Energy Distribution of a Relativistic Electron Beam Interacting with Plasma

The energy distribution of a relativistic electron beam which has interacted with a plasma was investigated. The beam parameters were 550 keV, 500 A, and 20 ns (full width at half-maximum). From the broadening of the energy spectrum by interaction with the plasma we calculated the axial-wave electric field of the electrostatic beam-plasma instability to be $E\approx 1.8\times {10}^6$ V/m. This is in reasonable agreement with values predicted from theory.