Electric field measurements in glow discharges using optogalvanic detection of Rydberg atoms

Spatially resolved electric field measurements in the cathode fall region are performed using linear Stark effects in Rydberg atoms. The large linear Stark effects of Rydberg atoms are straightforward to calculate. A wide range of electric fields can be observed by proper choice of principle quantum number. The Rydberg atoms are produced by laser excitation from metastable levels. The fragile Rydberg atoms are rapidly collisionally ionized, and are detected using optogalvanic effects. Single step excitation using a frequency doubled dye laser is used in He. Two step excitation using intersecting dye laser beams is used in Ne. The two step method provides pinpoint measurements of discharge fields. The pinpoint field measurements are integrated along a well defined path from anode to cathode and found to agree with the discharge voltage to /sup m9/ 1%. The field measurements provide a map of the cathode fall region