5P13

Characteristic Improvement of Inductively Coupled Electrode-less Metal Halide Lamps

Kozo Uemura (Toshiba Lighting and Technology Corp.), Toshihiko Ishigami (Toshiba Lighting and Technology Corp.), Akira Itoh (Toshiba Lighting and Technology

Corp.), Ichiro Yokozeki (Toshiba Lighting and Technology Corp.), Keiichi Shimizu (Toshiba Lighting

and Technology Corp.)

ABSTRACT

lamps were expected to show high efficacy and good life performance and had been studied extensively. At first, a t LS6 in 1992, a new inductively coupled HID lighting system was proposed. Since that, improvement of operating circuit efficacy and operation stability of the system has been discussed by using the current limitation of the co-axial cable for impedance matching circuit. On the other hand, dosing tin halides in those arc tubes was tried to extend their life.

use, improving lamp efficacy, confirming effect of tin halides on their life performance and improving their operation stability by decreasing Q value, which is resonance constant of their impedance matching circuit, were attempted. As a result, the lamp efficacy reached to 180 Im/W with white color and 58% of visible radiation power ratio to the input power was realized by optimizing rare gas pressure, input wattage, a sort of doses and by employing the elliptical-shape outer jacket with uniform temperature distribution on the arc tube surface. Their life performance was confirmed that the lamps with tin halides were abler to survive up to 60000 hours a t rated load operation without decreasing lumen output, because tin halides absorb iodine gas generated in the arc tube and prevent ulit problem, Optimizing the distance between the coil and the arc tube, the arc tube diameter and the rare gas pressure, Q value was decreased by 22 % without reducing their lamp performance.

lnductively coupled electrode-less metal halide

In this study, to put these systems into practical

Excimer Emission from Microhollow Cathode Discharges in Rare Gas Halides

A. El-Habachi, W. Shi, M. Moselhy, R.H. Stark, and K. H. Schoenbach

Physical Electronics Research Institute Old Dominion University, Norfolk, VA 23529

High-pressure gas discharges in rare gas halides have found applications in excimer lamps and excimer lasers. The lifetime of high-pressure glow discharges in rare gas halides and consequently the time of excimer emission are limited by instabilities to values on the order of 10 ns. Stable operation, however, can be achieved by operating rare gas halide discharges in a microhollow cathode discharge (MHCD) geometry. Similar to MHCDs in rare gases I l l , direct current discharges in rare gas halides could be operated up to atmospheric pressure using cathodes with hole diameters on the order of 100 pm. High pressure discharges in static ArF (1%F, 5% Ar, 94%He) and XeCl (l.S%Xe, 0.03 HCl, 0.06% H2, 98.41 Ne) mixtures were found to be intense sources of excimer radiation at 193 nm and 308 nm, respectively. The FWHM of both lines, the ArF and the XeCl line, i s 3-4 nm. Sustaining voltages are 400 V for ArF and 190 V for XeCI, at currents of several mA. Absolute measurements showed that the W N V radiant power for both sources is between 1%-3% of the input electrical power. Higher values seem to be obtainable with discharges operated in flowing gases. The possibility to form arrays of these discharges [2] allows the generation of flat panel quasi-monochromatic UV or W V lamps with radiant emittances on the order of 10 W/cm2. The power densi in the micro discharges is estimated to approach IO6

holds the promise for using MHCD plasma as a laser medium in dc micro excimer lasers. Experimental studies of the optical gain of the MHCD plasma at the excimer wavelength are underway.

Wlcm !? . Therefore, series operation of these discharges

[l] A. El-Habachi, and K.H. Schoenbach, Appl. Phys. Lett.

[2] W. Shi, R.H. Stark, and K.H. Schoenbach, EEE Trans. 72,22 (1 998).

Plasma Sci. 27, 16 (1 999).

This work is funded by the National Science Foundation.

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