The role of resonance radiation in the propagation of a positive pre-breakdown ionization wave in long discharge tubes

2021 ◽  
Author(s):  
Aleksei V Siasko ◽  
Yuri B Golubovskii ◽  
Sergei Valin
Keyword(s):  
Discharge Tube ◽  
Tube Wall ◽  
Finite Size ◽  
Ionization Wave ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Radiation Trapping ◽  
Discharge Tubes ◽  
Electron Photoemission

Abstract The work is devoted to calculating the flux of resonance photons towards the boundary of a cylindrical discharge tube of a finite size during the propagation of a pre-breakdown ionization wave of positive polarity. A cylindrical discharge tube of finite dimensions with argon at the pressure of p=1 Torr is considered. The propagation mechanisms of metastable and resonance atoms are compared. For the considered discharge conditions, the space-time distributions of metastable and resonance atoms are calculated. The manuscript presents a technique for calculating the flux of resonance photons onto the discharge tube wall with the account of the radiation trapping. It is shown that for the studied conditions the photon flux density towards the longitudinal boundary of the tube ahead of the ionization wave can reach 1013 cm-2s-1. The obtained results allow describing the appearance of seed electrons ahead of the positive ionization wavefront during its propagation due to the electron photoemission from the discharge tube wall.

scholarly journals STUDIES ON THE CULTIVATION OF THE STRAWBERRY UNDER THE LIGHT TRANSMISSION TYPE SOLAR CELL CONDITION

2017 ◽  
Vol 7 (1) ◽  
pp. 991-996
Author(s):  
Takayuki Tanaka ◽  
Hitoshi Kinouchi ◽  
Masako Akutsu
Keyword(s):  
Solar Cell ◽  
Flux Density ◽  
Light Transmission ◽  
Fruit Size ◽  
Control Area ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Roof Panel

We examined the cultivation of the strawberry under the light transmission type solar cell (panel) condition that absorbs the ultraviolet light for electricity, and passes ca. 20% of visible light from 400nm to 800nm for photosynthesis. Though the color of leaves under the solar cell was lighter than that under control area, the length and width of the leaves were not so different among the treatments. On the other hand, the number of honeybees visiting flowers and SSC were significantly correlated with the integrated photon flux density, and the number of fruits harvested and the yield showed strong correlation coefficient with it. However, the coefficient of correlation between the number of flowers bloomed or fruit size and the integrated photon flux density were relatively low, suggesting that the light interception by the solar cell does not affect much on the number of flowers bloomed or fruit size. As the yield and the quality of the strawberry fruits decreased with the light intensity by the light transmission type solar cell, the yield and the quality of the fruits can be improved by widening the space between the panels. Originally, the transmission type solar cell had been expected not only as ecological role of power generation, but also as the source of light in a room. Here, the authors propose an additional role of the transmission type solar cell as a roof panel of a greenhouse.

scholarly journals Interacting Effects of Light and Temperature on Sporulation of Peronospora tabacina on Tobacco Leaves

1976 ◽  
Vol 29 (3) ◽  
pp. 281 ◽  
Author(s):  
YigaI Cohen
Keyword(s):  
Light Level ◽  
Inhibitory Effect ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Present System ◽  
Tobacco Leaves ◽  
Spore Yield ◽  
Role Of Light ◽  
Effect Of Light

The interacting effects of light and temperature on spore formation of P. tabacina on tobacco leaves were investigated. The following points indicated that an enzymic build-up of an antisporulant during a wet light period and its enzymic decay over a dry dark period may explain the inhibitory effect of light upon sporulation, and its reversal by darkness. (1) Fluorescent blue light of relatively low photon flux density (3 �7 /lE m - 2 S -1) inhibited sporulation by 99 % at 20oe. (2) Light level and temperature during the sporulation period determined spore yield of the pathogen: at high temperatures (in the range 8-24�C) sporulation was inhibited at low light level, whilst no inhibition occurred at much higher light levels at low temperatures. (3) Preceding dry dark treatments given at 200e considerably diminished the inhibitory effect of light, but not if given at 100e. (4) The diffusion of an inhibitory compound from irradiated to unirradiated areas of detached leaves was demonstrated. (5) The continuing photosynthetic activity of the host in the light at 20oe, and the lack of sucrose following dark periods at lOoe, were not associated with the inhibitory effect of light. The similarity between the role of light in the present system and the role of light in activation and decay of phenylalanine ammonia-lyase is discussed.

scholarly journals The Role of La2O3 in Enhancement the Radiation Shielding Efficiency of the Tellurite Glasses: Monte-Carlo Simulation and Theoretical Study

