Classified
abstracts
459-471
described. Also high-efficiency roughing condensation described. I F Mikhaylov, Probl Atomic Sci Technol, Coll, Kharkov
pumps are 1911, 57-60
(in Russian). 459. Ultrahigh vacuum bakeable cryogenic pumps with low consums tion of working cooling agents. (USSR)
Ultrahigh vacuum bakeable cryogenic pumps with low consumption of working cooling agent are described. Consumption of liquid N, is 50 cm3/h in a pump with pumping speed of 1700 l/s for Hz, which provides ultimate pressure IO-” torr in a 100 1 volume. The helium condensation pump with pumping speed of 5600 l/s for H, has consumption of 200 cma/h of liquid He. S F Grishin et al, Probl Atomic Sci Technol, Coll, Kharkov 1971, 6062 (in Russian). 21 460. Development of the condensation technique of generation of vacuum at Physico-technical Institute of Academy of Sciences of USSR.
(USSR) A short survey of development of the condensation technique of generation of vacuum is presented. The technique enables one to reach high pumping speeds, attain lowest pressures in short times and it provides clean vacuum conditions. Application of condensation pumps in science and technology is shown. S F Grishin, Probl Atomic Sci Technol, Coll, Kharkov 1971, 3-5 (in Russian). 461. Attaining extremely low pressures by the condensation of pumping. (USSR)
21 technique
Using the condensation technique of pumping in vacuum chambers with walls cooled by liquid helium and having volume of about 1 1, the pressure of lo-l5 torr has been recorded for all gases except helium isotopes. For pumping of He4 a condensation pump has been developed with a temperature of condensation surface of 0.24”K and the He4 pressure of lo-” torr has been attained. In bakeable ultrahigh vacuum systems with volume of about 100 1 and pumped by hydrogen or helium condensation pumps the base pressure of 2 x lo- ’ 3 torr has been attained at chamber walls at room temperature. At pumping high amounts of hydrogen by the helium condensation pump the pressure 1 x lo-lo torr has been attained. S F Grishin et al, Probl Atomic Sci Technol, Coll, Kharkov 1971, 5-10 (in Russian). LI
462. High-throughput
oil diffusion pumps. (USSR)
Construction and performance of oil diffusion pumps with speeds of 20000 and 40000 l/s in the pressure range lo-“ to 10m5 torr are described. Pressure gradients in pumped gas connections and the measurement of pumping speed are considered. S N Vodolazhskiy et al, Probl Atomic Sci Technol, Coll, No 2, Kharkov 1972, 3-10 (in Russian). 21 463. Small-size
oil diffusion pump M-60. (USSR)
A small-size oil diffusion pump with baffle is described. The pumping speed of the pump is 50 l/s in the pressure range 1 x low3 to 1 x low6 torr. The rate of oil migration in the pumped volume is 1 to 5 x 10m3 mg/h cm2. The critical backing pressure is 0.2 torr. V V Sivokon, Probl Atomic Sci Technol, CON, No 2, Kharkov 1972, 10-l 5 (in Russian). 21 464. Small-size oil diffusion pump M-1000. (USSR) A small-size oil diffusion pump with baffle is described. The ultimate pressure is 2 x lo-’ torr, the pumping speed is 750 l/s in the pressure range 1 x 10e6 to 3 x lo-“ torr, the critical backing pressure is 0.2 torr. V V Sivokon, Probl Atomic Sci Technol, Coll, No 2, Kharkov 1972, 16-23 (in Russian).
