Ultrafast X-Ray Phase Contrast Imaging of Self-Assembled Bismuth Microparticle Explosion Using Pulsed Plasmas

Plasma-induced explosions of self-assembled bismuth microparticles in mineral oil have been observed using X-ray phase contrast imaging (PCI) at the Advanced Photon Source at Argonne National Laboratory. A laser-triggered nanosecond-pulsed plasma device was used to generate explosions in self assembled bismuth microspheres at a high repetition rate, and the fact that this target is inherently self-healing makes event turnaround time significantly faster than that of more conventional dynamic targets such as exploding wires. The flexibility of this imaging apparatus makes it easily adaptable for the investigation of explosions of a wide variety of different types of microparticles in different media (water, oils) at different input energies at high repetition rates. Observed dynamics include the rapid melting of the bismuth microparticles and vaporization of the inter-particle oil layer, with multiphase behavior between the mineral oil and the bismuth leading to repeated ellipsoidal bismuth structures. These imaging results were compared to a thermodynamic model of bismuth at different deposition energies, showing that the timescale of phase transition is consistent with plasma energy deposition timescales.