The stem-less evacuation speed for electro-vacuum devices

Classified

abstracts

855-866

of alkaline earth carbonates is higher on cores with tungsten additive than on cores of electrolytic nickel. V F Finov et al, Elektron (in Russian).

Tekh Priemno

Usilit Lumpy, 1,1970,123-124 31

855. The stem-less evacuation

speed for electro-vacuum

devices.

(USSR) A formula is obtained which enables calculation of the optimum evacuation speed in the stem-less evacuation of electro-vacuum devices. S F Budnikov and V A Antonov, Elektron Tekh Tekhnol Organiz Proizv, 5, 1970, 46-51

(in Russian).

856. Utilization of magnetic-discharge pumps, type evacuation of ultrahigh frequency devices. (USSR)

NORD,

31 for

Utilization of magnetic-discharge pumps type NORD with pumping speeds of 25 and 100 litres/sec in the manufacture of uhf devices enhanced the average life and per cent output of devices in comparison to systems using oil diffusion pumps. It is found that it is necessary to degas the magnetic-discharge pumps periodically to guarantee stable operation. A V Solovev et al, Elektron Tekh Tekhnol Organiz Proizv, 5, 1970, 57-60 (in Russian). 857. Application of mixed processing. (USSR)

evacuation

schemes

in oxide

31 cathode

Application of mixed evacuation scheme consisting of both oil and oil-free pumping for processing oxide cathodes in electro-vacuum device manufacture, is described. In the first stage covering the removal of gases from the free space inside the device, gases released on heating the device system and on heating the binder, and carbonate conversion, the pumping is performed by an oil diffusion pump equipped with a liquid nitrogen trap. After decrease of outgassing and after the carbonate conversion, further evacuation is by an electrical-discharge pump, and the oil diffusion pump with the trap are separated from the system by a valve. Low outgassing during the final stages of cathode processing permits the use of electro-discharge pumps with low pumping speeds. The whole evacuation cycle from switch-on of the oil diffusion pump to establishment of the normal regime of the emission current from the cathode lasts 36 hours. The mixed evacuation technique shortens the processing time on the evacuation plant and maintains the advantages of oil-free pumping. L V Sbtromberger and A V Anosbkin, Elektron Tekh Elektron SVCh, 10, 144-148 (in Russian). 858. Maintaining (USSR)

vacuum

in devices

with

metal-ceramic

31 envelope.

Changes in the composition of the residual gases in vacuum tubes with metal-ceramic envelope are investigated during prolonged storage and humidity resistance tests. The pressure changes in the tube were monitored by the inverse currents to the electrodes. The partial pressures of gases were measured with an omegatron head connected to the vacuum tube. The results showed that the construction of tubes, the materials and processing provide high vacuum tightness throughout prolonged storage. In prolonged humidity tests it is found that penetration of atomic hydrogen, which is formed during corrosion of metallic parts of the envelope by dissociation of water, is the cause of pressure increase in some tubes. At the same time the envelope exhibits a high degree of tightness for atmospheric gases. At the relative humidity of atmospheric air (98 per cent at40”C), the pressure of atmospheric hydrogen is 1 torr on theenvelopesurface. Application of porous titanium getters in the tubes results in disappearance of the pressure increase due to atomic hydrogen penetration and enhancement of humidity resistance. S P Zholtov et al, Elektron Tekh Priemno Usilit Lumpy, 1, 1970, 9-17 (in Russian). 859. Arrangement (USSR)

for

catapboretic

coating

of

wires

with

31 oxide.

An arrangement for cataphoretic coating of metallic wires by alkaline earth carbonates and the application of this method in vacuum tube manufacturing are described. G A Ionin and P I Kupersbtokb, Elektron Tekh Priemno Usilit Lumpy, 1, 1970, 129-133 (in Russian).

32. NUCLEONICS

32 860. Plasma acceleration by means of an external magnetic field. (Czechoslovakia) An experimental study of the possibility of accelerating a plasma cluster in a rail accelerator, by means of an external transverse magnetic field, is reported. The experimental equipment containing the vacuum system, electric circuit and an electrodynamic vacuum valve is described. J Malocb et al, Czech .I Phys, B20 (I 2), 1970, 1342-l 344. 32 861. Injector of fast hydrogen atoms. I. Magneto-optical system of injector. (USSR) The magneto-optical system of an injector of fast hydrogen atoms is described. The injector generates a 15 to 30 keV stream of hydrogen atoms with an intensity higher than 0.5 equivalent amperes. The hydrogen atom stream is generated in a magnesium vapour target by the charge exchange of an ion beam. The ion stream is generated in a gas-discharge ion source with transverse magnetic field, V M Kulygin et al, Zh Tekh Fiz, 40 (IO), Ott Russian).

1970, 2091-2098

(in 32

862. Applications (Germany)

of vacuum techniques

in nuclear technology.

Applications of vacuum technique in nuclear reactor technology are described, in particular, the manufacture of pure zirconium in a van-Arkel reactor, alloying of zirconium in an electron beam furnace, the manufacture of fuel pellets, electron beam welding of fuel rods, and the leak monitoring of fuel rods filled with helium. M Geguscb and W Scbimmel, Exper Tech Phys, 18 (l-2), 1970, 89-95 (in German). 863. Some aspects of 2-metre liquid hydrogen struction. (USSR)

bubble chamber

32 con-

The 2-metre liquid hydrogen bubble chamber and the construction of the steel vacuum envelope is described. A M Stepanov, Prib Tekh Eksper, No 5, Sept-Ott 1970, 54-57 (in Russian). 864. Construction of vacuum chamber and synchrocyclotron FTI AN SSSR. (USSR)

resonance

system

32 of

Construction of the high vacuum chamber and the resonance system of a 1 GeV synchrocyclotron is described. The volume of the vacuum chamber is 35 m3, weight 7200 kg. The working pressure of 3-5 x lo-& torr during acceleration is maintained by six-oil diffusion pumps with total pumping- speed of 36000 litresisec. The inleakaee rate is 9 x 10e3 1it;e to;r/sec. I F Malyshev et al, Tr VII Mezhdunar Konfer Uskorit Zaryazh Chast Vysok Energ, Tom 1, Erevan 1970, 363-369 (in Russian). 32 865. Vacuum system of stellarator

Uragan.

(USSR) The vacuum systeti of the stellarator Uragan and the process of degassing the inner walls by heating to 450°C are described which, enable pressures below lo-@ torr to be attained. The vacuum system contains the vacuum chamber, bakeable high vacuum valves and pumping and control means. The vacuum chamber is formed of two halves which are connected with straight sections through compensating bellows. The straight section consists of two compensating groups, diagnostic tubulations provided with sapphire windows and electric heads. The ceramic part is a tube with joining rings soldered through kovar transition pieces. It has two compensating groups and 12 diagnostic windows. Evacuation is by a mercury diffusion aggregate with liquid nitrogen trap. The pump provides evacuation to below 5x lO-‘O torr. Its pumping speed is 600 litresisec. A forevacuum pump with two liquid nitrogen traps is used. The parts of the vacuum system are joined with the aid of metallic gaskets with copper washers. The testing methods for the components and groups of the working chamber are described. Examination showed that the average value of minimal specific gassing obtained in three tested places amounted to 2.3 x lo-l4 litre torr/sec cm*. V K Gagen-Torn et al, Vestn Kharkov 71-75 (in Russian). 866. Some groups in the modernized Uragan. (USSR)

Politekh

Institut,

No 50, 1970,

32 vacuum system of the stellarator

Groups in the vacuum system of the stellarator Uragan are described. 365