In this work the broadening of the red wing of the 253.7 nm resonance mercury line is used to determine the radial distribution of the neutral atom density in a high-pressure mercury discharge. Abel inversion allows resolution of the integral relation between the wavelength at the maximum intensity of the red-wing resonance line and the square of the neutral atom density. This method, which does not require the assumption of local thermodynamic equilibrium, is applied to the pressure range 0.2 - 5 bar. Results are compared with those obtained from the broadening of the 491.6 nm mercury line.
In this paper, a high-frequency dimmable electronic power supply for the highpressure sodium lamp is presented. The method includes a full bridge rectifier generating a dc-link voltage and a half bridge inverter to generate a frequency swept lamp power signal to drive the lamp while avoiding acoustic resonance. A dimming technique for a resonant circuit electronic ballast based on a variable frequency is introduced. In addition, the ability in the dimming range is demonstrated by experiments and simulation in order to verify the performance of the proposed circuit. A dimming range from 100% to 50% has been achieved. The efficiency is always higher than 89% and the ballast can accurately follow a fixed dimming plan.
The determination of the radial profile of the ground state density without assuming local thermodynamic equilibrium (LTE) conditions in around atmospheric pressure (0.01 MPa<p<0.3 MPa) discharges used as light sources is a worthy investigation subject. This work deals with the high-pressure mercury discharge which could be considered as a “test case.” Particularly useful for the diagnostics of these plasmas is the self-reversed resonance mercury line 253.7 nm. In this article, two independent experimental methods were used: emission spectroscopy, called the “ΔλR method,” and interference shift measurements “hook method.” Using the Hg-253.7 nm resonance line, both experimental methods indicate similar deviations from LTE in particular for the lower pressure discharges (p<0.04 MPa). In those cases, the experimental errors for both methods are significantly lower than the detected deviations. Furthermore, the measured deviations are in good agreement with predicted values from a two-temperature, two-dimensional fluid model developed elsewhere.
Results of spectral and photometric measurements are presented for pulsed power operated high intensity discharges (HIDs). This investigation is related to the application of a pulsed power supply for pile driving of HID lamps. Specifically, we are interested in controlling the spectral response radiation of visible and ultraviolet (UV) lines for tertiary treatment of water using UV radiation. Simulations based on a physical model of the lamps were conducted. These results relate to the radial temperature, line intensity and electrical properties (voltage, power and conductivity). Good agreement has been found between the results of the simulations and the experimental findings.
This paper deals with radiation transfer in cylindrical high pressure discharges for which local thermodynamic equilibrium can be assumed. An S–N approximation (a set of N discrete directions) of the discrete ordinates method is used to solve the radiative transfer equation. A summary of the basic equations and numerical formulations is given in order to calculate the spectral intensities and then to evaluate radiative flux and net emission coefficient. Also, the net emission coefficient is described by a semi-empirical formula which contains terms representing the generation and absorption of radiation. The results are presented for a typical high pressure mercury discharge commonly used as a light source.
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