Discharge Lamps Research Articles

Recent progress on quantum frequency standards at BIRMM

Quantum frequency standards are crucial for time measurement, satellite navigation, telecommunication, and other essential applications. Beijing Institute of Radio Metrology and Measurement (BIRMM) has been working on quantum frequency standards and their applications for tens of years. This paper introduces the latest progress on quantum frequency standards at BIRMM, including a calcium optical clock, an active hydrogen maser, and a mercury ion microwave clock. Based on the 1S0-3P1 transition of calcium atoms, a transportable optical clock prototype is built with a stability of 8 × 10–15 at 1 s. A compact active hydrogen maser has been developed for the Chinese space station. It will be used for scientific research such as examining Einstein’s theory of general relativity and has just been lunched. The preliminary frequency stability of the maser is 1.27 × 10–15 at 10000 s. Additionally, a prototype mercury ion microwave clock is developed using the hyperfine transition between 62S1/2, F = 0 and 62S1/2, F = 1. The trapped Hg+ ions are pumped by mercury discharge lamps and cooled by Helium gas. The measured clock transition linewidth is about 1 Hz, and frequency stability of 4 × 10–13 at 1 s and 4 × 10–14 at 1000 s is achieved.

Self-reaction of C2H5O2 and its cross-reaction with HO2 studied with vacuum ultraviolet photoionization mass spectrometry

We present a study of the self-reaction of C2H5O2 and its cross-reaction with HO2 with VUV photoionization mass spectrometry. Hefei synchrotron radiation and a krypton discharge lamp are combined to ionize species. Key products including CH3CHO, C2H5OH, C2H5O and C2H5OOH formed from the reactions are directly observed and confirmed. In particular, the radical product C2H5O from the self-reaction is detected for the first time. The ionization energies of C2H5O and C2H5OOH are determined and the Franck-Condon factors are calculated to fit the photoionization spectra. Moreover, kinetic experiments are performed to confirm the products’ assignment and provide detailed reaction mechanism.

Semi-empirical studies on odd parity levels system of manganese atom in multiconfiguration approximation

We present the results of semi-empirical calculations of the fine structure (fs) and the hyperfine structure (hfs) for the odd-parity level system of the manganese atom in a large multiconfiguration basis. Recently, new measurements applying laser induced fluorescence on an atomic beam and in a hollow cathode discharge lamp provided the hyperfine structure constants A and B for altogether 50 odd-parity levels. Therefore, a hyperfine structure many-body parameterization method was successfully used for such complicated system, composed of 71 configurations. In general, a good agreement between the experimental and the calculated values for the fs and hfs fits was obtained.

BENZENE AND TOLUENE CONCENTRATION AT DIFFERENT TRAFFIC INTERSECTION DURING PRE-MID-POST WINTER SEASON, IN AMBIENT AIR OF ALIGARH AND ITS IMPACT ON HUMAN HEALTH

In current scenario, pollution in environment, is a big problem for all living species at around the world.We know that, Volatile Organic Compounds (VOCs) in presence of sunlight and oxides of nitrogen in atmosphere are considered as precursors for ozone production at the layer of Troposphere.Concentration of Benzene and Toluene (BT) in ambient air was measured near three major traffic sites in the city of Aligarh,India.All air samples were collected using for two times (in a month) during eight hours of normal working period time for in October – December 2020, and January - March 2021.The three selected sites used in this study represent traffic sites ( at Etah Chungi Chauraha, Quarsi Chauraha and Sootmil Chauraha, Aligarh ). In this study, real-time measurements of Benzene and Toluene concentration were performed the programmable compound specific PID detector designed to provide instantaneous exposure monitoring of a specific organic gas.It monitors a specific gas by utilizing a gas separation tube and the photo-ionization detector (PID) with a 9.8 eV gas discharge lamp (range- 50 ppb to 200 ppb) and whole data analyzed by SPSS software. The study the higher concentration 25.32 µg/m3 of Benzene in the evening shows at site 3 and lower concentration 10.22 µg/m3 of Benzene shows at site 2 in the morning.The higher concentration 22.22 µg/m3 in the evening of Toluene shows at site 1 and lower concentration 07.10 µg/m3 in the evening of Toluene shows at site 2, were observed respectively. Benzene and Toluene were widely used as a solvent in different products and petroleum. Exposure to a mixture of toluene and benzene in air led to an increase in the cytotoxic effect and DNA damage without any further repair and also its chronic effect on human health.The higher concentration of benzene and toluene co-exposure of benzene or toluene in this study.The relevance of these data on interactions for humans exposed at low benzene concentrations can be best assessed only when the mechanism of interaction is understood at a quantitative level and incorporated within a biologically based modelling framework for human health.

