Emission of electromagnetic waves from Langmuir waves generated by electron beam instability in pair plasmas

Using a two-dimensional electromagnetic and relativistic particle code, we show that electromagnetic waves can be emitted from Langmuir waves generated by an electron beam instability in pair plasmas. It is confirmed that the presence of a magnetic field is essential for the emission mechanism of the electromagnetic waves. The linear growth rate of the generation of electromagnetic waves is studied by many parameter runs changing the electron beam density, the electron beam velocity and the intensity of magnetic field. The plasma maser process is the most possible emission mechanism of the electromagnetic waves.