Nonlinear penetration of whistler pulses into collisional plasmas via conductivity modifications

A strong electromagnetic impulse (Δt≃0.2 μs) with central frequency in the whistler-wave regime is applied to a large laboratory plasma dominated by Coulomb collisions (${\nu }_{\mathit{e}\mathit{i}}$≃ω≪${\mathrm{\omega }}_{\mathit{c}\mathit{e}}$≪${\mathrm{\omega }}_{\mathit{p}\mathit{e}}$). Local electron heating at the antenna and transport along ${\mathit{B}}_0$ create a channel of high conductivity along which the whistler pulse penetrates with little damping. Because of its rapid temporal evolution, this new form of modulational instability does not involve ducting by density gradients which require ion time scales to develop.