Spectrum Of Discharge Research Articles

Spatiotemporal scaling of hydrological and agrochemical export dynamics in a tile‐drained Midwestern watershed

Conceptualizing catchments as physicochemical filters is an appealing way to link streamflow discharge and concentration time series to hydrological and biogeochemical processing in hillslopes and drainage networks. Making these links explicit is challenging in complex watersheds but may be possible in highly modified catchments where hydrological and biogeochemical processes are simplified. Linking hydrological and biogeochemical filtering in highly modified watersheds is appealing from a water quality perspective in order to identify the major controls on chemical export at different spatial and temporal scales. This study investigates filtering using a 10 year data set of hydrological and biogeochemical export from a small (<500 km2) agricultural watershed in Illinois, the Little Vermilion River (LVR) Watershed. A number of distinct scaling regimes were identified in the Fourier power spectrum of discharge and nitrate, phosphate, and atrazine concentrations. These scaling regimes were related to different runoff pathways and spatial scales throughout the catchment (surface drainage, tile drains, and channel flow in the river). Wavelet analysis indicated increased coupling between discharge and in‐stream concentrations at seasonal‐annual time scales. Using a multiresolution analysis, nitrate, phosphate, and atrazine loads exported at annual scales were found to exhibit near‐linear scaling with annual streamflow, suggesting that at these scales the export dynamics could be approximated as chemostatic responses. This behavior was pronounced for nitrate and less so for phosphate and atrazine. The analysis suggests that biogeochemical inputs built up legacy loads, leading to the emergence of chemostatic behavior at annual time scales, even at the relatively small scale of the LVR.

Emission Spectroscopy of Pulsed Powered Microplasma for Surface Treatment of PEN Film

Microplasma can be found in many applications. The technology is also used for surface treatment of polymers. The process of surface treatment by microplasma is environmental friendly, and it could be realized at low cost due to the relatively low discharge voltage (around 1 kV) even under atmospheric pressure and the small size of the power supply and reactor. This paper presents the surface treatment by microplasma of polyethylene naphthalate (PEN) film using Ar gas and mixtures of Ar with N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> and O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> . The microplasma process was analyzed by the emission spectroscopy method. An experimental Marx generator with MOSFET switches was used as a pulsed high-voltage power supply. The emission spectra were measured by an intensified charge coupled device camera, a spectrometer, and a photomultiplier tube. Surface wettability of the PEN film was confirmed by measuring the contact angle before and after the microplasma surface treatment. It was observed that the contact angle of the PEN film decreased, especially with the O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /Ar mixture. The analysis using an X-ray photoelectron spectrometer showed the decrease of C1s, which correspond to the C-H bond. The emission spectrum of the microplasma discharge in the N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /Ar mixture showed Ar peaks, OH peaks, N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> second positive band system peaks (N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> SPS), N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> first positive band system peaks ( N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> FPS), and decrease in the peak intensities of ArI and OH for microplasma discharge in the O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /Ar mixture. The lifetime emission signals for the N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> SPS for the microplasma discharge in 0.25% N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> in Ar were around 1 μs. The calculation of the microplasma rotational and electron temperatures shows low rotational and high electron temperatures.

Study of the optical properties of a pulse-periodic high-pressure cesium discharge

Results of theoretical and experimental studies of the optical spectrum of a pulse-periodic high-pressure cesium discharge are presented. The results of calculations are in good agreement with experimental data. The possibility of creating an efficient light source based on recombination emission from the discharge plasma is demonstrated. The formation mechanisms of the continuous spectrum of discharge radiation are considered.

Plasma diagnostics of the barrier discharge in humid argon by cross-correlation spectroscopy

Results of plasma diagnostics of the barrier discharge in humid argon are presented that were obtained by means of the method of cross-correlation spectroscopy. The emission spectrum of the barrier discharge in humid argon was determined. The development of a microdischarge in the system being considered is demonstrated to occur via a multiphase mechanism. The metastables of argon are shown to play a key role in this process.

Discharges in Water and Applications to Wasted Water Treatment

Recently the electrical discharge in water has been used for the water treatment. In this study, various shape of electrodes were examined to observe and measure the electrical discharge phenomena in water. Both the Marx generator and the pulsed power generator were used to generate the discharge in water. The oscillation on the waveforms of both applied voltage and discharge current was observed using the pulsed power generator whose peak applied voltage was about 80-120 kV and its discharge repetition rate was about one pulse per thirty seconds although it wasn't observed on the waveforms in the practical use of the high voltage generator (peak applied voltage was about 30-40 kV) with high repetition rate of discharge (20-300 pulses per second). Bubbles were introduced into the discharge region of main electrode using the ejector and the generation of hydroxyl radicals (OH) was confirmed by the measurement of emission spectrum of discharge in water and the intensity of OH radicals increased with the ratio of G/L (where, G is gas flow rate and L is water flow rate). The hydrogen peroxide (H2O2) was also measured and this reactor system was applied for the de-color of water.

