The operation of hot cathodes in high pressure discharge lamps has been investigated in a manner similar to that described by Ecker⁵⁾. The formalism of Dyke and Dolan⁸⁾ has been used to calculated emission of electrons from the cathode as a function of temperature and electric field. The electric field at the cathode surface is calculated from ion current and cathode fall, the largest contribution to that field being developed in the free-fall sheath less than one mean free path in thickness at the cathode surface. Two solutions to the coupled system of equations are found: a low-field, diffuse-mode solution in which electron emission is by the Shottky-amplified thermionic process, cathode fall increases with increasing current density, and the cathode spot tends to expand to fill the entire extent of the cathode tip; and a high field, hot-spot mode in which electrons are emitted as a result of the temperature-field mechanism. The lowest cathode fall in the latter mode occurs when the potential drop across the free fall sheath equals the cathode fall required by the cathode energy balance. The operating mode of the discharge in a given lamp depends on which of the two modes has the lowest cathode fall. Examples of each occur in various lamps and can be accounted for with reasonable values of material constants. It is shown that the hot-spot mode is favored over the diffuse mode by high pressures and low cathode work function. The latter surprising result is accounted for by the fact that field emission, varying as exp (-φ^3/2), is even more favored by low work function than thermionic emission.

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Several mathematical models for discharge lamps have already been offered. However, all these models are only used for the operating state. There are not any models for the starting process. This paper is concerned with the mathematical model for the starting process of discharge lamps. Newly introducing the concept of heat quantity, the authors were able to produce a mathematical model to represent the starting process of the low pressure sodium lamp. In this paper, the following comparison between the theoretical results using this model and experimental results on the low pressure sodium lamp are discussed.
(1) Lamp voltage and current waveforms in the starting process.
(2) Evaluation whether or not the lamp can get to operating state.
These investigations showed that this model is available for representing the starting process of the low pressure sodium lamp.

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This paper is concerned with the experimental investigation of the effects of the performance characteristics of the choke type constant wattage ballast on the lamp current waveforms or the values of the lamp current crest factor. The re-ignition phenomenon of the discharge lamp under AC operation is represented by an incomplete switch which consistes of a switch and an effective resistances in both the abnormal glow and the arc discharge regions. The high peaky lamp current is attributed to the transient phenomenon of the lamp operating circuit when the discharge lamp re-ignites. The effects of several ballast circuit elements, such as the magnitudes of both the capacitance and the series linear reactor, the magnetic characteristic and the geometry of the saturable auto-transformer, on the lamp current crest factor are experimentally investigated.

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Cylindrical parablic mirror reflectors prepared for solar energy experiments were evaluated for applicability in improving the lighting efficiency of conventional fluorescent lamps. The beam spread and the peak intensity was simply related to the lamp diameter. The one-half-peak spread and the peak intensity are typically 26 degrees and 3,000 candelas, respectively, for a luminaire with a 40 watt lamp and a mirror reflector of conventional size. The luminaire efficiency is high, 88% for direct lighting without using a diffuser. If a diffuser is needed at all, it can be a very thin one. In this case the luminaire efficiency is 80%.

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The spatial summation properties on background field and in dark were investigated by applying the spatial double stimuli method, in which summation indices were obtained for various separations between two stimuli. For some subjects summation index curves, which plotted summation index as a function of separation, showed diphasic nature having inhibitory interaction at separation of 5.2' when the background luminance was 8 cd/m². The curves from other subjects, however, showed monophasic nature. When background luminance was reduced to zero, the summation index curves of the subjects who showed the diphasic nature changed to monophasic, while those of other subjects did not change. It was concluded when the adapting level was reduced from 8 cd/m² to 0 cd/m² the inhibitory connection of the spatial summation property disappeared in contrast to no change of the excitatory connection.

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Luminous efficiencies for brightness are tabulated at every 10 nm step that were obtained for 2° field from 18 Japanese subjects and for 10° field from 9 Japanese subjects. The data were provided by various Japanese laboratories and analyzed in the Research Committee on the luminous efficiency functions in the Illuminating Engineering Institute of Japan. The efficiencies were all determined by the direct comparison method against a reference at some photopic retinal illuminance level. The mean luminous efficiency function of the 18 subjects for the 2° field is fairly close to that presented in a technical report of the CIE Technical Committee TC-1.4, Vision.

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