Low Pressure Sodium Research Articles

Light‐induced reduction of FE3+as related to causes of chlorosis in cotton

Abstract In growth chambers, cotton (Gossypium hirsutum L. genetic selection ‘M8') was grown in a synthetic growth medium under four light regimes: low pressure sodium (LPS), LPS + Incandescent (Inc), cool white fluorescent (CWF) and CWF + Inc lamps at 22 C under LPS lamps. Less chlorosis developed at 26 C than at 22 C and less under LPS + Inc than under LPS lamps. All plants were green under CWF and CWF + Inc light. Green and chlorotic plant tissue contained about the same concentrations of Fe. The proposed hypothesis was that chlorotic tissue’ contained less Fe2+ than green tissue. Chlorotic leaves treated with FeSO4 turned a green color. Enough CWF + Inc light passed through an intact leaf to reduce Fe3+ to Fe2+ in vitro. Also in vitro, Fe3+ was reduced by CWF, by Inc, but not by LPS light. The amount of Fe3+ reduced during an illumination period was directly proportional to the quantity of light used. In vitro, citrate and malate enhanced Fe3+ reduction, whereas phosphate, pyrophosphate, OH‐, Cu2+, Ni...

Trace element deficiency or toxicity dependent on plant genotype

Abstract Genetic adaptation of plants to innate environmental conditions has made them functionally diverse, and to predict how they will respond to a new environment is difficult. For example, cotton and lettuce were chlorotic when grown under low‐pressure sodium (LPS) but not chlorotic when grown under cool‐white fluorescent (CWF) lamps. Petunia was green under both type lamps. Chlorophyll synthesis in cotton and lettuce grown with CWF lamps was related to reduction of Fe3+ to Fe2+ in solutions. Plant species and cultivars differed in their response to Fe, Cu, Zn, Mn, B, and Mo deficiency stresses and in their tolerance to relatively high concentrations of either Mn or Al when grown in soils or in nutrient solutions. For example, Bragg soybean was Mn‐intolerant, Lee soybean was Mn‐tolerant and their progeny (B x L, L x B) varied in Mn‐tolerance when grown in a Mn‐toxic soil and in nutrient solutions containing 6.5 mg Mn/1. All plants contained about 500 mg Mn/μg dry matter top. Less Fe was absorbed and ...

Low-pressure sodium discharge lamps

The review article deals with the low-pressure sodium lamp, which, since its very introduction, has been the most efficient light source available. The principle of this lamp is that light is generated as the result of an electric discharge with sodium as emitting material and an inert gas as a ‘buffer gas’. The spectrum emitted by this lamp consists of the yellow sodium resonance lines of 589.0 and 589.6 nm wavelength. Before it was first introduced commercially in 1932 several difficulties had to be overcome. A glass for the discharge tube that was resistant to the highly reactive sodium had to be developed, the composition of the rare-gas filling had to ensure easy ignition of the lamp and the heat insulation had to ensure the wall temperature reached 260°C so as to give the correct sodium vapour pressure. One of the developments of the lamp that took place before the 1960s was that the detachable vacuum jacket, meant for heat insulation, was replaced by a sealed-on evacuated tube. The glass of the discharge tube has also undergone many improvements, resulting in a longer life for the lamp. The introduction of an indium-oxide coating as an infra-red reflecting layer has increased the luminous efficacy of the lamp up to 180 lm/W. The electrodes of the lamp also have an influence on the performance of the lamp. Other important phenomena, such as the imprisonment of resonance radiation, sodium migration and sodium depletion, greatly influence the life of the lamp and its luminous efficacy. Several experimental and theoretical studies give further insight into these discharge processes. Continuing research and development effort will probably lead to an increased luminous efficacy of the low-pressure sodium lamp in the future and the introduction of lower wattage lamps. Recently, hybrid ballast has been introduced with lower ballast losses than the conventional leakage-reactance transformer; also better insulation of the bend of the U-shaped tube has been applied in order to reduce the increase in lamp voltage that occurs during its life. The low-pressure sodium lamp finds application in street lighting, safety and security lighting.

Three Different Recombination Structures: Application and Effects in Low Pressure Gas Discharge Lamps

It has been shown that interesting new possibilities for lighting with fluorescent lamps appear when a tenuous glass-wool recombination structure is introduced into the discharge space. Now, the technological feasibility of the structure concept for application in fluorescent lamps is demonstrated by 1) the possibility of mechanical and reproducible filling of lamps with a wool structure, and 2) the manufacture, and the investigation of the effects, of two alternative structures. Moreover, the structure-inherent effects in low-pressure sodium lamps are discussed.

