US2290967A - Electron tube - Google Patents

Description

Patented July 28, 1942 UNITED STATES PATENT OFFICE ELECTRON TUBE Felix Herriger, Berlin, Germany, assignor to C. Lorenz Aktiengesellschaft, Berlin-Tempelhof, Germany, a company Application March 29, 1940, Serial No. 326,603 In Germany March 23, 1939 9 Claims. (Cl. Z50-27.5)

Discharge vessels are known whose wall is made of a ferromagnetic material. Materials of this kind have the advantage that they are easy to unite with glass and have a relatively small heat conductivity so that the sealing spot at which glass is sealed to the ferromagnetic material is not so highly heated as the middle of the discharge vessel. This use of ferromagnetic materials, however, also involves a drawback in case the discharge vessel is operated at, high l frequencies. In fact, great hysteresis losses due ode, and the other electrodes, while outside a to reversals of the magnetic field can arise in field between this anode and adjacent grounded this case, whereby the output of the discharge parts is effective. vessel will be reduced to a considerable extent. As stated before, the tubular end portion C of Such problems arise particularly in the case of the vessel is not coated with material By suitdischarge vessels of the external-anode type. able constructional arrangement it will be pos- These losses may be avoided by means of the sible to withhold field lines` from the uncoated invention described hereafter. part of the vessel.

The accompanying drawing is a sectional view The metallic coating may be aiiXed either showing a vacuum vessel for electron tubes which before arranging the head D or may be affixed is intended also to constitute the anode thereof thereafter. T he latter method will be suitable in well known manner. if the coating is liable to be affected by the seal- According to the invention the ferromagnetic ing process. material A of which the discharge device is made What is claimed is: n is coatted insitdealnc outsid with at roi-ferro .25 h 1. An extlelrgalilocelaxpaet lclclarllgea cgevce magne 1c ma eria excep or a u uar en aving a wa or s 1 p r o a portion C to which a glass head D is sealed. The material having ferromagnetic DIOpeltieS, Said coating B preferably consists of copper, silver, wall portion being provided inside and outside chromium cr rhodium. The coating within the with a coating of electrically good conducting vessel must have a vapor pressure small enough non-ferromagnetic material, Said Coating eX- not to affect the vacuum to an appreciable detending over. substantially all the surface of said gree underv operating temperature conditions. felloiailelrlllrmaifrlld. t l 1 Any ofthe well known methods may be employed 1S@ a ge eVlCe aCCOl" me 0 C 31m i for producing the coating B. For instance, this wherein the said coating is 0.1 to 2 millimeters may be producedt bg electtrolylss or ,ty lrijlaltirtlgg. mShlCldriesi-a devic c din t la' 1 in In the case of u eno dea ing wi h ig em- 1SC rge e a cor g o c 1m i peratures it has been found desirable to employ a WhlCh 011 end 0f Seid Wall POIIOII 1S 111100315661, coating of copper. For higher temperatures a, arid further comprising a glass head sealed to coating of chromium or preferably of rhodium ths r'lfogh-f manufacturing the bulb por will be suitable. 40

The precaution of arranging such coating on ugr; Ollelredcafngvm; vglecllrlneth all sides has for its object to prevent the elecn. p 0 .g g y c3" indrical envelope of a material having ferrotrcmagnetic field from entering the ferromagma nemo To ertes Seann la h ad t ne layer affixed to this material g .p p g a g SS .e o o neue mater 1&1 The th 45 end of said envelope, and then applying a coatmust 11e/me be of a' thlckness greater than e ing of non-ferromagnetic material having good Penetfawn depth 0f the eleiromagneilc fieldeiectric conductivity to substantially au of the The penetration depth depends on frequency. inner surface of Said envelope Since, however, in the case of low frequencies 5 The method of claim 4,J in which said goatthe arising losses are of little consequence these mg of good conductive material is applied to al1 considerations are only concerned with relatively high frequencies, such as 108 cycles per second. In this regard the penetration depth is in the order of magnitude of 2 millimeters or less.

Penetration depth less than 0.1 millimeter need not be considered here. The coating should hence be 0.1 to 2 millimeters in thickness.

The coating itself need not be vacuum-tight and may therefore be a coarse-grained electrolytic precipitate.

It is important that the ferromagnetic body should be provided on all sides with a well conducting coating of non-ferromagnetic material. Within the discharge vessel there is the field between the body so coated, which may be the anthe inner surface of said envelope except in the immediate vicinity of said glass head seal.

6. The method of claim 4, which includes the additional step of applying a coating of said non-ferromagnetic material having good electric conductivity to substantially all of the outer surface of said envelope.

7. An electron discharge device including a generally cylindrical wall portion of ferromagnetic material having high electric conductivity pn substantially all the inner surface of said wall f'portion, a glass head sealed to one end of said ,fwall portion, and an electrode-supporting mem- 1' ber of insulating material sealed to the other end of said wall portion.

8. An electron discharge device according to claim '7, further comprising a coating of nonaeedeev ferromagnetic material having high electric conductivity on substantially al1 the outer surface of said wall portion.

9. An electron discharge device according to claim rI, further comprising a coating of nonferromagnetic material having high electrical conductivity on substantially all the outer surface of said Wall portion, in which said coating of said non-ferromagnetic material extends over all of the surface of said ferromagnetic material except to the immediate vicinity of said glass head.

FELIX HERRIGER.

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