  Various systems can be modeled as a point-like explosion of ionized debris
into a magnetized, collisionless background plasma -- including astrophysical
examples, active experiments in space, and laser-driven laboratory experiments.
Debris streaming from the explosion parallel to the magnetic field may drive
multiple resonant and non-resonant ion-ion beam instabilities, some of which
can efficiently couple the debris energy to the background and may even support
the formation of shocks. We present a large-scale hybrid (kinetic ions + fluid
electrons) particle-in-cell (PIC) simulation, extending hundreds of ion
inertial lengths from a 3-D explosion, that resolves these instabilities. We
show that the character of these instabilities differs notably from the 1-D
equivalent by the presence of unique transverse structure. Additional 2-D
simulations explore how the debris beam length, width, density, and speed
affect debris-background coupling, with implications for the generation of
quasi-parallel shocks.
