ENGINEERING RESEARCH INSTITUTE COLLECTION AND ANALYSIS OF UPPER AIR SAMPLES Quarterly Report for the period October 15, 1954 to January 15, 1955 Submitted for the Project by L. M.. Jones Department of the Army Project No. 3-99-07-022 Meteorological Branch, Signal Corps Project No. 172B Contract No. DA-36-039 SC-56737 DEPARTMENT OF AERONAUTICAL ENGINEERING UNIVERSITY OF MICHIGAN ANN ARBOR

UNIVERSITY OF MICHIGAN PROJECT PERSONNEL Both Part Time and Full Time Filsinger, Edward A., Machinist Harrison, Lillian M., Secretary Howe, Robert M., Ph. D., Assoc. Prof. of Aero. Eng. Jones, Leslie M., B.S., Project Supervisor Liu, Vi-Cheng, Ph.D., Research Engineer Loh, Leslie T., M. S., Chemist Schumacher, Robert E., B. S., Assistant in Research Wenk, Norman J., B.S., Research Engineer Wenzel, Elton A., Research Associate

TABLE OF CONTENTS Section Topic Page 1 INTRODUCTION 1 2 PURPOSE I 3 ABSTRACT 2 4 NEW ANALYZER 2 5 BOTTLE PREPARATION 9 6 NEW TECHNIQUES 10 6. 1 Diffusivity of Helium Through Glass 10 6. 2 Methods of Removing Active Gasses, N2 and 02' From A Sample 10 6. 3 Use of Ion Gauge for Quantitative Pressure Measurements 10 6. 4 Small Mass Spectrometer and the Omegatron 10 6. 5 Miscellaneous 10 7 ANALYTICAL INVESTIGATIONS 11 8 REPORTS ISSUED AND LABORATORIES VISITED 11 9 ACKNOWLEDGMENT 11

ILLUSTRATIONS Figure No. Title Page 1 Schematic of New Analyzer 3 2 New Analyzer (Over-all View) 4 3 New Analyzer (Oven Lowered) 5 4 New Analyzer (Oven Raised) 5 5 Details of Column and Charcoal Oven Panel 6 6 Final Ion Gauge Electrometer Control Circuit 6 7 Mercury Still 6 8 Ion Gauge and Electrometer Input Box 7 9 Measuring and Compensating Piranis and Control Box 7 10 Bottle Seal 9 11 Sealer Parts 9

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN COLLECTION AND ANALYSIS OF UPPER AIR SAMPLES 1. INTRODUC TION This is the first in a series of Quarterly Reports on Contract No. DA-36-039 SC-56737 describing an experimental program of collecting and analyzing upper-air samples. The work is a continuation of one phase of a program of upper-air research which has been carried out since 1946 by the University for the Meteorological Branch of the Signal Corps. The other phase of the work, that of measuring pressure, density, temperature, and winds, wil continue on a separate contract. For background material, the reader is referred to the Final Reports of Contracts W-36-039 SC-323'07,DA-36-039 SC-125, and DA-36-039 SC-15443. The latter report summarizes the current status of the sampling program, the principal objective of which has been the investigation of diffusive separation. 2. PURPOSE The purpose of the research as given in Signal Corps Technical Requirements SCL-2370 of 19 January 1954 is as follows: "This specification covers the research into the necessary techniques for the collection and analysis of air samples in the region of 30 to 100 km altitude and a continuing review of the field of upper air research for the purpose of keeping in contact with work of interest to the Signal Corps. "The techniques shall be confirmed by field experiments using Aerobee or other rockets as vehicles. Emphasis shall be placed on the following experiments. "(a) The analysis of the upper air and control samples using the gas adsorption analysis and/or other techniques. "(b) The collection of samples in the region 30 to 100 kilometers. "(c) The performance of subsidiary experiments, reduction of data, calculation of results and preparation of reports." 1

