Microwave Energy and Light Energy Transformation: Methods, Schemes and Designs | IntechOpen

Nowadays, electrodeless sulfur lamps with microwave excitation ( ESLME ) are finding ever-widening application in energy-efficiency lighting systems. A reason of increased interest to these lamps is ascribable to high values of their parameters including a high light flux ( 120-145 klm ), a light saturation ( ~ 9000 four hundred ), a high respect of light end product ( 80-110 lm/W ), color rendition coefficient ( Ra ~ 90 ), a well as an application of environmentally friendly materials ( argon and sulphur ). This chapter presents a novel approach of creating an energy-efficiency lighting source on the footing of the ESLME. For an electrodynamic social organization of the light system, one can propose to use an optically diaphanous ( mesh topology ) waveguide alternatively of a microwave cavity. It is shown that the use of proximity of the spectrum of optical radiation generated by the sulfur lamp and solar radiation allows more efficiently ( in comparison with early light sources ) their application as the simulators of sunlight for testing photoelectric converters and solar cells. For extending application of the lighting systems on the basis of the sulphur lamp and far increasing an energy efficiency of these systems, their consolidation with other electron devices ( for case, solar cells ) is proposed .

1. Introduction

According to the estimates of the International Energy Agency ( IEA ), about a fifth of all consumed electricity in the global is spent on lighting. One way to reduce the proportion of consumed electricity and its economical outgo is the development of new energy-efficient light sources and lighting devices based on them. Requirements for such light sources are dictated by market demands, vitamin a well as the development and capabilities of modern technologies. Modern light sources must satisfy a count of parameters, combining senior high school light output and efficiency with the quilt of perceiving generated radiation sickness by the eye ( a broad spectrum of radiation and color rendering ), lastingness and environmental friendliness with low cost and a wide image of applications. It is known that the trouble of lighting is being solved by converting electric energy into optical energy ( visible ignite ) with the assistant of versatile media and the processes occurring in them : metals and thermal processes ( incandescent lamps ( IL ) ), gaseous media and discharge ( including plasma ) phenomenon ( fluorescent ( FL ) and metallic element halide ( MHL ) lamps, etc. ), american samoa well as semiconductor device materials and processes of spontaneous recombination of inject minority carriers ( light-emitting diodes ( LEDs ) ). relative efficiency of existing light sources is shown in Figure 1. It can be seen that the heat sources of light ( incandescent lamps ) in watch of their low efficiency ( only 3 % of the issue electric energy is converted into the energy of light waves ) are much deficient to discharge lamps and LEDs . Among the existing promise sources of light, particular care is paid to the development of plasma lighting devices based on the use of an electrodeless sulfur lamp with microwave excitation ( ESLME ). For the first time, such kind of lamp was presented in 1992 at the VI International Symposium on the Science and Technology of Light Sources in Budapest [ 1 ]. Later, based on it, Fusion Lighting Co. company created the lighting organization solar 1000 ( 1994 ), deoxyadenosine monophosphate well as its change Light-drive 1000 ( 1997 ). significant efforts to expand the use of these lamps were made by the korean company LG Electronics, which, in 2005, held a presentation of the plasma lamp Plasma Lighting System ( PLS ), and besides organized a series production of a numeral of designs of such light sources in the form of a ceiling lamp and foreground lamp. In parallel, studies of electrodeless sulfur lamp with microwave excitation were conducted in Europe by Plasma International Group [ 2 ]. In 2010, the lighting system AS1300 was presented, consisting of a exponent supply, a microwave generator ( magnetron ) and the lightly faculty. however, their product was complicated by the complexity of the design and the high cost of the light up device.

