Abstract

Light emanating from ac arcs operating on 60-Hz power exhibits a 120-Hz modulation of intensity. Although time-averaged spectra of such arcs are usually reported, the instantaneous light spectrum and its dependence on the oscillating plasma temperature is a more valuable source of spectroscopic information. An experimental technique is described for scanning the spectrum of an ac discharge at any fixed phase in the arc operating cycle. Spectra were recorded at phases corresponding to maximum and minimum light output for a pure Hg arc, a Hg–Na, Sc, Th metal-iodide arc, a Hg high-pressure Na arc, and a Hg–SnI2 arc. Intensity ratios Imax/Imin of spectral lines generally increased with increasing upper-state energy. Many of the dominant lines also exhibited sizable changes of line profile with variations of phase. In the Hg–Na, Sc, Th metal-iodide arc, the intensity variations of optically thin lines were used to obtain estimates of upper-state energies and relative gA values of some Th lines for which these quantities were previously unknown.

© 1972 Optical Society of America

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References

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  1. W. Elenbaas, The High Pressure Mercury Vapor Discharge (North–Holland, Amsterdam, 1951).
  2. G. H. Reiling, J. Opt. Soc. Am. 54, 532 (1964).
    [Crossref]
  3. K. Schmidt, in Proceedings of Sixth International Conference on Ionization Phenomena in Gases (North–Holland, Amsterdam, 1963), p. 323.
  4. T. Higashi, L. Mori, and S. Nagano, in CIE Proceedings, Sixteenth Session, Washington, D. C., 1967 (Bureau Central CIE, 25 rue de Pépinière, Paris, 1968), p. 208.
  5. J. F. Waymouth, Electric Discharge Lamps (MIT Press, Cambridge, Mass., 1971).
  6. Boxcar Integrator model No. Cw-1 is a product of the Princeton Applied Research Corporation, Princeton, N. J.
  7. D. E. Rothe, Phys. Rev. 177, 93 (1969).
    [Crossref]
  8. R. J. Zollweg and L. S. Frost, in Proceedings of Eighth International Conference on Ionization Phenomena in Gases (International Atomic Energy Agency, Vienna, 1967), p. 224.
  9. A. Adinarayana Murthy and P. B. V. Haranath, Curr. Sci. 38, 211 (1969).
  10. W. M. Vaidya and V. D. Dandawaite, J. Opt. Soc. Am. 56, 1963 (1966).
    [Crossref]
  11. R. Zalubas, New Description of Thorium Spectra, Natl. Bur. Std. (U. S.) Monograph No. 17 (U. S. Government Printing Office, Washington, D. C., 1960).
  12. C. H. Corliss and W. R. Bozman, Experimental Transition Probabilities for Spectral Lines of Seventy Elements, Natl. Bur. Std. (U. S.) Monograph No. 53 (U. S. Government Printing Office, Washington, D. C., 1962).

1969 (2)

D. E. Rothe, Phys. Rev. 177, 93 (1969).
[Crossref]

A. Adinarayana Murthy and P. B. V. Haranath, Curr. Sci. 38, 211 (1969).

1966 (1)

W. M. Vaidya and V. D. Dandawaite, J. Opt. Soc. Am. 56, 1963 (1966).
[Crossref]

1964 (1)

Adinarayana Murthy, A.

A. Adinarayana Murthy and P. B. V. Haranath, Curr. Sci. 38, 211 (1969).

Bozman, W. R.

C. H. Corliss and W. R. Bozman, Experimental Transition Probabilities for Spectral Lines of Seventy Elements, Natl. Bur. Std. (U. S.) Monograph No. 53 (U. S. Government Printing Office, Washington, D. C., 1962).

Corliss, C. H.

C. H. Corliss and W. R. Bozman, Experimental Transition Probabilities for Spectral Lines of Seventy Elements, Natl. Bur. Std. (U. S.) Monograph No. 53 (U. S. Government Printing Office, Washington, D. C., 1962).

Dandawaite, V. D.

W. M. Vaidya and V. D. Dandawaite, J. Opt. Soc. Am. 56, 1963 (1966).
[Crossref]

Elenbaas, W.

W. Elenbaas, The High Pressure Mercury Vapor Discharge (North–Holland, Amsterdam, 1951).

Frost, L. S.

R. J. Zollweg and L. S. Frost, in Proceedings of Eighth International Conference on Ionization Phenomena in Gases (International Atomic Energy Agency, Vienna, 1967), p. 224.

Haranath, P. B. V.

A. Adinarayana Murthy and P. B. V. Haranath, Curr. Sci. 38, 211 (1969).

Higashi, T.

T. Higashi, L. Mori, and S. Nagano, in CIE Proceedings, Sixteenth Session, Washington, D. C., 1967 (Bureau Central CIE, 25 rue de Pépinière, Paris, 1968), p. 208.

Mori, L.

T. Higashi, L. Mori, and S. Nagano, in CIE Proceedings, Sixteenth Session, Washington, D. C., 1967 (Bureau Central CIE, 25 rue de Pépinière, Paris, 1968), p. 208.

Nagano, S.

T. Higashi, L. Mori, and S. Nagano, in CIE Proceedings, Sixteenth Session, Washington, D. C., 1967 (Bureau Central CIE, 25 rue de Pépinière, Paris, 1968), p. 208.

Reiling, G. H.

Rothe, D. E.

D. E. Rothe, Phys. Rev. 177, 93 (1969).
[Crossref]

Schmidt, K.

K. Schmidt, in Proceedings of Sixth International Conference on Ionization Phenomena in Gases (North–Holland, Amsterdam, 1963), p. 323.

Vaidya, W. M.

