Langmuir-Slow Extraordinary Mode Magnetic Signature Observations with Parker Solar Probe

Abstract Radio emission from interplanetary shocks, planetary foreshocks, and some solar flares occurs in the so-called “plasma emission” framework. The generally accepted scenario begins with electrostatic Langmuir waves that are driven by a suprathermal electron beam on Landau resonance. These then mode-convert to freely propagating electromagnetic emissions at local plasma frequency f pe and/or its harmonic 2 . However, details of physics mode conversion unclear, so far magnetic component has not been definitively measured. Several spacecraft have measured quasi-monochromatic or slow extraordinary modes (sometimes called z -modes) wind. coherent expected weak component, which never observed an unambiguous way. Here we report direct measurement signature these using Search Coil Magnetometer sensor Parker Solar Probe/FIELDS instrument. Using simulations wave propagation inhomogeneous plasma, show appearance is highly influenced presence density inhomogeneities occasionally cause refractive index drop low values where strong properties.