Experimental Study of Microjetting from Triangular Grooves in Laser Shock-loaded Samples

When a shock wave interacts with a free surface, geometrical defects such as scratches, pits or grooves can lead to the production of high velocity, similar to mu m-size debris. Because their ballistic properties are a key safety issue for various applications involving high pressure dynamic loading, and because these debris may inhibit surface measurements commonly used in shock physics, this process usually referred to as 'material ejection' or 'microjetting' has motivated extensive research work for many years. Recently, we have started a systematic investigation of microjetting under laser driven shock loading of thin metallic samples with calibrated grooves in their free surface. Transverse shadowgraphy (complemented with Photonic Doppler Velocimetry) provides jet velocities for different metals, various groove angles, over a range of shock pressure, both below and above shock-induced melting. Besides, the short duration of pressure application allows partial sample recovery, which provides original insight into the early stage of jet formation.