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Combined magnetic-discharge getter-ion pump
Classified abstracts 175-184 21. PUMPS AND
PUMP FLUIDS
21 175. A gaskinetic method for the determination of the effective cross section of an orifice. (Germany) An experimental method for the determination of the effective cross section of an orifice has been described. The reverse flow out of the pump into the measuring chamber has been allowed for in the deduction of the formula o/V = 4.(dn/dt),,,/An.c.~/1 + K. The density, or the pressure difference is measured with a quadrupole mass-spectrometer. The measured quantity u/V is independent of the nature of the gas, of the pressure in the Knudsen region, and of the amplification factor. Some results from these measurements are given. (Germany) E Bailitis, Vakuum-Tech, 23 (5), 136-141 (in German). 176. Experimental investigations with after coolers of Roots-& pumps. (Germany) Heat transfer measurements and fluid mechanical investigations are described. These were carried out in after-coolers of Rootstype pumps. The heat transfer was determined by using a cooler of the multi-stage Roots pumps set which is in connection with the DFVLR space simulation chamber. The measurements were conducted with the total cooler as well as with single segments parallel to the pump axis. The distribution of the flow rate of gas back-streaming when the gas enters from the high pressure side across the width of the cooler was measured with the aid of a flow model. (Germany) H Hamacher, Vukuum-Tech, 23 (5), 1974, 129-135 (in German). 21 177. A vacuum sorption pump with a circulating sorbent. (USSR) A vacuum pump with a circulating sorbent is described; it consists of a cylindrical vacuum chamber with springs at the bottom supporting an inner cylinder with a spiral channel on the outside and a tube for the return path of the sorbent. Screens are provided to create a vacuum resistance between the sorption and desorption regions of the pump. An electric heating element for heating the sorbent is attached to the lower part of the inner cylinder. By adjusting the positions of the screens the vacuum resistance may be varied and hence so may the limiting pressure of the sorption pump as a whole. L A K&nits et al, Soviet Patent, class F 04 b, 37102, No. 383877, claimed 1lth Nov 1969, publd 3rd Ott 1973 (in Russian). 21:33 178. Apparatus with a cryogenic pump for studying field-emission cathodes. (USSR) A device incorporating a cryogenic pump for studying the behaviour of field-emission cathodes at pressures down to lo-“’ torr is described. The cathodes in question are intended for correcting the spherical aberration of electron microscopes on the holographic principle. Preliminary evacuation of the cryogenic pump is effected by means of conventional backing and oil diffusion aggregates. After its operation has been initiated, the cryogenic pump may be insulated from the other pumps without detriment to the final vacuum. The pumping section of the cryopump consists of a helium vessel with a space surrounded by copper walls at liquid-helium temperature and a nitrogen vessel with a screen; the vessels are made of stainless steel and the screen of copper. The limiting vacuum after 3 h is lo-lo torr. One filling with liquid helium lasts for 15 h work. P A Stoyanov et al, in Materials of the Ninth Conference on EIectron Microscopy, Tips, 1973 (Moscow, 1973, 38-39) (in Russian). 21 179. Combined magnetic-discharge getter-ion pump. (USSR) The combined magnetic-discharge getter-ion pump here described differs from the conventional variety in that it has a cooled sorption surface in the form of two profiled cylinders; the surface passes around the evaporator of the getter inside the magnetic-discharge section of the pumping system. An initial rarefaction is created in the system by means of an ordinary zeolite pump. The magneticdischarge section is then set in action, and a further degree of rarefaction is created by virtue of the absorption of gas on the surface of the electrode system in this section, and also by virtue of the absorption of gas by the titanium deposited on the outside of the sorption surface. On reaching a rarefaction of 5 x 10m5 torr the evaporator is started, and titanium is deposited on the inside of the sorption surface, in the helical cavities of which a coolant is freely
circulated. As a result of the action of all these pressure-reducing mechanisms together with liquid-nitrogen cooling, a final vacuum of lo-l2 torr may be achieved. M P Zheltov et al, Soviet Patent, class H 01 j, 41100, No. 387465, claimed 8th Feb 1972, publd 19th Ott 1973 (in Russian). 21 180. A centripetal pumping device. (USSR) Ordinary centripetal pumping devices containing a hermeticallysealed chamber with rotor and stator discs have certain practical disadvantages; in the version here proposed the stator disc is sited relative to the rotor with an eccentricity at least equal to 0.2 of the radius of the latter, an arrangement which increases both the head and the rate of flow of the gas being evacuated. The rotor is set in motion with a conventional type of drive, and on reaching a certain prespecified number of revolutions per minute the stator disc is advanced towards the rotor, whereupon gas flows through the small gap remaining between the rotors. The head and rate of flow may be conveniently varied by varying the eccentricity. Z P Shul’man et al, Soviet Patent, class F 04 d, 17/02, No. 383886, claimed 1st Feb 1971, publd 11th Sept 1973 (in Russian). 