**3. Simulators of solar radiation**

Simulators of solar radiation (SSR) are radiation sources that form and direct a light stream into a fixed area. Such devices can be used for investigating the light characteristics of the photoelectric converter and solar batteries for space and ground applications as well as for carrying out high-temperature studies and tests on the resistance to light effects of various dyes and paint coatings, paper and labels, optical components, etc., [6–8]. The SSRs create a stream of pulsed or continuous optical radiation whose spectral characteristics are close to those of solar radiation. Ideally, the simulators should, with the best approximation, reproduce all the parameters of solar radiation including its spectral composition, flux density, parallelism of rays, stability in time and uniformity of illumination. However, such devices are extremely complex and expensive, demand qualified maintenance, and therefore, as the specific purpose requires, the specialized simulators are created (for example, large SSR for testing space vehicles [7]).

The solar simulators include powerful gas discharge, halogen or other lamps, correcting filters and also serving subsystems. There are quite a lot of familiar artificial light sources used to simulate solar radiation beginning with the carbon arc lamp; with sodium lamps, argon arc lamps, quartz-tungsten halogen lamps, mercury xenon lamps, arc xenon lamps, xenon flash lamps, metal halide lamps, light-emitting diodes and super sources of continuous laser radiation also being applied, but only incandescent and gas-discharge lamps were used in PC studies.

**Figure 9** presents a comparison of the spectral characteristics of extra-atmospheric solar radiation and the simulators of solar radiation on the basis of lamps of the artificial lighting.

In the second expression (2), the total average total energy < *E*<sup>2</sup> > depends on the value of

total energy in the waveguide is equal to the sum of the energies of the main and counter

not equal to the sum of the energies of the waves running toward each other, but in the wave-

Of practical interest for exciting a sulfur lamp in a waveguide causes is the case when the

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 *L* with

**Figure 8** demonstrates a schematic diagram of lighting device based on an electrodeless sulfur lamp in the case excitation by adding two counter-propagating coherent monochromatic waves. For this excitation method, an electromagnetic wave is generated by a magnetron 5 and through a waveguide tee 4 through waveguide 3 enters a mesh waveguide 2 within

Simulators of solar radiation (SSR) are radiation sources that form and direct a light stream into a fixed area. Such devices can be used for investigating the light characteristics of the photoelectric converter and solar batteries for space and ground applications as well as for carrying out high-temperature studies and tests on the resistance to light effects of various dyes and paint coatings, paper and labels, optical components, etc., [6–8]. The SSRs create a stream of pulsed or continuous optical radiation whose spectral characteristics are close to those of solar radiation. Ideally, the simulators should, with the best approximation, reproduce all the parameters of solar radiation including its spectral composition, flux density, parallelism of rays, stability in time and uniformity of illumination. However, such devices are extremely complex and expensive, demand qualified maintenance, and therefore, as the specific purpose requires, the specialized simulators are created (for example, large SSR for

The solar simulators include powerful gas discharge, halogen or other lamps, correcting filters and also serving subsystems. There are quite a lot of familiar artificial light sources used to simulate solar radiation beginning with the carbon arc lamp; with sodium lamps, argon arc lamps, quartz-tungsten halogen lamps, mercury xenon lamps, arc xenon lamps, xenon flash lamps, metal halide lamps, light-emitting diodes and super sources of continuous laser radiation also being applied, but only incandescent and gas-discharge lamps were used in PC studies.

**Figure 7** shows the distributions of full energy of the electromagnetic waves <sup>&</sup>lt; *<sup>E</sup>*<sup>1</sup>

ing devices on the basis of the electrodeless sulfur lamp with microwave excitation.

which is introduced from different ends of the waveguide as fundamental <sup>&</sup>lt; *<sup>E</sup>*<sup>1</sup>

→ <sup>1</sup> ⋅ *E* →

<sup>2</sup> <sup>&</sup>gt; <sup>=</sup> 0 is fulfilled. As a result, it is possible to ensure a uniform distribution of

<sup>2</sup> > electromagnetic waves. **Figure 8** schematically presents diagram of light-

