BASIC VACUUMPRACTICE.ppt

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1、BASIC VACUUM PRACTICE,Why is a Vacuum Needed?,(Page 5 manual),Why is a Vacuum Needed?,Contamination (usually water),Clean surface,Atmosphere,(High)Vacuum,HOW DO WE CREATE A VACUUM?,VACUUM PUMPING METHODS,BAROMETER,WATER,MERCURY,760 mm,Mercury: 13.58 times heavier than water: Column is 13.58 x shorte

2、r : 10321 mm/13.58=760 mm (= 760 Torr),10.321 mm,29,9 in,(Page 12 manual),PRESSURE OF 1 STANDARDATMOSPHERE:,760 TORR, 1013 mbarAT SEA LEVEL, 0O C AND 45O LATITUDE,Pressure Equivalents,THE ATMOSPHERE IS A MIXTURE OF GASES,(Page 13 manual),VAPOR PRESSURE OF WATER AT VARIOUS TEMPERATURES,(Page 14 manua

3、l),(Page 15 manual),Vapor Pressure of some Solids,(Page 15 manual),PRESSURE RANGES,RANGEROUGH (LOW) VACUUMHIGH VACUUMULTRA HIGH VACUUM,PRESSURE759 TO 1 x 10 -3 (mbar)1 x 10 -3 TO 1 x 10 -8 (mbar)LESS THAN 1 x 10 -8 (mbar),(Page 17 manual),GAS FLOW CONDUCTANCE,(Page 24 manual),Viscous and Molecular F

4、low,FLOW REGIMES,Viscous Flow: Distance between molecules is small; collisions betweenmolecules dominate; flow through momentum transfer;generally P greater than 0.1 mbarTransition Flow: Region between viscous and molecular flowMolecular Flow: Distance between molecules is large; collisions betweenm

5、olecules and wall dominate; flow through random motion;generally P smaller than 10 mbar,-3,(Page 25 manual),MEAN FREE PATH,MOLECULAR DENSITY AND MEAN FREE PATH,FLOW REGIMES,Conductance in Viscous Flow,Under viscous flow conditions doubling the pipe diameter increases the conductance sixteen times. T

6、he conductance is INVERSELY related to the pipe length,(Page 28 manual),Viscous Flow (Long Round Tube; air),d = diameter of tube in cm l = length of tube in cm P1 = inlet pressure in torr P2 = exit pressure in torr,Viscous Flow (Long Round Tube; nitrogen),EXAMPLE: d = 4 cm P1 = 2 torr l = 100 cm P2

7、= 1 torr,Conductance in Molecular Flow,Under molecular flow conditions doubling the pipe diameter increases the conductance eight times. The conductance is INVERSELY related to the pipe length.,Conductance in Molecular Flow (Long Round Tube),d = diameter of tube in cm l = length of tube in cm T = te

8、mperature (K) M = A.M.U.,Conductance in Molecular Flow (Long Round Tube),EXAMPLE: T = 295 K (22 OC) M = 28 (nitrogen),SYSTEM,PUMP,C1,C2,Series Conductance,RT = R1 + R2,1 = 1 + 1,C1,C2,CT,1 = C1 + C2,C1 x C2,CT,CT = C1 x C2,C1 + C2,(Page 29 manual),GAS LOAD,Outgassing,Leaks,Virtual,Real,Backstreaming

9、,Diffusion,Permeation,GAS LOAD (Q) IS EXPRESSED IN: mbar liters per second,Pumpdown Curve,Pressure (mbar),Time (sec),10-11,10 1,10 3,10 5,10 7,10 9,10 11,10 13,10 15,10 17,10+1,10-1,10-3,10-5,10-7,10-9,Volume,Surface Desorption,Diffusion,Permeation,Roughing Pumps,2,(Page 39 manual),VACUUM PUMPING ME

10、THODS,Sliding Vane Rotary Pump,Reciprocating Displacement Pump,Entrapment Vacuum Pump,Positive Displacement Vacuum Pump,Kinetic Vacuum Pump,Rotary Pump,Diaphragm Pump,Piston Pump,Liquid Ring Pump,Rotary Piston Pump,Rotary Plunger Pump,Roots Pump,Multiple Vane Rotary Pump,Dry Pump,Adsorption Pump,Cry

11、opump,Getter Pump,Sputter Ion Pump,Cold Trap,Ion Transfer Pump,Turbine Pump,Axial Flow Pump,Radial Flow Pump,Liquid Jet Pump,Gas Jet Pump,Vapor Jet Pump,Diffusion Pump,Diffusion Ejector Pump,Self Purifying Diffusion Pump,PUMP OPERATING RANGES,10-12,10-10,10-8,10-6,10-4,10-2,1,10+2,P (mbar),Rough Vac

12、uum,High Vacuum,Ultra High Vacuum,High Vac. Pumps,Ultra-High Vac. Pumps,VACUUM SYSTEM USE,1,2,4,6,5,9,8,8,7,7,3,3a,(Page 44 manual),Rotary Vane, Oil-Sealed Mechanical Pump,(Page 45 manual),Pump Mechanism,How the Pump Works,(Page 46 manual),Pump Down Curves,OIL BACKSTREAMING,PRESSURE LEVELS: LESS THA

13、N 0.2 mbar,The Molecular Sieve/Zeolite Trap,(Page 48 manual),Dry Vacuum Pumps,Blower/Booster Pump,(Page 61 manual),One Stage Roots Blower Pump Assembly,VACUUM SYSTEM USE,(Page 62 manual),Piston Type Pump,(Page 51 manual),Piston design,(Page 50 manual),Sorption Pump,Sorption Pump Components,(Page 54

