Magnetosonic wave

A magnetosonic wave is a longitudinal wave^[1] of ions (and electrons) in a magnetized plasma propagating perpendicular to the stationary magnetic field. The wave is dispersionless with a phase velocity ω/k given by

,

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where v_s is the speed of the ion acoustic wave, v_A is the speed of the Alfvén wave, and c is the speed of light in vacuum.

In the limit of low magnetic field (v_A→0), the wave turns into an ordinary ion acoustic wave. In the limit of low temperature (v_s→0), the wave becomes a modified Alfvén wave. Because the phase velocity of the magnetosonic mode is almost always larger than v_A, the magnetosonic wave is often called the "fast" hydromagnetic wave.

References

1. ^ The wave is longitudinal in the perturbation of the fluid velocity, although the perturbation of the magnetic field is transverse. See Schmidt, Physics of High Temperature Plasmas, p.101.

See also

• Waves in plasmas
• Alfvén wave
• Ion acoustic wave