The low-frequency magnetoelectronic excitations in a pair of armchair carbon nanotubes are studied within the self-consistent-field approach. The intertube Coulomb interactions would induce the coherent and incoherent plasmon modes. Their existence, intensity, frequency, and group velocity are investigated in detail. They are dominated by the transferred momentum. the intertube distance, the magnitude, and the direction of the magnetic field. (c) 2005 American Vacuum Society.