RU2254639C1 - Spectroscopic gas-discharge lamp - Google Patents

Abstract

FIELD: hollow-cathode spectroscopic gas-discharge lamps for nuclear absorption analyzing equipment.

SUBSTANCE: proposed spectroscopic gas-discharge lamp has bulb with radiation output uviol glass window transparent in ultraviolet spectrum; this bulb accommodates anode and hollow cathode placed in insulating tube and provided with internal discharge surface in the form of cylinder open on radiation output end which is made of material whose spectrum is to be obtained. Hollow cathode is provided with 2 or 4, or 8, or 16, or 32 additional discharge surfaces in the form of incomplete cylinders disposed over circle in parallel to discharge surface which are crossing the latter to form single discharge surface with common glow-discharge area. Distance between main-surface cylinder axis and axes of additional-surface cylinders meets expression l = Ro + (0.5 - 0.8) Rg, where Ro is radius of main-surface cylinder and Rg is that of additional gas-discharge surface cylinders.

EFFECT: enhanced radiation intensity of cathode resonant lines.

1 cl, 2 dwg

Description

The present invention relates to a class of gas-discharge spectral light sources intended for use in atomic absorption analysis equipment.

A known design of a gas-discharge spectral lamp with a hollow cathode emitting spectra of various chemical elements, containing a flask with an uvole window for the emission of radiation transparent in the ultraviolet part of the spectrum, and an anode and a hollow cathode located in it, placed in an electrical insulation tube having an internal discharge surface in the form a cylinder open on the output side of radiation made of a material whose spectrum is to be obtained [Л1]. The anode has the shape of a cylinder with a rod mounted inside it.

The hollow cathode is placed in an insulating tube with a small gap. To increase the radiation intensity, elements of wire or foil are inserted inside the cathode cavity. The anode, cathode and electrical insulating tube are assembled on a glass leg. The lamp is filled with an inert gas (neon) to a certain pressure. When such a lamp is connected to a power source between the inner surface of the cathode and the anode, a glow discharge in an inert gas is ignited. Under the influence of intense ion bombardment in a glow discharge, the cathode material is atomized.

Spray products in the form of neutral atoms fall into the gas discharge, are excited there and emit lines belonging to the spectrum of this element, the radiation intensity of which is used in atomic absorption analysis devices.

The disadvantages of lamps of this design include a small value of the radiation intensity of the resonance lines of the cathode element.

Despite the fact that additional elements in the form of a wire or a foil are inserted into other types of structures inside the discharge cavity of the cathode, the radiation intensity of the resonance lines has slightly increased, but not enough 2. A more substantial increase is required for high-quality operation in atomic absorption analysis equipment. Moreover, not every metal can have additional elements. For metals such as potassium, sodium, arsenic, etc., additional elements cannot be manufactured. Therefore, to increase the radiation intensity for many metals, other technical solutions must be sought.

The technical result of the invention is to increase the intense radiation of the resonance lines.

To achieve a technical result in a spectral atomic absorption gas discharge lamp containing a flask with a uviole window for the emission of transparent radiation in the ultraviolet part of the spectrum and anode and hollow cathode located in it, placed in an electrical insulating tube having a main internal discharge surface in the form of a cylinder open with the output side of radiation made from a material whose spectrum is to be obtained.

, где R_o - радиус цилиндра основной разрядной поверхности, R_д - радиус цилиндров дополнительных разрядных поверхностей.The hollow cathode is made with 2, or 4, or 8, or 16, or 32 additional discharge surfaces, having the form of incomplete cylinders, arranged in a circle and parallel to the main discharge surface and intersecting with it, forming a single discharge surface with a total combustion area. Moreover, the distance from the cylinder axis of the main discharge surface to the cylinder axis of the additional surfaces satisfies the expression:

where R _o is the radius of the cylinder of the main discharge surface, R _d is the radius of the cylinders of the additional discharge surfaces.

The main discharge surface together with additional discharge surfaces form one common hollow cathode having such a complex configuration. Due to this, it was possible to increase the combustion area of the glow discharge by the value of the total combustion area of additional surfaces, this gives a significant gain in the radiation intensity of the resonance lines.

