Related Experiment Video
Updated: Apr 27, 2026

Investigation of Early Plasma Evolution Induced by Ultrashort Laser Pulses
Published on: July 2, 2012
Measurement of the laser-pulse group velocity in plasma waveguides
J van Tilborg1, J Daniels2, A J Gonsalves1
1Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720, USA.
Abstract:
Electrically discharged plasma channels can guide laser pulses, extending the laser-plasma interaction length to many Rayleigh ranges. In applications such as the laser-plasma accelerator, the laser group velocity in the channel plays a critical role. The laser travel time (and thus the averaged group velocity) was measured through two-pulse frequency-domain interferometry and was found to depend on the on-axis plasma density and laser spot size. The data is in agreement with theory.
Related Concept Videos
Propagation Speed of Electromagnetic Waves
Propagation of Waves
Consider a scenario where a wave propagates from a string of low linear mass density to a string of high linear mass density. In such a case, the reflected wave is out of phase with respect to the incident wave, however the...

