The Visible Radiation from Helium in a Strong Shock Wave Page: 32
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U obeetvsblt — the MiiiMd position of the shock line in Fig. 9(c) vas
mrked by • scratch on the flla. The absence of a shock line Is In agree-
cent with Turner's* conclusion that the shock line In his argon experl-
■ent vas due to light froa easily excited Impurity materials. Figure 9(a)
demonstrates the necessity of an Initially clean shock tube and Fig. 9(b)
the necessity of a plane wave.
The phrase "clean helliss spectrum" was used in the previous para-
graph to describe a case where H« and were clearly present. These
lines persisted in tLl cases, but because of their wavelengths and low
intensities they were not detrimental to the experlaents.
All detailed analyses of spectrograms were node on traces from a
recording micro photometer. In thq case of time-Integrated spectra three
traces were usually made from a plate: the "shock" trace along the center
of the shock tube Image, the "reference" trace along the nearest reference
spectrum, and the "half and half" trace, which Included a portion of the
above regions. The reference trace provided data for a spectrograph
dispersion curve which could be plotted directly on the trace, and the
half and half trace mode It possible to locate the reference trace and
dispersion curve with respect to the shock trace.
Without changing the sensitivity or focus of the microphotometer,
traces were made at various wavelengths from a step-wedge calibration
*E. B. Turner, "The Production of Very High Temperatures in the
/Shock Tube with an application to the Study of Spectral Line Broadening,"
v AFOSR TN-56-150, ASTIA Document Ho. AD-86309 (1956).
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Seay, Glenn Emmett. The Visible Radiation from Helium in a Strong Shock Wave, report, January 1957; Los Alamos, New Mexico. (https://digital.library.unt.edu/ark:/67531/metadc502356/m1/39/: accessed June 19, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.