recently, there have been designs of relatively low-power plasma lighting devices based on light emitting plasma ( LEP ) lamps with ability from ~160 W to 300–400 W, in which solid-state microwave generators are used as an electromagnetic discipline source [ 3 ]. immediately, the scope of such lamps is growing : from architectural light and street lighting to their application in the car industry. The peculiarity of the topic of plasma light sources with microwave excitation is the long and changeless interest to them ( more than 25 years ), which is expressed in a big number of scientific publications, including monograph, articles, patents obtained in different countries of the world. What is the enhance concern to the lighting systems based on plasma lamps with microwave excitement in ? The answer to this interrogate lies in the singular combination of their technical and unhorse characteristics and parameters that most amply meet the requirements for light sources formulated above. For model, light generated by these lamps is characterized by high fall blend ( 120–145 klm ), clean volume ( ~9000 compact disk ) and brightness, equally well as good unhorse output ( 80–110 Lm/W ). technical parameters of lighting devices based on plasma light sources with microwave excitation are characterized by relatively first gear might consumption, a continuous spectrum close to natural ( solar ) illumination with a discolor coefficient Ra > 90 ( with a utmost value of 100 ) and the ability to control the intensity of light. An important advantage is besides their environmental friendliness, which is due to the miss of mercury and the function of environmentally friendly materials—argon and sulphur. Among the problems that need to be addressed, we should note the insufficiently long service life of magnetrons and the uneven heating of the surface of the lamp light bulb, which requires to provide its rotation in the pit distance adenine well as studies aimed at selecting modern materials. This will increase the lastingness of the lamp, which today does not exceed ~50 thousand hours. This chapter is organized in five main sections. section 1 describes the construction of a lighting device based on an electrodeless sulfur lamp with microwave excitation, gives a brief feature of its chief components and analyzes their operation parameters. section 2 considers an application of the electrodeless sulphur lamps with microwave excitement as the simulators of solar radiation, gives the comparative characteristics of such lamps with other lighting sources. section 3 concerns promise directions for practical application of a lighting facility based on an electrodeless sulphur lamp with microwave excitement, in particular, for using in greenhouses. incision 4 presents the construction of the alight system with the possibility of regenerating the energy of ocular radiation into direct current department of energy for increasing its full efficiency. The main conclusions are formulated in part 5 .Advertisement

2. Principle of operation and designs

A general outline for the genesis of ocular radiation in the visible wavelength stove ( visible lightly ) using plasma illuminating devices based on an electrodeless sulfur lamp with microwave excitation is shown in Figure 2. It is necessary to note that these devices use the transformation of electrical energy into the energy of light waves by stages. In the first stage, the secondary world power generator 1 converts the understudy voltage of 220 V and the frequency of 50 Hz into a ceaseless electric potential of 3.8–4.2 kV, which is fed to the anode of the magnetron . In the second stage, the magnetron generator 2 converts the DC energy into the energy of electromagnetic oscillations. As a result, at the output signal of the magnetron in the waveguide 4, there are oscillations having the frequency of 2.45 GHz and the output exponent of about ~900 W. These oscillations excite the electromagnetic battlefield in the electrodynamic structure 5, at the maximum of the electric field of which the sulphur lamp is placed. At the third phase, physicochemical processes proceed in the inner distance of the sulfur lamp under the influence of an electromagnetic field, as a resultant role of which is the generation of ocular radiotherapy in the visible wavelength range ( 380–780 nanometer ). This radiation sickness is focused and output into the barren space. In arrange to determine the energy efficiency of the lighting system, the might consumed by the magnetron generator from the external ( primary ) network was investigated. The results of these studies are shown in Figure 3. It can be seen that the power consumed from the network by the ignition system is constantly increasing until the appearance of the primary luminescence of the lamp, which corresponds to 1700–1750 W of power consumption. thereafter the world power consumption from the network is stopped ; the energy of the electromagnetic field is absorbed at once by the argon-sulfur mixture. As result, the coevals of ocular radiation takes position. The lighting organization consumes ~2000 W in a stationary mood providing stable light discharge . The main elements of the alight device and values of its main parameters are shown in Figure 4 . An important element of the unhorse device on the basis of the sulphur lamp is the construction of an electrodynamic structure, the chief purpose of which is to form a extra structure of the electromagnetic field required to excite ( pump ) an electrodeless sulfur lamp. A bulb of the sulphur lamp is placed at the maximum of the electric component of the electromagnetic airfield excited in the electrodynamic structure. As an electrodynamic structure, one is normally used optically diaphanous ( mesh ) cylindrical microwave cavity, inside of which a quartz glass medulla oblongata of the sulphur lamp is placed [ 4 ]. The outside coat of the cavity is done from thin wire and has net surface for rid enactment of optical radiotherapy. A general horizon of the cavity with a bulb of the sulphur lamp is shown in Figure 5 . The chief necessity for a resonant method of excitement of the electrodeless sulphur lamp is to maintain a mode of stable oscillations of the electromagnetic field in the pit ( resonance ) ( for exemplar, for cylindrical pit, one can use the follow modes of oscillations : TE111, TЕ112, TE011, TM010 and TM111 ). The consumption of a cylindrical cavity allows reasonably just to hold the sulphur lamp along its longitudinal bloc, to ensure its stable rotation for consistent cool of its surface and frankincense to select an optimum temperature government for its operation. In accession to the evocative method of exciting the sulphur lamp, of capital interest is the method acting enabling to form an electromagnetic field in a waveguide by adding two counter-propagating coherent monochromatic waves E→1and E→2possessing the identical linear polarization [ 5 ]. The general view of the light device in which used this excitation method acting of the sulphur lamp is shown in Figure 6 . In this case, there is a condition satisfied for the frequencies of these waves to be the same ( ω1=ω2=ω ) and their generation constant to be complex and equal to γ=α+jβ, where αis the attenuation changeless determined by plasma parameters and βis the phase changeless of the traveling electromagnetic wave. According to the principle of superposition, the intensity of the vector sum electromagnetic field is E→=E→1+E→2

