Energy and angular spreads of beam electrons and microwave radiation due to strong beam-plasma turbulence

A plasma becomes a strong Langmuir turbulence state when an intense relativistic electron beam (IREB) is injected into it. Investigation of the beam properties after passing the plasma is important. The energy and angular spreads of the IREB were measured by a magnetic energy analyzer and an angle analyzer, respectively. The theory of transit-time interactions was applied to analyze the observed energy and angular spreads and to estimate the turbulent field strengths. These results were in good agreement with the spectroscopic measurements. The broadband microwave radiation was also observed simultaneously with the angular spread measurement. We found correlation between the radiation and the angular spread of the IREB. The wider the angular spread, the stronger the microwave radiation.