  We formulate a possible description of the deflection of a relativistic $e^-$
beam in an inhomogeneous copper plasma, encountered by the beam when
propagating through a accelerating cell that has undergone a high
electric-field RF-breakdown. It is well known that an inhomogeneous plasma
forms and may last for up to a few micro-seconds, until recombination in an
accelerating structure where a field-emission triggers melting and ionization
of RF-cell wall deformity. We present a preliminary model for the beam
deflection due to collective plasma response based upon the beam density,
plasma density and interaction length.