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3913
Author(s):  
Aljawhara H. Almuqrin ◽  
Mohamed Hanfi ◽  
K. G. Mahmoud ◽  
M. I. Sayyed ◽  
Hanan Al-Ghamdi ◽  
...  
Keyword(s):  
Monte Carlo Simulation ◽  
Theoretical Study ◽  
Radiation Shielding ◽  
Photon Flux ◽  
Transmission Factor ◽  
Tellurite Glasses ◽  
Attenuation Coefficients ◽  
Binary Glass ◽  
Buildup Factors

The radiation shielding competence was examined for a binary glass system xLa2O3 + (1 − x) TeO2 where x = 5, 7, 10, 15, and 20 mol% using MCNP-5 code. The linear attenuation coefficients (LACs) of the glasses were evaluated, and it was found that LT20 glass has the greatest LAC, while LT5 had the least LAC. The transmission factor (TF) of the glasses was evaluated against thicknesses at various selected energies and was observed to greatly decrease with increasing thickness; for example, at 1.332 MeV, the TF of the LT5 glass decreased from 0.76 to 0.25 as the thickness increased from 1 to 5 cm. The equivalent atomic number (Zeq) of the glasses gradually increased with increasing photon energy above 0.1 MeV, with the maximum values observed at around 1 MeV. The buildup factors were determined to evaluate the accumulation of photon flux, and it was found that the maximum values for both can be seen at around 0.8 MeV. This research concluded that LT20 has the greatest potential in radiation shielding applications out of the investigated glasses due to the glass having the most desirable parameters.

scholarly journals Effect of Pre-Harvest Supplemental UV-A/Blue and Red/Blue LED Lighting on Lettuce Growth and Nutritional Quality

Horticulturae ◽  
2021 ◽  
Vol 7 (4) ◽  
pp. 80
Author(s):  
Triston Hooks ◽  
Joseph Masabni ◽  
Ling Sun ◽  
Genhua Niu
Keyword(s):  
Blue Light ◽  
Nutritional Quality ◽  
Uv Light ◽  
Ultra Violet ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Daily Light Integral ◽  
Lettuce Growth ◽  
Supplemental Lighting

Blue light and ultra-violet (UV) light have been shown to influence plant growth, morphology, and quality. In this study, we investigated the effects of pre-harvest supplemental lighting using UV-A and blue (UV-A/Blue) light and red and blue (RB) light on growth and nutritional quality of lettuce grown hydroponically in two greenhouse experiments. The RB spectrum was applied pre-harvest for two days or nights, while the UV-A/Blue spectrum was applied pre-harvest for two or four days or nights. All pre-harvest supplemental lighting treatments had a same duration of 12 h with a photon flux density (PFD) of 171 μmol m−2 s−1. Results of both experiments showed that pre-harvest supplemental lighting using UV A/Blue or RB light can increase the growth and nutritional quality of lettuce grown hydroponically. The enhancement of lettuce growth and nutritional quality by the pre-harvest supplemental lighting was more effective under low daily light integral (DLI) compared to a high DLI and tended to be more effective when applied during the night, regardless of spectrum.

scholarly journals Light Quality Affects Water Use of Sweet Basil by Changing Its Stomatal Development

Agronomy ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 303
Author(s):  
Sungeun Lim ◽  
Jongyun Kim
Keyword(s):  
Stomatal Conductance ◽  
Blue Light ◽  
Water Use ◽  
Growth Parameters ◽  
Stomatal Density ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Stomatal Development ◽  
Sweet Basil ◽  
Stomatal Responses

Different light qualities affect plant growth and physiological responses, including stomatal openings. However, most researchers have focused on stomatal responses to red and blue light only, and the direct measurement of evapotranspiration has not been examined. Therefore, we quantified the evapotranspiration of sweet basil under various red (R), green (G), and blue (B) combinations using light-emitting diodes (LEDs) and investigated its stomatal responses. Seedlings were subjected to five different spectral treatments for two weeks at a photosynthetic photon flux density of 200 µmol m−2 s−1. The ratios of the RGB light intensities were as follows: R 100% (R100), R:G = 75:25 (R75G25), R:B = 75:25 (R75B25), R:G:B = 60:20:20 (R60G20B20), and R:G:B = 31:42:27 (R31G42B27). During the experiment, the evapotranspiration of the plants was measured using load cells. Although there were no significant differences in growth parameters among the treatments, the photosynthetic rate and stomatal conductance were higher in plants grown under blue LEDs (R75B25, R60G20B20, and R31G42B27) than in the R100 treatment. The amount of water used was different among the treatments (663.5, 726.5, 728.7, 778.0, and 782.1 mL for the R100, R75G25, R60G20B20, R75B25, and R31G42B27 treatments, respectively). The stomatal density was correlated with the blue light intensity (p = 0.0024) and with the combined intensity of green and blue light (p = 0.0029); therefore, green light was considered to promote the stomatal development of plants together with blue light. Overall, different light qualities affected the water use of plants by regulating stomatal conductance, including changes in stomatal density.

