ecnebiid that .uch signals are attecuited, But (t .o he eet out otoprior theoretical Caleclations had predicted. Program C: Airborne Measurements of Thermal and Electromagnetic Phenomena There were six projects in Program C: four investigating thermal phenomena (Projects 8.2, 8.3, 8.4, and 8.5) and two studying electromagnetic effects (Projects 6.10 and 6.13). Six aircraft were used, three equipped with thermal instrumentation and three with electromagnetic equipment. All proj- ects were successful on both shots. For shot Teak there was a single thermal pulse lasting a few tenths of a second. Most of this energy came from molecular emission bands rather than from the blackbody radiation common to surface or near-surface burats. The Infrared radiation was intense but brief--about 2} sec in duration. The maximum radius of the infrared fireball was almost 20 miles. The thermal pulse from shot Orange showed some of the characteristics of a sea-level shot. There was some evidence of a minimum and a second maximum. Some of the energy was radiated in a continuous spectrum, in addition to spectral bands similar to those from Teak. The infrared emission lasted about 18 sec, and the infrared fireball radius reached a maximum of about 15 miles. Radar echoes from the ionized cloud were received by two of the aircraft. Returns were observed on UHF band radarsfor a period of about an hour for both Teak and Orange. One of the aircraft also carried atmospheric sounding equipment and measured disturbances of the ionosphere produced during both shots. It was found that the electrical properties of the ionosphere were disturbed in excess of 4 hr out to distances of several hundred miles. 2.2 TASK UNIT 1, LASL PROGRAMS Task Unit 1 carried out experiments to determine device performance, to measure physical quantities of interest in weapon design, and to under- stand the mechanisms by which the various effects of the devices are pro~ D) duced. In Operation Hardtack new methods were used to determine the con- figuration of the active material during the reaction period. Programs 10 and 18, Fireball Physics and Thermal Radiation wD oe g “—Oscilloscopes and photomultiplierswith optical narrow pass filters were used to record gamma-induced light from the air about two-stage devices. Photomultipliers and oscilloscopes with high time resolution were used for observations of narrow bands of the optical spectrum. 43 eee Aga no Ye