Events
Plasma Physics (Physics/ECE/NE 922) Seminars |
Events on Monday, November 9th, 2026
- Nonlinear Waves in Magnetized Pair Plasmas: Dispersive Shocks and Sudden Dissipation
- Time: 12:00 pm - 1:00 pm
- Place: 2241 Chamberlin Hall
- Speaker: Pablo Bilbao, University of Oxford
- Abstract: How intense radio emission escapes neutron-star magnetospheres is a central open question in the physics of pulsars and fast radio bursts. In this talk, I will investigate the nonlinear propagation of low-frequency extraordinary (X-mode) waves in strongly magnetized electron–positron plasmas, combining analytical drift-fluid theory with particle-in-cell simulations. We show that finite-amplitude waves steepen into sharp cusps with a characteristic (k^{-4/3}) amplitude spectrum, before plasma dispersion transforms them into trains of solitons. As the wave amplitude increases, these solitons develop progressively smaller spatial scales, eventually breaking particle adiabaticity and triggering stochastic acceleration of a small fraction of particles to relativistic energies. This leads to an abrupt onset of collisionless dissipation at wave amplitudes well below the conventional fluid wave-breaking limit, while most of the plasma remains cold. I will discuss how this mechanism constrains the propagation of intense electromagnetic transients through neutron-star magnetospheres, placing limits on the coherent radio luminosity that can escape, with implications for Crab giant pulses and fast radio bursts.
- Host: Vladimir Zhdankin