Abstract
We visualize ps-time-scale evolution of an electron density bubble—a wake structure created in atmospheric density plasma by an intense ultrashort laser pulse—from the phase “streak” that the bubble imprints onto a probe pulse that crosses its path obliquely. Phase streaks, recovered in one shot using frequency-domain interferometric techniques, reveal the formation, propagation, and coalescence of the bubble within a 3 mm long ionized helium gas target. 3D particle-in-cell simulations validate the observed density-dependent bubble evolution, and correlate it with the generation of a quasimonoenergetic electron beam. The results provide a basis for understanding optimized electron acceleration at a plasma density , inefficient acceleration at lower density, and dephasing limits at higher density.
- Received 28 March 2014
DOI:https://doi.org/10.1103/PhysRevLett.113.085001
© 2014 American Physical Society