US2980317A - Vacuum device - Google Patents

Description

April 18, 1961 e. REICH 2,980,317

VACUUM DEVICE Filed April 14, 1958 United States Patent VACUUM DEVICE Giinter Reich, Koln-Zollstock, Germany, assignor to E. Leyboids Nachfolger, Koln-Bayentai, Germany Filed Apr. 14, 1958, Ser. No. 728,175

1 Claim. (Cl. 230-69) It is known that gases are absorbed at very low pressures while at the same time with an electric discharge or in combination with an ion source metals or nonmetals are vaporized or absorptive clean metallic surfaces are produced (getter efiect). Usually for this a special ion source and, separately from this, a vapor source are provided. But it has already been proposed to generate discharges at cold cathodes which have special capacity for absorbing gases, for example, zirconium cathodes in discharge systems of the Penning vacuum gauge type.

Accordingly, it is an object of the present invention to provide a pumping device which permits to structurally combine the ion source with the vapor source and at the same time permits operation with an incandescent cath-v ode, which at very low pressures ofiers advantages as opposed to the cold cathode. Thus, as will be seen in the following description of the appended drawing, it is not necessary for the gas gettering to have a vapor source continuously in activity but it is sufificient from time to time either to bring a fresh charge to the vessel walls by vaporization or to renew the active surface by vaporization.

'The drawing showing schematically a longitudinal section through an embodiment according to this invention will serve to explain its mode of operation. In a glass vacuum vessel 1 an incandescent filament cathode 2 is mounted, said cathode being connected to a heating battery 23 via ducts 21 and 22. Surrounding the incandescent cathode 2 there is a getter helix 3, which is built self-supporting and can be heated directly via ducts 31 and 32 by the current derived from a second heating battery 33. This getter helix is located opposite cathode 2 and is maintained at a positive potential of 200 to 300 volts by means of a voltage source 34 and serves as electron collector for the ionization arrangement. In a portion of the getter coils some getter material 4 in wire or strip form is placed about the getter wire. By direct current flow through the getter wire the getter material and the getter metal can be heated at once. Moreover, this heating serves for one-time or step-wise vaporization of the getter metal.

A getter metal film 5 condensed on the glass wall 1 receives from the current source 52 a negative potential of 30 to volts relative to the cathode 2 via the duct 51. This getter film 5 serves as the ion collector for the ionization device.

To increase the electron path in the ionization device, a magnetic field of 300 to 500 gauss can be provided parallel to the cathode with the aid of coil 6.

At 7 is connected the chamber to be evacuated.

The pumping occurs in such a manner that, after the pre-evacuation of the receptacle and pump and the outgassing of the getter and the getter metal, the getter metal is vaporized,

With the set-up according to the invention a very low pressure can be produced in the fore-evacuated vessel and after closing can be maintained directly for a very long period.

What is claimed:

A vacuum pumping device comprising a vacuumtight container, a getter coating on the inner wall of said container, an ofitake duct joined near one end of said container, a thermionically-emissive filament supported by and positioned Within said container, means to supply current to said filament, potential means for maintaining said getter coating on the wall of said container at a negative potential with respect to said filament, a getter helix having spaced turns surrounding said filament and carrying a getter material, and means for maintaining said getter helix at a positive potential with respect to said filament, whereby said getter helix serves both as a getter material carrier and source as well as an electron collector.

References Cited in the file of this patent UNITED STATES PATENTS 2,636,664 Hertzler Apr. 28, 1953 2,726,805 Lawrence Dec. 13, 1955 2,727,167 Alpert Dec. 13, 1955 2,755,014 Westendorf July 17, 1956 2,796,555 Connor June 18, 1957

Images