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

A dense (approximately 0 to the 17th power/cu cm) plasma was heated via the relativistic two-stream instability using a 3 MeV, intense (5 x 10 to the 5th power A/sq cm) electron beam. Evidence for heating was 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 were attempted. The measured strong dependence of heating on beam transverse temperature and the very short interaction length ( 4 cm) are consistent with beam-plasma coupling due to the relativistic electron-electron two-stream instability. Soft X-ray measurements made 100 ns after the beam pulse are consistent with a plasma temperature 150 eV and line emission near 80 to 90 eV.