Plasma emission mechanism for radio spikes from solar flares Original Research Article

Narrowband spiky radio bursts, at decimetric and decametric wavelengths, with high degree of circular polarization are observed in solar flares. We discuss a new plasma emission mechanism for solar radio spikes. It is shown that narrowband radio bursts of right- and left-hand circular polarizations can be produced via nonlinear conversion of Langmuir waves into high-frequency electromagnetic electron cyclotron waves near the plasma frequency by coupling to low-frequency electromagnetic cyclotron waves such as Alfvén-ion cyclotron or magnetosonic-whistler waves.