DE1079214B - Incandescent cathode for gas or vapor-filled discharge tubes, which consists of directly heated individual elements connected in parallel - Google Patents

Description

The invention relates to a hot cathode for gas or vapor-filled discharge tubes for large ones Amperage with directly heated parallel-connected, appropriately arranged symmetrically to an axis Single elements.

It is already known in gas or vapor-filled Discharge tubes use cathodes consisting of a number of separate cathodes placed in parallel exist. The great difficulty with such cathodes is that a uniform distribution of the Emission current over the entire cathode surface can usually only be achieved with difficulty, since the discharge, in particular at higher gas or vapor pressures, e.g. B. of the order of 1 mm Hg, which seeks to to huddle together at certain points on the activated surface. This depends on the fact together that a gas discharge, which is concentrated on a part of the cathode, a strong local Brings about a temperature increase, which in turn increases the emission disproportionately, so that the discharge stops at this point.

In order to remedy this disadvantage, very short and thick cathode elements have been used to connect in parallel. In the case under consideration, this had the consequence that a very low heating voltage, z. B. of 1 volt or less, had to be selected with a very high heating current.

On the other hand, there is a disadvantage of the proportional enlargement of the conventional, one-element helical, directly heated ones Hot cathode !! for the purpose of increasing the current strength in that the emission surface only according to the The square of the linear dimensions increases, while the volume or weight of the cathode material increases according to the 3rd power of the linear measurement. As a result, hot cathodes are of great power, whose basic element consists of a very thick, helically wound tungsten wire, disproportionately expensive., to manufacture, e.g. B. with an emission current of 60 Amp. 77 times as expensive as with an emission current of 6 amps.

The invention aims to achieve a cathode, the effective surface by union a number of equivalent individual elements is formed, so that the size of the effective surface is practically proportional to the weight of the cathode, avoiding the disadvantages of the known: parallel cathodes, among other things, restriction to low heating voltages.

For this purpose, the parallel cathode according to the invention is designed such that the symmetrical arranged individual elements at several closely spaced points of the same potential with one another are conductively connected, so that at these

Hot cathode for gas or vapor filled discharge tubes that are made from directly heated and individual elements connected in parallel

consists

Applicant:

Philips Patentverwaltung GmbH,
Hamburg 1, Mönckebergstr. 7th

Claimed priority:
Netherlands March 27, 1940

Applications according to Act No. 8 AHK have been submitted to the Arbitration Commission for Goods, Rights and Interests

pending in Germany

Johannes Gijsbertus Wilhelm Mulder,

Eindhoven (Netherlands),
has been named as the inventor

Make heat differences and irregularities in ■ the emission load of the cathode balanced with open spaces between the elements - at least of the order of 0.5 cm - remain, which offer the possibility of the discharge, right into the interior of the perforated cathode structure to penetrate.

It is possible to use large cathodes of this type for normal heating voltages up to the order of magnitude of 3 volts or more to produce a very even distribution of the emission current have over the activated surface of the various cathode elements.

It is best to do the aforementioned senior. Cross connections by sintering on nickel, To form iron or any mixture of these or related metals. Often it arises as a result the advantage that a layer is formed to which the emissive material adheres better than the core wire of the, which is usually made of a material with a high melting point Cathode element (if necessary combined with this measure, it can be advantageous to use the cross connections by binding with thin, heat-resistant metal wire).

For the purpose of assembling a. cathode according to the invention can advantageously be separated from

909 769/433

Claims (9)

