Heating of a dense plasma using an intense, relativistic electron beam

We report observations of heating of a dense (∼1017 cm−3) plasma using a 3-MeV electron beam with a current density of 5×105 A/cm2. The measured, strong dependence of heating on beam transverse temperature and the short saturation distance (<4 cm) are evidence that the beam-to-plasma energy transfer takes place via a fast growing microinstability such as the relativistic electron-electron two stream.