UA55726A - Electric-discharge selective excimer lamp with visible radiation - Google Patents

Abstract

The proposed electric-discharge selective excimer lamp with visible radiation contains electrodes and gas working medium. As the gas working medium, mix of mercury dibromide vapors with helium is used. The main working wavelengths of the lamp are disposed within the band with the maximal wavelength of 502 nm corresponding to the spectral band of mercury monobromide molecule (HgBr) at the B-X transition. The gas working medium is in a cavity restricted by coaxially arranged quartz tubes with the welded up ends. Surface discharge is used as the plasma electrode for forming the discharge through dielectric. The radiation pulse frequency of the lamp is 2000 Hz. The maximal averaged power of the visible radiation of the lamp is 0.6 W.

Description

The invention relates to gas-discharge electronics, lighting technology and can be used for pumping solid-state and liquid lasers, in biotechnology, agrophysics and medicine.

A known excimer source of spontaneous radiation in the visible range on the system of molecular bands NOV!" (B-X transition) with a maximum emission at a wavelength of 7. equal to 502 nm, which is excited during the photodissociation of NoVig vapors by the light of a continuous xenon lamp previously passed through the monochromator 11.

The disadvantage of the known source is that the optical pumping of mercury monobromide molecules by a xenon lamp using a monochromator complicates and makes the experimental setup cumbersome.

The prototype for the proposed excimer lamp is a radiation source that contains a system of electrodes, a volume with a working mixture, which was excited by long-term (10 - 15 μs) broadband radiation of a surface discharge with a linearly stabilized spark channel (21. Generation was carried out at Vexx transitions of NOV molecules, which were formed from the original NOV molecules: as a result of photodissociation under the action of short-wave UV radiation. The maximum radiation was observed at X wavelengths equal to 502 and 504 nm. The energy in the radiation pulse was equal to 0.5 J, the duration of the radiation pulse was equal to 4 μs. The maximum pulse repetition rate was equal to 0 ,1 Hz.

Common essential features of the prototype and the invention: a source of radiation in the visible range, which contains a system of electrodes, a volume with a working mixture of mercury dibromide vapors with a buffer gas, the main working waves of which are the radiation of the mercury monobromide molecule NoVg at the B-X transition with a maximum at the length waves of 502 nm

The known device has a drawback. The maximum repetition frequency of pulses is limited by the recovery time of the electrical strength of the interelectrode space of the surface discharge and cannot exceed 100 Hz |21.

The task of the invention is to increase the frequency of repetition of discharge pulses of the lamp and to use a discharge system in the excimer lamp of the visible range, in which the surface discharge is a plasma electrode for discharge through the dielectric.

The task is achieved in such a way that an electric discharge lamp of the visible range, containing a system of electrodes, a volume with a working mixture of mercury dibromide vapors with helium, the main working radiation waves of which are a system of molecular bands with a maximum at a wavelength of 502 nm of a molecule of mercury monobromide NoVg per V -X - transition, which according to the invention differs in that the volume with the working mixture is limited by coaxially placed quartz tubes that are welded at the ends, and in the electrode system the surface discharge is a plasma electrode for discharge through the dielectric, while the frequency of repetition of radiation pulses is equal to 2000Hz, and the maximum average power of visible radiation M/ is 0.6W.

The advantages of the proposed electric discharge excimer lamp of the visible range over the prototype are an increase in the frequency of following discharge pulses up to 2000 Hz, the use of a discharge through a dielectric, in which the surface discharge plays the role of a plasma electrode.

Fig. 1, 2 shows the design of the excimer lamp in longitudinal and transverse sections. An excimer lamp for the visible region of the spectrum consists of coaxially installed quartz tubes 1 and 2 with a length of 20 cm, which are welded at the ends. The outer diameters of the tubes are 15mm and 35mm, respectively. The electrodes of the DRT-240 mercury lamp, which are welded into the side surface of the cuvette, are used as inputs. A nickel foil tube 4 is installed inside the quartz tube 1. A grid 5 with a radiation transmission coefficient of 7295 was attached to the outer diameter of tube 2. Electrodes 6, which have the shape of rings, are made of stainless steel. The distance between them is 18 cm.

