JPS60148179A - Improvement of discharge tube - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] The present invention relates to improvement of a discharge tube, and specifically,
It concerns a laser discharge tube of the metal vapor type in which the active medium is a metal vapor or a mixture of metal vapor and a gas such as helium and cadmium.

Laser discharge tubes usually have a "positive column" or "hollow cathode"
It is of any type. The former uses the long positive column part of the DC discharge, and the hollow cathode tube uses the negative glow part of the DC discharge tube.

The overflowing hollow cathode tube is equipped with a discharge vessel which surrounds the electrodes and in which the active medium is contained. The electrodes are arranged coaxially around the optical axis,
It forms an area where electric discharge is generated to produce a laser effect.

These hollow cathode tubes have some defects.

Long hollow cathodes are known to be unstable. Any slight change in the discharge conditions, such as a variation in temperature, will cause a deviation from the optimum conditions, leading to large disturbances, possibly leading to termination of the discharge and interruption of the laser action.

It is also difficult to carry out effective temperature control to maintain optimum conditions, since temperature control usually relies on the heating effect of the discharge itself.

Another problem arises from the construction of the tube, which must accommodate the conductors necessary to carry current from a power source outside the discharge vessel to the electrodes within the tube. Because the electrodes are housed within the tube, each conductor must pass through the wall of the discharge vessel via an insulated side arm (where it is sealed in place). The required temperatures within the discharge vessel are in the range of several hundred degrees Celsius, resulting in large temperature gradients. Because the conductor passing through the vessel wall breaks the coaxial symmetry of the electrodes and discharge vessel, temperature gradients cause non-uniform stresses on the seal. Insulated side arms must be very carefully manufactured to withstand these effects and are therefore expensive to manufacture.

Another problem particularly experienced in metal vapor laser discharge tubes is the reduced amount of metal available during operation of the lede. Metal is typically stored in side arms that open across the main discharge vessel and onto the vessel. When the laser is operating, the side arm is heated and the metal vaporizes and enters the main body of the discharge vessel where it travels by diffusion and electrophoresis.

Electrophoresis is the effect of an ion moving towards an electrode of opposite charge to the ion, and in the case of metal ions it is generally cataphoresis. As the metal vapor travels the length of the discharge vessel, it is collected in a heat sink that is similar in structure to the side arms and extends across the discharge vessel. Therefore, sooner or later the metal reservoir stored in the side arm will become empty and the lede will stop functioning. The side arms and heat sinks are also bulky and easily damaged because they protrude from the main body of the tube. Furthermore, the steam source is remote from the parts of the discharge tube that require steam.

Another drawback of popular metal vapor discharge tubes is that they rely on diffusion and electrophoresis to distribute the metal vapor within the tube, thereby lacking control over the reeds and therefore the distribution. Rather than all metal vapor entering the heat sink,
Metal vapors become solidified on cold surfaces within the discharge vessel, such as end mirrors and windows, which are located within the discharge vessel but outside the active volume. When metal vapor is deposited on the window of the discharge tube, scattering loss occurs and the radar action is terminated.

The present invention provides an improved metal vapor discharge tube that reduces or eliminates seven or more of the above problems.

The metal vapor segmented discharge tube according to the invention comprises a plurality of tubular electrodes, each electrode surrounding the path of the discharge through the tube, the electrodes being arranged in an alternating manner along the length of the tube. 6 J for anode and cathode), arranged in such a way that at least one of these electrodes can receive a controlled heating effect from outside the tube.

Although it is possible to pass a controllable heating current through the tubular electrode or each tubular electrode to be subjected to the heating effect from outside the tube, this is not preferred.

Preferably, the plurality of tubular electrodes are arranged such that at least seven of them can receive a heating effect induced from a heat source external to the tube.

In an embodiment of the tube according to the invention, the heating effect is generated by seven or more heating coils whose turns encircle the tube. In another embodiment of the tube according to the invention, the tube is surrounded by an envelope and the cavity formed between the tube and this envelope contains a fluid, preferably oil.

This provides a thermally stable environment for the tubes due to the large heat capacity of the oil.

Preferably all tubular electrodes are arranged such that they are subject to a heating effect controlled from outside the tube, in which case this heating effect is provided by heating coil means;
The heating coil means preferably comprises a single coil in which at least some of the seven turns surround at least a portion of each tubular electrode.

Preferably, the tubular electrodes are separated by an insulator inserted between them, such that the electrodes and insulator together form part of the outer envelope of the tube.

The insulator may be any electrically insulating material, such as glass or ceramic.

Preferably, the interior of at least seven tubular electrodes includes a source of metal vapor positioned such that it can be heated by the heating effect experienced by the electrodes.

Preferably, a plurality of tubular electrodes are arranged so that their potential during operation can be adjusted to obtain a desired potential distribution.

Preferably, the tube has an odd number of electrodes and is arranged so that the center electrode operates at a potential of opposite polarity to that of the end electrodes.

Embodiments of the present invention will be described below with reference to the accompanying drawings.

The helium-cadmium laser shown in FIG. 1 includes a discharge vessel 1 according to the invention. The discharge vessel 1 has a tubular shape centered on a common axis X, and has electrodes 2 adjacent to each other.
and a glass insulator 3. Electrode 2 and insulator 3
are arranged alternately along the X-axis and L [matching sections are overlapped to form a mechanically strong structure. Electrode 2
is cylindrical, and the insulator 3 is folded away from the X axis.

By forming the envelope of the electrode 2 and the insulator 3, there is no need for a separate container or electrode enclosing sleeve. Electrode 2 is accessible for heating.