Landé [formula omitted] factors of the odd-parity electronic levels of the terbium atom determined by laser spectroscopy

In the present work the experimentally determined values of Landé gJ factors for 20 odd-parity electronic levels of atomic terbium are presented. The Zeeman splitting of the hyperfine structure was investigated using the method of laser induced fluorescence in a hollow cathode discharge lamp in a constant magnetic field. All of the values were determined for the first time, by the analysis of 32 spectral lines, recorded in the spectral range between 492 and 609 nm. Moreover, the gJ factors for 15 even-parity energy levels, reported in the available literature, were verified.

An experimental and theoretical characterization of the electronic structure of doubly ionised disulfur

Using time-of-flight multiple electron and ion coincidence techniques in combination with a helium gas discharge lamp and synchrotron radiation, the double ionisation spectrum of disulfur (S_2) and the subsequent fragmentation dynamics of its dication are investigated. The S_2 sample was produced by heating mercury sulfide (HgS), whose vapour at a suitably chosen temperature consists primarily of two constituents: S_2 and atomic Hg. A multi-particle-coincidence technique is thus particularly useful for retrieving spectra of S_2 from ionisation of the mixed vapour. The results obtained are compared with detailed calculations of the electronic structure and potential energy curves of S_2^{2+} which are also presented. These computations are carried out using configuration interaction methodology. The experimental results are interpreted with and strongly supported by the computational results.

Impact of Ultraviolet Radiation on the Pigment Content and Essential Oil Accumulation in Sweet Basil (Ocimum basilicum L.)

In this study, we investigated the effects of additional ultraviolet radiation (UV) on the main growth fluorescent lamp light on pigment content and essential oil accumulation in sweet basil (Ocimum basilicum L.). Three different UV light sources from light-emitting diodes and discharge lamps, which emit UV in the UV-A (315–400 nm), UV-B (280–315 nm) and UV-C (100–280 nm) ranges, were tested for basil plant growing. The plants, growing under additional UV-A and UV-B from mercury lamps, on the 60th growing day were higher than control plants by 90% and 53%, respectively. The fresh leaf mass of the UV-A irradiated basil plants was 2.4-fold higher than the control plant mass. The dry mass/fresh mass ratio of the UV-A and UV-B irradiated plants was higher by 45% and 35% in comparison to the control plants. Leaf area was increased by 40% and 20%, respectively. UV-C affected the anthocyanin content most strongly, they increased by 50%, whereas only by 27% and 0% under UV-A and UV-B. Any UV addition did not affect the essential oil total contents but altered the essential oil compositions. UV-A and UV-B increased the linalool proportion from 10% to 20%, and to 25%, respectively, in contrast to UV-C, which reduced it to 3%. UV-C induced the eugenol methyl ether accumulation (17%) and inhibited plant growth. Moreover, UV increased the proportion of α-guaiene, β-cubebene and α-bulnesene and decreased the proportion of sabinene and fenchone. Thus, we concluded that UV (except UV-C) used jointly with main light with PPFD 120 ± 10 μmol photons·m−2·s−1 for sweet basil cultivation may be justified to stimulate basil growth and optimize the essential oil accumulation.

Use of broadband radiation to reduce microbial contamination of livestock building air and evaluation of its effectiveness

One of the most important tasks of veterinary practice is to find and develop an effective and environmentally friendly method of disinfecting livestock room air that can be used in the presence of animals and service personnel. Currently, low-pressure discharge lamps are used for indoor air sanitation as a source of ultraviolet (UV) radiation. However, these devices can pose serious environmental pollution risks. Therefore, the main objective of this work was to investigate the bactericidal effectiveness of pulsed broadband optical radiation on the microbial contamination of the house air of livestock and concerning sanitary positive microorganisms. In the article, the authors presented a description of the technical characteristics of the Zarya-1 device based on the use of pulsed high-intensity optical radiation of a continuous spectrum. This spectrum is generated by powerful high-temperature (10000 – 40000 K) plasma sources, developed by SRIP (State Ryazan Instrument Plant) JSC. The bactericidal effect of broadband radiation on the microflora of the air in the livestock building was investigated. The experiment was carried out in the vivarium. Open Petri dishes with dense nutrient media were placed at three points for the deposition of dust particles, microorganisms, and aerosol droplets by gravity. The results obtained were recorded after 24 h. In their study, the authors revealed a reduction in the total microbial count of air in all five variants after exposure to irradiation for durations of 14, 16, 17, 18, and 19 min. Therefore, at the 14 min duration of irradiation, the effectiveness of the sanitary parameters reached 97.12 % and at the 19 min duration 99.78 %.

