  Collimated outflows (jets) are ubiquitous in the universe appearing around
sources as diverse as protostars and extragalactic supermassive blackholes.
Jets are thought to be magnetically collimated, and launched from a magnetized
accretion disk surrounding a compact gravitating object. We have developed the
first laboratory experiments to address time-dependent, episodic phenomena
relevant to the poorly understood jet acceleration and collimation region. The
experimental results show the periodic ejections of magnetic bubbles naturally
evolving into a heterogeneous jet propagating inside a channel made of
self-collimated magnetic cavities. The results provide a unique view of the
possible transition from a relatively steady-state jet launching to the
observed highly structured outflows.