14、manual),Vapor Pressure,(Page 56 manual),Cryo-condensation,Cryo-sorption,(Page 55 manual),HIGH VACUUM PUMPS,3,(Page 63 manual),VACUUM PUMPING METHODS,Sliding Vane Rotary Pump,Reciprocating Displacement Pump,Entrapment Vacuum Pump,Positive Displacement Vacuum Pump,Kinetic Vacuum Pump,Rotary Pump,Diaph

15、ragm Pump,Piston Pump,Liquid Ring Pump,Rotary Piston Pump,Rotary Plunger Pump,Roots Pump,Multiple Vane Rotary Pump,Dry Pump,Adsorption Pump,Cryopump,Getter Pump,Sputter Ion Pump,Cold Trap,Ion Transfer Pump,GaseousRing Pump,Turbine Pump,Axial Flow Pump,Radial Flow Pump,Liquid Jet Pump,Gas Jet Pump,Va

16、por Jet Pump,Diffusion Pump,Diffusion Ejector Pump,Self Purifying Diffusion Pump,PUMP OPERATING RANGES,10-12,10-10,10-8,10-6,10-4,10-2,1,10+2,P (Torr),Rough Vacuum,High Vacuum,Ultra High Vacuum,Roughing Pumps,Turbo Pump,Diffusion Pump,Cryo Pump,Ion Pump,Tit. Subl. Pump,Liquid Nitrogen Trap,VACUUM SY

17、STEM USE,1,4,6,5,9,8,8,7,3,3a,2,8,2,Oil Diffusion Pump,Pump Construction,(Page 66 manual),How the Pump Works,How the Pump Works,Release of Vapors,(Page 67 manual),First stage vapors are separated from others,Pumping Speed,Maximum Tolerable Foreline Pressure,(Page 73 manual),LN2 reservoir with baffle

18、s,(Page 78 manual),How the LN2 Trap Works,Gas,Approximate Vapor Pressure (mbar),Water (H2O) Argon (A) Carbon Dioxide (CO2) Carbon Monoxide (CO) Helium (He) Hydrogen (H2) Oxygen (O2) Neon (Ne) Nitrogen (N2) Solvents,10-2250010 -7 760 760 760350 76076010 -10,(Page 79 manual),VACUUM SYSTEM USE,LN2 COLD

19、TRAP,(Page 80 manual),Turbomolecular Pump,ROTOR BODY,HIGH PUMPING SPEED,HIGH COMPRESSION,EXHAUST,HIGH FREQ. MOTOR,INLET FLANGE,STATOR BLADES,BEARING,BEARING,(Page 81 manual),Rotor - stator assembly,(Page 82 manual),Pump Operation,Molecule,V,Moving Wall with Speed V,Principle of the Turbomolecular Pu

20、mp,(Page 83 manual),Roughing through the turbo,(Page 91 manual),Pumping by Cryocondensation,Cryosorption in charcoal,(Page 98 manual),Charcoal placement,Gauges,5,(Page 123 manual),Gauge Operating Ranges,10-12,10-10,10-8,10-6,10-4,10-2,1,10+2,P (mbar),Rough Vacuum,High Vacuum,Ultra High Vacuum,Residu

21、al Gas Analyzer,Spinning Rotor Gauge,Bourdon Gauge,How the gauge works,Heat Transfer Gauges,Thermocouple gauge and Pirani Gauge,Thermocouple Gauge,How the gauge works,Ionization gauges,Ionization current is the measure of vacuum,Residual Gas Analyzer,How the RGA works,RGA SPECTRUM,RGA SPECTRUM,LEAK

22、DETECTION,9,(Page 249 manual),Introduction,Problems that appear to be Leaks,Trapped Volumes,Vented Screw,Double O ring sealed shafts,Atmosphere (760 torr),Vacuum,Differential Pumping,Atmosphere (1013 mbar),Vacuum,To Pump,1 mbar,PERMEATION LEAKS,Permeation “leaks” are different than real leaks becaus

23、e the only way to stop them is to change to a less permeable material,One standard cubic centimeter/sec (std. cc/sec),Leak rate of 1 x 10-1 std cc/sec,Leak rate of 1 x 10-3 std cc/sec,Leak Rates over Time,LEAK RATES,10 -1 STD CC/SEC - 1 CC/10 SEC 10 -3 STD CC/SEC - 3 CC/HOUR 10 -5 STD CC/SEC - 1 CC/

24、DAY 10 -6 STD CC/SEC - 1 CC/2 WEEKS 10 -7 STD CC/SEC - 3 CC/YEAR 10 -9 STD CC/SEC - 1 CC/30 YEARS,Permeation may occur 1X10-8 std cc/sec,Why Helium is used,HELIUM,Helium is very light and small Low concentration in air (0.0005%) Permits dynamic testing Permits non-destructive testing Helium is safe,

25、CONVENTIONAL LEAK DETECTOR,7,6,12,4,1,3,8,11,2,9,10,Ion Separation in Magnetic Field,Ion Source,To Pre-Amplifier,Collector,Magnetic Field Deflects He Ions 90O, other ions more or less than 90O.,He ions pass through slit and are collected,Lighter ions: more,Heavier ions: less,Ion Gauge,Tracer probe leak detection technique,Leak detectors are calibrated with the “permeation leak”,