Abstract

A study was made of the feasibility of increasing the efficiency of fluorescent lamps at high powers by increasing the Hg 237-Å resonance radiation through a reduction of self-absorption. Specifically, we attempted to reduce the Hg 2537-Å self-absorption by introducing a higher pressure of a foreign gas (argon) to alter the Hg 2537-Å absorption line shape and width by collision broadening. The intensity of the Hg 2537-Å line in Hg + Ar discharges was measured as an independent function of mercury pressure (0.7 mTorr to 27 mTorr), argon pressure (5 Torr to 400 Torr), and dc input power (5.5 W to 97 W). A detailed theoretical analysis indicates that there are four ways that additional argon reduces the Hg 2537-Å self-absorption: (1) The Hg 2537-Å line gets broader simply because the additional argon atoms increase the Hg–Ar collision frequency; (2) adding argon causes the gas temperature to rise and this drives the Hg–Ar collision frequency still higher; (3) the rise in gas temperature also causes an increase in the Hg 2537-Å doppler width; (4) the additional argon changes the Hg 2537-Å line shape from doppler dominated to a collision dominated profile. The experiments demonstrate, however, that no gain is achieved in the Hg 2537-Å intensity with the addition of extra argon in spite of the beneficial effect on the self-absorption escape rate. This advantage is apparently offset by the argon’s reduction of the electron energy which leads to fewer mercury atoms excited to the Hg 63P1 state.

© 1971 Optical Society of America

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References

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  1. T. Holstein, Phys. Rev. 83, 1159 (1951).
    [CrossRef]
  2. T. Holstein, Phys. Rev. 72, 1212 (1947).
    [CrossRef]
  3. A. C. G. Mitchell, M. W. Zemansky, Resonance Radiation and Excited Atoms (Cambridge University Press, Cambridge, 1934), pp. 92–96.
  4. (a)C. F. Gallo, Phys. Rev. 158, 1 (1967); (b)Bull. Am. Phys. Soc. 15, 413 (1970).
    [CrossRef]
  5. Reference 1, Eq. 6.6.
  6. For instance, see J. W. Marden, N. G. Beese, G. Meister, Trans. Illum. Eng. Soc. 34, 55 (1939); R. J. Forbes, R. J. Diefenthaler, Illum. Eng. 41, 872 (1946).
    [PubMed]
  7. Reference 1, Eq. 6.3.
  8. Ref. 3, p. 170.
  9. F. A. Uvarov, V. A. Fabrikant, Opt. Spectrosc. 18, 323 (1965); Ref. 3, pp. 171, 179.
  10. W. Furssov, A. Vlassov, Phys. Zeits. Sowjetunion 10, 378 (1936). This reference was taken from Ref. 2, Eq. 5.17. Also see W. V. Huston, Phys. Rev. 54, 884 (1938).
    [CrossRef]
  11. P. J. Walsh, Phys. Rev. 116, 511 (1959).
    [CrossRef]
  12. C. Kenty, M. A. Easley, B. T. Barnes, J. Appl. Phys. 22, 1006 (1951), Figs. 2 and 4.
    [CrossRef]
  13. For instance, see A. Von Engel, Ionized Gases (Clarendon Press, Oxford, 1965), pp. 242–251; R. Papoular, Electronic Phenomena in Gases (Iliffe Books, London, 1965), pp. 131–137.

1967 (1)

(a)C. F. Gallo, Phys. Rev. 158, 1 (1967); (b)Bull. Am. Phys. Soc. 15, 413 (1970).
[CrossRef]

1965 (1)

F. A. Uvarov, V. A. Fabrikant, Opt. Spectrosc. 18, 323 (1965); Ref. 3, pp. 171, 179.

1959 (1)

P. J. Walsh, Phys. Rev. 116, 511 (1959).
[CrossRef]

1951 (2)

C. Kenty, M. A. Easley, B. T. Barnes, J. Appl. Phys. 22, 1006 (1951), Figs. 2 and 4.
[CrossRef]

T. Holstein, Phys. Rev. 83, 1159 (1951).
[CrossRef]

1947 (1)

T. Holstein, Phys. Rev. 72, 1212 (1947).
[CrossRef]

1939 (1)

For instance, see J. W. Marden, N. G. Beese, G. Meister, Trans. Illum. Eng. Soc. 34, 55 (1939); R. J. Forbes, R. J. Diefenthaler, Illum. Eng. 41, 872 (1946).
[PubMed]

1936 (1)

W. Furssov, A. Vlassov, Phys. Zeits. Sowjetunion 10, 378 (1936). This reference was taken from Ref. 2, Eq. 5.17. Also see W. V. Huston, Phys. Rev. 54, 884 (1938).
[CrossRef]

Barnes, B. T.

C. Kenty, M. A. Easley, B. T. Barnes, J. Appl. Phys. 22, 1006 (1951), Figs. 2 and 4.
[CrossRef]

Beese, N. G.