Fluorescent lamps and low pressure sodium lamps

Fluorescent lamps and low pressure sodium lamps

Degradation analysis in switched low pressure sodium lamps

This paper presents the results of a laboratory investigation of the degradation of the parameters of low pressure SOX 35 watt lamps under switched conditions, and an analysis of these results to give reliability figures for these lamps. In order to define lamp failure, three parameters were chosen and failure was represented by the following changes from the 200 hrs. burning level: a drop of 33 per cent in light output; a rise of 40 per cent in power consumption; and a drop of 55 per cent in luminous efficacy. A statistical sample of the lamps was cycled in the laboratory at different switching rates and parameter degradation was measured at regular intervals. The changes in the lamp parameters with time and with differing switching rates are presented in this paper. A statistical analysis of the lamp failure data was then performed using the Weibull distribution whose parameters were estimated using maximum likelihood. In this manner measures of stress due to switching and switching rate and also characteristic lives for the lamps for the different failure criteria were estimated and are presented here. The results of the analysis suggest that if light output were the only factor of concern, long characteristic lives of over 13, 000 hours could be expected. However, it is proposed that the most important criterion in measuring lives and reliabilities of the 35 W SOX lamps tested should be the decrease of luminous efficacy yielding characteristic lives of the order of 9, 000 hours.

Relative Efficiency of High- and Low-pressure Sodium and Incandescent Filament Lamps Used to Supplement Natural Winter Light in Greenhouses1

Abstract The relative efficiencies of high-pressure (HPS) and low-pressure sodium (LPS) lamps for plant growth were determined for 32 species of foliage and flowering plants in greenhouse under winter conditions at 37°N latitude. HPS with a relatively wide spectral emission peaking at 589 nm, and low-pressure sodium (LPS) with a monochromatic line at 589 nm were compared at 42 W/m2 irradiance in the 400–700 nm region for various lengths of time at various times of day. Although radiation in the far-red region (700–800 nm) differed, HPS and LPS equally accelerated rates of increase in fresh weights, and heights, and flowering of most herbaceous and tropical foliage plants evaluated. High-pressure sodium and LPS were ineffective, however, in promoting growth of deciduous trees and some woody plants and had no more effect than exposure of the plants to natural winter days with 0.9 W/m2 from incandescent lamps for 8 hrs (2000-0400) night interruption (long day controls). After 16 hours, about half the species showed photomorphogical differences between plants grown at intensities of 21 and plants grown at 42 W/m2 from LPS. All showed significantly better growth characteristics (fresh weight, height, early flowering) than the long day controls. Lighting during the day or night (42 W/m2 from 0800–1600 or from 2000–0400) was equally effective in promoting growth responses with 15 of the 32 species evaluated. Night lighting was more effective than day lighting with 10 of the 32 species tested. The majority of the species grew equally well when lighted 16 hours daily (0800-2400) with 21 W/m2 or 8 hours daily (2000–0400) with 42 W/m2. Effectiveness of the lighting was generally unrelated to the photoperiodic requirements of the plants. Many of the plants, which were previously classified as day-neutral (DN), flowered as if they were long day plants. Such day-neutral plants apparently required adequate light (intensity and duration) for photosynthesis. Increased daylength alone, without regard to intensity, was not sufficient to accelerate growth and early flowering of day-neutral plants. Since HPS and LPS were equally effective on most species tested, we concluded that light quality was less important than total irradiation (energy) for the growth and early flowering of many herbaceous plants.

Effect of Light Quality and Temperature on Fe3+ Reduction, and Chlorophyll Concentration in Plants1

