US1761175A - Electric discharge device - Google Patents

Description

June 3, 1930. c. BOL ET AL ELECTRIC DISCHARGE DEVICE Filed March 15, 1928 S N A M .u L" S S Y RB PM E O m N TS R N O EEE Wm" 1 M C Y B Patented June 3,- 1930 UNITE-D STATES PATENT OFFICE UORNELIS BOL, or EINDHOVEN, AND JOHANNES .mcauns HUMANS, or mnvnnsum,

NETHERLANDS, ASSIGNORS TO RADIO CORPORATION Tron or DELAWARE OI AMERICA, A CORPORA- ELEGTRIC DISCHARGE DEVICE Application filed March 15, 1928, Serial No. 261,833, and in the Netherlands March 10, 1927.

however, been found that in the case ofheavy high frequency currents being introduced by a current lead which is secured to such a member, the latter may be strongly heated as a result of the hysteresis'losses occurring in it and which are caused by the magnetic field around the current lead.

' The strong heating may result in the damage of the seal between the metal and the glass so that it is no longer hermetic, hence resulting in tube deterioration. V

This invention has for its object the removal of the said disadvantage and to provide for an improved construction of the metal members used in connection with the tube leads.

According to the invention a discharge tube, in which at least one current lead to one of the electrodes within the tube is hermetica-lly sealed by means of. a metallic member having its border sealedto the glass of the discharge tube,- is characterized in that on and adjacent the seal the said member consists of iron "or an iron alloy and the remainder of. the material between the member and lead having small hysteresis losses. Y v I .In order that any heat which possibly may still be produced in the iron or the iron alloy, may be carried away, it may be desirable that the material having small hysteresis losses should also have a high thermal conductivity. In addition it is advisable to so shape the metallic member or to secure to this member so shaped parts of to the magnetic field of electric currents in the current lead. I

As material having small hysteresis losses and a high thermal conductivity preferably copper may be employed. In addition it is desirable that during the operation of the tube the seal should be cooled by suitable cooling means, for example, by a liquid which flows along it or is squirted on to it.

The invention will be more clearly understood by reference to the embodiments shown in the accompanying drawing. In

the said drawing:

" Fig. 1 is a sectional view'of a current seal for an electrode, such as a grid, of a transmission valve; and

Fig. 2 shows a slightly different construction of such a'seal which also is provided with a cooling device.

Referring to Fig. l, 1 is the glass tube wall which is sealed at 2 to a ferrochrome bushing This bushing surrounds a copper disc 4 which has secured to it a current lead 5 which is also of copper. This conductor 5 serves to supply high frequency currents to one of the electrodes, as for example, the grid of the transmission valve. The cylindrical copper screens 6 and 7 are secured to the disc l so as to screen off the ferrochrome bushing 3 from the magnetic field around the current lead and to assist cooling.

According to Fig. 2, the conductor 5 of Fig. 1 is replaced bya copper cylinder 8 the upper end of which has secured to it a head 9 on which the active portion of an electrode can be arranged. To the said tube 8 is secureda copper ring 10 and to the latter a ferrochrome bushing 3. A second copper tube 11 of smaller diameter is arranged within the tube 8. The lower end of the tube 8 and the glass tube wall 1- are surrounded by an iron sheath 15 which is .provided with a waste tube 14 and which is secured by rubber bushings 16 and 17 to the glass tube wall 1 and the copper tube 8 finally it is thrown through apertures 12 of the tube 8 against the seal 2, so that the latter is -cooled, whereupon the liquid is carried oif via the enclosures 13 and the tube 14:.

In this modification screen 6 may be omitted if desired. Further openings 12 may be placed at the lower portion of the trough formed by inner tube 11 and outer cylinder 8. In addition the direction of flow of the cooling fluid may be the reverse of that indicated.

It is obvious that in addition to the con a structions above described various other constructions may be devised which fall within the scope of the invention.

Having now described our invention what We claim is: I

1. A lead-in structure for an electric discharge device comprising a lead, a member having relatively high hysteresis losses encircling said lead and sealed at one end to a glass wall of the discharge device, a second member havirg relatively low hysteresis losses and ha.ing a high thermal conductivity between said first member and said lea and a screen between said first member.

and said lead attached to said second member.

discharge device comprising a lead, a cylindrical member of ferro-chrome encircling said lead and embedded at one of its ends in a glass wall of the device, an annular ring of copper between and joining said lead and said ring, and a screen encircling .a

portionof said lead and attached to said ring of copper.

CORNELIS BOL.

JOHANNES JACQUES NUMANS.

2. A lead-in seal structure for an electric

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