Excitation and propagation of beam-plasma instabilities in a weakly ionized laboratory plasma as a model for the magnetized solar wind dynamics

The thesis aims at the investigation of the excitation of Langmuir waves in a small-scale cylindrical experiment where a weakly ionized plasma is produced in the presence of a magnetic field. One of the aims is to replicate the condition met in the solar wind plasma where satellites (such as Parker Solar Probe and Solar Orbiter) detect electrostatic waves (typically Langmuir waves) destabilization inside the so-called magnetic holes (region of space where magnetic field intensity is significantly reduced). Langmuir waves, which are typically strongly damped in laboratory plasmas due to kinetic effects (Landau damping mechanism), will be induced through the excitation of the two-stream instability by using a suprathermal electron beam propagating in a background plasma. The role of an externally applied magnetic nozzle, in determining the dispersion properties of the waves, both in the direction parallel and perpendicular with respect to the magnetic field itself, will be investigated in a variety of experimental conditions also in terms of background gas, pressure, and ionization fraction.