  An experimental study to investigate the effect of an external magnetic field
on the propagation of ion-acoustic waves (IAWs) has been carried out in
hydrogen plasma containing two-temperature electrons and dust grains. A
low-pressure hot cathode discharge method is opted for plasma production. The
desired two electron groups with distinct temperatures are achieved by
inserting two magnetic cages with a cusp-shaped magnetic field of different
surface field strengths in the same chamber. The dust grains are dropped into
the plasma with the help of a dust dropper, which gain negative charges by
interacting with the plasma. The IAWs are excited with the help of a mesh-grid
inserted into the plasma. A planar Langmuir probe is used as a detector to
detect the IAWs. The time of flight technique has been applied to measure the
phase velocity of the IAWs. The results suggest that in the presence of a
magnetic field, the phase velocity of IAWs increases, whereas introducing the
dust particles leads to the lower phase velocity. The magnetic field is
believed to have a significant effect on the wave damping. This study will aid
in utilising IAWs as a diagnostic tool to estimate plasma parameters in the
presence of an external magnetic field. Moreover, the study might be useful for
estimating the relative ion concentrations in a two positive ion species
plasma, as well as the relative concentration of the negative ions in the
presence of an external magnetic field.
