Abstract

The behavior of long linear xenon discharges with metallic halide additives in narrow-bore quartz tubes is described. For various lamp applications, these discharges may have several desirable characteristics: (1) controllable line emission or continuum emission as desired, with excellent color rendition, (2) reasonable efficiency, (3) fast startup (~20 see), (4) elimination of the need for mercury and its pollution hazard, (5) possible efficient operation in the range between a few watts per linear cm and ~30 W/linear cm. The present lamps are in the laboratory stage, and several problems remain to be solved. It is argued that the continuum emission which sometimes appears in these xenon + metallic halide discharges (and also in commercial mercury arc lamps with certain metallic halide additives) is correlated with a high vapor pressure of the metallic halide additive. Thus, this continuum may be due to either molecular radiation or transitions involving free electrons originating copiously from the ionization of the metallic additive which has a comparatively low ionization potential. If a sufficiently high vapor pressure of any metallic halide can be achieved in the discharge, then a continuum emission seems to be a fairly common phenomenon. A scheme for achieving this objective is described.

© 1971 Optical Society of America

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References

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  1. T. J. Hammond, C. F. Gallo, Appl. Opt. 10, 58 (1971).
    [CrossRef] [PubMed]
  2. D. A. Larson, H. D. Fraser, W. V. Cushing, M. C. Unglert, Illum. Eng. 58, 434 (1963).
  3. G. H. Reiling, J. Opt. Soc. Am. 54, 532 (1964).
    [CrossRef]
  4. T. H. Rautenberg, P. D. Johnson, Appl. Opt. 3, 487 (1964).
    [CrossRef]
  5. C. F. Gallo, Appl. Opt. 6, 1563 (1967).
    [CrossRef] [PubMed]
  6. D. M. Speros, R. M. Caldwell, W. E. Smyser, R. H. Springer, R. P. Taylor, Illum. Eng. 65, 641 (1970).
  7. See Ref. 5 and the references cited therein.

1971 (1)

1970 (1)

D. M. Speros, R. M. Caldwell, W. E. Smyser, R. H. Springer, R. P. Taylor, Illum. Eng. 65, 641 (1970).

1967 (1)

1964 (2)

1963 (1)

D. A. Larson, H. D. Fraser, W. V. Cushing, M. C. Unglert, Illum. Eng. 58, 434 (1963).

Caldwell, R. M.

D. M. Speros, R. M. Caldwell, W. E. Smyser, R. H. Springer, R. P. Taylor, Illum. Eng. 65, 641 (1970).

Cushing, W. V.

D. A. Larson, H. D. Fraser, W. V. Cushing, M. C. Unglert, Illum. Eng. 58, 434 (1963).

Fraser, H. D.

D. A. Larson, H. D. Fraser, W. V. Cushing, M. C. Unglert, Illum. Eng. 58, 434 (1963).

Gallo, C. F.

Hammond, T. J.

Johnson, P. D.

Larson, D. A.

D. A. Larson, H. D. Fraser, W. V. Cushing, M. C. Unglert, Illum. Eng. 58, 434 (1963).

Rautenberg, T. H.

Reiling, G. H.

Smyser, W. E.

D. M. Speros, R. M. Caldwell, W. E. Smyser, R. H. Springer, R. P. Taylor, Illum. Eng. 65, 641 (1970).

Speros, D. M.

D. M. Speros, R. M. Caldwell, W. E. Smyser, R. H. Springer, R. P. Taylor, Illum. Eng. 65, 641 (1970).

Springer, R. H.

D. M. Speros, R. M. Caldwell, W. E. Smyser, R. H. Springer, R. P. Taylor, Illum. Eng. 65, 641 (1970).

Taylor, R. P.

D. M. Speros, R. M. Caldwell, W. E. Smyser, R. H. Springer, R. P. Taylor, Illum. Eng. 65, 641 (1970).

Unglert, M. C.

D. A. Larson, H. D. Fraser, W. V. Cushing, M. C. Unglert, Illum. Eng. 58, 434 (1963).

Appl. Opt. (3)

Illum. Eng. (2)

D. A. Larson, H. D. Fraser, W. V. Cushing, M. C. Unglert, Illum. Eng. 58, 434 (1963).

D. M. Speros, R. M. Caldwell, W. E. Smyser, R. H. Springer, R. P. Taylor, Illum. Eng. 65, 641 (1970).

J. Opt. Soc. Am. (1)

Other (1)

See Ref. 5 and the references cited therein.

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Figures (5)

Fig. 1
Fig. 1

Emission spectrum from a typical commercial mercury arc lamp with T1I additive. Notice that the spectrum is dominated by line emission, particularly radiation from atomic thallium. This spectrum has been corrected for the wavelength sensitivity of the optical detection system.

Fig. 2
Fig. 2

Emission spectrum from a mercury arc lamp with tin chloride and tin iodide additives as taken from Ref. 5. Notice that a sizable continuum is observed from this lamp. This spectrum has been corrected for the wavelength sensitivity of the optical detection system.

Fig. 3
Fig. 3

Emission spectrum from one of our typical long linear xenon discharges with TlI additive. Notice the strong continuum as contrasted with the spectrum from a typical commercial Hg + TlI are lamp shown in Fig. 1. In our xenon lamps, the quantity of TlI is much greater than that normally added to Hg arcs. This is an important point and enables us to achieve a much higher vapor pressure of TlI through the physical distribution of the additive as shown in Fig. 5 and discussed in the text. This particular lamp spectrum was taken under the following detailed conditions: (a) inside diameter of the quartz tube, 3.5 mm; (b) outside diameter of the quartz tube, 5.5 mm; (c) distance between electrodes which were not externally heated, ~15 cm; (d) ac input power, 498 W at 4.54 kV and 110 mA; (e) xenon cold-fill pressure, 77 Torr. This spectrum has not been corrected for the wavelength sensitivity of the optical detection system.

Fig. 4
Fig. 4

Emission spectra from some typical Xe + TlI lamps at various Xe cold-fill pressures. These spectra have been corrected for the wavelength sensitivity of the optical detection system by an incremental technique, which accounts for the distorted line shapes. Notice the strong continuum as contrasted with Fig. 1. These lamps contain an unusually large quantity of TlI as shown in Fig. 5 and described in the text. The quartz tube dimensions are the same as described in the caption of Fig. 3.

Fig. 5
Fig. 5

Pictorial schematic of an electrode in our xenon additive lamps. Notice that sufficient metallic halide has been added to substantially fill the volume behind the electrodes. This enables the delicate quartz-to-metal seal to operate below its critical value <500 K, while the free surface of the metallic halide additive can be considerably hotter, thus yielding a higher vapor pressure of the additive.

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