At 2 miles long and 50 GeV, the Stanford Linear Collider (SLC) is the highest energy linear accelerator in the world, and the only linear collider. Along with the Large Electron Positron Collider (LEP) at CERN, it has succeeded in unveiling much of the detailed physics of the standard model of elementary particles and fields. However, the Higgs boson and the ultimate test of the standard model appear now to lie above 100 GeV and therefore out of the reach of the SLC. The results of the last runs of LEP were suggestive of the fact that the discovery of the Higgs may have been just beyond the reach of that machine [1,2]. In this report, we describe a scenario for doubling the energy of a collider by using a plasma wake field accelerator section several meters long placed at the end of each beam line just before the collision point. Such a doubling scheme could be used to extend the high-energy physics reach of the SLC or a future linear collider. The concept of a plasma wake field accelerator has received considerable attention recently [3‐ 7]. In a plasma wake field accelerator, the space charge of a particle bunch displaces the electrons of a preformed quiescent plasma to produce a large plasma wake field that can accelerate a subsequent bunch at a very high rate. In this report, 3D simulation models are used to show that the amplitude of the accelerating wake scales with the inverse square of the bunch length and that this scaling continues to hold for parameters far exceeding the linear theory from which it is derived. This leads us to propose the concept of a plasma afterburner — a specifically designed plasma that accelerates as well as focuses each beam from a linear collider in a single, short, final stage. Finally, we outline the critical issues that remain to be addressed in order to realize this concept. The afterburner concept is illustrated schematically in Fig. 1. Electrons and positrons are accelerated to the collider’s nominal operating energy (e.g., 50 GeV for the SLC example), overcompressed to form two microbunches each, then the trailing half-bunches are doubled in energy over a few meters in the plasma afterburner. To sustain the luminosity at the interaction point (IP) at the nominal level of the original collider without the plasma, the reduction in number of particles must be offset by a smaller spot size at the IP. Reduction of the spot size is possible in the strong focusing fields of the plasma; thus, higher density plasma lenses are added to the design just before the interaction point. To guide the discussion of the simulations to follow, we begin by reviewing key features of plasma wake field excitation in linear theory [8]. The linear response of a plasma to a Gaussian bunch is optimized when the plasma density no is chosen such that the bunch length and plasma wavelength are matched; more precisely, for kpsz p 2,