Rapatronic Photography at the Nevada Test Site; Nevada Test Site History DOE/NV - - 1136
Las Vegas, NV: National Nuclear Security Administration, Nevada Field Office, Office of Public Affairs, 2013. Presumed First Edition, First 2013 printing thus. Single sheet, printed on both sides. Format is approximately 8.5 inches by 11 inches. Illustrations and text on both sides. The Nevada Test Site was the primary testing location of American nuclear devices from 1951 to 1992; 928 announced nuclear tests occurred there. Of those, 828 were underground. (Sixty-two of the underground tests included multiple, simultaneous nuclear detonations, adding 93 detonations and bringing the total number of NTS nuclear detonations to 1,021, of which 921 were underground.) The site is covered with subsidence craters from the testing. The NTS was the United States' primary location for tests smaller than 1 Mt (4.2 PJ). 126 tests were conducted elsewhere, including most larger tests. Many of these occurred at the Pacific Proving Grounds in the Marshall Islands. The last atmospheric test detonation at the Nevada Test Site was "Little Feller I" of Operation Sunbeam, on July 17, 1962. The rapatronic camera (a portmanteau of rapid action electronic) is a high-speed camera capable of recording a still image with an exposure time as brief as 10 nanoseconds. The camera was developed by Harold Edgerton in the 1940s and was first used to photograph the rapidly changing matter in nuclear explosions within milliseconds of detonation, using exposures of several microseconds. To overcome the speed limitation of a conventional camera's mechanical shutter, the rapatronic camera uses two polarizing filters and a Faraday cell (or in some variants a Kerr cell). The two filters are mounted with their polarization angles at 90° to each other, to block all incoming light. The Faraday cell sits between the filters and changes the polarization plane of light passing through it depending on the level of magnetic field applied, acting as a shutter when it is energized at the right time for a very short amount of time, allowing the film to be properly exposed. In magneto-optical shutters, the active material of the Faraday cell (e.g. dense flint glass, which reacts well to a strong magnetic field) is located inside an electromagnet coil, formed by a few loops of thick wire. The coil is powered from a pulse forming network by discharging a high-voltage capacitor (e.g. 2 microfarads at 1000 volts), into the coil via a trigatron or a thyratron switch. In electro-optical shutters, the active material is a liquid, typically nitrobenzene, located in a cell between two electrodes. A brief impulse of high voltage is applied to rotate the polarization of the passing light. For a film-like sequence of high-speed photographs, as used in the photography of nuclear and thermonuclear tests, arrays of up to 12 cameras were deployed, with each camera carefully timed to record sequentially. Each camera was capable of recording only one exposure on a single sheet of film. Therefore, in order to create time-lapse sequences, banks of four to ten cameras were set up to take photos in rapid succession. The average exposure time used was three microseconds. Rapatronic images provided a valuable tool for scientists to understand events that occur in milliseconds after the detonation of a nuclear bomb. Condition: Very good.
Keywords: Nevada Test Site, Atomic Energy, Rapatronic Photography, Rapatronic Camera, Harold Edgerton, Edgerton, Germeshausen & Grier, EG&G, Fireballs, John Malik
[Book #90863]
Price: $20.00