Electron-beam guiding by a reduced-density channel

A new regime of density-channel guiding of a relativistic electron beam in air has been found using a three-dimensional charged-particle simulation code, and confirmed in a double-pulse electron-beam experiment. The guiding results from the temperature dependence of the electron-neutral momentum-transfer frequency ${\nu }_{\mathit{m}}$. The mechanism does not require a deep channel to obtain a significant guiding force. For the 13-kA MEDEA II (and beams of similar parameters), guiding persists 10 ns into the beam pulse with the force per channel displacement as high as 4 G/cm.