ELECTRIC-FIELD MEASUREMENTS IN DISCHARGES BY 2+1 PHOTON LASER STARK SPECTROSCOPY OF ATOMIC-HYDROGEN

We have developed a new method for measuring electric field magnitude using 2 + 1 photon laser-induced fluorescence of ground-state hydrogen atoms. The atoms are excited to the n = 2 level by two 243-nm photons, then further excited to the n = 6 level by one photon at 41 0 nm and detected by cascaded H(alpha) fluorescence. The electric field magnitude is deduced from the Stark splitting of the n = 6 level. The method was calibrated using H atoms from a distant source flowing through a region of known electric field. Results are presented for field profiles in dc discharges in 0.3 and 1 Torr pure H-2.