Ablation-induced explosion of metal using a high-power Nd:YAG laser

Abstract

The interaction of a high-power pulsed-laser beam with metal targets in air from a 1.06 μm, 5 ns, 3 J/pulse, Nd:YAG pulsed laser is investigated together with hydrodynamic theories of laser-supported blast wave and multimaterial reactive Euler equations. The high-speed blast wave generated by the laser ablation of metal reaches a maximum velocity of several thousand meters per second. The apparently similar flow conditions to those of reactive shock wave allow one to apply the equations of motion for energetic materials and to understand the explosive behavior of metal vaporization upon laser ablation. The characteristic time at which the planar to spherical wave transition occurs is investigated at low (20 mJ/pulse) to high (200 mJ/pulse) beam intensities. The flow structure behind the leading shock wave during the early planar shock state is confirmed by the high-resolution multimaterial hydrocode originally developed for shock compression of condensed matter. A repeatable lab-scale blast wave experiment is conducted at various energy levels with three different ablative targets, and both theoretical and computational analyses are used to verify the flow structures behind the leading shock front that remains spherically symmetric until all the momentum transferred from the absorbed intensity dissipates into open air a few microseconds later.

Explosive boiling of a metallic glass superheated by nanosecond pulse laser ablation

“…22,23 Instead, the hightemperature matter is the only capture that can be visible to the camera as bright sparks. It is well accepted that the emission of high-temperature matter provides important evidence for explosive boiling, 6,7,15,22,24 thus indicating that an explosive boiling process might have taken place in the Vitreloy 1 glass after the ns-pulse laser ablation. The glassy target should have experienced an explosion-type vaporization from its superheated liquid, resulting in a violent ejection of a high-temperature mixture of vapor and droplets.…”

“…Explosive boiling is considered as the most efficient thermal mechanism for laser ablation on various crystalline solids. 6,7,[13][14][15] Metallic glasses represent a relatively novel class of non-crystalline solids that are frozen from highly viscous melts through the glass transition. 16,17 They are naturally in metastable states with intrinsic density or free-volume fluctuations.…”

Synthesis of Anatase Phase Titanium Dioxide Using High-Power Nd:YAG Laser Focused on Titanium Wire in Water

“…In order to capture an image of a pulsed bubble, a camera (digital camera with telephoto lens, Pentax) and Nd:YAG laser (maximum intensity 25 mJ of 532 nm wavelength, Minilite PIV Specification, Continuum Inc.) were aligned to the sample target perpendicular to the ablation beam. 18,19) Another Nd:YAG laser beam of 532 nm with a 10 ns pulse width and a repetition rate of 10 Hz (maximum intensity 3 J/pulse, Powerlite Plus, Continuum Inc.) was used as an ablation pulse for focusing on the target to synthesize oxides. In the present work, the experiment was performed at 1 J/pulse for 5 h for powder recovery.…”

Light erosive optical discharges investigation. I. Investigation of radially confined light erosive pulsed optical discharges

“…Преобладание того или иного механизма определяется как положением мишени относительно плоскости фокусировки воздей-ствующего излучения, так и возможностью инициирования экзотер-мических реакций при данных условиях лазерного воздействия. При наличии канала у поверхности мишени радиальное распространение абляционного потока ограничено стенками канала и отраженными от них ударными волнами, что затрудняет переход характера распро-странения ударной волны из плоского в сферический (изначально плоский характер распространения обусловлен конечным размером источника, а время перехода составляет около 150 нс [27]), т. е. ско-рость фронта уменьшается медленнее.…”