Measurement of laser driven shock wave transit time through thin aluminium targets by optical shadowgraphy |
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Authors: | L J Dhareshwar N Gopi C G Murali N K Gupta B K Godwal |
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Institution: | (1) High Pressure Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai, 400085, India |
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Abstract: | Laser driven shock wave transit time in thin aluminium targets was experimentally estimated by determining the shock emergence
time at the rear of thin aluminium foils of varying thickness from 5 to 35 μm. A 20 J, 5 ns Nd:glass laser was focused to
produce laser intensity of 1012 to 5 × 1013 W/cm2 on the targets which were placed in vacuum. Target foil movement was measured to an accuracy of 10 μm using optical shadowgraphy
technique. This technique was used to accurately measure the shock transit time by recording the optical shadowgrams at various
instants of time and thus identify the instant at which the foil is just set into motion. Shock transit time measured in foils
of different thickness can give the value of shock velocity at a given laser intensity. Target motion recorded by shadowgraphy
can also give the target foil velocity from which shock pressure can be estimated. Experimental values of shock transit time,
shock velocity and shock pressure were observed to agree well with the values using one-dimensional multi-group radiation
hydrodynamic simulations.
PACS 52.50Jm; 52.50Lp; 52.25
Communicated by K. Takayama |
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Keywords: | Laser shock Plasma Shock velocity |
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