Abstract

A study has been made of the variations of some spectrochemically significant properties of pulsed arc discharges produced by a condensed arc source unit. Quantitative responses of sensitivities, line ratios, and electrode heating to changes in pulse form have been determined.

© 1949 Optical Society of America

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References

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  1. D. A. Sinclair, J. Opt. Soc. Am. 38, 547 (1948).
    [Crossref] [PubMed]
  2. M. F. Hasler and H. W. Dietert, J. Opt. Soc. Am. 33, 218 (1943).
    [Crossref]
  3. A. Walsh, Metal Industry 68, 243 (1946),and Bulletin Brit. Non-Fer. Met. Res. Assoc. No. 201, 60 (1946).
  4. D. A. Sinclair, J. Opt. Soc. Am. 34, 689 (1944).
    [Crossref]
  5. M. F. Hasler and J. W. Kemp, J. Opt. Soc. Am. 34, 21 (1944).
    [Crossref]

1948 (1)

1946 (1)

A. Walsh, Metal Industry 68, 243 (1946),and Bulletin Brit. Non-Fer. Met. Res. Assoc. No. 201, 60 (1946).

1944 (2)

1943 (1)

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Figures (9)

F. 1
F. 1

Circuit diagram of source unit with main discharge loop in heavy line. C10–124 μFL10–168 mHR10–50 ohmsC25 μFL20.75 HR275 ohmsC30.002 μFT11:8 H.F. Trans.R30–1000 ohmsC40.0015 μF0.025 mHR40–300 ohmsC54–6 μFT21:100 H.V. Trans.G1 Analytical gap. G2 Trigger spark-gap consisting of a synchronous rotary electrode system giving frequencies of 100, 50, or 25 per sec.

F. 2
F. 2

Variations of line/background ratios plotted against circuit variables.

F. 3
F. 3

Variations of line/background plotted against peak pulse-current. Scales for L type and R type pulses are related by equivalence of mean 2.5th power of current (see text). For compactness a continuous vertical log scale is used with reference levels marked (thus —5—) for each element group. In each group curves are drawn through series of points obtained with capacities 8, 32, 124 μF., the ascending order being the same except for the R type in the band-line group only where the reverse order holds.

F. 4
F. 4

Variations of line/background ratio for spark line Al 2816. Actual peak current values used for both types of pulse. The three curves of each type are for series with 8, 32, 124 μF. from left to right in that order.

F. 5
F. 5

Variation of excitation conditions as indicated by line ratio Al 2816/Al 2652. Results for R type pulses are plotted (a) using actual peak current values, solid line (b) using peak values adjusted as in Fig. 3, broken line. (Order of curves as in Fig. 4.)

F. 6
F. 6

Variations of line to line ratios used in analysis. For the R type pulses peak current has been adjusted as in Fig. 3. Element groups have been set at arbitrary heights on the continuous vertical scale.

F. 7
F. 7

Arc gap voltages and cathode-heating rates with continuous d.c. arc.

F. 8
F. 8

Cathode-heating rates with pulsed arcs of varying peak current. Pulse duration would vary inversely with peak-current since charging current was held approximately constant in each series.

F. 9
F. 9

Cathode-heating rates with pulsed arcs of varying duration but fixed peak-current.

Tables (4)

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Table I Technique details.

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Table II Actual currents and cathode-heating rates at various settings.

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Table III Heating rates by high voltage spark source. Capacity 0.005 μF., charging current 50 cycle 0.025 amp. r.m.s., upper electrode graphite.

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Table IV Relative limits of detection of tin, lead, and cadmium at three levels of band line strength.

Equations (1)

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T = K d 2 f C 1 2 ( 1 + R + 2 L ) 1 2 / A 2 ,