Luminescent inorganic mixed borate phosphors materials for lighting

The need of new materials with desirable optical properties has become important in recent years. In particular, a need has emerged for compounds having better luminescence properties in various practical applications. The introduction of rare earth ions as activators improves the luminescence properties of the compounds considerably. Boron is one of the most abundant elements in nature. It readily combines with almost all other elements. In combination with oxygen; it forms borates comprised of various anions such as BO3 3- , B2 O5 4- , etc. Apart from these simple borates, several complex compositions exist involving mixed anions as well as double metal borates, due to the three-fold, or four-fold coordination of borate atoms. Borates intrinsically possesses characteristics that are advantageous for optical materials, which include a wide transparency range, large electronic band gap, good thermal and chemical stability, low preparative temperature, optical stability with good nonlinear characteristics, and an exceptionally high optical damage threshold. The unique crystal structure of borates determines their enhanced ultraviolet light transparency, good nonlinearity, and relatively high resistance against laser-induced damage. Some of these complex borates have interesting luminescence properties that are covered in this review. These include double borates containing rare earths RM3 (BO3 )4 , pentaborates LaMgB5 O10 , M3 R2 (BO3 )4 , where M is an alkaline earth, mixed anion borates such as aluminoborate SrAl2 B2 O7 , silicate-borates such as pekovite, SrB2 Si2 O8 , haloborates, M2 B5 O9 X, where M is an alkaline earth and X is a halogen, phosphate borates, and MBPO5 , where M is an alkaline earth. Phosphors based on these compositions find use in various applications such as fluorescence lamps, colour TVs, plasma display panels, high-intensity discharge lamps based on xenon, optically pumped solid-state lasers, eye-safe lasers, and X-ray imaging.

Research and development of pulse electronic control devices with UV lamps

Objectives. When used in lighting installations with tubular low-pressure ultraviolet (UV) lamps, electronic ballasts should meet the following basic requirements: low cost, reliable ignition at low temperatures, as well as combining high energy efficiency with reliable lamp operation. As compared with electromagnetic ballasts, electronic ballasts allow the luminous efficiency and power factor of discharge lamps to be increased, reducing the consumption of scarce materials along with the weight of devices. In order to improve their energy efficiency, complete UV lamps are based on low-pressure discharge lamps with pulsed electronic ballasts supplying power at the frequency of 22–50 kHz. Various circuit designs include such basic units as mains filter, rectifier, power factor corrector, smoothing filter, high-frequency converter, ballast, and ignition device. The present study aimed to develop an electronic semiconductor circuit for switching on and powering a discharge lamp of increased energy efficiency using a pulsed electronic ballast.Methods. Classical methods of mathematical research were applied for determining the flux of the 254-nm mercury resonance line using a structural electronic ballast diagram along with a mathematical description and adaptive model.Results. Equations for determining the parameters of pulses formed by an envelope having the form of input voltage and current supplied at industrial frequency were formulated for different instants of time. A mathematical description is given for determining pulse duration and lamp current depending on the values of nominal and operating voltage, as well as nominal current. Diagrams for instantaneous voltage values at the high-frequency switch input and generated pulsed current are presented. The parameters of the ‘UV lamp–electronic ballast’ set were calculated using an adaptive model for determining the flux of the 254-nm mercury resonance line according to the condition of lamp power constancy.Conclusions. Relative values for radiant efficiency of the 254-nm mercury line for UV lamps under study were determined. Theoretical research of electronic ballasts led to the development of a semiconductor switching and power supply circuit for the discharge lamp based on high-frequency rectangular pulses. The parameters of the element base were calculated along with selected basic initial characteristics of the blocking generator.