For instance, see J. W. Marden, N. G. Beese, G. Meister, Trans. Illum. Eng. Soc. 34, 55 (1939); R. J. Forbes, R. J. Diefenthaler, Illum. Eng. 41, 872 (1946).
[PubMed]

Easley, M. A.

C. Kenty, M. A. Easley, B. T. Barnes, J. Appl. Phys. 22, 1006 (1951), Figs. 2 and 4.
[CrossRef]

Fabrikant, V. A.

F. A. Uvarov, V. A. Fabrikant, Opt. Spectrosc. 18, 323 (1965); Ref. 3, pp. 171, 179.

Furssov, W.

W. Furssov, A. Vlassov, Phys. Zeits. Sowjetunion 10, 378 (1936). This reference was taken from Ref. 2, Eq. 5.17. Also see W. V. Huston, Phys. Rev. 54, 884 (1938).
[CrossRef]

Gallo, C. F.

(a)C. F. Gallo, Phys. Rev. 158, 1 (1967); (b)Bull. Am. Phys. Soc. 15, 413 (1970).
[CrossRef]

Holstein, T.

T. Holstein, Phys. Rev. 83, 1159 (1951).
[CrossRef]

T. Holstein, Phys. Rev. 72, 1212 (1947).
[CrossRef]

Kenty, C.

C. Kenty, M. A. Easley, B. T. Barnes, J. Appl. Phys. 22, 1006 (1951), Figs. 2 and 4.
[CrossRef]

Marden, J. W.

For instance, see J. W. Marden, N. G. Beese, G. Meister, Trans. Illum. Eng. Soc. 34, 55 (1939); R. J. Forbes, R. J. Diefenthaler, Illum. Eng. 41, 872 (1946).
[PubMed]

Meister, G.

For instance, see J. W. Marden, N. G. Beese, G. Meister, Trans. Illum. Eng. Soc. 34, 55 (1939); R. J. Forbes, R. J. Diefenthaler, Illum. Eng. 41, 872 (1946).
[PubMed]

Mitchell, A. C. G.

A. C. G. Mitchell, M. W. Zemansky, Resonance Radiation and Excited Atoms (Cambridge University Press, Cambridge, 1934), pp. 92–96.

Uvarov, F. A.

F. A. Uvarov, V. A. Fabrikant, Opt. Spectrosc. 18, 323 (1965); Ref. 3, pp. 171, 179.

Vlassov, A.

W. Furssov, A. Vlassov, Phys. Zeits. Sowjetunion 10, 378 (1936). This reference was taken from Ref. 2, Eq. 5.17. Also see W. V. Huston, Phys. Rev. 54, 884 (1938).
[CrossRef]

Von Engel, A.

For instance, see A. Von Engel, Ionized Gases (Clarendon Press, Oxford, 1965), pp. 242–251; R. Papoular, Electronic Phenomena in Gases (Iliffe Books, London, 1965), pp. 131–137.

Walsh, P. J.

P. J. Walsh, Phys. Rev. 116, 511 (1959).
[CrossRef]

Zemansky, M. W.

A. C. G. Mitchell, M. W. Zemansky, Resonance Radiation and Excited Atoms (Cambridge University Press, Cambridge, 1934), pp. 92–96.

J. Appl. Phys. (1)

C. Kenty, M. A. Easley, B. T. Barnes, J. Appl. Phys. 22, 1006 (1951), Figs. 2 and 4.
[CrossRef]

Opt. Spectrosc. (1)

F. A. Uvarov, V. A. Fabrikant, Opt. Spectrosc. 18, 323 (1965); Ref. 3, pp. 171, 179.

Phys. Rev. (4)

T. Holstein, Phys. Rev. 83, 1159 (1951).
[CrossRef]

T. Holstein, Phys. Rev. 72, 1212 (1947).
[CrossRef]

(a)C. F. Gallo, Phys. Rev. 158, 1 (1967); (b)Bull. Am. Phys. Soc. 15, 413 (1970).
[CrossRef]

P. J. Walsh, Phys. Rev. 116, 511 (1959).
[CrossRef]

Phys. Zeits. Sowjetunion (1)

W. Furssov, A. Vlassov, Phys. Zeits. Sowjetunion 10, 378 (1936). This reference was taken from Ref. 2, Eq. 5.17. Also see W. V. Huston, Phys. Rev. 54, 884 (1938).
[CrossRef]

Trans. Illum. Eng. Soc. (1)

For instance, see J. W. Marden, N. G. Beese, G. Meister, Trans. Illum. Eng. Soc. 34, 55 (1939); R. J. Forbes, R. J. Diefenthaler, Illum. Eng. 41, 872 (1946).
[PubMed]

Other (5)

Reference 1, Eq. 6.3.

Ref. 3, p. 170.

Reference 1, Eq. 6.6.

