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BASIC VACUUM PRACTICE. To move a particle in a (straight) line over a large distance. Why is a Vacuum Needed?. (Page 5 manual). To provide a clean surface. Why is a Vacuum Needed?. (High)Vacuum. Atmosphere. Contamination (usually water). Clean surface. HOW DO WE CREATE A VACUUM?. - PowerPoint PPT Presentation
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BASIC VACUUMPRACTICE
Why is a Vacuum Needed?
To move a particle in a (straight) line over a large distance
(Page 5 manual)
Why is a Vacuum Needed?
Contamination(usually water)
Clean surface
Atmosphere (High)Vacuum
To provide a clean surface
HOW DO WE CREATE A VACUUM?
VACUUM PUMPING METHODS
Sliding VaneRotary Pump
MolecularDrag Pump
TurbomolecularPump
Fluid EntrainmentPump
VACUUM PUMPS(METHODS)
ReciprocatingDisplacement Pump
Gas TransferVacuum Pump
DragPump
EntrapmentVacuum Pump
Positive DisplacementVacuum Pump
KineticVacuum Pump
RotaryPump
DiaphragmPump
PistonPump
Liquid RingPump
RotaryPiston Pump
RotaryPlunger Pump
RootsPump
Multiple VaneRotary Pump
DryPump
AdsorptionPump
Cryopump
GetterPump
Getter IonPump
Sputter IonPump
EvaporationIon Pump
Bulk GetterPump
Cold TrapIon TransferPump
Gaseous Ring Pump
TurbinePump
Axial FlowPump
Radial FlowPump
EjectorPump
Liquid JetPump
Gas JetPump
Vapor JetPump
DiffusionPump
DiffusionEjector Pump
Self PurifyingDiffusion Pump
FractionatingDiffusion Pump
Condenser
SublimationPump
BAROMETER
WATER MERCURY
760mm
Mercury: 13.58 times heavier than water: Column is 13.58 x shorter :10321 mm/13.58=760 mm (= 760 Torr)
10.321mm
29,9in
(Page 12 manual)
PRESSURE OF 1 STANDARD ATMOSPHERE:
760 TORR, 1013 mbar
AT SEA LEVEL, 0O C AND 45O LATITUDE
Pressure Equivalents
Atmospheric Pressure (Standard) =
014.729.9760760760,000101,3251.0131013
gauge pressure (psig)pounds per square inch (psia)inches of mercurymillimeter of mercurytorrmillitorr or micronspascalbarmillibar
THE ATMOSPHERE IS A MIXTURE OF GASES
PARTIAL PRESSURES OF GASES CORRESPOND TO THEIR RELATIVE VOLUMES
GAS SYMBOLPERCENT BY
VOLUMEPARTIAL PRESSURE
TORR PASCAL
NitrogenOxygenArgonCarbon DioxideNeonHeliumKryptonHydrogenXenonWater
N2
O2
ACO2
NeHeKrH2
XH2O
7821
0.930.03
0.00180.00050.0001
0.000050.0000087Variable
5931587.1
0.251.4 x 10-2
4.0 x 10-3
8.7 x 10-4
4.0 x 10-4
6.6 x 10-5
5 to 50
79,00021,000
940331.8
5.3 x 10-1
1.1 x 10-1
5.1 x 10-2
8.7 x 10-3
665 to 6650
(Page 13 manual)
VAPOR PRESSURE OF WATER AT VARIOUS TEMPERATURES
T (O C)
100
25
0
-40
-78.5
-196
P (mbar)
1013
32
6.4
0.13
6.6 x 10 -4
10 -24
(BOILING)
(FREEZING)
(DRY ICE)
(LIQUID NITROGEN)
(Page 14 manual)
(Page 15 manual)
Vapor Pressure of some Solids
(Page 15 manual)
PRESSURE RANGES
RANGE
ROUGH (LOW) VACUUM
HIGH VACUUM
ULTRA HIGH VACUUM
PRESSURE
759 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 FLOWCONDUCTANCE
(Page 24 manual)
Viscous and Molecular Flow
Viscous Flow(momentum transferbetween molecules)
Molecular Flow(molecules moveindependently)
FLOW REGIMESViscous Flow:
Distance between molecules is small; collisions between molecules dominate; flow through momentum transfer;generally P greater than 0.1 mbar
Transition Flow: Region between viscous and molecular flow
Molecular Flow: Distance between molecules is large; collisions betweenmolecules 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
1013 mbar (atm) 1 x 10-3 mbar 1 x 10-9 mbar
#mol/cm3
MFP
3 x 10 19
(30 million trillion)4 x 10 13
(40 trillion)4 x 10 7
(40 million)
2.5 x 10-6 in6.4 x 10-5 mm
2 inches5.1 cm
31 miles50 km
FLOW REGIMES
Mean Free PathCharacteristic Dimension
Viscous Flow: is less than 0.01
Mean Free PathCharacteristic Dimension
Molecular Flow: is greater than 1
Mean Free PathCharacteristic Dimension
Transition Flow: is between 0.01 and 1
Conductance in Viscous Flow
Under viscous flow conditions doubling thepipe diameter increases the conductance sixteen times.The conductance is INVERSELY related to the pipe length
(Page 28 manual)
Conductance in Molecular Flow
Under molecular flow conditions doublingthe pipe diameter increases the conductanceeight times.The conductance is INVERSELY related tothe pipe length.
