WMOD00376

• Contract/Permit #: 14-06-D-5640
• Project Name: Park Range Atmospheric Water Resources Program
• Title: Park Range Atmospheric Water Resources Program - Phase II - Parts A and B
• Date: 10/6/1967
• Weather Modification - Doc Type: Report

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NUCLEI GENERATOR DESIGN AND CALIBRATION
(C. E. Robertson)

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The silver iodide generators used routinely in FY66 and FY67 are the
same in principle as the generator design of Fuquay and Baughman (1962).
These "Skyfire hi-output" generators consume 1 gal/hr of 4% AgI-in-acetone
solution (2g/min of AgI). Two of the generators were operated simultaneous-
ly in our field tests, and two more generators were held in reserve. Only
one of the reserve units had to be used, and then only for a short period. All
four gene rator s have been calibrated at Colorado State Unive rsity> and the
results of two calibration runs are shown in Figure 2.

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During the Fall of 1966, a field calibration technique. similar to that
employed by D. M. Fuquay of the U. S. Forest Service's Project Skyfire in
calibrating many of the early silver iodide generators, was te sted. It con-
sists of I) placing a vertical wind tunnel over the generator, 2) extracting a
sample of the generator effluent from the top of the flue with a syringe, 3}
diluting with the syringe a number of times, 4} injecting the diluted contents
of the syringe into a 300 liter Mylar bag which was filled with nitrogen and
5) connecting the Mylar bag to the intake of an NCAR-type ice nucleu.s coun-
ter. From the resulting count, it is possible to calculate back to the genera-
tor output and compare field calibration re suIts with those in which fewer as-
sumptions are made - for example the calibration performed at Colorado
State University.

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Field te sts of the calibration technique indicate that it can produce use-
ful relative results, provided fuel flow to the generator is measured simul-
taneously with a flowmeter.

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ISOPROPYLAMINE TYPE GENERATOR

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An isopropylamine (IPA) silver iodide generator developed by R. L.
Steele (1966), was also tested at Emerald M:ountain and used on several oc-
casions for diffusion studie s. During one diffusion run, the concentrations

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- II =