The parametric decay of a finite-extent cold-electron plasma wave (slow wave) was studied experimentally. Using a frequency of ${\omega }_0\gtrsim 10{\omega }_{\mathrm{pi}}$, it was found that the decay waves propagated along the pump wave rather than in the ${\overrightarrow{\mathrm{E}}}_0\times \overrightarrow{\mathrm{B}}$ direction. This is in agreement with the recent theoretical predictions of finite-length stabilization.

• Received 7 November 1977

DOI:https://doi.org/10.1103/PhysRevLett.40.554