Quantum-optical spectroscopy for plasma electric field measurements and diagnostics
Christopher L. Holloway, Matthew T. Simons
Measurements of plasma electric fields are essential to the advancement of plasma science and applications. Methods for non-invasive in situ measurements of plasma fields on micrometre length scales with high sensitivity over a large field range remain an outstanding challenge. Here, we demonstrate a new spectroscopic approach for plasma electric field measurements that employs electromagnetically induced transparency as a high-resolution quantum-optical probe of plasma-embedded Rydberg atoms that serve as highly-sensitive field sensors with a large dynamic range. The method is applied in diagnostics of plasmas photo-excited out of a cesium vapor. The plasma electric fields are extracted from spatially-resolved measurements of field-induced shape changes and shifts of Rydberg resonances in rubidium tracer atoms. Measurement capabilities over a range of plasma densities and temperatures are exploited to characterize plasmas in applied magnetic fields and to image electric-field distributions in cyclotron- heated plasmas.