SYSTEM
PUMP
C1
C2
Series Conductance
RT = R1 + R2
1 = 1 + 1C1 C2CT
1 = C1 + C2
C1 x C2CT
CT = C1 x C2
C1 + C2
(Page 29 manual)
GAS LOAD
Outgassing
Leaks
Virtual
Real
BackstreamingDiffusion
Permeation
GAS LOAD (Q) IS EXPRESSED IN:mbar liters per second
Pumpdown CurveP
ress
ure
(m
bar
)
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 METHODS
Sliding VaneRotary Pump
MolecularDrag Pump
TurbomolecularPump
Fluid EntrainmentPump
VACUUM PUMPS(METHODS)
ReciprocatingDisplacement Pump
Gas TransferVacuum Pump
DragPump
EntrapmentVacuum Pump
Positive DisplacementVacuum Pump
KineticVacuum Pump
RotaryPump
DiaphragmPump
PistonPump
Liquid RingPump
RotaryPiston Pump
RotaryPlunger Pump
RootsPump
Multiple VaneRotary Pump
DryPump
AdsorptionPump
Cryopump
GetterPump
Getter IonPump
Sputter IonPump
EvaporationIon Pump
Bulk GetterPump
Cold TrapIon TransferPump
Gaseous Ring Pump
TurbinePump
Axial FlowPump
Radial FlowPump
EjectorPump
Liquid JetPump
Gas JetPump
Vapor JetPump
DiffusionPump
DiffusionEjector Pump
Self PurifyingDiffusion Pump
FractionatingDiffusion Pump
Condenser
SublimationPump
PUMP OPERATING RANGES
10-12 10-10 10-8 10-6 10-4 10-2 1 10+2
P (mbar)
Rough VacuumHigh VacuumUltra High Vacuum
Venturi Pump
Rotary Vane Mechanical Pump
Rotary Piston Mechanical Pump
Sorption PumpDry Mechanical Pump
Blower/Booster Pump
High Vac. PumpsUltra-High Vac. Pumps
VACUUM SYSTEM USE
1
2
4
6
5
9
8
8
7
123
3a456789
ChamberHigh Vac. PumpRoughing PumpForeline PumpHi-Vac. ValveRoughing ValveForeline ValveVent ValveRoughing GaugeHigh Vac. Gauge
7
33a
(Page 44 manual)
Rotary Vane, Oil-Sealed Mechanical Pump
(Page 45 manual)
Pump Mechanism
How the Pump Works
(Page 46 manual)
OIL BACKSTREAMING
2
PRESSURE LEVELS: LESS THAN 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
123456789
101112
ChamberForelineRoughing ValveRoughing GaugeRoughing PumpForelineForeline ValveForeline GaugeHigh Vacuum ValveBooster/BlowerVent ValveHigh Vacuum Gauge
1
9
3
12
4
11
5
2
678
10
(Page 62 manual)
Sorption Pump Components
(Page 54 manual)
Vapor Pressure
(Page 56 manual)
Cryo-condensation
Cryo-sorption
(Page 55 manual)
HIGH VACUUM PUMPS
3
(Page 63 manual)
VACUUM PUMPING METHODS
Sliding VaneRotary Pump
MolecularDrag Pump
TurbomolecularPump
Fluid EntrainmentPump
VACUUM PUMPS(METHODS)
ReciprocatingDisplacement Pump
Gas TransferVacuum Pump
DragPump
EntrapmentVacuum Pump
Positive DisplacementVacuum Pump
KineticVacuum Pump
RotaryPump
DiaphragmPump
PistonPump
Liquid RingPump
RotaryPiston Pump
RotaryPlunger Pump
RootsPump
Multiple VaneRotary Pump
DryPump
AdsorptionPump
Cryopump
GetterPump
Getter IonPump
Sputter IonPump
EvaporationIon Pump
Bulk GetterPump
Cold TrapIon TransferPump
Gaseous Ring Pump
TurbinePump
Axial FlowPump
Radial FlowPump
EjectorPump
Liquid JetPump
Gas JetPump
Vapor JetPump
DiffusionPump
DiffusionEjector Pump
Self PurifyingDiffusion Pump
FractionatingDiffusion Pump