Millimeterwave spectrum of DC discharge produced ICN in excited vibrational states

An indigenously built 50 kHz source-modulated millimeter-wave spectrometer was used to produce cyanogen iodide (ICN) in the excited vibrational states (0110), (0330), (1000), (2000) and (0200) and record their corresponding rotational spectra. The analysis of the recorded spectra was carried out in the frequency range of 57.0–98.0 GHz. ICN was produced using a DC glow discharge through a mixture of methyl iodide (CH3I) and benzyl cyanide (C6H5CH2CN) vapor at low pressure. 127I nuclear quadrupole hyperfine structure and the l-type doublet spectra of (0110) state have been resolved. The observed and assigned rotational transition frequencies were used in a least-square fit to determine more accurate values of molecular constants. The agreement between the derived parameters and those reported earlier clearly indicate that the reported spectral lines belong to ICN in the excited vibrational states. It also indicates that ICN could be produced in selective excited vibrational states by DC glow discharge technique.

Characteristics of emissive spectrum and the removal of nitric oxide in N 2/O 2/NO plasma with argon additive

Although the approach using non-thermal plasma (NTP) for deNO x has been studied for over 15 years, how to achieve higher removal efficiency with lower cost is still a barrier for its industrial application. In order to investigate the impact of the argon additive on electron density, energy and nitric oxide reduction process in plasma, the spectrum of the dielectric barrier discharge at atmospheric pressure in a coaxial reactor was measured using the monochromater with high resolution. The comparative experiments for NO reduction were carried out simultaneously in N 2/O 2/NO plasma stream with and without argon, respectively. The nitrogen molecular spectrum which is attributed to the energy level transition (C 3π u → B3π g) was compared in the wavelength range 300–480 nm and the electron density and temperature were determined based on the relative intensities and Stark broadening width of spectral lines. The spectrum results indicated that the argon additive could enhance the intensity of emissive spectrum of plasma, thus the electron concentration as well as the energy was increased, and finally prompted the ionization rate to produce active N, O and O 3. The results of NO reduction showed that NO conversion efficiency increased in the range of 10%–30% with 5% addition of argon in stream comparing with the condition without argon additive. This study will play a positive role in the industrial application of dielectric barrier discharge deNO x reactor.

Visible emission spectrum of pulse-periodic discharge in high-pressure cesium vapor

The spectrum of pulse-periodic discharge in high-pressure cesium vapor has been studied by experimental and theoretical methods. Experiments confirmed a significant shift of the 6P and 5D recombination continuum thresholds toward longer wavelengths, which was theoretically predicted previously for the emission from discharge in a dense cesium plasma. The overlapping continua form an almost continuous spectrum of emission in the visible spectral range. The results of calculations well agree with the experimental data. It is established that the discharge under consideration is an effective, mercury-free source of light with a color rendering index of Ra = 98 and a light yield of η = 81 lm/W.

Ar gas discharge lamp with heated LiF window: A monochromatized light source for photoemission

We present a simple, inexpensive, and highly effective method for monochromatizing the vacuum ultraviolet light emitted from an Ar gas discharge for use, e.g., in photoemission experiments. By using a slightly heated window of LiF acting as low-pass filter, the emission spectrum of the Ar gas discharge is reduced to the Ar line at 11.62eV (106.7nm). The performance of the low-pass filter is demonstrated by photoemission measurements on Cu(111). Furthermore, we compare our light source with an unmonochromatized He gas discharge, which represents the most widely used laboratory photon source in photoemission.

