Experimental Apparatus and Results
Laser oscillators, barely discovered a decade ago [1, 2] (*), can now be modulated by the use of Kerr or Póckels cells [3, 4] to yield stroboscopic light pulses of only several nanoseconds in half-width at a frequency of an order of a megacycle per second
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L E C T U R E S - No.
100
ANTONI K. OPPENHEIM AND
MOST AF A M. KAMEL UNIVF..RSITY OF CALIFORNIA
LASER CINEMATOGRAPHY OF EXPLOSIONS
LECTURES DELIVERED DURING THE COURSE
ON EXPERIMENTAL METHODS IN MECHANICS OCTOBER l97il
UDJNE 19'il
SPRINGER-VERLAG WIEN GMBH
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apecifically th011e of tnnalation, reprinting, re-uae of illustrationa, broadcuting, reproduction by photocopying machine or similar meana, and storage in data banks. © 1972 by Springer-Verlag Wien OriginaUy published by Springer-Verlag Wien New York in 1972
ISBN 978-3-211-81179-5 DOI 10.1007/978-3-7091-2860-2
ISBN 978-3-7091-2860-2 (eBook)
PREFACE Explosions are familiar events of every-day's life be they of cosmic~ terrestrial~ or man made origin. Their effects range from the cosmic displays of star explosions and solar flares~ to the destructiveness of lightnings~ earthquakes~ volcanic eruptions~ and meteoroid impacts; from the potential hazards of air pollution and sonia boom~ to the more immediate danger of thermonuclear holocaust. Thus the idea of harnessing~ or controlling~ these destructive processes for useful and productive purposes is most attractive. A prelude to controllability~ however~ is a through understanding of the phenomena under consideration. The scientific endeavor directed towards this aim has become known as the Gasdynamias of Explosions. The description of its fundamental features can be found in the text of Oppenheim (~~) . Shortly then~ the objective of this novel branch of fluid mechanics is to contribute to the knowledge of the interrelationships between the exothermic rate processes that are at the heart of explosions and the non-steady gasdynamia phenomena that manifest,in effeat,their mechanical work output~ the energy that can be employed for destructive or productive purposes. (*)Oppenheim, A.K., Introduction to Gasdynamics of Explosions, International Center for Mechanical Sciences (CISM), Udine, Italy, 1971.
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Preface
From its inception, th~ pace of theoretical progress in the field of Gasdynamics of Explosions has been geared to, as well as controlled by, advances in the experimental techniques utilized in observing the explosion phenomena. Since the significant period of the generation of an explosion has a duration, in most cases, of less than a microsecond, the event should be observed with an instrument having a nanosecond resolution in time. In order to visualize the magnitude of this resolving power, one has only to realize that the ratio of one nanosecond to a second is approximately equivalent to one second in the life span of a thirty year old man. This experimental capability has on~y recently become available, primarily by the controllable laser beam associated with solid state electPonic techniques. An example of the latter is the fast response pressure transducer as described in the texts of Oppenheim (*) and Soloukhin (~H~). The objective of this monogPaph is to present the
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