The electrode 2 and the P3 edge 3 enclose a cavity lying along the X-axis, which cavity consists of an active volume 4 in which the electrical discharge and lasing action occur during operation.

Each electrode 2 is connected to a power source (not shown) via a conductor 5 so that each electrode can control its potential independently of the other electrodes. The electrodes are alternately cathode and anode.

The cadmium used as the active medium is introduced into the discharge vessel 1 in the form of a metal tube 6 lined with the inner surface of each electrode 2. A coil 7 surrounds the discharge vessel 1 and provides heating for discharge. Heat is conducted through the electrodes 2 from a portion of the turns of the coil T surrounding a portion of each electrode 2 as shown.

Since the electrode 2 can be in close contact with the turns of the coil 7, the problem of maintaining an optimum temperature is reduced. The cadmium is evaporated by the heat from the coil 7, which is also used to control the temperature within the discharge vessel 1.

The number of electrodes 2 is an odd number. The central electrode 28 is a cathode,
Electrodes 2b and 2c at each end of the discharge vessel 1 are anodes. The positive cadmium ions are thus kept in the active volume 4 by cataphoresis and the solidification of metal on the optical components located at the ends of the discharge vessel 10 is reduced.

As mentioned above, each electrode 2 can be controlled independently from the other electrodes. This allows the individual electrodes to be connected, depending on the application, to various circuits (none of which are shown) designed to optimize the distribution of the components of the active medium, in particular of metal vapors or metal ions. It is possible to electrically connect to the

Tubes 6 forming two innings in each heatable electrode 2
By providing a source of metal vapor in the form of a tube, it is possible to distribute the metal vapor to the same degree as in a common tube without relying on electrophoretic processes, and it is possible to obtain a uniform distribution of metal vapor by both evaporation and sputtering processes. It will assist in the generation of distributions. Furthermore, the metal vapor path length to the center of the discharge is never greater than the radius of the discharge tube, thus reducing the response time to any stabilization control.

As a result, control over the distribution of metal vapor or ions is greater than in conventional discharge tubes.

By folding the insulator 3 as described above, a relatively large area of the insulator is obtained for a given axial length, so that the insulator is formed by solidification of metal vapor on the inner surface of the insulator. The risk of short circuits due to conductive paths is reduced.

Electrode 8 of metal vapor segment type discharge tube for laser shown in Fig. 2
The insulator 9 is surrounded by a wall 10, and a cavity 11 surrounded by the wall 10 contains oil. The oil is about 4
Suitable for discharge tube temperature ranges up to too°C. The relatively large heat capacity of the oil provides the necessary thermal stability to stabilize the Rade radiation output.

The tube includes a total of one cornered window 12 and 13 at each end thereof. Wall 10 is arranged in thermal contact with windows 12 and 13 to keep these windows at the same temperature as the rest of the tube, thereby preventing metal vapor from condensing on the windows.

[Brief explanation of the drawing]

FIG. 1 is a rear cross-sectional view of a portion of a metal vapor segment type Rede discharge tube according to the present invention, and FIG. 2 is a longitudinal cross-sectional view of another metal vapor segment type laser discharge tube according to the present invention. 1... 1 discharge container, 2.8... Electrode (2a... center electrode, 2b, 2C... end electrode), 3.9... Insulator, 4... Active volume, 5... Conductor, 6... Source of metal vapor, T... Coil, 10... Wall, 11... Cavity, 12.13... Window.

Claims (1)

[Claims] / A metal vapor segmented discharge tube comprising a plurality of tubular electrodes, each electrode surrounding a path of discharge through the tube, the electrodes extending along the length of the tube. A tube characterized in that anodes and cathodes are arranged alternately along the tube, such that at least one of these electrodes can be subjected to a heating effect controlled from outside the tube. A tube according to claim 1, characterized in that the plurality of tubular electrodes are arranged such that at least one of them can receive a heating effect induced from a heat source external to the tube. 3. The plurality of tubular electrodes are arranged in such a way that a controllable heating current can be passed from the outside of the tube to each tubular electrode subjected to a heating effect.
Or the tube described in -. A tube according to claim 1, characterized in that the heating effect is produced by one or more heating coils whose turns encircle the tube. Left: a unit arranged such that all of the tubular electrodes can receive a heating effect controlled from outside the tube, with at least a portion of one turn surrounding at least a portion of each tubular electrode; The tube according to claim 1, characterized in that it uses one coil. 4. The tube according to claim 1, wherein a cavity surrounded by a wall and formed between the tube and the wall contains a fluid. 7. The pipe according to claim B, characterized in that the fluid is oil. 8. The tube according to claim 7, characterized in that it includes a window arranged in thermal contact with the wall. D. the tubular electrodes are separated by an insulator inserted between them, the electrodes and the insulator together forming part of the outer envelope of the tube; A tube according to any of the claims. /θ A tube according to claim 4, characterized in that said insulator is a glass or ceramic material. // Claim characterized in that at least seven said tubular electrodes include a source of metal vapor positioned inside the electrodes so that it can be heated by the heating effect to which the electrodes can be subjected. 10. The tube according to any one of 10 to 10. /U Claims characterized in that the plurality of tubular electrodes are arranged so that their potential during operation can be adjusted so as to obtain a desired potential distribution.
The tube described in any of the above. /3. Any of claims / to / /, characterized in that it has an odd number of electrodes and is arranged so that the center electrode operates at a potential of opposite polarity to the polarity of the potential of the end electrodes. The tube described in. /11. A radar array comprising a discharge tube according to any one of claims / to / 3.