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN 3. ABSTRACT Progress in the construction of a selective adsorption analyzer for upper-air samples is described. Development of a new method of constructing control and upper-air sample bottles is described. Continuing investigations of the effect of sampling on composition and of possible new analysis techniques are noted. 4. NEW ANALYZER The necessity for constructing a new analyzer, the reason for choosing a charcoal adsorption type, and the design of the new analyzer were discussed in Progress Reports of the previous contract. The work during the quarter was devoted to the construction, testing, and assembly of components. With one exception, the construction of the analyzer proceeded without difficulty according to design. Fig. 1 is a schematic of the analyzer and Fig. 2 a view of the nearly completed apparatus. Figs. 3 to 9 show details of various parts of the analyzer. The transfer of the gas from the upper-air sample bottle to the analyzer storage vessel has been a difficult problem. A toepler pump was used in the Durham and first Michigan analyzers. Becuase it'is slow and requires 24 pounds of mercury for an 800-cc pump (which imposes a mechanical problem), it was hoped to replace the toepler. The best possibility seemed to be a mercury-vapor pump, either single- or multistage. Tests showed that either pump would transfer the samples quickly without contamination. Soft-glass models of each pump were made with some difficulty, and a three-stage mercury-vapor pump was installed in the analyzer. On two trials the pump fractured at the bottom mercury-return joint where the temperature gradient is highest. A successful soft-glass pump for this application presumably could be worked out. - However, it was decided that something else should be tried in order to get the analyzer in operation. Various alternatives were then considered. One of these, charcoal-trap pumping,. was tried. It was found to work, but had no advantage in speed'over the toepler in transferring helium'. Other pumps such as mechanical displacement, Archimedes, carrier-gas toepler, etc., were temporarily rejected as involving considerable development. It was decided to defer the development of a fast transfer system and install a large (800 cc) toepler with automatic operation. This adds 3 to 4 hours to an analysis time. However, the other time-saving features of the new analyzer, i. e., bake-out oven, small size, and final ionization gauge, will still make it possible to perform an analysis much more rapidly than heretofore. A commercially available pirani gauge, RCA 1947, was purchased. The gauge, which is in a soft-glass envelope, will be used in a temperaturecompensating bridge circuit to monitor the sample-bottle pressure when the bottle is attached to the analyzer. Two gauge tubes and the electric controlling device are seen in Fig. 9. 2

r OVEN-UP POSITION VACUUM // \\ COMPRESSED AIR / ATMOSPHERIC PRESSURE INLET I Toepler Pump, D. Small Toepler and Storage Vessel, E. Mercury Cut-Offs, F. CO2 Cold Trap, G. Oxygen Cell Toepler, H. Oxygen Cell, J. Column Toepler, K. Fractionating Column, L. Pipette, M. Ion Gauge Cold Trap, N. Ion Gauge, P. System Pirani Gauge, Q. Control Sample Vial. R. Breaker, Mercury containers and stopcocks in the lower part of the diagram are for operating the pumps, valves, or columns to which they are connected.

Fig. 2. New Analyzer. A. Large Toepler, B. Fractionating Column, C. Ion Gauge Shield, D. Analyzer Electrical Control Panel, E. Analyzer Operating Stopcocks, F. Pirani Gauge.

:1 Fig. 3. New Analyzer. Oven in Fig. 4. New Analyzer. Oven in lowered position showing plug-in raised po s it i o n showing main strip heaters and convection plates. mechanical and diffusion pumps. Oven control is behind the analyzer. Analyzer-operating stopcocks are Electrical control panel is is in the in a row just below the oven upper right corner.

Fig. 5. Details of Column and Fig 6 Final Ion Gauge Electrometer Fig. 7 Mercury Still. Charcoal Oven Panel. Control Circuit

ENGINEERING RESEARCH INSTITUTE* UNIVERSITY OF MICHIGAN Fig. 8. Ion Gauge and Electrometer Fig. 9. Measuring Input Box. Piranis and Contro The distribution coefficient> of charcoal for aCa eerie h percentage of gas that will be transferred in each cycle pumping device using active charcoal at the temperature..~~~~~~~~~~~~~~~~~~~~~F a pumping medium. The distribution coefficients of charcoal for h nitrogen are shown below. The "calculated" values were experimental values by Glfickauf1 to accommodate the fac coefficient is a function of the amount of gas and charcoal ured values were obtained at Michigan during the quarter V Distribution Coefficient = g V +V g a where Vg -vol. of gas in gaseous phase Va = vol. of gas in adsorbed phase at same pres AM~~_ 1, InE. GlBckauf, A Microanalysis of the Helium and Neon Con o Proc. RToy. Soc., A 185 (1946), p. 98. nitogn reshwnbeow Te 'clcuatd"vaue wrecacuatd 7o