E1

Herein consider the energy description of the wave processes and put the first formula ( 1 ) in the square. After averaging over meter, we ultimately obtain ==++2⋅

E2

In the second gear expression ( 2 ), the total average full energy depends on the value of the interference term . In the case when =0(there is no interference), the total energy in the waveguide is equal to the sum of the energies of the main and counter electromagnetic waves. When the condition is fulfilled, when ≠0, the total energy is not equal to the sum of the energies of the waves running toward each other, but in the waveguide, there is interference of the waves. Of hardheaded interest for exciting a sulphur lamp in a waveguide causes is the case when the condition =0is fulfilled. As a result, it is possible to ensure a uniform distribution of the total electromagnetic field in the region of the electrodeless lamp location and a stable gas discharge in the lamp by creating a standing wave in a waveguide of arbitrary length Lwith optically transparent outside surface (mesh surface). number 7 shows the distributions of full energy of the electromagnetic waves +, which is introduced from different ends of the waveguide as fundamental and counter-propagating electromagnetic waves. Figure 8 schematically presents diagram of lighting devices on the basis of the electrodeless sulfur lamp with microwave excitation. digit 8 demonstrates a conventional diagram of lighting device based on an electrodeless sulfur lamp in the case excitement by adding two counter-propagating coherent monochromatic waves. For this excitation method acting, an electromagnetic roll is generated by a magnetron 5 and through a waveguide tee 4 through waveguide 3 enters a enmesh waveguide 2 within which an electrodeless sulfur lamp 1 is located .Advertisement

3. Simulators of solar radiation

Simulators of solar radiotherapy ( SSR ) are radiation sources that form and direct a light flow into a pay back area. such devices can be used for investigating the luminosity characteristics of the photoelectric converter and solar batteries for space and ground applications ampere well as for carrying out high-temperature studies and tests on the resistance to light effects of diverse dyes and paint coatings, paper and labels, ocular components, etc., [ 6, 7, 8 ]. The SSRs create a stream of pulse or continuous ocular radiotherapy whose spectral characteristics are close to those of solar radiation. ideally, the simulators should, with the best approximation, reproduce all the parameters of solar radiotherapy including its spectral typography, flux concentration, parallelism of rays, constancy in time and uniformity of illumination. however, such devices are extremely complex and expensive, necessitate qualified alimony, and consequently, as the specific aim requires, the specialize simulators are created ( for case, large SSR for testing space vehicles [ 7 ] ). The solar simulators include brawny gas free, halogen or other lamps, correcting filters and besides serving subsystems. There are quite a set of familiar artificial light sources used to simulate solar radiation beginning with the carbon arch lamp ; with sodium lamps, argon bow lamps, quartz-tungsten halogen lamps, mercury xenon lamps, discharge xenon lamps, xenon flash lamps, metallic element halide lamps, light-emitting diodes and super sources of continuous laser radiation besides being applied, but alone incandescent and gas-discharge lamps were used in personal computer studies. figure 9 presents a comparison of the spectral characteristics of extra-atmospheric solar radiation and the simulators of solar radiation on the footing of lamps of the artificial light . For testing the photoelectric converters and solar batteries, as a rule, the incandescent and gas-discharger lamps are applied in the SSRs as the light sources. This is due to the requirements to get the values of parameters such as the identity of the SSRs discharge spectrum and spectrum of solar radiation, the color temperature ( the discolor temperature of the extra-atmospheric solar radiation is ∼5900 K ), the high constancy of the radiation flux and the belittled nonuniformity of energy illumination that determines the sufficiency of measuring the parameters of the photoelectric converters and solar cells [ 8 ]. At the same time, for case, a necessity of temporal role stability of the radiation magnetic field is a significant restrict factor for using a count of arc sources in photovoltaic investigations, although their apparitional composing is most coherent with the solar discharge under conditions of zero atmospheric multitude ( AM0 ). The use of pulsate gas-discharge lamps having a satisfactory spectral constitution, in addition to the indicated irregular imbalance associated with the characteristics of their launch systems, requires to use high-speed measure equipment, which importantly increases the expenses for creating the integral facility. According to the above parameters, the greatest interest can be found in such sources as :

