Magnetic field effects on the dynamics and geometry of precursor solitons generated by a supersonically moving charged object in a plasma

We study the effect of ambient magnetic fields on ion-acoustic precursor solitons generated by a finite-sized charged object moving supersonically through a plasma using 2D3V particle-in-cell simulations. A magnetic field parallel to the source velocity (Bx) couples with the out-of-plane velocity (vz), producing inward transverse forces that suppress lateral expansion and accelerate forward propagation, forming compact, focused soliton structures. In-plane perpendicular (By) and out-of-plane (Bz) fields induce longitudinal and transverse suppression, with By opposing the disturbance and Bz generating a clockwise shear that inhibits propagation. Oblique fields tilt soliton structures along the field direction, resulting in asymmetric evolution. Comparison across plasma densities shows that soliton formation is primarily governed by the magnetization parameter, Ωc/ωp, where Ωc is the cyclotron frequency and ωp is the plasma frequency for ions and electrons. These effects associated with the magnetic field orientation and strength provide new insights into the dynamics of precursor solitons that can be tested in laboratory experiments and can prove useful in space plasma applications.