Condenser
SublimationPump
PUMP OPERATING RANGES
10-12 10-10 10-8 10-6 10-4 10-2 1 10+2
P (Torr)
Rough VacuumHigh VacuumUltra High Vacuum
Roughing Pumps
Turbo Pump
Diffusion Pump
Cryo Pump
Ion Pump
Tit. Subl. Pump
Liquid Nitrogen Trap
VACUUM SYSTEM USE
1
4
6
5
9
8
8123
3a456789
ChamberHigh Vac. PumpRoughing PumpFore PumpHi-Vac. ValveRoughing ValveForeline ValveVent ValveRoughing GaugeHigh Vac. Gauge
7
33a
28
2
Oil Diffusion Pump
Pump Construction
(Page 66 manual)
How the Pump Works
How the Pump Works
First stage vapors are separated from others
Pumping Speed
10-10 10--3 10--1
Pu
mp
ing
Sp
eed
(A
ir)
1 2 3 4
Inlet Pressure (Torr)
Critical Point
1. Compression Ratio Limit2. Constant Speed3. Constant Q (Overload)4. Mechanical Pump Effect
Maximum Tolerable Foreline Pressure
(Page 73 manual)
LN2 reservoir with baffles
(Page 78 manual)
How the LN2 Trap Works
GasApproximate Vapor
Pressure (mbar)
Water (H2O)Argon (A)Carbon Dioxide (CO2)Carbon Monoxide (CO)Helium (He)Hydrogen (H2)Oxygen (O2)Neon (Ne)Nitrogen (N2)Solvents
10-22
500 10 -7
>760>760>760 350>760 760 <10 -10
(Page 79 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 OperationMolecule V
Moving Wall with Speed V
Principle of the Turbomolecular Pump
(Page 83 manual)
Roughing through the turbo
123456
ChamberTurbo PumpRoughing PumpVent ValveRoughing GaugeHigh Vac. Gauge
1
67
4
3
25
2
(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 VacuumHigh VacuumUltra High Vacuum
Bourdon Gauge
Thermocouple Gauge
Cold Cathode Gauge
Capacitance Manometer
Hot Fil. Ion Gauge
Residual Gas Analyzer
Pirani Gauge
Spinning Rotor Gauge
McLeod 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
QUADRUPOLEHEAD
CONTROL UNIT
How the RGA works
MASS NUMBER (A.M.U.)
RE
LA
TIV
E I
NT
EN
SIT
Y
NORMAL (UNBAKED) SYSTEM
H2
H2O
N2,, CO
CO2
(A)
RGA SPECTRUM
MASS NUMBER (A.M.U.)
RE
LA
TIV
E I
NT
EN
SIT
Y
SYSTEM WITHAIR LEAK
H2
H2O
N2
CO2
(B)
O2
RGA SPECTRUM
LEAK DETECTION
9
(Page 249 manual)
Introduction
Problems that appear to be Leaks
Outgassing
Leaks
Virtual
Real
Backstreaming
DiffusionPermeation
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 because 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 SEC10 -3 STD CC/SEC --- 3 CC/HOUR10 -5 STD CC/SEC --- 1 CC/DAY10 -6 STD CC/SEC --- 1 CC/2 WEEKS10 -7 STD CC/SEC --- 3 CC/YEAR10 -9 STD CC/SEC --- 1 CC/30 YEARS
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
CONVENTIONAL LEAK DETECTOR
123456789
101112
Test PieceTest PortHigh Vac. PumpRoughing PumpFore PumpRoughingValveTest ValvePump ValveSpectrometer TubeCold TrapRoughing GaugeVent Valve
7 6
12
45
1
3
8
11
2
9 10
Ion Separation in Magnetic Field
Ion Source
To Pre-Amplifier
Collector
Magnetic FieldDeflects He Ions90O, other ions more or less than90O.
He ions passthrough slit andare collected
Lighter ions:more
Heavier ions:less
Ion Gauge
Tracer probe leak detection technique