Cr-Ne hollow cathode spectral line source.
In conjunction with the calibration of the faint object spectrograph (FOS) on the Hubble Space Telescope (HST), radiances of a sealed spectral line source with a platinum and chromium hollow cathode and a carrier gas of neon were determined. This lamp was mounted in the vacuum space telescope optical simulator which was then used to calibrate the FOS. The Pt/Cr lamp was developed by members of a team that produced a pure platinum hollow cathode lamp for space applications. The bimetallic cathode was formed by mixing and compressing fine powders of platinum and chromium and sintering the mixture onto an iron post. The lamp was then constructed as shown in Fig. 1 with a magnesium fluo­ ride window. The lamp with the pure platinum cathode has already been used in a space experiment, but it provides a suitable spectral line density only from 115 to ~320 nm. When chromium is added to the platinum cathode, the wave­ length coverage is extended to ~540 nm. Above 540 nm the