For the pumping out and inflow of gases, a pipe 7 made of quartz glass was welded into the side surface of the cuvette, inside which there is a capillary with a diameter of 1 mm, which serves to reduce the removal of mercury dibromide vapors from the cuvette into the pumping system.

The thickness of the discharge region is 8 and the burning length of the volumetric discharge is 7.5 mm and 9 cm, respectively. The radiation is emitted from the gas discharge cuvette normally to the surface of the outer quartz tube.

An excimer lamp of the visible range works as follows: 100 - 200 kPa of helium was injected into a discharge tube previously pumped to a pressure of 107 "Pa, which contained mercury dibromide powder in the amount of bOmg. When the working mixture was excited only by a barrier discharge, a pulse voltage of 15 - 21 kV at a pulse tracking frequency of 1-2kHz, a pulse was applied between tube 4 and grid 5, while when barrier and surface discharges were used at the same time, high voltage was applied to metal tube 4 and one of the electrodes 3, and the second electrode C and the grid were grounded.

With the simultaneous application of barrier and surface discharges, the latter played the role of a plasma electrode for the barrier discharge.

Dissociative excitation of mercury dibromide by discharge electrons takes place in the plasma based on the NoVg/He mixture, as a result of the reaction NoVign-"NoVg(V)-Vgne" excimer molecules of NoVi are formed, which spontaneously transition to the ground X state with the emission of a system of bands with a maximum at the wavelength X, equal to 502nm NoVg(V-X).The working surface of the lamp is that part of the side surface of the discharge tube that is covered with a grid.

An increase in the helium pressure to 200 kPa for the NoVig/He mixture leads to an increase in the average radiation power by 1.7 times compared to the value at a helium pressure equal to 141 kPa.

The highest average radiation power from the entire side surface of the lamp is 0.6 W at a value of the coefficient of useful action in relation to the input power of 19565. It can be increased by increasing the repetition frequency of the pump pulses to values of 4 - 5 kHz and the voltage on the electrodes of the excimer lamp.

The effectiveness of the invention is determined by the fact that, compared to the prototype, the repetition frequency of radiation pulses is increased by 20,000 times (from 0.1Hz to 2000Hz), the average radiation power is increased by 2-3 times at the same efficiency values.

The invention can be used in conducting scientific research in biotechnology, agrophysics, medicine and quantum electronics.

Sources of information 1. Bazhulin S.P., Basov N.G., Zuev V.S., Leonov Yu.S., Stoilov Yu.Yu. Generation at X-502nm during long-term light pumping of NovVig vapors" // Quantum electronics. 1978. T.5, Me3. P.684 - 686. 2. Bazhulin S.P., Bugrymov S.N., Kamrukov A.S., Kashnikov G.N., Kozlov N.P., Ovchinnikov P.A., Opekai A.G., Orlov

V.K., Protasov Yu.S. Blue-green laser! on vapors of mercury halides with broadband optical excitation // Proceedings of the KhII All-Union Conference on Coherent and Nonlinear Optics. 1985. Part 2. P.713 - 714. (prototype).

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Claims (1)

Electric discharge selective excimer lamp of the visible range, containing a system of electrodes, a volume with a working mixture of mercury dibromide vapors with helium, the main working radiation waves of which are a system of molecular bands with a maximum at a wavelength of 502 nm of a molecule of mercury monobromide NeVIi at the B-X transition , which differs in that the volume with the working mixture is limited by coaxially placed quartz tubes, which are welded at the ends, and in the electrode system, the surface discharge is a plasma electrode for discharge through the dielectric, while the repetition frequency of radiation pulses is 2000 Hz, and the maximum average the power of visible radiation V is 0.6 W.