  The phase dynamics of the stack of long Josephson junctions has been studied.
Both inductive and capacitive couplings between Josephson junctions have been
taken into account in the calculations. The IV--curve, bias current dependence
of radiation power and dynamics of each JJs of the stack have been
investigated. The coexistence of the charge traveling wave and fluxon states
has been observed. This state can be considered as a new collective excitation
in the system of coupled Josephson junctions. We demonstrate that the observed
collective excitation leads to the decreasing of radiation power from the
system.