Figure 1 shows a spectral discharge lamp for atomic absorption, a General view, and figure 2 a hollow cathode (top view).

The lamp is a glass cylinder 1 of a cylindrical shape with a flat window 2 for the exit of radiation transparent in the ultraviolet part of the spectrum. Anode 3 is made of nickel wire, has a Ford ring with a pin. The hollow cathode 4 has a main discharge surface 5 in the form of a cylinder open to the radiation output side, made of material whose spectrum must be obtained, but it is made with 2, 4, 8, 16, or 32 additional surfaces (6 ), having the form of cylinders, located around and parallel to the main surface and intersecting with it, forming a single discharge surface, with a total combustion area, and the distance from the cylinder axis of the main discharge surface to the axis of the cylinders additional surfaces satisfying isfies expression:

,

,

where R ₀ is the radius of the cylinder of the main discharge surface,

R _d - the radius of the cylinders of the additional discharge surfaces.

The hollow cathode is placed in an insulating tube 7 with a small (0.2-0.3) mm gap. This prevents the glow discharge from burning on the outer surface of the hollow cathode and concentrates the discharge inside the cylinders of the main and additional surfaces of the hollow cathode. The cathode, anode and electrical insulating tube are assembled on a glass leg 8 using molybdenum leads 9.

To isolate from gas discharge, the anode terminal inside the lamp is placed in a glass tube 10. The lamp is filled with inert gas neon to a pressure of about 8 mm Hg.

When such a lamp is connected to a power source between the anode 3 of the main 5 and an additional 6 surfaces, glow discharges in an inert gas are ignited.

The spray products from all surfaces in the form of neutral atoms fall into the gas discharge, are excited there by collisions with electrons and in the form of emission of spectral lines through a flat window 2 exit the lamp.

In addition, sputtering products from additional surfaces fall into the main discharge cavity, are excited there and, in the form of additional radiation, increase the radiation of resonance lines along the axis of the main cathode cavity. Thus, in the presence of additional surfaces, an increase in the radiation intensity of the resonance lines occurs.

The more additional surfaces, the more neutral atoms will be excited in a gas discharge, the more radiation comes out of the lamp along the discharge axis of the main radiation cavity.

The proposed invention is new - a new design of the hollow cathode and the lamp as a whole.

Made an inventive step. The hollow cathode of the lamp is made with 2, or 4, or 8, or 16, or 32 additional discharge surfaces having the form of incomplete cylinders located in a circle and parallel to the main discharge surface and intersecting with it, forming a single discharge surface with a total area combustion, and the distance from the cylinder axis of the main surface to the cylinder axes of the additional surfaces satisfies the expression:

,

,

where R _o is the radius of the cylinder of the main discharge surface,

R _d - the radius of the cylinders of the additional discharge surfaces.

The invention is industrially applicable in the production of spectral lamps to improve the characteristics of the lamp, increasing the radiation intensity of the resonance lines.

Literature

A.S. USSR No. 1553255 "Spectral discharge lamp", H 01 J 61/09, publ. 03/23/90.

A.C. USSR No. 1804597 "Spectral lamp for AA", H 01 J 63/02, publ. 03/23/93.

Claims (1)

A spectral gas discharge lamp for atomic absorption, comprising a flask with a uvole window for the exit of radiation transparent in the ultraviolet part of the spectrum, and an anode and a hollow cathode located therein, placed in an insulating tube having an internal discharge surface in the form of a cylinder open on the radiation exit side, made of a material the spectrum of which is to be obtained, characterized in that the hollow cathode is made with 2, or 4, or 8, or 16, or 32 additional discharge surfaces having the form of incomplete s cylinders, arranged in a circle and parallel to the discharge surface and intersecting with it, forming a single bit a surface with a total area of combustion, where the distance from the main axis of the cylinder to the cylinder axes other surfaces satisfies the expression

where R _o is the radius of the cylinder of the main discharge surface; R _d - the radius of the cylinders of the additional discharge surfaces.

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