Po River discharges: a preliminary analysis of a 200-year time series

Daily stage data measured at the closing section of the Po River (Northern Italy), collected from historical archives of the “Hydrological Office of the Po River—Parma”, allowed to estimate daily discharges for the period 1807–1916, therefore to extend the time series of Po River discharges for 110 years before the actually published time series. This paper provides a detailed description of the stage–discharge conversion and of the tests performed for checking homogeneity of reconstructed data. In particular, monthly discharge data were compared with approximated catchment-average data of precipitation and evapotranspiration for the period 1831–2003, which were estimated, respectively, from monthly data of local precipitation (at Milan, Turin and Parma) and local air temperature (at Milan and Turin). It emerges that estimated values of precipitation, evapotranspiration and discharge provide a coherent picture of the hydrological dynamics in the basin throughout the study period. Specifically, an apparent progressive depletion of basin reservoirs is observed since 1920, i.e., when concomitant sudden changes (regime shifts) occurred in precipitation (downward shift) and evapotranspiration (upward shift). The 1920-shift is amongst the likely causes of the fact that prolonged drought periods as those observed in the 1940s and since 2003 are not observed in the pre-shift period, when accumulation of reservoirs occurred. The increase in peak-flow discharges observed in recent decades, with values well above the maximum discharge estimated for the nineteenth century as well as for the early twentieth century, is apparently the result of the massive levee works along the river network that were completed in the 1960s. On decadal time scales, discharge variability is found to essentially reflect the changes in precipitation patterns. In particular, peaks of comparable magnitude are found in the 128-month (∼11 years) wavelet spectra of precipitation and discharge. Furthermore, concurrent changes are observed in the persistence (i.e., autocorrelation) of precipitation and discharge data. Since the red-noise background spectrum of discharge is much lower than that of precipitation, river discharge is the likely hydrological variable to be preferred for assessing the basin’s response to the background climatic variability occurring at the decadal and multi-decadal time scales, notwithstanding the fact that changes in water management and other anthropogenic impacts can be important on long time scales. Concerning the seasonal to interannual response to climatic forcing, a robust dependence of wintertime precipitation and discharges on the state of the NAO was observed. This dependence results in stronger (weaker) precipitation and higher (lower) discharges during negative (positive) anomalies of the NAO index.

DC-excited discharges in vapour bubbles in capillaries

DC-excited discharges in vapour bubbles in capillaries are studied. A bubble is generated in a capillary filled with a NaCl solution due to Joule heating. The fluid columns on either side of the bubble serve as electrodes for the electrical discharges inside the bubble. The electrical breakdown (corresponding to a corona-to-spark transition) of quasi-static vapour bubbles is discussed. The breakdown electrical field decreases with bubble length. For larger bubbles, the reduced electrical field is smaller than the electrical field where electron attachment equals ionization, indicating that the discharge is a surface discharge. Linear translation of bubbles in the cathode direction, coinciding with intense discharges inside the bubbles, is observed and can be explained by asymmetric heating due to the plasma. The optical emission spectrum of a vapour bubble discharge consists of excited hydroxyl, hydrogen and sodium emission. A delay in the range of 0.1 s is observed between the emission of hydroxyl and sodium. The sodium emission is most intense on the anode side of the bubble where orange anode spots are visible.

Spectroscopic Observation of the Resonance-Stabilized 1-Phenylpropargyl Radical

The gas-phase laser-induced fluorescence (LIF) spectrum of a 1-phenylpropargyl radical has been identified in the region 20,800-22,000 cm(-1) in a free jet. The radical was produced from discharges of hydrocarbons including benzene. Disregarding C2, C3, and CH, this radical appears as the most strongly fluorescing product in a visible wavelength two-dimensional fluorescence excitation-emission spectrum of a jet-cooled benzene discharge. The structure of the carrier was elucidated by measurement of a matching resonant two-color two-photon ionization spectrum at m/z = 115 and density functional theory. The assignment was proven conclusively by observation of the same excitation spectrum from a low-current discharge of 3-phenyl-1-propyne. The apparent great abundance of the 1-phenylpropargyl radical in discharges of benzene and, more importantly, 1-hexyne may further underpin the proposed importance of the propargyl radical in the formation of complex hydrocarbons in combustion and circumstellar environments.

Mechanism for generating stimulated VUV emission of the Xe*Kr dimer in a dc capillary discharge

The emission spectrum of a dc capillary discharge in krypton with a small (&#8804;0.1%) xenon impurity has been experimentally studied in the 115-850-nm range. It is shown that most of the radiation energy is concentrated in a narrow VUV spectral band adjacent to the 146.96-nm resonance line of xenon and belonging to the heteronuclear Xe*Kr molecule. The power of the narrow-band VUV radiation and its angular dependence have been measured. A conclusion is drawn that the appearance of the narrow-band VUV radiation represents amplified spontaneous emission caused by transillumination of the broad-band amplifying medium by a narrow-band "seed."

Spectroscopic investigation of the bipolar pulsed discharge in water-air mixture

Emission spectrum of the bipolar pulsed discharge in water-air mixture has been measured in the near-ultraviolet (UV) region using an Inspectrum 300 charge-coupled device (CCD) spectrograph. Effects of several parameters including peak-to-peak voltage, pulse repetitive frequency, etc., on the relative UV radiation intensity have been investigated. Experimental results show that bipolar pulsed discharge in water-air mixture emits strong UV radiation. The emission spectrum of the discharge has a wide range. The applied peak-to-peak voltage, pulse repetitive frequency, and air flow rate have positive effect on the relative intensity of the second positive band of nitrogen at 337.1 nm. However, solution conductivity has negative effect

The Effect of Buffer Gas and Excitation Mode in Low Pressure Nitrogen Discharges

In this paper we demonstrate the influence of buffer gas atoms on the emission spectrum of a low-pressure nitrogen discharge. If the conditions of operation of the discharge allow for the population of the energy levels of the buffer gas atoms then energy stored in the metastable states of these atoms can be transferred through collisions to the atoms of the active medium. This results in a higher degree of excitation of the latter with significant effects on the optical output of the source.

