  A plasma beam dump uses the collective oscillations of plasma electrons to
absorb the kinetic energy of a particle beam. In this paper, a modified passive
plasma beam dump scheme is proposed using either a gradient or stepped plasma
profile to maintain a higher decelerating gradient compared to a uniform
plasma. The improvement is a result of the plasma wavelength change preventing
the re-acceleration of low energy particles. Particle-in-cell simulation
results show that both stepped and gradient plasma profiles can achieve
improved energy loss compared to a uniform plasma for an electron bunch of
parameters routinely achieved in laser wakefield acceleration.
