Time-resolved measurements of the far UV output of a BRV source.
The BRV spark source, which was invented in 1961, has proved to be a very useful tool in UV and VUV studies of atoms and molecules. Under various configurations the spark is capable of producing a fairly smooth continuum from about 50 Å to the visible range. However, until now little work has been done to characterize the intensity or the time history of the output. In this Letter we review the existing data on the intensity and report measurements of the time behavior of the output at 300 Å and 600 Å for such a source in the end-on mode, the commonly used configuration. Such information is needed when the source is to be used to study transient phenomena as in the two recent experiments performed in this laboratory. Essentially, the BRV source is a vacuum spark with ex­ tremely low inductance which is triggered by an auxiliary sliding spark (Fig. 1). Refractory high-Z anode materials, such as uranium or tungsten, perform reliably and generally give the smoothest continuum. In our work uranium gave good results between 150 Å and 400 Å; below 150 Å tungsten gave slightly higher output.