RU2089971C1 - Method for pumping glow lamp having negative-polarity gases in working mixture - Google Patents

Abstract

FIELD: lighting engineering. SUBSTANCE: voltage is applied to lamp electrodes and current is passed through working mixture. Voltage is supplied in unipolar pulses of length t chosen from condition 10^-5s ≅ t ≅ 10^-2 and amplitude exceeding firing voltage and sufficient to pass unipolar current through lamp, average density j of current being for each voltage pulse within the range of 10^-2A/cm²s ≅ j ≅ 10^-1A/cm² within time t₁ found from expression 0,25 ≅ t₁≅ 0,7t. EFFECT: improved mean radiation power and efficiency of lamp. 2 dwg

Description

 The invention relates to the field of lighting, and more particularly to methods for pumping glow lamps with electronegative gases in a working mixture. Such lamps have been intensively studied recently and are beginning to be used in science and technology.

Known methods for pumping glow lamps with electronegative gases, which include passing direct current through a lamp [1,2]. When these pump methods were implemented, due to the correct choice of the working mixture, comparatively high radiation efficiencies were obtained for KrCl ^* and XeCl ^* molecules. However, when pumped with direct current, the distribution of radiation power along the length of the lamp is uneven.

There are also known methods of pumping glow lamps with electronegative gases in the working mixture, based on passing current pulses through the working mixture [3-5] The method [5] for the set of essential features we have chosen as a prototype. Due to the non-optimal parameters of the pump pulses (current density, pulse duration, the relationship between the pulse duration and the pause duration between pulses), as well as the composition of the working mixture, low average radiation powers and efficiencies were obtained in these methods, in particular, on transitions of KrCl ^* and XeCl molecules ^* .

 The present invention is to increase the average radiation power and efficiency of the lamp.

The solution to this problem is achieved by the fact that in the known method of pumping a glow discharge lamp with electronegative gases in a working mixture, which consists in applying voltage to the electrodes and passing current through the working mixture, according to the invention, the voltage is supplied by unipolar pulses of duration t, selected from condition 10 ^-5 s ≅ t ≅ 10 ^-2 s, and the value of the amplitude value exceeding the discharge initiation voltage and sufficient to pass through the lamp unipolar current, average density value for each j which counts lsa voltage lies in the range of 10 ^-2 A / cm ² ≅ j ≅ 10 ^-1 A / cm ² for a time t _1, the relation defined 0,25t ≅ t ₁ ≅ 0,7t.

When voltage pulses are applied to the lamp electrodes, a breakdown of the working gas occurs, leading to the flow of a unipolar current through the lamp during the action of the voltage pulse. When current flows, the working mixture is excited and ionized. Further, as a result of plasma-chemical reactions, exciplex RX ^* molecules are formed, the radiation of which is the useful radiation of the lamp.

 Figure 1 presents a diagram of a device with which the inventive method is implemented; figure 2 is a graph of the efficiency of the lamp on current density.

 The device diagram contains a pulsed pump source 1 and a cylindrical quartz tube 2, at the ends of which there is a pipe for pumping and filling the working mixture 3 and electrodes 4. The quartz tube 2 with electrodes 4 is a lamp emitter.

 The device operates as follows.

A working mixture is injected into the lamp emitter, for example, a mixture of krypton with chlorine, and pump source (generator) 1 is turned on, which provides unipolar voltage pulses to the electrodes 4 with a duration of 10 ^-5 s ≅ t ≅ 10 ^-2 s and an amplitude value exceeding the value the breakdown voltage of the working mixture, which leads to the development of a pulsed discharge between the electrodes 4. After the breakdown of the working mixture, the pump source 1 provides a current with an average density j passing through the lamp emitter, the value of which lies within 10 ^-2 A / cm ² через j ≅ 10 ^-1 A / cm ² during the time t ₁ determined by the ratio of 0.25t ≅ t ₁ ≅ 0.7t. When current flows through the working mixture as a result of excitation and ionization of krypton and dissociative attachment of electrons to Cl ₂ (for the Kr-Cl ₂ mixture), mainly KrCl * molecules are formed due to the harpoon reaction, which emit ≈80% of the energy emitted at the B – X, λ transition ≈ 222 nm. Work with the above ranges of parameters allows you to get maximum efficiency and average radiation power with a relatively uniform distribution of radiation density along the length of the lamp.

