august 31b
TRANSCRIPT
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VACUUM PUMPING METHODS
Sliding Vane
Rotary Pump
Molecular
Drag Pump
Turbomolecular
Pump
Fluid Entrainment
Pump
VACUUM PUMPS
(METHODS)
Reciprocating
Displacement Pump
Gas Transfer
Vacuum Pump
Drag
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
Cryopump
Getter
Pump
Getter Ion
Pump
Sputter Ion
Pump
Evaporation
Ion Pump
Bulk Getter
Pump
Cold TrapIon Transfer
Pump
Gaseous
Ring Pump
Turbine
Pump
Axial Flow
Pump
Radial Flow
Pump
Ejector
Pump
Liquid Jet
Pump
Gas Jet
Pump
Vapor Jet
Pump
Diffusion
Pump
Diffusion
Ejector Pump
Self Purifying
Diffusion Pump
Fractionating
Diffusion Pump
Condenser
Sublimation
Pump
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Pressure EquivalentsAtmospheric Pressure (Standard) =
0
14.7
29.9760
760
760,000101,325
1.013
1013
gauge pressure (psig)
pounds per square inch (psia)
inches of mercurymillimeter of mercury
torr
millitorr or micronspascal
bar
millibar
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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)
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Viscous and Molecular Flow
Viscous Flow
(momentum transfer
between molecules)
Molecular Flow
(molecules move
independently)
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FLOW REGIMES
Viscous 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 between
molecules and wall dominate; flow through random motion;
generally P smaller than 10 mbar-3
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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)
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Viscous Flow
(Long Round Tube; air)
C = 1.38 x 102 x d4 x P1 + P2 (l/sec)
2l
d = diameter of tube in cm
l = length of tube in cm
P1 = inlet pressure in torr
P2 = exit pressure in torr
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Viscous Flow
(Long Round Tube;nitrogen)
EXAMPLE:d = 4 cm P1 = 2 torr
l = 100 cm P2 = 1 torr
C = 138 x d4 x P1 + P2 (liter/sec)
2l
C = 138 x 256 x 3 (liter/sec)
2100
C = 530 (liter/sec)
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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.
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Conductance in Molecular Flow
(Long Round Tube)
d = diameter of tube in cm
l = length of tube in cmT = temperature (K)
M = A.M.U.
C = 3.81 x d3 x T
Ml
(l/sec)
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Conductance in Molecular Flow
(Long Round Tube)EXAMPLE:
T = 295 K (22O
C)M = 28 (nitrogen)
C = 3.81 x d3 x T
Ml
(l/sec)
= 3.81 x d3 x 29528
(l/sec)
l
= 12.36 x d3
l
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EXAMPLE:
T = 295 K (22
O
C) d = 4 cmM = 28 (nitrogen) l = 100 cm
C = 3.81 x d3
xT
Ml (l/sec)
= 3.81 x d3 x295
28
(l/sec)
l
= 12.36 x d3
l= 12.36 x 0.64
= 7.9 (l/sec)
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SYSTEM
PUMP
C1
C2
Series Conductance
RT = R1 + R2
1 = 1 + 1C1 C2CT
1 = C1 + C2C1 x C2CT
CT = C1 x C2
C1 + C2
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GAS LOAD
Outgassing
Leaks
Virtual
Real
Backstreaming
Diffusion
Permeation
GAS LOAD (Q) IS EXPRESSED IN:
mbar liters per second
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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
DiffusionPermeation
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PUMP OPERATING RANGES
10-12 10-10 10-8 10-6 10-4 10-2 1 10+2P (mbar)
Rough VacuumHigh VacuumUltra High
Vacuum
Venturi Pump
Rotary Vane Mechanical PumpRotary Piston Mechanical Pump
Sorption Pump
Dry Mechanical Pump
Blower/Booster Pump
High Vac. PumpsUltra-High Vac. Pumps
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Rotary Vane, Oil-Sealed
Mechanical Pump
(Page 45 manual)
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Pump Mechanism
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OIL BACKSTREAMING
2
PRESSURE LEVELS: LESS THAN 0.2 mbar
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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
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VACUUM SYSTEM USE
1
4
6
5
9
8
81
23
3a
45
6
7
8
9
Chamber
High Vac. PumpRoughing Pump
Fore Pump
Hi-Vac. ValveRoughing Valve
Foreline Valve
Vent Valve
Roughing Gauge
High Vac. Gauge
7
33a
2
8
2
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Oil Diffusion Pump
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Pump Construction
(Page 66 manual)
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How the Pump Works
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How the Pump Works
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Release of Vapors
(Page 67 manual)
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First stage vapors are
separated from others
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Pumping Speed
10-10 10--3 10--1
Pu
mpingSp
eed(Air)
1 2 3 4
Inlet Pressure (Torr)
Critical Point
1. Compression Ratio Limit
2. Constant Speed
3. Constant Q (Overload)
4. Mechanical Pump Effect
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Maximum Tolerable Foreline
Pressure
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VACUUM SYSTEM USE
LN2 COLD
TRAP
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Turbomolecular Pump
ROTOR BODY
HIGH PUMPING SPEED
HIGH COMPRESSION
EXHAUST
HIGH FREQ. MOTOR
INLET FLANGE
STATOR BLADES
BEARING
BEARING
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Rotor - stator assembly
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Pump Operation
Molecule V
Moving Wall with Speed V
Principle of the Turbomolecular Pump
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Roughing through the turbo
1
2
3
45
6
Chamber
Turbo Pump
Roughing Pump
Vent ValveRoughing Gauge
High Vac. Gauge
1
67
4
3
2
5
2