Experimental and theoretical investigations of a low-pressure He–Xe discharge for lighting purpose

Abstract

Low-pressure cylindrical dc glow discharges in a mixture of helium and 2% xenon are studied by experiment and self-consistent modeling. They can be used for the design of mercury-free vacuum ultraviolet sources and fluorescent lamps for publicity lighting. Experimental diagnostics of the column plasma includes measurements of the axial electric field strength and of the axis densities of the four lowest excited states of xenon. The electric field is determined from probe measurements. The particle densities are derived from the results of tunable diode laser absorption spectroscopy. Experimental investigations are assisted by a self-consistent analysis of the dc positive column plasma. A comparison between calculated and measured values of the axial electric field strength and the densities of excited xenon atoms is presented and discussed. The validated model is used for optimization of the discharge conditions by variation of the discharge current, gas pressure, and tube radius with respect to the radiation power and efficiency of the 147 nm resonance line of xenon. The discussion includes an analysis of the power budget of the column plasma.

Fundamentals of cavity-enhanced polarimetry for parity-nonconserving optical rotation measurements: Application to Xe, Hg, and I

“…The production of Xe metastable states 6s 2 [3/2] o 2 and Hg 3 P J has been realized using low-pressure electrical discharge lamps [41,42] or optical pumping [43], yielding steady-state densities of about 10 12 cm −3 , allowing column densities of about 10 14 cm −2 (over a single-pass path-length of 100 cm). Similarly, high iodine atom densities of ∼ 10 16 cm −3 have been achieved in glow discharges (requiring high precursor and carrier gas pressures).…”

Cavity-Enhanced Parity-Nonconserving Optical Rotation in Metastable Xe and Hg

“…To obtain measurable PNC optical rotation signals, column densities of ∼ 10 18 cm −2 thermal atoms are typically required [4][5][6], so as to achieve about 20 absorption lengths, for which optical rotation is ∼ 5 R. Such column densities of excited-state atoms are generally not available due to the short excited-state lifetimes. The metastable states Xe 3 P 2 and Hg 3 P J have been produced at steady-state densities of about 10 12 cm −3 , using electrical discharge lamps [19,20] or optical pumping [21], allowing column densities of about 10 14 cm −2 (over a path length of 100 cm). For these column densities and calculated values of R, an enhancement factor of about 10 4 is necessary to obtain signal levels comparable to previous optical rotation experiments [4][5][6].…”

“…We note that all even isotopes will have similar spectra, whereas odd isotopes will have hyperfine structure; in addition, all eight Xe and seven Hg stable isotopes are commercially available (each low pressure lamp requires ∼1 µmol of isotopically pure gas). We plot the PNC optical rotation, 2Nϕ PNC , multiplied by the transmission, as a function of the laser frequency about the absorption line center, for metastable 202 Hg column densities of 3.8 × 10 18 cm −2 (∼107 absorption lengths) [19] , and 132 Xe column densities of 1 × 10 18 cm −2 (∼20 absorption lengths) [20]. Collisional line broadenings for Hg and Xe are estimated to be 20 MHz and 10 MHz respectively.…”

ZIF-Derived Nitrogen-Doped Porous Carbons for Xe Adsorption and Separation

“…Noble gas xenon plays an important role in human industrial development and has increasingly extensive applications in aspects of lighting 1 , medicine 2 3 , nuclear magnetic resonance 4 and so on. In order to obtain pure Xe for further utilization, the energy-intensive cryogenic fractional distillation was often used to concentrate the noble gas Xe from air.…”