21 181. Another centripetal pumping device. (USSR) The centripetal pump here described differs from existing versions in that the stator disc is set in a bellows support and furnished with a drive for vertical motion, while the rotor disc is placed on shockabsorbers. This arrangement increases the pressure head and the rate of flow of the gas being evacuated and eliminates the vibrations arising from the rotation of the rotor disc. When the rotor has reached a prespecified angular velocity the stator is brought close to it, forming a narrow gap between the discs, and the gas being evacuated streams between these. The gap may be varied by changing the degree of compression of the bellows, and the head and rate of flow v&y accordingly. Z P Shul’man, Soviet Patenr, class F 04 d, 17102, No. 383887, claimed 1st Feb 1971, &bid 11th Seit 1973 (in Russian). 21 182. Oil-free mechanical backing pump. (USSR) A new form of oil-free mechanical backing pump designed for long service and a relatively high vacuum is described. The body of the pump has a strictly uniform radius while the shell is installed in a stressed state, and in that state has a diameter equal to the inner diameter of the body. The elastic shell is pressed against the body by means of pressure rings. By operating a system of rollers the elastic shell is deformed and the gas in the working chamber is forced out by progressive motion. The system is more efficient than its predecessors by virtue of the better fit achieved between its component parts. N A Yazykov and V A Afanas’ev, Soviet Patent, class F 04 B, 43/08, No. 387137, claimed 29th April 1971, publd 25th Sept 1973 (in Russian). 21 183. An ion-sorption pump of the orbitron type. (USSR) An improved design of ion-sorption pump of the orbitron type intended to increase the working time between servicings (replacement of the evaporators) is described. The pump is provided with an additional space bounded by an end reflector with an anode passing through the aperture. In the region of the anode is a series of bushings made of the same or different getter materials. The bushings are held in place by solder or thin low-melting-point wire, After one getter has been expended a current is passed through the anode to melt the solder and bring the next getter into the working position. The period of continuous service may thus be extended by five or ten times. V A Usbakov et al, Soviet Patent, class F 04 b, 37100, H 01 j, 41100, No. 354175, claimed 26th June 1970, publd 23rd Nov 1972 (in Russian). 21 184. Apparatus for monitoring the time of fault-free operation of vacuum pumps. (USSR) An apparatus for monitoring the period of fault-free operation of vacuum pumps in relation to the conditions of the external medium and the loading conditions is described. The apparatus is based on the conversion of pressure readings into electrical signals, incorporating an amplification stage. The final output signal gives a measure of the worsening vacuum as the pump becomes older and 85
PUMP FLUIDS
21 175. A gaskinetic method for the determination of the effective cross section of an orifice. (Germany) An experimental method for the determination of the effective cross section of an orifice has been described. The reverse flow out of the pump into the measuring chamber has been allowed for in the deduction of the formula o/V = 4.(dn/dt),,,/An.c.~/1 + K. The density, or the pressure difference is measured with a quadrupole mass-spectrometer. The measured quantity u/V is independent of the nature of the gas, of the pressure in the Knudsen region, and of the amplification factor. Some results from these measurements are given. (Germany) E Bailitis, Vakuum-Tech, 23 (5), 136-141 (in German). 176. Experimental investigations with after coolers of Roots-& pumps. (Germany) Heat transfer measurements and fluid mechanical investigations are described. These were carried out in after-coolers of Rootstype pumps. The heat transfer was determined by using a cooler of the multi-stage Roots pumps set which is in connection with the DFVLR space simulation chamber. The measurements were conducted with the total cooler as well as with single segments parallel to the pump axis. The distribution of the flow rate of gas back-streaming when the gas enters from the high pressure side across the width of the cooler was measured with the aid of a flow model. (Germany) H Hamacher, Vukuum-Tech, 23 (5), 1974, 129-135 (in German). 21 177. A vacuum sorption pump with a circulating sorbent. (USSR) A vacuum pump with a circulating sorbent is described; it consists of a cylindrical vacuum chamber with springs at the bottom supporting an inner cylinder with a spiral channel on the outside and a tube for the return path of the sorbent. Screens are provided to create a vacuum resistance between the sorption and desorption regions of the pump. An electric heating element for heating the sorbent is attached to the lower part of the inner cylinder. By adjusting the positions of the screens the vacuum resistance may be varied and hence so may the limiting pressure of the sorption pump as a whole. L A K&nits et al, Soviet Patent, class F 04 b, 37102, No. 383877, claimed 1lth Nov 1969, publd 3rd Ott 1973 (in Russian). 