John J. Curry

Compilation of Wavelengths, Energy Levels, and Transition Probabilities for Ba I and Ba II

Energy levels, wavelengths, and transition probabilities for the first and second spectra of barium, Ba I and Ba II, have been compiled. Wavelengths of observed transitions and energy levels derived from those wavelengths have been obtained from a critical evaluation of the available literature. Measured and calculated transition probabilities for some of the observed transitions have been obtained from the recent compilation of Klose et al. [J. Z. Klose et al., J. Phys. Chem. Ref. Data 31, 217 (2002)].

Wavelengths, Transition Probabilities, and Energy Levels for the Spectra of Barium "Ba III through Ba LVI…

Energy levels, with designations and uncertainties, have been compiled for the spectra of barium ( Z = 56 ) ions from doubly ionized to hydrogenlike. Wavelengths with classifications, intensities, and transition probabilities are also tabulated. In addition, ground states and ionization energies are listed. For many ionization stages experimental data are available; however, for those for which only theoretical calculations or fitted values exist, these are reported. There are a few ionization stages for which only a calculated ionization potential is available.

X-ray induced fluorescence measurement of density distributions in a metal–halide lighting arc

The use of x-ray induced fluorescence to measure elemental densities in a metal–halide lighting arc is described. High-energy synchrotron radiation generated on the Sector 1 Insertion Device beam line at the Advanced Photon Source induces K-shell fluorescence in a high-pressure plasma arc. The detected fluorescence is spectrally resolved, so that multiple elemental species are observed simultaneously. Absolute calibration of the measured densities is straightforward and robust. The penetrating nature of high-energy photons allows these measurements to be made in situ, with the arc contained by an optically translucent polycrystalline alumina (Al2O3) arc tube and a glass vacuum jacket. Spatial distributions extending from one end of the arc tube to the other and from the arc core all the way to the wall have been obtained for all the principal elements in the arc. A volume element measuring 1 mm × 1 mm × 1 mm is resolved in the present work, with significantly better spatial resolution possible. Densities ...

Temperature profiles and thermal losses in 150 W high-intensity discharge lamps

A series of 150 W quartz metal-halide test lamps containing four different chemistries has been studied with optical emission spectroscopy and x-ray absorption imaging. The four chemistries are pure Hg, Hg–HgI2, Hg–NaI and Hg–NaI–DyI3. Core temperatures and comprehensive distributions of Hg vapour densities were measured and combined to obtain comprehensive gas temperature distributions. The concentrations of additives in these specially designed test lamps were found to be much smaller than is typical for a commercial metal-halide lamp. As a consequence, the core temperatures in all lamps are largely characteristic of a pure Hg discharge. The gas temperature distributions have been used to determine power losses resulting from thermal conduction through the Hg vapour. The fraction of total input power dissipated thermally was found to be 0.49 ± 0.01 in pure Hg, similar to published measurements for such lamps. In the Hg–NaI and Hg–NaI–DyI3 lamps, thermal losses are 0.41 ± 0.01 and 0.42 ± 0.01, respectively. The Hg–HgI2 lamp has thermal losses of 0.29 ± 0.03.

X-ray absorption imaging of Hg vapour in a ceramic metal-halide lamp using synchrotron radiation

The diagnostic technique of x-ray absorption imaging of Hg vapour in high-intensity discharge lamps has been extended. X-ray absorption imaging has been used previously to determine the time-averaged absolute Hg density (Curry J J, Sakai M and Lawler J E 1998 J. Appl. Phys. 84 3066). Now, using an intensified charge-coupled device detector and synchrotron radiation, time-resolved measurements have been made. Although no significant time-dependence was seen as a function of the electrical phase for an electronically ballasted lamp, real-time observations were made of the decaying Hg density during the cool-down period. The cold-spot temperature in a 150 W ceramic lamp containing Hg and rare-earth iodides decreased with a time constant of 48.4 s following arc extinction. The primary limitation to the sensitivity of these measurements has been identified, and methods for overcoming this limitation in future work are proposed. Other aspects of the technique are also discussed.