AbstractPlant species differ in their response to light; some grow best in full sunlight, some in partial shade, and others in full shade. Inside, under growth chamber conditions, cool white fluorescent (CWF) lamps, in combination with supplemental incandescent (Inc) lamps, have been a satisfactory light source. Low pressure sodium (UPS) lamps have also been used. The spectral radiant power curve for the CWF lamps extends from 350 (includes UV and blue) to above 700 nm, whereas the spectral curve for LPS lamps is between 560 to 610 nm (no UV or blue) with no radiation below 550 nm. This study was conducted to determine affect of LPS and CWF lamps, alone and in combination with Inc lamps, on plant growth and reduction of Fe3+ to Fe2+. Lettuce (Lactuca saliva L. ‘Grand Rapids’), cotton (Gossypium hirsutum L. ‘M8’) and petunia (Petunia hybrida Vilm. ‘Pink Cascade’) were grown in environmental control cabinets at 22 and 28 C under LPS or CWF lamps, with and without Inc lamps. Reduction of Fe3+ to Fe2+ was determined as Fe2+ ferrorine [disodium salt of 3‐(2‐pyridyl)‐ 5,6‐bis(4‐phenylsulfonic acid‐l,2,4‐triazine] in solution under all light treatments to determine if chlorophyll concentration in plant tops was related to Fe3+ reduction in solution. We had observed that cotton was chlorotic under LPS, but not under CWF lamps. Only small amounts of Fe3+ were reduced to Fe2+ at wavelengths above 420 nm, and more Fe3+ was reduced to Fe2+ in solution under CWF than under LPS lamps. Chlorophyll concentration in lettuce and cotton leaves followed about the same pattern as Fe3+ reduced to Fe2+ in solution. Chlorophyll levels were greater in leaves grown under CWF than under LPS lamps, and generally greater in leaves grown at 28 than at 22 C. If we assume that CWF light mediates reduction of Fe3+ to Fe2+ in plant foliage as it does in ferric‐ferrozine solutions then it could make Fe2+ available for biochemical reactions related to chlorophyll synthesis. Petunia did not respond to the light regimes and temperature as did lettuce and cotton.

Evidence for two photoreceptors controlling growth in de-etiolated seedlings

The effect of blue light on hypocotyl extension in de-etiolated seedlings of lettuce, cucumber and tomato was investigated under conditions which precluded the involvement of phytochrome. Small but highly inhibitory amounts of blue light were added to a high intensity background illumination from low pressure sodium lamps. A log-linear response for inhibition of hypocotyl extension against the blue light fluence rate was obtained for lettuce and cucumber, and inhibition in tomato was also related to the blue light fluence rate. The added blue light did not alter phytochrome photostationary state and its effect was independent of the total fluence rate. Growth inhibition by Pfr could be demonstrated in tomato and cucumber but not in lettuce. The results indicate that two photoreceptors may normally be involved in the control of seedling growth but their relative importance varies greatly between species.

Two Light Sources Differentially Affected Ferric Iron Reduction and Growth of Cotton

In growth chambers, low pressure sodium (LPS) plus incandescent (Inc) lamps and fluorescent cool-white (FCW) plus Inc lamps were used to determine their effects on growth of cotton (Gossypium hirsutum L.) and on the reduction of Fe(3+) to Fe(2+). Cotton plants grown under LPS + Inc light developed chlorosis and grew poorly, whereas plants grown under FCW + Inc lights were green. The chlorophyll concentration and top and root weights of cotton grown under LPS + Inc were lower than those under FCW + Inc. In solution, FCW + Inc lamps reduced about eight times more Fe(3+) to Fe(2+) than did LPS + Inc lamps. Fe(3+) is transported to plant tops as Fe(3+) citrate and if we assume that FCW + Inc light reduces Fe(3+) to Fe(2+) in plant foliage as it did in the solutions, then reduction of Fe(3+) by the light environment will make Fe(2+) in the tops more available for biochemical reactions.

The effect of Supplemental Light Source, Illumination and Quantum Flux Density on the Flowering of Seed-Propagated Geraniums

SummaryThe time required for flowering of four cultivars of F1 seed-propagated geraniums (Pelargonium χ hortorum Bailey) grown under different quantum flux density levels (27 or 54 μ E m-2 s-1), illuminations (2.7 or 5.4 klx) and durations (2, 4 and 6 weeks) of high pressure sodium (HPS) and low pressure sodium (LPS) light were compared with plants grown under ambient light. Days from seeding to flower were reduced for all cultivars with HPS light, but days to flower were not reduced by LPS treatment for any cultivars compared with the control plants. Cumulative supplemental quanta (E m-2) for HPS light only was significantly negatively correlated with days to flower for three of the cultivars, indicating the value of supplemental HPS light at an early stage of plant development.

Studies concerned with improvement of the low pressure sodium discharge lamp

In the low pressure sodium-rare gas discharge lamp the generation of light is strongly dependent on the realization of an optimum sodium vapour pressure and optimum plasma conditions within the complete halfcycle of a.c. operation. Various diagnostic techniques will be discussed which give information about the plasma conditions and thus the light generation in the discharge. The influence of the current waveform and magnitude will also be considered. These studies indicate the necessary conditions which must be fulfilled if improvements in lamp performance are to be realized. Finally the application of these results to the improvement of the low pressure sodium discharge lamp and its associated ballast will be described.