<sup>2</sup> <sup>&</sup>gt; <sup>=</sup> <sup>0</sup> (there is no interference), the

<sup>2</sup> <sup>&</sup>gt; <sup>≠</sup> 0, the total energy is

<sup>2</sup> <sup>&</sup>gt; +< *<sup>E</sup>*<sup>2</sup>

<sup>2</sup> > and counter-

<sup>2</sup> >,

→ <sup>1</sup> ⋅ *E* →

<sup>2</sup> <sup>&</sup>gt;. In the case when <sup>&</sup>lt; *<sup>E</sup>*

the interference term < *E*

→ <sup>1</sup> ⋅ *E* →

condition < *E*

propagating <sup>&</sup>lt; *<sup>E</sup>*<sup>2</sup>

→ <sup>1</sup> ⋅ *E* →

optically transparent outside surface (mesh surface).

which an electrodeless sulfur lamp 1 is located.

**3. Simulators of solar radiation**

testing space vehicles [7]).

guide, there is interference of the waves.

electromagnetic waves. When the condition is fulfilled, when < *E*

82 Emerging Microwave Technologies in Industrial, Agricultural, Medical and Food Processing

For testing the photoelectric converters and solar batteries, as a rule, the incandescent and gasdischarger 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 emission spectrum and spectrum of solar radiation, the color temperature (the color temperature of the extra-atmospheric solar radiation is ∼5900 K), the high stability of the radiation flux and the small nonuniformity of energy illumination that determines the adequacy of measuring the parameters of the photoelectric converters and solar cells [8]. At the same time, for example, a necessity of temporal stability of the radiation flux is a significant limiting factor for using a number of arc sources in photovoltaic investigations, although their spectral composition is most consistent with the solar emission under conditions of zero atmospheric mass (AM0). The use of pulse gas-discharge lamps having a satisfactory spectral composition, in addition to the indicated temporary instability associated with the characteristics of their launch systems, requires to use high-speed measuring equipment, which significantly increases the expenses for creating the entire installation. According to the above parameters, the greatest interest can be found in such sources as:


**Figure 9.** Spectral emission curves of the extra-atmospheric solar emission and sources of radiation for SSRs.


out in [10, 11], the leaves of different systematic groups had approximately the same spectra of photosynthesis activity. An average curve of the spectrum of photosynthesis activity of

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

http://dx.doi.org/10.5772/intechopen.73755

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All parts of the solar spectrum are important for the normal outgrowth of plants. More detailed information about results of an impact of the optical radiation having spectrum close

280–320 nm Harmful to plant growth and development. Some plants require a low effect of this spectrum for

320–400 nm It influences the regulatory processes in the development of plants. The presence of this range

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

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

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

In general, the effect of stretching the stem, a pronounced regulatory action; a few percent in the

the green leaf is shown in **Figure 10**.

**Wavelength Effects on plants**

400–500 nm ("blue")

500–600 nm ("green")

600–700 nm ("red")

red")

700–750 nm ("far

to the solar spectrum is shown in **Table 2**.

**Figure 10.** Averaged curve of the spectrum of photosynthesis activity of green leaf.

should be a few percent of the radiant flux.

to the formation of stunted plants with thickened stems.

formation of plants with elongated axial organs and thin leaves.

excess can lead to abnormal development or to the death of the plant.

normal development.

radiant flux is sufficient.

**Table 2.** Effect of the spectrum of optical radiation on plants.

**Table 1.** Characteristics of lamps.

As shown in **Figure 9**, the spectral characteristic of the electrodeless sulfur lamp has a continuous quasisolar spectrum of optical radiation and is very close to the solar spectrum in its visible region. The second advantage of this lamp worth noting is its durability, which is important for its application in the SSRs [9].

**Table 1** demonstrates the comparison of the lamps' characteristics that are most widely used in SSRs, as well as the parameters of the electrodeless sulfur lamp with microwave excitation.

Analyzing the characteristics of the electrodeless sulfur lamp with microwave excitation and comparing them with other light sources that applied in the SSRs, we can say that this lamp can also 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 also to provide correct modeling of various modes of their operation under laboratory conditions.