21:33 178. Apparatus with a cryogenic pump for studying field-emission cathodes. (USSR) A device incorporating a cryogenic pump for studying the behaviour of field-emission cathodes at pressures down to lo-“’ torr is described. The cathodes in question are intended for correcting the spherical aberration of electron microscopes on the holographic principle. Preliminary evacuation of the cryogenic pump is effected by means of conventional backing and oil diffusion aggregates. After its operation has been initiated, the cryogenic pump may be insulated from the other pumps without detriment to the final vacuum. The pumping section of the cryopump consists of a helium vessel with a space surrounded by copper walls at liquid-helium temperature and a nitrogen vessel with a screen; the vessels are made of stainless steel and the screen of copper. The limiting vacuum after 3 h is lo-lo torr. One filling with liquid helium lasts for 15 h work. P A Stoyanov et al, in Materials of the Ninth Conference on EIectron Microscopy, Tips, 1973 (Moscow, 1973, 38-39) (in Russian). 21 179. Combined magnetic-discharge getter-ion pump. (USSR) The combined magnetic-discharge getter-ion pump here described differs from the conventional variety in that it has a cooled sorption surface in the form of two profiled cylinders; the surface passes around the evaporator of the getter inside the magnetic-discharge section of the pumping system. An initial rarefaction is created in the system by means of an ordinary zeolite pump. The magneticdischarge section is then set in action, and a further degree of rarefaction is created by virtue of the absorption of gas on the surface of the electrode system in this section, and also by virtue of the absorption of gas by the titanium deposited on the outside of the sorption surface. On reaching a rarefaction of 5 x 10m5 torr the evaporator is started, and titanium is deposited on the inside of the sorption surface, in the helical cavities of which a coolant is freely
circulated. As a result of the action of all these pressure-reducing mechanisms together with liquid-nitrogen cooling, a final vacuum of lo-l2 torr may be achieved. M P Zheltov et al, Soviet Patent, class H 01 j, 41100, No. 387465, claimed 8th Feb 1972, publd 19th Ott 1973 (in Russian). 21 180. A centripetal pumping device. (USSR) Ordinary centripetal pumping devices containing a hermeticallysealed chamber with rotor and stator discs have certain practical disadvantages; in the version here proposed the stator disc is sited relative to the rotor with an eccentricity at least equal to 0.2 of the radius of the latter, an arrangement which increases both the head and the rate of flow of the gas being evacuated. The rotor is set in motion with a conventional type of drive, and on reaching a certain prespecified number of revolutions per minute the stator disc is advanced towards the rotor, whereupon gas flows through the small gap remaining between the rotors. The head and rate of flow may be conveniently varied by varying the eccentricity. Z P Shul’man et al, Soviet Patent, class F 04 d, 17/02, No. 383886, claimed 1st Feb 1971, publd 11th Sept 1973 (in Russian). 21 181. Another centripetal pumping device. (USSR) The centripetal pump here described differs from existing versions in that the stator disc is set in a bellows support and furnished with a drive for vertical motion, while the rotor disc is placed on shockabsorbers. This arrangement increases the pressure head and the rate of flow of the gas being evacuated and eliminates the vibrations arising from the rotation of the rotor disc. When the rotor has reached a prespecified angular velocity the stator is brought close to it, forming a narrow gap between the discs, and the gas being evacuated streams between these. The gap may be varied by changing the degree of compression of the bellows, and the head and rate of flow v&y accordingly. Z P Shul’man, Soviet Patenr, class F 04 d, 17102, No. 383887, claimed 1st Feb 1971, &bid 11th Seit 1973 (in Russian). 21 182. Oil-free mechanical backing pump. (USSR) A new form of oil-free mechanical backing pump designed for long service and a relatively high vacuum is described. The body of the pump has a strictly uniform radius while the shell is installed in a stressed state, and in that state has a diameter equal to the inner diameter of the body. The elastic shell is pressed against the body by means of pressure rings. By operating a system of rollers the elastic shell is deformed and the gas in the working chamber is forced out by progressive motion. The system is more efficient than its predecessors by virtue of the better fit achieved between its component parts. N A Yazykov and V A Afanas’ev, Soviet Patent, class F 04 B, 43/08, No. 387137, claimed 29th April 1971, publd 25th Sept 1973 (in Russian). 21 183. An ion-sorption pump of the orbitron type. (USSR) An improved design of ion-sorption pump of the orbitron type intended to increase the working time between servicings (replacement of the evaporators) is described. The pump is provided with an additional space bounded by an end reflector with an anode passing through the aperture. In the region of the anode is a series of bushings made of the same or different getter materials. The bushings are held in place by solder or thin low-melting-point wire, After one getter has been expended a current is passed through the anode to melt the solder and bring the next getter into the working position. The period of continuous service may thus be extended by five or ten times. V A Usbakov et al, Soviet Patent, class F 04 b, 37100, H 01 j, 41100, No. 354175, claimed 26th June 1970, publd 23rd Nov 1972 (in Russian). 21 184. Apparatus for monitoring the time of fault-free operation of vacuum pumps. (USSR) An apparatus for monitoring the period of fault-free operation of vacuum pumps in relation to the conditions of the external medium and the loading conditions is described. The apparatus is based on the conversion of pressure readings into electrical signals, incorporating an amplification stage. The final output signal gives a measure of the worsening vacuum as the pump becomes older and 85