Abstract
A NUMBER of experiments have been reported recently in which electron densities have been determined from the refractivity of free electrons in the visible region of the spectrum1–3. In none of these, however, has an independent check been made on the values obtained. We wish to report some recent measurements of the optical refractivity of free electrons in a hydrogen plasma in which simultaneous determinations of electron density are obtained from the Stark effect broadening of Hβ and Hγ (ref. 4) and from a measurement of the absolute continuum intensity. A measurement of the electron temperature from the ratio of the total line intensity of Hβ to the continuum5 is used to confirm the high degree of ionization obtained and the dominant role of the free electrons in determining the refractive index.
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References
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RAMSDEN, S., McLEAN, E. Optical Refractivity of Free Electrons. Nature 194, 761–762 (1962). https://doi.org/10.1038/194761b0
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DOI: https://doi.org/10.1038/194761b0
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