Andrey Timokhin, of the Janusz Gil Institute of Astronomy at the University of Zielona Gora, gives this Institute for Advanced Study astrophysics seminar on how pulsars generate the dense electron-positron plasma that powers their radio emission. He focuses on the polar caps, the small regions near a pulsar's magnetic poles where intense electric fields rip charged particles from the stellar surface and accelerate them to energies high enough to trigger pair production cascades. Timokhin walks through the plasma physics governing this process, including how the cascades regulate themselves and why the plasma output fluctuates on short timescales, drawing on his own theoretical models of polar cap discharge. The talk addresses open questions about what sustains the pair plasma and how it connects to the pulsar's observed radio signal, delivered to a specialist audience in the Bloomberg Lecture Hall.