scholarly journals LED Illumination Spectrum Manipulation for Increasing the Yield of Sweet Basil (Ocimum basilicum L.)

Plants ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 344
Author(s):  
Md Momtazur Rahman ◽  
Mikhail Vasiliev ◽  
Kamal Alameh
Keyword(s):  
Growth Rate ◽  
Fold Increase ◽  
Photosynthetic Photon Flux Density ◽  
Ocimum Basilicum ◽  
Photon Flux ◽  
Photon Flux Density ◽  
White Led ◽  
Experimental Conditions ◽  
Sweet Basil ◽  
Optimal Illumination

Manipulation of the LED illumination spectrum can enhance plant growth rate and development in grow tents. We report on the identification of the illumination spectrum required to significantly enhance the growth rate of sweet basil (Ocimum basilicum L.) plants in grow tent environments by controlling the LED wavebands illuminating the plants. Since the optimal illumination spectrum depends on the plant type, this work focuses on identifying the illumination spectrum that achieves significant basil biomass improvement compared to improvements reported in prior studies. To be able to optimize the illumination spectrum, several steps must be achieved, namely, understanding plant biology, conducting several trial-and-error experiments, iteratively refining experimental conditions, and undertaking accurate statistical analyses. In this study, basil plants are grown in three grow tents with three LED illumination treatments, namely, only white LED illumination (denoted W*), the combination of red (R) and blue (B) LED illumination (denoted BR*) (relative red (R) and blue (B) intensities are 84% and 16%, respectively) and a combination of red (R), blue (B) and far-red (F) LED illumination (denoted BRF*) (relative red (R), blue (B) and far-red (F) intensities are 79%, 11%, and 10%, respectively). The photosynthetic photon flux density (PPFD) was set at 155 µmol m−2 s−1 for all illumination treatments, and the photoperiod was 20 h per day. Experimental results show that a combination of blue (B), red (R), and far-red (F) LED illumination leads to a one-fold increase in the yield of a sweet basil plant in comparison with only white LED illumination (W*). On the other hand, the use of blue (B) and red (R) LED illumination results in a half-fold increase in plant yield. Understanding the effects of LED illumination spectrum on the growth of plant sweet basil plants through basic horticulture research enables farmers to significantly improve their production yield, thus food security and profitability.

Effect of leaf age on photosynthesis and transpiration of cassava (Manihot esculenta)

1977 ◽  
Vol 55 (17) ◽  
pp. 2288-2295 ◽  
Author(s):  
M. Aslam ◽  
S. B. Lowe ◽  
L. A. Hunt
Keyword(s):  
Chlorophyll Content ◽  
Manihot Esculenta ◽  
Leaf Age ◽  
Gas Analysis ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Genotypic Differences ◽  
Specific Leaf Weight ◽  
Manihot Esculenta Crantz ◽  
Leaf Weight

The effect of plant and leaf age on CO2-exchange rates (CER) and transpiration rates in 15 genotypes of cassava (Manihot esculenta Crantz) was measured in situ by infrared gas analysis. The plants were grown in a controlled-environment room with a 14-h photoperiod, day–night temperatures of 29–24 °C, and 60–70% relative humidity.Plant age had no effect on leaf CER, whereas transpiration rates in 14-week-old plants were significantly greater than those in 7-week-old plants. Both CER and transpiration rates decreased with leaf age. The decline was negligible when measured at low photosynthetic photon flux density. At saturating light, however, both CER and transpiration rates decreased significantly in most of the genotypes. Significant genotypic differences were observed in the pattern of decline. Both stomatal (rs) and residual (rr) resistances to the diffusion of CO2 increased with leafage in all the genotypes. The relative increase in rr was much greater than the increase in rs. In all the genotypes the ratio rr:rs was greater than unity, suggesting that rr is the major component of the total resistance to photosynthesis. Chlorophyll content and specific leaf weight also varied significantly among the genotypes. However, chlorophyll content decreased and specific leaf weight increased with leaf age.

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