As an example, we present the results of the implementation of the proposed method when receiving radiation on KrCl ^* molecules, l ≈ 222 nm, in Kr-Cl ₂ (HCl) mixtures, substantiating the indicated limits for current density, current pulse duration, and the relationship between current pulse durations and pauses between current pulses. So, when conducting tests, the average radiation power was obtained in the region l ≈ 222 and 308 nm> 100 W with an efficiency of up to 14%, which significantly exceeds the results obtained in the prototype [5] and analogues [1-4]
With increasing current density, the efficiency initially increases, reaches a maximum at j ≈ 3 • 10 ^-2 A / cm ² , and then begins to decrease. So, at j ≈ 10 ^-1 A / cm ^{2 the} radiation efficiency of KrCl ^* molecules decreased by 2 times. The experimentally obtained dependence of the efficiency on the current density is shown in FIG. 2. With a decrease in current density j <10 ^-2 A / cm ^{2, the} discharge becomes unstable and the radiation power decreases by an order of magnitude or more. Based on these and similar experiments, the range of the claimed current densities was chosen.

For pulse durations ≥ 10 ^-2 s, when the discharge approaches a continuous one, the distribution of the radiation power density along the tube length begins to deteriorate, similar to [4] and the average radiation power and efficiency decrease by ≈15% in the stationary mode. When reducing the pulse duration <10 ^-5 s, the average power and efficiency also begin to decrease due to the fact that the discharge formation time becomes comparable with the duration of the current pulses. Note that for pulse durations of ≅ 5 • 10 ^-7 s, the efficiency and average radiation power decrease by more than an order of magnitude.

Replacing unipolar pump pulses with bipolar ones under optimal conditions led to a decrease in the average radiation power and efficiency by more than 25%
A change in the ratio between the duration of the current pulse and the duration of the pause between pulses showed that for t ₁ ≥ 0.7t the pump mode begins to approach the pump mode with a continuous current, which leads to a decrease in the lamp efficiency and a deterioration in the uniformity of the distribution of the average radiation power along the lamp length. So, for a KrCI lamp at t ₁ > 0.7t, the average radiation power decreased by 15%. At t ₁ 0.25t for a KrCI lamp, the radiation efficiency decreased by 30% and then continued to decrease at t ₁ > 0.25t.

In addition to the emission of KrCI ^* molecules, we also studied the parameters of pumping and emission of XeCI ^* molecules, l ≈ 308 nm, both in binary mixtures of Xe CI ₂ (HCI) and in ternary mixtures with buffer gases helium or neon, and similar results were obtained. Measurements for Xe NF ₃ mixtures in which XeF ^* molecules emit, l ≈ 305 nm, performed for a narrower range of parameters for current densities and pulse durations also confirm the parameters for current densities and durations indicated in the present invention.

Sources of information
1. A.P. Golovinsky. Possibilities of creating effective ultraviolet emitters based on a continuous glow discharge in mixtures of inert gases and halogens // Letters in ZhTF, vol. 18, p. 73-76, 1992.

 2. A.P. Golovinsky. V.S. Kahn. Characteristics of ultraviolet excimer radiation of a continuous glow discharge of low pressure // Optics and Spectroscopy, vol. 75, v. 3, pp. 604-609, 1993.

 3. V.A. Vizier, V.S. Skakun, G.V. Smorudov, E.A. Sosnin, V.F. Tarasenko, E.A. Fomin. Coaxial excilamps pumped by barrier and longitudinal discharges // Quantum Electronics, vol. 22, No. 5, pp. 519-522, 1995.

 4. H. Kumagai, M. Obara. Theoretical and Experimental Study of KrF Fluorescence in a Multimicrosecond Longitudinal Discharge // IEEE Transactions on Plasma Science, v. 16, No. 4, p. 453-458.

 5. R.S. Taylor, K.E. Leopold, and K.O. Tan. Continuons B-X excimer fluorescence using direct current discharge excitation // Appl. Phys. Lett. v. 59, N 5, p. 525-527, 1991.

Claims (1)

The method of pumping a glow discharge lamp with electronegative gases in the working mixture, which consists in applying voltage to the electrodes and passing current through the working mixture, characterized in that the voltage is supplied by unipolar pulses of duration t, selected from the condition 10 ^{- 5} s ≅ t ≅ 10 ^{- 2} s , and with an amplitude value exceeding the value of the discharge ignition voltage and sufficient for passing a unipolar current through the lamp, the average density j of which for each voltage pulse is in the range 10 ^{- 2} A / cm ² ≅ j ≅ 10 ^{- 1} A / cm ² , during the time t ₁ defined by the relation 0.25 t ≅ t ₁ ≅ 0.7 t.

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