Gap junction blockade does not alter eupnea or gasping in the juvenile rat

The role of gap junctions in the brainstem respiratory control system is ambiguous. In the present study, we used juvenile rats to determine whether blocking gap junctions altered eupnea or gasping in the in situ, arterially perfused rat preparation. Blockade of gap junctions with 100 microM carbenoxolone or 300 microM octanol did not produce any consistent changes in the timing or amplitude of integrated phrenic discharge or in the peak frequency in the power spectrum of phrenic nerve discharge during eupnea or ischemic gasping beyond those changes seen in time-control animals. These findings do not rule out a role for gap junctions in the expression of eupnea or gasping, but they do demonstrate that these intermembrane channels are not obligatory for either rhythm to occur.

Application of wavelet analysis for monitoring the hydrologic effects of dam operation: Glen Canyon Dam and the Colorado River at Lees Ferry, Arizona

Wavelet analysis is a powerful tool with which to analyse the hydrologic effects of dam construction and operation on river systems. Using continuous records of instantaneous discharge from the Lees Ferry gauging station and records of daily mean discharge from upstream tributaries, we conducted wavelet analyses of the hydrologic structure of the Colorado River in Grand Canyon. The wavelet power spectrum (WPS) of daily mean discharge provided a highly compressed and integrative picture of the post-dam elimination of pronounced annual and sub-annual flow features. The WPS of the continuous record showed the influence of diurnal and weekly power generation cycles, shifts in discharge management, and the 1996 experimental flood in the post-dam period. Normalization of the WPS by local wavelet spectra revealed the fine structure of modulation in discharge scale and amplitude and provides an extremely efficient tool with which to assess the relationships among hydrologic cycles and ecological and geomorphic systems. We extended our analysis to sections of the Snake River and showed how wavelet analysis can be used as a data mining technique. The wavelet approach is an especially promising tool with which to assess dam operation in less well-studied regions and to evaluate management attempts to reconstruct desired flow characteristics. Copyright © 2005 John Wiley & Sons, Ltd.

Calibration of a calorimeter for measuring the spark energy of an electrostatic discharge

This paper deals with the factors that influence the accuracy of the measurements performed with a calorimeter, developed to detect the optical signal emitted by the spark generated to facilitate experiments with electrostatic discharge. Experiments are described which were performed with a special calorimeter and a compound optical source consisting of a spark gap, a human-body-model electrostatic discharge (ESD) signal generator, and four LEDs. The spark gap was used as a versatile and more powerful source of optical emission than the human-body-model circuit; the LED source was used for calibration and alignment. For control, the spectrum of the spark discharge was measured with a spectrometer and a broadband photodetector. The calorimeter was used as a means for the determination of the energy contained in the optical signal, yielding the value of the spark-gap emission in the fundamental units for energy. The long-term stability of the system was measured, and the system response was studied for threshold optical signals. The calorimeter detectivity, defined as the overall instrument sensitivity, measured in volts per joule, was D=4.3/spl times/10/sup 7/ V.J/sup -1/ and its detection limit 2.3/spl times/10/sup -13/ J. The system's response to the IEC standard human-body-model circuit was consistent with the measurements of the system's detectivity. Most parts of the developed apparatus have been tested in an industrial environment.

The VUV Absorption Spectra of SiF and SiF+

The absorption spectrum of a microwave discharge (2450 MHz) in flowing helium with traces of SiF4has been recorded on the SA61 beam line of SUPERACO between 2000 and 500 Å. Two new ionization energies have been observed at 15.12 and 17.27 eV corresponding, respectively, to theA1Π andB1Σ+states of SiF+. TheA1Π ← X1Σ+transition of the ion has been identified for the first time on high-resolution spectra obtained in 1992 with the 35-foot Eagle spectrograph in Meudon.

Observation of multiple-peaked structure in the time-of-flight spectrum of the Sinp-tokamak discharge

In the present article a multiple-peaked structure in the time-of-flight (TOF) spectrum obtained in a TOF analyzer system installed in the Sinp-tokamak has been reported. An explanation of the nature of the measured TOF spectrum has been given on the basis of a proposed model describing acceleration, in the radial direction, of radially diffusing ions in the ambipolar electric field. It is concluded that the particle diffusion across the magnetic field as a result of acceleration by the dynamic ambipolar electric field and charge-exchange collisions can be studied by a TOF analyzer system coupled with a research tokamak.