Summary form only given. The feasibility of using an ionizing shock wave to produce high-density plasmas suitable for the propagation of large-amplitude relativistic plasma waves is being investigated. A 20-kV arc-driven shock tube of coaxial geometry produces a hypersonic shock wave (10 < Mach < 60) in argon gas, which leaves in its wake a high-density plasma (n/sub p/ > 10/sup 17/ cm/sup -3/). The shock can be made to reflect off the end of the tube, collide with its wake, and thus increase the plasma density further. After reflecting, the plasma is at rest. The shock speed is measured using piezoelectric pressure probes, and the ion density is measured using laser-induced fluorescence (LIF) techniques on argon 488.0 nm and 422.8 nm lines. Implications for the application of high-density plasmas produced in this way to such devices as a plasma wave accelerator, a photon accelerator, a plasma wave undulator, and a plasma lens have been examined.