UNCLASSIFIED — sroospheric Storage of Strontium : me atwosphere has been sseapled at various altitudes to estimate -resently stored in suspended forn, Sr 90 ’ Methods of Sampling 1$ cubic Lower atmosphere (200 fect) — Samples were collected at a Teet per e an MSA Comfo filter which has an Flow of efficiency of over 90% at 0.3 micron. The samples were collected on the roof bf the frou yew York Operations Office. Samples have been collected continuo se = Q00 feet) —- The region of the tropopaupe has } equipped with cellulose filters. Duplioe a been 8 cate samples are collected at 2 flow of approximately 6000 cubic f per ainute. The efficiency of collection of the filter paper appears the range 90-95% (Appendix B ). Stra to design Four flights have been completed. tb be in re (40 ~ 100,000 feet)— It was necessary for the] Laboratory spec or sampling in this region of ateosphere from which dust had not previously been collected. the Although many devices are available for dust sampling in the lower psphere, the problems presented in the sampling at 100,000 feet aske these dbvices entirely unsuitable. Preliminary calculations based on the best estimates of expected concentration of activity set the requirement of volums ofjeir to be ' sampled at approximately 1000 cubic meters. Mince the only practich) means of attaining this altitude is by means of non-extensible helius filledi balloons, consideration of weight of tie sampler and its self-contained powerl supply vere of great import. These factors in sddition to the great reduciion in air pressure end temperature at this altitude prompted the investightion of electrostatic precipitation for the solution of this probles. The most inviting feature of the electrostatic Pabsage of air through the device without pitator is the free ction allowing the freateat air moving efficiency. At these altitudes, the ease of producing c#rona ioniss- wae Without the use of excessively high voltages greatly reduces Feaents in the charging device. power re- Prelininary testa in an evacuated bell jar demonstrated the feasibility of : Aining contolled corona discharge restricted to a small region afound the talents Wire at this pressure by using a quasi-constant current powsr supply. the tions indicated reasonable dimensions would efficiently precipitate dusts of interest. rcure Ll iliustrates the basic features of the device. It cons ef four ions ot © O.D. by 1/16* wall aluminas tubing each 13" long. first seetion aichrs Ontains an insert §" long reducing the inner diameter to 2]785". me wire .012" in diamster is supported qn an insulator and funs centrally -—_——— 1051002