Density modulation of a solid-state plasma using acoustic pressure

We are studying the plasma density response with pressure in indium antimonide (InSb), with the goal of developing a solid-state pressure gradient transducer [1]. We use intrinsic InSb, where the free carrier concentration depends only on the energy band gap and temperature. We have developed two techniques to apply pressure modulation to an InSb sample. One method, which we call a Lumped Parameter Resonator (LPR), applies pressure at low frequency (~2 kHz) with no spatial dependence. The second method uses higher frequency (~200 kHz) in a resonant structure to generate a standing wave. We have also developed a laser plasma diagnostic to directly measure the plasma density.