3 4 th elements or units made of tungsten wire go out form a hollow prismatic body, on which a wrapping in a known manner, can be, the side surfaces of the gesonz. B. made of wire made of the same material or from other elements, while the on-nickel is attached. adjacent elements of the separate zigzag on the service in question, it is possible, 5 loops alternately on the inner side 2 and to cathodes for high current strengths \ ^r erschiedener the outer side 3 of the body by Querverbindun-size to be formed, characterized in that a corresponding Angels are united, which form the peaks of a four-sided number of unit elements on the previously more flat pyramids. At the two ends of the cathode way connected in parallel and with cross connections. design are the inner connection points with is provided. It is particularly advantageous to connect an io strong wire rings 4, which serve as a series of usual emission currents from heating lines for the heating current, which is determined by the cathodes of the same heating voltage, is fed to the method carriers 5,
the current strengths being a multiple of a certain basic current strength that can be shown for a particular type of cathode in Fig. 2 schaubildlich th. Ziges unit element are billed 15 Fig. 3 a and 3 b show in a corresponding manner how can. ... a prismatic cathode with a star-shaped profile An advantageous design is formed by processing in such a way that a number Processing of the individual elements in the form of an expedient zigzag-shaped element 1 together in a star shape symmetrical braided body obtained in which are arranged so that a series of peaks 6 the crossing points of the wire-shaped elements ao of these elements in a common longitudinal axis comes to lie in the manner already described as a cross-connection and in the manner described above genes are trained. is united by cross-connections, the The individual elements of the cathodes can flatten the side ends of the elements 7 and 8 together in an egg-shaped manner a hollow cylindrical or star-shaped lie and together with the power supply lines 9 of the form prismatic body. With a reasonable choice 25 cathode are connected. of the ratio of the cross section or the length. In FIG. 4, the construction according to FIG. 3 is diagrammatic this body finds the discharge not just represented by. the openings of the side surfaces, but also of the While for larger cathodes, z. B. for hundreds both ends provide access to the inner emission of amperes, the hollow design according to FIGS. 1 and 2 area. 30 is easier to assemble As a shape for the individual elements of the cathodes Fig. 3 and 4, particularly recommended for cathodes, the zigzag shape or that of medium currents, e.g. B. for emission form of a flat-wound helix in question, which there currents of 100 amps. Or less.
allows you to use it in the manner of the switch gate. As an example of an element, one of the previous ones. After again having transverse cathodes mentioned above, a zigzag connection according to the invention can be attached. Tungsten wire are mentioned, the diameter of which is, at the same time mechanical connections, 0.4 mm, the nickel wire of 0.15 mm, the result is a particularly rigid whole. is wound and on it in 68 mm long zigzag However, it is also possible to bend the design in such a way that the width is 5 mm and that the cathode has no interior space, 40 distance between two successive peaks but the star-shaped individual elements on the same side are 3 mm. A cathode that remains easily accessible from the outside. For this purpose, these elements, which are also formed from flat elements and coated with an activating barium-wound coils of metal wire or metal strip oxide layer, can be formed for one, can be arranged in this way be that 45 average rectified current from 60 to the successive loops or turns 100 Amp. at a peak value of approximately each element together a straight, long 200 Amp. are used and requires an annealed and practically in a single plane wire energy of 3.2 volts by 70 amps.
The cathodes according to the invention can be arranged in ferti-radial planes around a common axis around a common axis in a known manner with a cover so that one row of peaks of the separate layer of nickel are provided for the purpose , the zigzag loops or windings are arranged along the axis to be obtained in question for adhesion of the emitting oxide layer and with the favorable,
speaking peaks of the other elements in the Axis forms a number of cross connections, so 55 claims:
that there is a body of star-shaped cross-section results, which at both ends with the current 1. hot cathode for gas- or vapor-filled discharge leads is connected. Charge tubes with higher gas or steam The invention is shown in the drawing on execution pressures for large currents with directly examples explained in more detail. . 60 heated in parallel, repeatedly kinked Fig. 1 and 2 show in front and side view or curved and the same in several places or graphically a cathode, the zigzag potentials of which are conductively connected to one another, shaped elements share a hollow prism separated by radiators, between which are open form star-shaped cross-section; ■ Spaces remain through which the discharge to Fig. 3 and 4c show in the same views a Ka, - 65 into the interior of the perforated cathode structure thod'e that is able to come together from corresponding elements, characterized in that is built, the star-shaped-along a common that a number of equivalent, preferably Axis are arranged. zigzag or as a flat-wound helix In Fig. 1a and 1b, in.zwei projections shown radiator is symmetrical to the shows how separate zigzag-shaped elements 1 are arranged in the axis and parallel to it. 2. glow cathode according to claim 1, characterized in that the individual elements each for themselves are so arranged in radial planes around a common axis that a body of star-shaped Cross-section is created, which is connected to the power supply lines at both ends is. 3. glow cathode according to claim 1, characterized in that the individual elements each for themselves form the side surfaces of a prismatic body, which at both ends with the Strotn feed lines connected is. 4. glow cathode according to claim 1, 2 or 3, characterized in that the individual elements of the Cathode consist of tungsten wire, on which a wrapping, e.g. made of wire, in a known manner made of the same material or made of nickel. 5. glow cathode according to one of claims 1 to 4, which consists of a number arranged in parallel and unit elements provided with cross-connections, the number of which are to be permitted Intensity of the emission current is appropriate. 6. glow cathode according to one of claims 1 to 5, characterized in that the individual elements are processed in the form of a suitably symmetrical and braided body, in which the crossing points of the wire-shaped elements in the manner already described as cross connections are trained. 7. Glow cathode according to one of the preceding claims, characterized in that the individual elements form the side surfaces of a hollow cylindrical or star-shaped prismatic body. 8. Glow cathode according to one of the preceding claims, characterized in that the individual elements Zigzag or are designed as a flat-wound helix and in the manner of the Switch gate are intertwined. 9. glow cathode according to one of claims 1 to 5, characterized in that zigzag Elements or flat-wound coils made of metal wire or metal tape, whose successive loops or turns together a straight, elongated and form practically lying in a single plane body and each for itself in such a way planar in radial order arranged around a common axis that the a series of peaks of the separate zigzag loops or turns is arranged along the axis in question and with the corresponding Rows of peaks of the other elements in the axis have a number of cross connections forms, so that a body of star-shaped cross-section arises, which at its two Ends connected to the power supply lines. 1 sheet of drawings © 909 769/433 3.