US2020428A - Vacuum tube - Google Patents

Description

Nov. 12, 1935- l. E. MOUROMTSEFF VACUUM TUBE Original Filed March 6, 1929 .RW. Y m m 2 m V0 T WW ,V.A E m 9 6 z 2. MV a0 M W w /2 W 0 w f f, 2 I z T n M 6 h x 5 a J V A M 2 7 w Z W 9 2 WITNESSES:

Patented Nov. 12, 1935 UNITED STATES PATENT OFFICE VACUUM TUBE Pennsylvania Continuation of application Serial No. 344,772, March 6, 1929. This application April 14, 1933,

Serial No. 666,162

. 4 Claims. (Cl. 250-275) This application is a continuation of my copending application Serial No. 344,772, filed March 6, 1929, now Patent 1,944,190, issued Jan. 23, 1934, and the invention herein described is 5 disclosed in Fig. '7 of this copending application.

My invention relates to electron discharge tubes having a control electrode and particularly to electron discharge tubes designed for generating large amounts of power or for generating very high frequency currents.

It has hitherto been proposed to make the control electrode a cylindrical body with longitudinally extending grooves therein, and to place the filaments forming the cathode structure of the tube at the bottom of the grooves. I have found, however, that when the grid is positive this large mass of material substantially enclosing the filament absorbs a large part of the electrons emitted from the filament, and hence cuts down the plate 20 current to the anode. I have further found that the enclosing grid structure of this type of tube narrows the beam of electrons-directed towards the anode with the result that they are concentrated on a small portion of the area of theanode I 25 and cause overheating and puncture of the tube at these particular areas. Furthermore, in order to have an appreciable value of amplification, the filaments must be located very close to the bottom of these grooves with the result that any sagging of the filament is likely to cause the filament to touch the surrounding grid structure and short circuit thereto.

I avoid these disadvantages of the prior art construction just referred to by having a built up central grid structure with radial projections therefrom having enlarged ends and by locating the filaments so that they are adjacent only to these enlarged ends and not to the remaining sections of the grid structure.

Other features and advantages of my invention will appear from the following description taken in conjunction with the accompanying drawing in which:

Figure 1 is a view in longitudinal section of a power tube constructed in accordance with my invention; and,

Fig. 2 is a view in lateral section taken on the line II-II of Fig. 1 with the details of the upper end portion of the tube left out for the sake of clearness.

Referring to the drawing the apparatus comprises a vacuum tight container formed by an outer metal tube In which acts as the anode and which is closed at the upper end by a metal piece in g i th u The lower end of the tube is closed by means of a glass member I2 which is sealed to it by means of a metallic reentrant portion I3 sealed to a reentrant portion of the glass member I2 at the seal I4.

The metallic reentrant portion I3 forms the 5 structural part of the grid of the power tube and is in the form'of a metal tube I5 closed at the upper end by means of a metal piece integral with it. A pipe I 6 is positioned within and spaced from the tube I5. By means of this structure the 10 grid may be cooled by forcing water or some other cooling fluid into the reentrant portion I3 between the tube I5 and the pipe I6 and out through the pipe I6.

Surrounding the pipe I5 is a tube I8 to which a plurality of U-shaped members I9 of sheet material are welded or otherwise suitably attached. These members are assembled in contact with each other to form ribs projecting laterally from the tube I8. Each rib supports a rod welded 20 or otherwise suitably attached thereto in such position that it is parallel and adjacent to a filament 2i, whereby a very effective grid control is obtained. The control effect is exerted by the rods 26 while the ribs formed by members I9 conduct the heat away from the rods.

The upper ends of the filament 2| are supported and electrically connected by means of rods 22 secured to a metal ring 23. The supporting structure for the ring 23 comprises a rod 24 of insulating material such as quartz that is clamped in a split supporting member 25 which is welded or otherwise attached in any suitable manner to the upper end of the reentrant portion I3. The ring 23 is attached to the upper end r of the rod 24 by means of another split supporting member 26 which is attached to the ring 23 and clamped to the rod 24.

The lower ends of the filaments 2i are attached to rods 21, supported by means of rings 28 which are bolted to terminal rods seated in the reentrant portions 29 of the glass member I2. Several filaments are supported by each of these rings 28.

It will thus be noted that I have provided an electron discharge device with an exterior anode and a central control electrode or grid structure and a cathode structure comprising a plurality of filaments intermediate the central electrode structure and the exterior anode. The filament structure is placed adjacent to the outer enlarged ends of the control electrode and hence the grid structure will not absorb a large massof electrons when the grid is positive, as would be the case if the filaments were located well within the U-shaped members H). The enlarged ends 20 of the radial projecting portion of the grid will thus control the anode current without producing a detrimental robbing effect thereon. The electrons passing from the filament 2| to the anode ID 'will have a large area upon which to strike the anode I0 and will not be restricted to a small area, as they would be if they were located in the bottom of the trough formed by the U-shaped members 19.

Various modifications may be made in my invention without departing from the spirit and scope thereof, and I desire-therefore, that only such limitations shall be placed thereon as are shown by the prior art and set forth in the appended claims.

I claim as my invention:

1. An electron discharge device comprising a vacuum tight container, an anode constituting a portion of the outer wall thereof, a control electrode-within .said container vand having projections extending towards .said anode and a cathode structure intermediate said controlelectrode and said anode, and closer to the latter than are the ends of said projections.

2. An electron discharge device comprising a vacuum tight container,.an anode constituting a portionof the outer wall thereof, a control electrode structure within said container, means for directing a cooling medium to a portion of said control electrode structure, radial projecting portions of said control electrode structure extending toward said anode, and a cathode structure intermediate said control electrode structure and said anode, and spaced closer to the outer ends of said radial projecting portions than to the remainder of said control electrode structure.

3. An electron discharge device comprising a vacuum tight container, an anode constituting a portion of the outer wall thereof, a control electrode structure within the central portion of said containenradial projecting portions of said control electrode structure extending toward said anode, the ,outer ,ends of said portions being greatly enlarged over the intermediate section of said radial projecting portions and a cathode structure intermediate said control electrode structure and said anode, and spaced closer to the outer ,ends of said radial projecting portions than to the remainder of the control electrode structure.

,4. An electrondischarge device comprising a control electrode .having radial projecting portions, a cathode structure comprising filaments and an anode surrounding said control electrode 25 projecting portions.

ILIA E. MOUROMTSEFF.

Images