Research of continuous fiber laser sustained Xe plasma

High-speed optical inspection of wafers requires a high-brightness and broadband light source. The brightness of traditional arc discharge lamps is difficult to increase, which is limited by the cathode current density. Laser sustained plasma (LSP) is a promising method to overcome the limitations of existing light source technologies. Then the characteristics of fiber laser sustained plasma in a xenon bulb were investigated, the absorption coefficient was measured, and the spectrum was analyzed. The results show that with the increase of laser power, the volume of plasma gradually increases and moves towards the direction of laser incident. With the increase of Gaussian beam focusing number F, the threshold laser power required to maintain the stable existence of plasma decreases gradually. There are upper and lower limits for laser power at which the LSP could be sustained. When the laser incident at the optimal incident angle, the laser propagation in the plasma is the optimal path for laser energy deposition, and the plasma has higher absorption coefficient, temperature and brightness. When F ≥ 10, the Xe plasma will show spatial instability due to refraction effect. Compared with the traditional short-arc xenon lamp, the LSP spectrum has a higher proportion in short wavelength.

Realization of an dimmable electronic ballast for a discharge lamps fed by an LSCSCP circuit and a PFC stage

<p>This paper presents an electronic ballast for discharge lamps. The ballast consists of two stages: i) a boost-buck chopper that performs the power factor correction and provides an approximately variable DC link voltage to drive the second stage and ii) a half-bridge MOSFET inverter with an improved series-parallel inductor-capacitor-inductor (LsCpLp) resonant circuit to drive the high-frequency discharge lamp. The electronic ballast designed here is a multi-purpose ballast which was experimentally tested for high-pressure sodium discharge lamps 150 W and metal halide lamps 150 W. It was revealed that this mode of operation makes it possible to vary and dim the light of the lamp and to improve the quality of the power supply while reducing the harmonic currents in networks.</p>

Landé [formula omitted] factors of the even-parity electronic levels of the terbium atom

In the present work Landé gJ factors for 17 even-parity electronic levels of the terbium atom are presented. The spectra of the Zeeman splitting of the hyperfine structure were recorded with the method of laser spectroscopy in a hollow cathode discharge lamp in a constant magnetic field, with laser induced fluorescence detection. The analysis of 47 spectral lines of terbium in the spectral range between 490 and 609 nm enabled the determination of the gJ factors for the presented even-parity levels for the first time. Moreover, verification of the gJ factor values for 17 odd-parity levels, previously reported by other authors from the analysis of Fourier transform spectra.

Controlling The Brightness of Light by Using Touch Sensor

A Red Light Emitting Diodes (LED) replaces HID lamps in street lighting system to include dimming feature. A Arduino is used to control the intensity that drives a TIP122 to switch the LED’s according to achieve desired operation.In the present system, mostly the lightning up of highways is done through High Intensity Discharge lamps (HID), whose energy consumption is high. Its in tensity cannot be controlled according to the requirement so there is a need to switch on to an alternative method of lightning system i.e., by using LED’s. This system is build to overcome the present day drawbacks of HID lamps. This system demonstrates the usage of the LED’s (light emitting diodes) as the light source and its variable intensity control, according to the requirement.

Characterization of a robot-assisted UV-C disinfection for the inactivation of surface-associated microorganisms and viruses

Microorganisms pose a serious threat for us humans, which is exemplified by the recent emergence of pathogens such as SARS-CoV-2 or the increasing number of multi-resistant pathogens such as MRSA. To control surface microorganisms and viruses, we investigated the disinfection properties of an AI-controlled robot, HERO21, equipped with eight 130-W low pressure UV-C mercury vapor discharge lamps emitting at a wavelength of 254 nm, which is strongly absorbed by DNA and RNA, thus inactivating illuminated microorganisms. Emissivity and spatial irradiance distribution of a single UV-C lamp unit was determined using a calibrated spectrometer and numerical simulation, respectively. The disinfection efficiency of single lamps is determined by microbiological tests using B. subtilis spores, which are known to be UV-C resistant. The required time for D99 disinfection and the corresponding UV-C irradiance dose amount to 60 s and 37.3 mJ•cm−2 at a distance of 1 m to the Hg-lamp, respectively. Spatially resolved irradiance produced by a disinfection unit consisting of eight lamps is calculated using results of one UV-C lamp characterization. This calculation shows that the UV-C robot HERO21 equipped with the mentioned UV-C unit causes an irradiance at λ=254 nm of 2.67 mJ•cm−2•s−1 at 1 m and 0.29 mJ•cm−2•s−1 at 3 m distances. These values result in D99 disinfection times of 14 s and 129 s for B. subtilis spores, respectively. Similarly, human coronavirus 229E, structurally very similar to SARS-CoV-2, could be efficiently inactivated by 3–5 orders of magnitude within 10 - 30 s exposure time or doses of 2 - 6 mJ•cm−2, respectively. In conclusion, with the development of the HERO21 disinfection robot, we were able to determine the inactivation efficiency of bacteria and viruses on surfaces under laboratory conditions.

