Heating of a dense plasma with an intense relativista electron beam: Initial observations

A dense (∼10¹⁷cm⁻³) plasma has been heated via the relativistic two-stream instability usint) a 3MeV, intense (5×10⁵A/cm²) electron beam. Evidence for heating has been obtained with diamagnetic loops, thin-foil witness plates, and a 2-channel, broad-band soft x-ray detector. Measurements of energy loss from the beam using calorimetry techniques have been attempted. The measured strong dependence of heating on beam transverse temperature and the very short interaction length (<4cm) are consistant with beam-plasma coupling due to the relativistic electron-electron two-stream instability. Soft X-ray measurements made >100ns after the beam pulse are consistent with a plasma temperature < 150eV and line emission near 80–90eV.