  1. The mirror incandescent and quartz glass halogen lamps that provide a satisfactory apparitional composition of the radiation located in the range of 0.4–1.1 μm. These lamps are used in simple SSRs in regulate to simulate solar radiation for research and technical purposes in the tests of photovoltaic cells .
  2. The arc-shaped gas-discharge xenon lamps ( including with combined accelerator fill ) for high-quality SSRs, used in precise measurements of the photovoltaic convertors parameters .
  3. The most widely used are arch xenon ball-shaped lamps, which have a spectrum very close to the solar one ( see Figure 9 ) ; however, owing to an energy turn in the infrared region of its spectrum, it is necessity to use corrective ocular filters in the SSRs that use the lamps of this character .

As shown in Figure 9, the spectral characteristic of the electrodeless sulfur lamp has a continuous quasisolar spectrum of ocular radiation and is very close to the solar spectrum in its visible region. The second advantage of this lamp worth note is its lastingness, which is significant for its application in the SSRs [ 9 ]. table 1 demonstrates the comparison of the lamps ’ characteristics that are most wide used in SSRs, angstrom well as the parameters of the electrodeless sulfur lamp with microwave excitation .

Characteristic Halogen lamp KG-220-10000 Gas discharge xenon lamp OSRAM XBO 10000 Sulfur lamp Plasma-i AS1300
Power consumption (kW) 10 10 1.3
Light output (lm/W) 26 50 140
Luminous flux (lm) 260,000 500,000 163,000
Color temperature (K) 3200 6000 6000
Operating time (h) 2000 500 50,000

Table 1.

Characteristics of lamps. Analyzing the characteristics of the electrodeless sulfur lamp with microwave excitement and comparing them with other light sources that applied in the SSRs, we can say that this lamp can besides be successfully used in SSRs enabling to produce not only high-precise measurements of the characteristics of the photovoltaic convertors and solar cells of space application, but besides to provide right model of assorted modes of their operation under lab conditions .Advertisement

4. The features of application of the lighting systems in greenhouses

The advent of the energy-efficient light sources on the footing of the electrodeless sulphur lamps with microwave excitement having a wide spectrum of radiation in visible area of electromagnetic spectrum ( from 0.38 to 0.78 μm ) allows to extend practical application of artificial light sources. In finical, the greatest concern is an application of such alight sources in advanced greenhouse and cattle-breeding farms for raising the tied of crop give and cost economy. On the one hand, the fortune of the sectorial electricity consumption in the technological processes of the greenhouse farms using ocular radiotherapy is 10–15 %, and the losses in them reach to ∼40 %. To reduce electricity consumption, it is necessary to modernize lighting systems with energy-intensive light sources to modern energy-efficient and economic ones. On the other hand, choosing artificial luminosity sources that must have a sealed spectral characteristic, the charm of ocular radiation on the efficiency of the main photochemical processes of the plant is first base of all taken into account. This is because each paint has its own person assimilation spectrum and, thereafter, its own spectral feature of the lighter activeness of the excite radiation. The most authoritative and energy-intensive action is the process of photosynthesis. As shown, an probe of the spectrum efficiency of the photosynthesis, that was carried out in [ 10, 11 ], the leaves of different taxonomic groups had approximately the same spectrum of photosynthesis bodily process. An median arch of the spectrum of photosynthesis action of the k leaf is shown in Figure 10 . All parts of the solar spectrum are important for the normal outgrowth of plants. More detail information about results of an shock of the ocular radiation having spectrum close to the solar spectrum is shown in board 2 .