Effect of Carbon on the Emission Performance of Tungsten Electrode Electron in Gas Discharge Lamps

Tungsten electrodes are widely used as electric light sources because of their excellent performance. Impurity elements, such as carbon, can be easily introduced during the preparation of lamp tubes; therefore, it is necessary to analyze the influence of carbon impurities on the performance of gas discharge lamps and propose reasonable solutions. In this study, we investigated the manner in which carbon enters a gas discharge lamp and compared the electron emission properties of carbon and noncarbon electrodes through extensive experiments. The results showed that the current density was reduced by more than 50% at 1450°C, and the most obvious change was 75.00%. Furthermore, we propose a detailed solution for the introduction of carbon, which provides technical support for the quality control of gas discharge lamps.

Experimental investigation of the hyperfine structure of Tm I with Fourier transform spectroscopy, part A: In the visible wavelength range (400–700 nm)

The spectra emitted by a thulium hollow-cathode discharge lamp with argon or neon as inert gases have been recorded with a Bruker IFS 125 HR fourier transform spectrometer in the visible wavelength region from 400 to 700 nm. The paper presents the investigation of the hyperfine-structure splitting of 50 spectral lines of neutral thulium. As a result, the magnetic dipole hyperfine structure constant A for 20 fine structure levels of Tm I have been determined for the first time.

Non-monochromatic He I and He II UPS spectra of polycrystalline silver

The surface composition of clean polycrystalline Silver (Ag) was analyzed by ultraviolet photoelectron spectroscopy (UPS) at optimal instrument operation parameters for both nonmonochromatic He I and He II emission. UPS valence band spectra were obtained using a differentially pumped He gas-discharge lamp (He I: 21.2 eV; He II: 40.8 eV). Fermi levels (Ef) in UPS spectra arising from each source line are observed—where the energy difference between Ef arising from He I or He II is equivalent to the difference in source energy of He I and He II primary lines (19.6 eV), useful for calibration of UPS systems or spectra analysis.

Numerical investigation of regimes of current transfer to anodes of high-pressure arc discharges

Unified 1D numerical modeling of high-pressure high-current arc discharges is revisited. Two regimes of current transfer to anodes are investigated. The “passive anode” regime occurs for low and moderate anode surface temperatures Ta. The energy flux from the plasma to the anode surface, qpl, depends on Ta rather weakly in this regime and may be conveniently expressed in terms of the local current density jc, and the so-called anode heating voltage Uh. Uh is independent of the arc length and the cathode surface temperature, although it weakly varies with jc between approximately 6 and 8.5 V for jc in the range from 105 to 108 A m−2. In the “active anode” regime, qpl is higher than in the passive anode regime and varies with Ta. The active anode regime may occur on hot refractory anodes, such as those of high-intensity discharge lamps, when Ta exceeds approximately 3000 K and the thermionic electron emission from the anode comes into play. The latter causes an increase in the electron density near the anode. One consequence is the increase in the electron energy transport from the bulk plasma to the near-anode layer by electron heat conduction. The other effect contributing to increase in qpl is the formation of a negative near-anode space-charge sheath with a positive voltage drop. In non-stationary simulations, the active regime occurs via the development of a thermal instability similar to that causing the appearance of spots on thermionic arc cathodes. The occurrence of the active regime is strongly affected by parameters, in particular, by the distance between the anode surface and the cooling fluid.

Dynamic Impedance Calculation of Gas Discharge Lamp

In this paper, a dynamic impedance calculating method of capacitive discharge lamp is proposed from the attenuation coefficient and oscillation frequency of the voltage waveform. The voltage waveform is divided into sections between peaks and valleys to calculate resistance and capacitance values at each point. The dynamic resistance and capacitance values are calculated from an actual discharge lamp system, and the validity is confirmed by comparing the calculated phase angles and the measured phase angles. As for the dynamic impedance of the lamp measured in this paper, the lamp resistance gradually increased up to the 3/4 point of the half-cycle and then decreased sharply, and the lamp capacitance remained constant up to the 2/3 point of the half-cycle and then decreased.