W. M. Vaidya and V. D. Dandawaite, J. Opt. Soc. Am. 56, 1963 (1966).
[Crossref]

Waymouth, J. F.

J. F. Waymouth, Electric Discharge Lamps (MIT Press, Cambridge, Mass., 1971).

Zalubas, R.

R. Zalubas, New Description of Thorium Spectra, Natl. Bur. Std. (U. S.) Monograph No. 17 (U. S. Government Printing Office, Washington, D. C., 1960).

Zollweg, R. J.

R. J. Zollweg and L. S. Frost, in Proceedings of Eighth International Conference on Ionization Phenomena in Gases (International Atomic Energy Agency, Vienna, 1967), p. 224.

Curr. Sci. (1)

A. Adinarayana Murthy and P. B. V. Haranath, Curr. Sci. 38, 211 (1969).

J. Opt. Soc. Am. (2)

W. M. Vaidya and V. D. Dandawaite, J. Opt. Soc. Am. 56, 1963 (1966).
[Crossref]

G. H. Reiling, J. Opt. Soc. Am. 54, 532 (1964).
[Crossref]

Phys. Rev. (1)

D. E. Rothe, Phys. Rev. 177, 93 (1969).
[Crossref]

Other (8)

R. J. Zollweg and L. S. Frost, in Proceedings of Eighth International Conference on Ionization Phenomena in Gases (International Atomic Energy Agency, Vienna, 1967), p. 224.

W. Elenbaas, The High Pressure Mercury Vapor Discharge (North–Holland, Amsterdam, 1951).

K. Schmidt, in Proceedings of Sixth International Conference on Ionization Phenomena in Gases (North–Holland, Amsterdam, 1963), p. 323.

T. Higashi, L. Mori, and S. Nagano, in CIE Proceedings, Sixteenth Session, Washington, D. C., 1967 (Bureau Central CIE, 25 rue de Pépinière, Paris, 1968), p. 208.

J. F. Waymouth, Electric Discharge Lamps (MIT Press, Cambridge, Mass., 1971).

Boxcar Integrator model No. Cw-1 is a product of the Princeton Applied Research Corporation, Princeton, N. J.

R. Zalubas, New Description of Thorium Spectra, Natl. Bur. Std. (U. S.) Monograph No. 17 (U. S. Government Printing Office, Washington, D. C., 1960).

C. H. Corliss and W. R. Bozman, Experimental Transition Probabilities for Spectral Lines of Seventy Elements, Natl. Bur. Std. (U. S.) Monograph No. 53 (U. S. Government Printing Office, Washington, D. C., 1962).

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Figures (12)

Fig. 1
Fig. 1

Block diagram of experimental equipment used to record spectra of ac arcs at any fixed phase in the operating cycle. L is an arc lamp; S, a spectrometer; PM, a photomultiplier; A, a preamplifier; BI, a Boxcar Integrator; and SC, an oscilloscope.

Fig. 2
Fig. 2

The 120-Hz intensity modulation of the 5770-Å line of a pure Hg arc.

Fig. 3
Fig. 3

Spectra of a pure Hg arc at phases corresponding to maximum and minimum light output. Dashed curve indicates spectral response of monochromator and photomultiplier combination.

Fig. 4
Fig. 4

Continuum spectra in a pure Hg arc.

Fig. 5
Fig. 5

Spectra of a Hg–Na, Sc, Th metal-iodide arc.

Fig. 6
Fig. 6

Spectra of a Hg high-pressure Na arc. The Hg lines are labeled. All other emission lines are due to Na.

Fig. 7
Fig. 7

Line spectra of a Hg–SnI2 arc. The Na and Li lines are due to impurities.

Fig. 8
Fig. 8

The continuum spectra of a Hg–SnI2 arc. Distinguishable HgI and I features are indicated. These are superposed on a very broad continuum extending throughout the visible, and believed to be due to either SnI or SnI2 molecules.

Fig. 9
Fig. 9

Line profiles of selected lines in a pure Hg arc at phases corresponding to maximum and minimum light output.

Fig. 10
Fig. 10

Open circles indicate the variation of the 4078-Å intensity as a function of phase compared with variations of instantaneous power input V × I and conductivity I/V. This was a pure Hg arc.

Fig. 11
Fig. 11

Plot of log(Imax/Imin) vs upper-state energy E for Th lines of known E. Solid line represents a fit of the data assuming LTE. The Th lines are in the wavelength range 3300–4000 Å.

Fig. 12
Fig. 12

Plot of log(gA/Iminλ) vs E for Th lines of known gA. Values of gA were obtained from Corliss and Bozman. The solid line is a best least-squares fit of the data.

Tables (6)

Tables Icon

Table I Ratios of maximum to minimum spectral intensities in a vertically operating Hg arc. The quantity E is the upper-state energy.

Tables Icon

Table II Ratios of maximum to minimum spectral intensities in a vertically operating Hg–Na, Sc, Th metal-iodide arc.

Tables Icon

Table III Ratios of maximum to minimum spectral intensities in a vertically operating Hg high-pressure Na arc.

Tables Icon

Table IV Ratios of maximum to minimum spectral intensities in a vertically operating Hg–SnI2 arc.

Tables Icon

Table V Relative intensities at phases of maximum and minimum light output for Th lines of previously known E and gA.

Tables Icon

Table VI Upper-state energies E and relative gA values of Th i determined from measurements of Imax/Imin and relative Imin. The gA values are normalized to those listed for Th in the tables of Corliss and Bozman (Ref. 12).

Equations (2)

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I = C ( N / u ) ( g A / λ ) exp ( - E / k T ) ,
I 2 / I 1 = ( N 2 / N 1 ) ( u 1 / u 2 ) exp [ ( E / k T 2 ) ( T 2 / T 1 - 1 ) ] .