22 of an oxide solid electrolyte partial pressure gauge. (USA)
as a vacuum
oxygen
Calcia stabilized zirconia of nominal composition CaO., 32r0.8501 .81 has been used as the electrolyte of a galvanic cell for quantitative measurements of oxygen pressure in a vacuum chamber over the 226
22 466. Automatic mass spectrometer for deuterium analysis in dynamical regime. (Roumania)
An automatic mass spectrometer for determination of relative changes in concentrations of isotopes with mass 2 and 3 during the separation process is described. The mass spectrometer operates in the range 20 to 500 ppm with accuracy &lx. M Pascalau, Rev Roum Phys, 18 (l), 1973, 129-131. 22 467. Standard manometric equipment with measuring range 10v4 to 1O-7 torr. (USSR) An equipment for reproduction of pressure unit in the range lo-“ to lo-’ torr for calibration of vacuum gauges is described. The dynamic method of pressure reduction is used. V V Kuzmin and V A Ryzhov, Moscow 1973, 59-64 (in Russian).
Unique Instruments,
CON, No 13,
22 468. Features of mass spectrometric apparatus intended for measurement of partial pressures of gases in high vacuum. (USSR)
The interaction of mass spectrometric partial pressure gauge head with gases is considered. Hot cathode causes ionization of complex molecules and stimulates various chemical reactions with participation of cathode material and carbon. Omegatron possesses the smallest influence on gas ambient of all known mass spectrometers. A P Averina, Proc of 1st All-Union Conf on Mass Spectrom, Leningrad 1972, 360-369
(in Russian).
469. Measurement
22 of vacuum reached by cryogenic pumping methods.
(USSR) Peculiarities of measurement of vacuum at low temperatures are considered. It is shown that the cold cathode magnetron discharge gauges are the most suitable in low temperature conditions. Calibration of vacuum gauges is also discussed. It is shown that the well known dependences of saturation vapour pressure of various substances on temperature can be easily used for calibration of vacuum gauges in the ultrahigh vacuum range. Using the saturation vapour pressures of H, and NZ, both hot cathode and cold cathode ionization gauges were calibrated. Using a chamber immersed in liquid helium, a Redhead magnetron gauge was calibrated in the pressure range of 10e6 to lo-l5 torr. The hot cathode and inverted magnetron gauges were calibrated in the pressure range 10v8 to lo-l2 torr using the calibrating gas at room temperature. S F Grishin et al, Probl Atomic Sri Technol, CON, Kharkov 1971, 11-31 (in Russian). 22 470. Miniature thermoelectric
vacuum gauge. (USSR)
A miniature thermoelectric vacuum gauge with a time constant of 5 to 20 ms is described. A nickel microwire is used as a sensitive element. The microgauge is calibrated with the aid of a McLeod gauge in the range of lo-’ to 50 torr. E Ya Radinter et al, Microwires and Resistance No 9, Kishinev 1972, 276280 (in Russian). 471. The control unit of a ionization vacuum limits 1.33 x 10e5 to 133 Pa. (Poland)
22. GAUGES
465. Performance
range l-lo-’ torr. The low pressure limit is determined both by permeation of oxygen through the electrolyte and interaction with active residual gases such as CO, H, and hydrocarbons. The response of the cell to changes in oxygen pressure is dependent on the pressure and independent of the electrolyte temperature over the range 600800°C. The rate of approach to a steady-state following step changes in oxygen pressure over the range ~10-7-10-4 torr can be represented by the empirical equation (d E/d t)aAEm, where E is the cell emf, t is time, AE is the departure of the emf from the steady-state value, m = 1 for step increases in pressure, and m = 1.5 for step decreases in pressure. The time constant for relaxation following an increase in pressure has been measured as =[8 x 10-5/P0,(torr)l s, where PO, is the vacuum oxygen pressure. C J Mogab, J Vat Sri Technol, 10 (5), 1973, 852-858.
Instruments,
Coil,
22 gauge with measuring
The stabilization of electron current of a gauge head with oxide cathode operated in a broad pressure range is described in detail. A circuit with field-effect transistor for measurement of ion collector current is presented. M Moraw and R Smiechowicz. Prace Nauk Polytech Wrocl, No 8, 1973, 81-88 (in Polish).
Inst Technol Elektron