Wavelength Effects on plants
280–320 nm Harmful to plant growth and development. Some plants require a low effect of this spectrum for normal development.
320–400 nm It influences the regulatory processes in the development of plants. The presence of this range should be a few percent of the radiant flux.
400–500 nm (“blue”) Absorbed by yellow pigments, is the second peak of absorption by chlorophyll, the second peak of photosynthesis. Included to ensure photosynthesis and regulation. However, its excess leads to the formation of stunted plants with thickened stems.
500–600 nm (“green”) It has a high penetrating power, is useful for photosynthesis of optically dense leaves, leaves of lower layers, thick plantings, the smallest physiological reaction. Its surplus leads to the formation of plants with elongated axial organs and thin leaves.
600–700 nm (“red”) The zone of the maximum photosynthetic effect of chlorophyll synthesis, the most important site for the development and regulation of processes. Required in a radiant stream. However, its excess can lead to abnormal development or to the death of the plant.
700–750 nm (“far red”) In general, the effect of stretching the stem, a pronounced regulatory action; a few percent in the radiant flux is sufficient.

Table 2.

effect of the spectrum of ocular radiation on plants. The part of the solar radiation reaching the plants and used for the process of photosynthesis is called photosynthetically active radiation ( PAR ). PAR is the density of the photosynthetic photon flux, that is, the entire number of photons emitted per second in the wavelength range from 400 to 700 nm ( μmol m−2 s−1⋅ ). different plant species, adenine well as the identical species at different age stages, may have different requirements for the PAR spectrum. To obtain full-fledged plants when growing under artificial light conditions, a certain proportion of energy over the spectrum in used lamps is required : 20–25 % —in the blue area ( 380–490 nanometer ) ; 20–25 % —in the green one ( 490–600 nanometer ) and 60–50 % —in the crimson one ( 600–700 new mexico ). The use of the sources of artificial light up in crop output is divers, but not all of them are effective and safe. The characteristics of widely used lamps in the lighting systems of greenhouses are presented in mesa 3 .

Lamp type Source of radiation P, kW τ, thousand hours Efficiency PAR, %
Fluorescent lamps FL-40 0.04 12 22
Osram Fluora 0.018 10 20–22
High-pressure mercury lamps DRLF-400 0.4 1 11
DRF-1000-04 1.0 2
High-pressure sodium lamps MASTER SON-T PIA
Agro-400
0.4 17 28
DNaZ-400 0.4 12 26
DNaZ-600 0.6 18 30
Sylvania Grolux SHP-TS 0.25 24 26–28
Sylvania Grolux SHP-TS 0.4 24 26–28
MASTER GreenPower 0.6 10 26–28
PLANTASTAR 0.6 12 35
Metal halide lamps Growmaster HIT 0.25 10 25
DRI 2000–6 2.0 2 26
Xenon lamps DKSTL 10000 10.0 <1 12–16
DKSTV 6000 6.0 <1
LED lamps LED GLOW-Е27 0.135 50 20–35
AGRO-24 0.024 50 30–35
Sulfur lamp PLS-PSH07 0.73 60 70–80

Table 3.

