6.152J/3.155J D Molecules physically removed from chamber a)MechanIcal pump b)Oll diffusion pump c) Turbo molecular pump But pumps from momentum transfer to gas, pres're Incr's away from chamber 1 atm to whIch Is pumped out. s 2X 10Us S=12AUS gas pumped by backing pump. No oll. s= 103 L/s 104T Wed, Sept. 10, 2003 2) Molecules adsorbed on a surface, or burled In a layer a)Sputter/on pump(wlth TI sublimation b)Cryo pump Gas Is ionized 760To by hI-V lons splral In b fleld embed in anode Very clean, Coated by TI molecules condense No moving parts, on cold (120 K surfaces no oll o moving parts, s 3A(cm2L/ depends on 6.152J3.155 Wed, Sept 10, 2003(760 Torr 1 Torr 1 milli 6.152J/3.155J 6.152J/3.155J Wed., Sept. 10, 2003 13 1) Molecules physically removed from chamber a) Mechanical pump b) Oil diffusion pump c) Turbo molecular pump Hot Si oil vaporized, jetted toward fore pump, momentum transfer to gas, which is pumped out. S = 12A L/s Oil contamination, Vibrations. But pumps from 1 atm to mT. S 2 x 104 L/s 1 atm ) 1 milliT 10-6 T 10-9 T Rotating (25 krpm) vanes impart momentum to gas, pres’re incr’s away from chamber, gas pumped by backing pump. No oil. S = 103 L/s 6.152J/3.155J Wed., Sept. 10, 2003 14 2) Molecules adsorbed on a surface, or buried in a layer a) Sputter/ion pump (with Ti sublimation) b) Cryo pump Gas is ionized by hi-V, ions spiral in B field, embed in anode, Coated by Ti. No moving parts, no oil. S depends on pump size and S(H) >>>S(O,N,H2O) B v 1 atm (760 Torr) 1 Torr T 10-6 T 10-9 T Very clean, molecules condense on cold (120 K) surfaces, No moving parts. S 3A (cm2)L/s 7