Observation of vapor pressure enhancement of rare-earth metal-halide salts in the temperature range relevant to metal-halide lamps

Total vapor-phase densities of Dy in equilibrium with a DyI3/InI condensate and Tm in equilibrium with a TmI3/TlI condensate have been measured for temperatures between 900 K and 1400 K. The measurements show strong enhancements in rare-earth vapor densities compared to vapors in equilibrium with the pure rare-earth metal-halides. The measurements were made with x-ray induced fluorescence on the sector 1-ID beam line at the Advanced Photon Source. The temperature range and salt mixtures are relevant to the operation of metal-halide high-intensity discharge lamps.

Power balance in highly loaded fluorescent lamps

Discrepancies reported in the literature between numerical predictions and experimental measurements in low-pressure Hg discharges at high current densities are considered. Elements of a one-dimensional fluid model and recent spectroscopic and Langmuir probe measurements are combined in a semi-empirical way to individually examine components of the positive column power balance and the discharge conductivity. At a Hg vapour pressure of 0.81 Pa (6.1 mTorr) and a current density of 300 mA cm−2, previous discrepancies in the power balance and discharge conductivity are simultaneously resolved by assuming a higher electron density than that obtained from the Langmuir probe measurements. This conclusion is supported by independent measurements of ion density reported in a companion paper. The importance of radial cataphoresis under these conditions, particularly with regard to radiation transport, is highlighted. This work is of particular interest for the design of fluorescent lamps operating at high current densities.

Direct observation of de-mixing in a ceramic metal-halide arc lamp

De-mixing of additives in a vertically-operated, ceramic DyI3–CsI–Hg metal-halide arc lamp has been observed by examining the ratios of absolute elemental densities as a function of position. As the elemental densities have been obtained directly by x-ray induced fluorescence (Curry J J, Adler H G, Shastri S D and Lee W-K 2003 J. Appl. Phys. 93 2359), this approach reveals the extent of mixing (or de-mixing) with no intervening assumptions about equilibrium, the local temperature, or the accuracy of partition functions. The metal additives in the arc studied show complex de-mixing. Depletion of Dy and Cs from the core is attributed to ambipolar cataphoresis. These same additives also exhibit a relative enhancement in a layer just outside the core before decreasing again toward the wall. Thermochemical data are used to derive radial distributions of molecular species given the experimentally obtained elemental densities and the gas temperature assuming a lamp operating pressure of 106 Pa (10 atm).

Enhancement of lanthanide evaporation by complexation: Dysprosium tri-iodide mixed with indium iodide and thulium tri-iodide mixed with thallium iodide

The vapors in equilibrium with condensates of DyI3, DyI3/InI, TmI3, and TmI3/TlI were observed over the temperature range from 900 K to 1400 K using x-ray induced fluorescence. The total densities of each element (Dy, Tm, In, Tl, and I) in the vapor, summed over all atomic and molecular species, were determined. Dramatic enhancements in the total vapor densities of Dy and Tm were observed in the vapors over DyI3/InI and TmI3/TlI as compared to the vapors over pure DyI3 and pure TmI3, respectively. An enhancement factor exceeding 10 was observed for Dy at T ≈ 1020 K, decreasing to 0 at T ≈ 1250 K. An enhancement factor exceeding 20 was observed for Tm at T ≈ 1040 K, decreasing to 0 at T ≈ 1300 K. Such enhancements are expected from the formation of the vapor-phase hetero-complexes DyInI4 and TmTlI4. Numerical simulations of the thermo-chemical equilibrium suggest the importance of additional complexes in liquid phases. A description of the measurement technique is given. Improvements in the absolute calibration lead to an approximately 40% correction to previously reported preliminary results [J. J. Curry et al., Chem. Phys. Lett. 507, 52 (2011); Appl. Phys. Lett. 100, 083505 (2012)].

Use of phosphor image plates for measuring intensities in vacuum ultraviolet spectra

We describe the use of phosphor image plates for recording spectra in the vacuum ultraviolet (VUV) and for determining accurate relative and absolute intensities. We investigated the spatial uniformity, noise, linearity of the response to VUV light, fading characteristics, saturation characteristics, reproducibility of the image when scanned multiple times, and long-term stability and lifetime of the plates. We find that the plates have a linear intensity response with a dynamic range of more than 4 orders of magnitude. We also show that they have potential as an absolute detector for VUV radiation.