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN Volume of Weight of Gas Phase Charcoal Distribution Gas (ml) (gm) C o efficient 8200 5 0. 9935 calc. 8200 50 0.94 " Helium 8990 20 0.977 " 8990 20 0.986 meas. Neon 8200 50 0.583 Nitrogen 785 20 0. 0005 meas. A low distribution coefficient results in the transfer of a higher percentage of gas per cycle of operation. The relation between percentages of gas transferred and the distribution coefficients after operating this pumping device a given number of cycles is shown below: Distribution % Gas Transferred Gas Coefficient* 5 cycles 10 cycles 20 cycles 40 cycles 0.9935 3.2 6.3 12.2 23 0.94 26.6 46 71 91.6 Helium 0.977 11 21 37 60 0. 986 7 13 25 43 0.924 33 55 80 96 N eon I (0.583 93 99.6 99.99 100 Nitrogen 0. 0005,100, 100 100 100 8

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN - 5. BOTTLE PREPARATION The development of a method of closing a bottle without heat and providing a reusable vacuum-tight seal was continued. A successful flaretype fitting was described in the previous report. A simpler device, shown in Figs. 10 and 11, was designed, tested, and found to be successful. Subsequent designs of a seal using Teflon and silicone rubber "O" rings were built and tested. These methods were discarded as unreliable. The seals discussed here are used during the laboratory preparation of the bottles and should not be confused with the cold-weld sealers used in the collection of samples during a rocket flight (See previous report). NUT I"' COPPER TUBE STEEL PLATE COPPER WASHER COLLAR BTLE Fig. 10. Bottle Seal. Fig. 11. Sealer Parts. 9..

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN 6. NEW TECHNIQUES In November, R. M. Howe discussed several aspects of the analyzer problem with W. Nottingham, J. Houston, and W. Lange of the Physical Electronics Group at MIT. Further discussions are anticipated with people engaged in high-vacuum work in a continuing effort to keep informed on new techniques which may have application to the air analysis program. At the meeting the following topics were discussed: 6. 1 Diffusivity of Helium Through Glass. A reference2 to recent work on this subject was noted. The possibility of using pyrex in an analyzer for helium was discussed. It was felt that this might be done successfully if a) the pyrex were cooled well below room temperature, b) the pyrex were coated either by evaporation or electrolytically with metal, c) the vacuum system were immersed in a second, medium vacuum system. 6. 2 Methods of Removing Active Gases, N2 and 02, From A Sample. It was suggested that an ion gauge operated at about 18 volts would clean up all active gases by dissociating them, whereupon they would be so active chemically as to combine with any part, particularly metal, in the system. It was thought that noble gas clean-up would be negligible at this voltage. Various new getter techniques using tantalum and titanium, were noted to be effective. 6. 3 Use of Ion Gauge for Quantitative Pressure Measurements. A new, commercially available ion gauge capable of reproducing sensitivity to 10 per cent or better at 1 micron Hg pressure was discussed. 6. 4 Small Mass Spectrometer and the Omegatron. A new mass spectrometer having possible application to air analysis was discussed. The possible application of the ion resonance gauge or omegatron to our problem was reviewed. The omegatron has been under development at MIT for several years. The current design, which was discussed in detail, is thought to be applicable to the analysis of helium, neon, and argon in air, particularly if the amounts of N2 and 02 are reduced. 6. 5 Miscellaneous. Various problems and techniques of manipulating and measuring small amounts of gas were discussed. 2 G. J. Norton, Helium Diffusion Through Glass, General Electric Research Laboratory Report.10

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN 7. ANALYTICAL INVESTIGATIONS A discussion of the sampling results to date was given in the previous report. It was pointed out that some serious objections to Martin's3 interpretation of separation as being caused by a flow phenomenon exist. Nevertheless, such a phenomenon may operate during sampling, and work on the problem continued. The current approach is to calculate the pressure and temperature distributions in the field of the inlet flow. The mass rate of flow into the bottle of each component will then be calculated. The total amounts accumulated during the sampling interval will be obtained by integration. Two aerodynamic problems concerning pressure measurements on rockets are being investigated. In the case of a pressure gauge connected to the point of measurement with a tube, the temperature gradient along the tube is a source of error. The magnitude and possibility of correcting this error is being analyzed. In a pitot-tube operating at supersonic velocity at low density, the relaxation time is a source of error. The magnitude and correction of this error is being determined. 8. REPORTS ISSUED AND LABORATORIES VISITED No reports were issued during the quarter. The following places were visited during the quarter: Aerojet-General Corporation Jet Propulsion Laboratory MIT Physical Electronics Group (See Sec. 6) 9. ACKNOWLEDGMENT Thanks are due to the Meteorological Branch of the Signal Corps Engineering Laboratories for continued cooperation and financial support. G. R. Martin, "The Composition of the Atmosphere Above 60 Km, 'i' J. of Atmos. and Terr. Phys., Special Supplement, 1 (1954), p. 161. 11

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