Use of glass in electric lamps

The term 'glass' refers to a wide range of non-crystalline inorganic materials differing in their compositions and properties. The formation of glasses is discussed: five main types of glass, including vitreous silica, are considered and shown to meet the requirements of materials for envelopes and other components in electric lamps. Brief descriptions are given of the various stages of glass manufacture. Applications of soda-lime and lead glasses in GLS incandescent lamps and fluorescent lamps are described. Reference is made to the special requirements of envelopes for low pressure sodium lamps. Finally the properties of vitreous silica and its use in tungsten-halogen lamps, in high pressure mercury vapour lamps and in metal-halide lamps are considered and the need for the material to be of high purity is emphasized.

Real Energy Saving Fluorescent Lamps

Real energy savers are lamps with an essentially higher luminous efficacy than existing light sources used for domestic and commercial applications. An ideal lamp should combine the advantages of incandescent and fluorescent lamps. By appropriate design, based on low pressure sodium vapor discharge with a recombination structure and the use of narrow band phosphors of outstanding quality, it is possible to make an efficient small fluorescent lamp-ballast unit with good color rendering properties. In the commercial lighting area new lamps with efficacies of 90 to 100 lumens per watt and good color rendering properties will become available by using these narrow band phosphors together with a change in lamp design. Compared with the present standard lamps one can now maintain the illumination level with lower annual costs and lower energy consumption.

Arc Voltage Control in Low and High Pressure Sodium Lamps

In low and high pressure sodium lamps many parameters influence the arc voltage. Ultimately, all these factors have their influence on the arc voltage through the vapor pressures of sodium, and sodium and mercury. This paper discusses methods that have been developed for the measurements of these pressures in burning lamps. Using these methods, the causes of changes in vapor pressure and the resulting rise of arc voltage can be identified, and appropriate measures can be taken.

Soft x-ray gain in the alkali earths

An unsuccessful attempt was made to observe gain in low pressure sodium vapor at 372 A at an x-ray pumping power level of 0.1 GW/cm(2) . As a result we suggest that high density alkali-earth vapors be used instead. With a system of tunable dye lasers of moderate power, it should be possible to reduce substantially the lower laser level population and achieve gains on the order of 1-3 cm(-1). The calculations reported verify this. The additional outer electron in the alkali-earths is necessary to use the dye laser scheme. The tradeoff is that the upper laser level can Auger decay. Our calculations indicate that this is not too severe a limitation in Ca. Since the calculations may be in error, we further suggest that the dye laser scheme is applicable to alkali-earths which have been preexcited to levels for which Auger decay is forbidden in LS coupling.

THE SPECTRUM OF LIGHT POLLUTION AT MOUNT HAMILTON.

ABSTRACT Observed spectra of the night sky above Lick Observatory are presented, showing the light pollution due to lights in San Jose and other communities in the Santa Clara Valley. Spectra of several types of street lights are shown, and of these the low-pressure sodium lamp would cause the least additional light pollution if it were adopted for all future installations. Key words: light pollution - Lick Observatory - street-lamp spectra

Blur of the Retinal Image of an Object Illuminated by Low Pressure and High Pressure Sodium Lamps

The IES Roadway Lighting Committee sought to establish a criterion that might be used when choosing between high pressure and low pressure sodium lights. The quality of the optical image on the retina was a major consideration. The author, then serving on the IERI Technical Advisory Committee on Light and Vision, volunteered to apply to these two light sources a method that he had developed for assessing image quality in such cases. The method can also be applied to other types of light sources.

Gas Discharge Lamps for Electrophotographic Exposure

The multitude of uses for lamps in the various steps of the xerographic process are enumerated. Particular emphasis is placed on the use of gas-discharge lamps for exposure, with their requirement of spectral control and adequate radiant power. The characteristics of various types of lamps are considered and the existence of a trouble-some ``power gap'' is uncovered. The efficient performance of low-pressure arcs (such as fluorescent and low-pressure sodium lamps) is limited to low powers by electron de-excitation in the presence of self-absorption. On the other hand, high-pressure arc lamps perform efficiently at high powers, but it is difficult to operate these lamps at lower powers in the ``power gap'' because of a complex set of interrelated reasons. Lamp designs which may fill this power gap are discussed. The radiant emission from various lamps is considered as well as techniques for manipulating the spectra, particularly the use of metallic halide additives. Overall, a major problem is that commercially available lamps reservice are designed for general illumination purposes while the electrophotographic requirements are different and more demanding.

High Efficacy Low Wattage HPS Lamp for Street Lighting and other Applications

In densely populated residential districts, the illumination level has been continuously increased for crime prevention. Because of the energy crisis, many power companies would like to replace high wattage incandescent, mercury or sodium vapor lamps with a lower wattage light source. However, they would still like to maintain the same illumination level. Here, the results of performance studies, reliability, and the design parameters of low wattage high pressure sodium lamps are presented.