Characteristics of radiation sources. As can be seen, the most position lamps for practical application as a modern source of visible radiation are light-emitting diode ( LED ) lamps and electrodeless sulphur lamps with microwave excitement [ 12, 13, 14 ]. The LED and sulfur lamps are durable, economic, have a high PAR efficiency ( LED : 30–45 %, sulfur lamp : 70–80 % ), are environmentally friendly ( do not contain mercury and do not require disposal ). however, there are a number of differences between these lamps that allow them to occupy different fields of application. The LED lamps are low exponent and effective when the light flux is about ∼100 lumen, so they can be used for small rooms. Besides, the LED lamps have a narrow-minded ring of optical radiation. In order to obtain the entire range of the visible spectrum, it is necessary to use LEDs with different apparitional characteristics, the overall spectrum of which can cover the entire region ( 380–700 new mexico ). This complicates the technology of manufacturing the LED lamp, since the equate currents have to be selected for each LED. The electrodeless sulphur lamp with microwave excitation, on the contrary, is a powerful alight reservoir having a quasisolar emission spectrum with boil down volume in the area of ultraviolet and infrared radiation ( Figure 11 ), and providing light fluxes of ~140 klm, which is three orders of order of magnitude higher than that of the LEDs arsenic good as color temperature of ~6400 K. besides, the electrodeless sulphur lamp with microwave excitation has the ability to control the radiation power, which allows imitating the modes of sunrise and sunset . therefore, the mod alight system under conditions of protected dirt ( greenhouses ) has to economically reduce electricity costs, angstrom well as raise the quantity and quality of the craw yields. The promise sources of artificial light are LED and electrodeless sulphur lamps with microwave excitation. The LED lamps are most successfully used in humble greenhouses, while the sulfur lamps are desirable for larger greenhouse complexes .Advertisement

5. The prospects of evolution and application of the lighting systems

Despite the fact that electrodeless sulfur lamps with microwave excitation are still identical young, powerful lighting devices based on them have opened a newfangled direction in lighting and found a raw application of microwave technologies, which can become evening more massive than the use of microwave ovens. due to the convinced qualities of the light characteristics, an area of lotion of ocular radiotherapy sources on the basis of the electrodeless sulphur lamps with microwave excitation is well extended [ 15, 16 ]. From problems of a lighting technology associated with lighting by a narrow, intense beam of light ( spotlamp ) or lighting of streets, large areas, tunnels, cosmetic light up of interiors, lighting fountains, architectural monuments and other municipal facilities and services, to the consolidation of lighting systems in versatile technical processes. The execution of newly technical foul solutions for the design of lighting systems on the basis of the electrodeless sulfur lamp with microwave excitement has become possible ascribable to the function of its incontrovertible qualities and advantages as, for case, the handiness of a quasisolar spectrum of radiation sickness with boil down degree of radiotherapy in the ultraviolet and infrared regions of an electromagnetic spectrum. This allows apart from the creation of therapeutic and preventive effects on humans and other wildlife to provide besides safe working conditions, excluding the destructive, dangerous or other harmful effects of ultraviolet and infrared radiations on illuminate objects and the environment, particularly at senior high school clarification levels. further build up of the electrodeless sulfur lamps with microwave excitation can be their integration with other electron devices for creating the power energy-efficient lighting systems. As an example of such system, one can be considered a light device developed on the basis of linking the electrodeless sulphur lamp with microwave excitation and solar batteries [ 17 ]. A general see of block diagram of proposed light device is schematically shown in Figure 12 . The solar batteries allow to achieve fond re-formation of the electric power, which are connected to the control condition unit of measurement by an miniature system, a store of electric energy and an external exponent network. The principle of operation of the lighting device on the footing of the electrodeless sulphur lamp with microwave excitation is in employing solar batteries 2 for converting the optical radiotherapy generated by the light system 1 directly to the direct current. A master unit of the lighting device controls a process of charge-discharge of the storehouse batteries 4, and in the font of their abject voltage, it switches to an external power network 5.

Taking into account the spectrum of radiation of the sulphur lamp close to a spectrum of natural ( solar ) radiation as the solar batteries, one can use their criterion construction, which normally applies for transformation of lifelike ( solar ) light liquefy in address current. The solar batteries are located inside the structure of premises ( for example, greenhouses ), allowing respective advantages : first, it facilitates the maintenance of the solar batteries ( avoiding snow, rain, hail and other natural phenomena ) ; second, with reducing cheery days, the necessity to use artificial light increases ( for example, when the plants get supplementary lighting in greenhouses ), but if the light up devices have a spectrum stopping point to that of the sun, solar batteries can more effectively produce electricity and reduce the premier cost of output as a solid ( for case, in a greenhouse grow when growing agricultural products ). therefore, when using a light-emitting device on the basis of an electrodeless sulfur lamp with microwave excitement in combination with solar batteries, one has an extra regeneration of electricity for its far consumption in the make of both the light up device itself and other electric equipment or to feed it into the power network .