A. C. G. Mitchell, M. W. Zemansky, Resonance Radiation and Excited Atoms (Cambridge University Press, Cambridge, 1934), pp. 92–96.

For instance, see A. Von Engel, Ionized Gases (Clarendon Press, Oxford, 1965), pp. 242–251; R. Papoular, Electronic Phenomena in Gases (Iliffe Books, London, 1965), pp. 131–137.

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Figures (11)

Fig. 1
Fig. 1

The efficiency of a typical commercial fluorescent lamp (lumens per watt) vs the input power. The data were kindly supplied by J. R. Morin of Sylvania.

Fig. 2
Fig. 2

Schematic diagram of the water bath used to control the mercury vapor pressure in the Hg + Ar lamps. Radiation was measured from the exposed portion of the positive column.

Fig. 3
Fig. 3

Mercury 2537-Å radiant power vs input power for argon pressures of 5 Torr, 20 Torr, 100 Torr, 200 Torr, and 400 Torr and uncontrolled mercury pressures determined by the input power and ambient thermal losses.

Fig. 4
Fig. 4

The mercury 2537-Å radiant power vs the input power at a constant argon pressure of 5 Torr and at various mercury pressures. Notice the reduction in Hg 2537-Å intensity as the mercury pressure increases.

Fig. 5
Fig. 5

The mercury 2537-Å radiant power vs the input power at a constant argon pressure of 20 Torr and at various mercury pressures.

Fig. 6
Fig. 6

The mercury 2537-Å radiant power vs the input power at a constant argon pressure of 100 Torr and at various mercury pressures.

Fig. 7
Fig. 7

The mercury 2537-Å radiant power vs the input power at a constant argon pressure of 200 Torr and at various mercury pressures.

Fig. 8
Fig. 8

The mercury 2537-Å radiant power vs the input power at a constant argon pressure of 400 Torr and at various mercury pressures.

Fig. 9
Fig. 9

The ratio of the change in Hg 2537-Å intensity to the change in mercury pressure (ΔIPHg) evaluated at constant input power vs the argon pressure. This experimental curve reflects the dependence of Hg 2537-Å self-absorption on the argon pressure. Compare this experimental result with the theoretical calculations shown in Fig. 10.

Fig. 10
Fig. 10

The calculated dependence of self-absorption factor (ST) VS the argon pressure for various mercury pressures and constant input power. Compare this theoretical result with our analysis of the experimental data shown in Fig. 9.

Fig. 11
Fig. 11

The self-absorption factors(S) vs the mercury pressure at constant argon pressure and constant current. The term ST denotes the self-absorption factor in the simultaneous presence of doppler and collision broadening [Eq. (11)]. The term Sc is the self-absorption factor in a situation where the absorption line width and profile are determined by collisions [Eq. (10)], whereas Sd is the self-absorption factor when doppler broadening determines the absorption line width and profile [Eq. (8)]. For the particular situation shown in the graph, the doppler and collision contributions to the line width are approximately equal; but notice that the complete self-absorption factor (ST) is dominated by the collision factor (Sc) rather than by the doppler factor (Sd).

Equations (13)

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I = N * E ( A / S ) ,
0 K ( ν ) d ν = ( λ 2 A 8 π ) ( g 2 g 1 ) N = ( constant ) N ,
S c = ( 0.448 ) λ ( N R ) 1 2 ( g 2 / g 1 ) 1 2 ( A / Z T ) 1 2 ,
Z T = Z s + Z f .
I = ( 2.23 ) N * E λ - 1 ( A / N R ) 1 2 ( g 1 / g 2 ) 1 2 ( Z s + Z f ) 1 2 .
S d = ( 1.11 ) K 0 R ( ln K 0 R ) 1 2 ,
K 0 = ( 0.016 ) λ 3 ( N A ) ( g 2 / g 1 ) ( M Hg / k T g ) 1 2 .
S d = ( 10 8 ) P Hg ( T g ) - 3 2 { ln [ ( 9.1 ) ( 10 ) 7 P Hg ( T g ) - 3 2 ] } 1 2 ,
Z f = 2 ρ 2 D ( 2 π R T g ) 1 2 ( M Hg - 1 + M Ar - 1 ) 1 2 ,
S c = ( 1.23 ) ( 10 ) 5 ( P Hg ) 1 2 ( P Ar ) - 1 2 ( T g ) - 3 4 ,
S T = ( 1.8 ) S c S d [ ( 1.1 ) S c exp ( - S c 2 / S c d 2 ) + ( 1.6 ) S d erf ( S c / S c d ) ] - 1 ,
S c d = ( 28 ) ( k T g / M Hg ) 1 2 ( ln K 0 R ) 1 2 / ( A + Z T ) λ .
S c d = ( 71.4 ) { ln [ ( 9.1 ) ( 10 ) 7 P Hg T g - ³ / ] } 1 2 T g - 1 2 + ( 0.194 ) P Ar .

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