US2250698A - Magnetron - Google Patents

Description

July 29, 1941. s, BERLINE 2,250,698

MAGNETRON Filed Nov. 3, 193a INVENTOR. E I SYLVAl V BERL/NE} ATTORNEY.

Patented July 29, 1941 .QN TED STATES PATENT, F

pagnic Generale de Telegraphic sans .Fil, a corporation of France I Application November 3, 1938, Serial No.1238j516 In France December 10,1937. "I

3 Claims. (Cl. 250-275) This invention relates to improvements in magnetrons for generating or sustaining electrical oscillations of very high frequency of the order of centimeters for example.

The invention has particularly for its object improved anodes permitting oscillations of higher frequency than in the case of conventional anodes, for given dimensions, and for given values of the magnetic field and of the applied voltages. Inversely, these same anodes make it possible, for given frequencies, to construct magnetrons of larger dimensions operating with a lower magnetic field or a lower applied potential, i. e. to provide higher powers and to increase the stability and the output.

Briefly these new anodes of magnetrons for ultra-short waves are formed essentially by a single metal cylinder in which slots or openings are provided, the slots having such shape and dimensions that the conducting parts which remain and form part of open or closed circuits can be in a state of resonance at the wavelength which is sustained by the tube.

The novel features which I believe to be characteristic of my invention are set forth with par.- ticularity in the appended claims, but the invention itself will best be understood by reference to the following description taken in connection with the accompanying drawing in which Figure 1 is a transverse section of an electron discharge device made according to my invention, Figure 2 is a longitudinal section of the tube shown in Figure 1, Figures 3, 4 and 5 are longitudinal sections of modifications of electron discharge devices made according to my invention, and Figtires 6 and 7 show antenna coupling arrangements which can be used with a tube made according to my invention.

Figures 1 and 2 represent respectively a transverse and longitudinal cross section of a tube made according to my invention and having an anode composed of a series of plates B arranged in the generating line of an interrupted cylinder C with the axis 00. At the one of their ends, the plates B (numbering 6 in the figure and in the form of segments) are connected by a plate disc A having a central opening serving for admission of the cathode K arranged in the axis 00.

The end disc A may be a full disc or a slot shown at 1 may be cut therein. The direct plate potential +V is applied by means of lead-in E.

The electrode assembly is enclosed in a bulb E suitably evacuated and the electrode assembly is subjected to the action of a magnetic field H produced by coil M and the lines of force of which are directed parallel to the axis 00.

Applicant has found that with such a magnetron, stable oscillations are obtained forsuitable and relatively low values of the direct potential V and of the magnetic field H. The wavelength of these oscillations corresponds moreover to twice the length of the mean path abcd of the open oscillatory circuit formed by two of the cylindrical plates B and by the part of the disc A connecting said plates. In other words, this open circuit oscillates at A2 wavelength.

In order to show the importance of such an arrangement, it is pointed out that there has been obtained, for example, a stable oscillation of a wavelength of 8.5 centimeters with an anode of 8 plates having a diameter D='7.5 millimeters and a length of L=20 millimeters for a field H of 450 gaus and a voltage Vof 650 volts.

Somewhat diiferent modesof construction are shown in the Figures 3, 4 and 5, in which all transverse cross sections correspond to Figure 1.

Figure 3 shows a twin assembly composed of the anodes AB and A"B which are identical to the preceding ones and are connected'to each other symmetrically at the end plates A'-A..

The voltage feeding of the anodes is performed by a connection EE" which may be arranged inside the envelope and with the lead brought out in its center F.

In Figure 4 the two preceding anodes are connected so as to form a sort of squirrel cage A'AB. The feeding may also be carried out in a symmetrical fashion across EE" and F.

Figure 5 represents a squirrel cage anode such as that of Figure '4 but in which the plates B are furthermore connected to each other at intermediate points by means of circular rings G.

The two end plates AA could also be omitted. The feeding can be carried out across Eli" and F or across the intermediate rings.

The coupling of the magnetron with the antenna could in all cases be made in any desired manner, for instance by leading around the anode one or several turns Sp of the antenna Ae' proper or of the feeder feeding the antenna. Such an arrangement is shown in Figure 6.

It is also possible (Figure 7) to omit the entire outside antenna at the magnetron and to place said antenna for instance at M in the focal point of a cylinder P of parabolic cross-section.

While I have indicated the preferred-embodiments of my invention of which I am now aware and have also indicated only one specific application for which my invention may be employed,

it will be apparent that my invention is by no means limited to the exact forms illustrated or the use indicated, but that many variations may be made in the particular structure used and the purpose for which it is employed without departing from the scope of my invention as set forth in the appended claims.

What I claim as new is 1. An electron discharge device having an envelope containing a straight thermionic cathode, an anode surrounding said cathode and comprising a plurality of parallel segments, a disc at one end of said segments and electrically connecting the adjacent ends of all of said segments together and provided with an aperture through which said cathode extends, said segments being the only segments surrounding the cathode along their axial length, and means for inducing a magnetic field between said cathode and anode and parallel to said cathode,

velope containing, a straight thermionic cathode,

a single anode surrounding said cathode and comprising a metal cylinder having slots extending along the length of said cylinder, one end of said cylinder being closed by a disc provided with an aperture through which the cathode extends and means for inducing a magnetic field between said cathode and anode and parallel to said cathode.

SYLVAIN BERLINE.

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