This document provides an overview of vacuum technology. It discusses different types of vacuum including high vacuum and ultra-high vacuum. It describes various vacuum pumps such as diffusion pumps, rotary pumps, turbo pumps, and ion pumps that are used to achieve different pressure ranges. It also discusses vacuum measurement devices like Pirani gauges and Penning gauges. Group members Md. Mohymenul Islam and Shaila Sharmin submitted this document to their professor MD. Didarul Islam Bhuyan on the topics of vacuum technology.

1. Group Members:
Md. Mohymenul Islam (PH 12004)
Shaila Sharmin (PH 12006)
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Submitted To
MD. Didarul Islam Bhuyan
Assistant Professor
Dept. of Physics
MBSTU

2. Content:
 Introduction
 High Vacuum
 Ultra High Vacuum
 Principle of pumping system
 Terminology used in vacuum technology
 Diffusion Pump
 Rotary Pump
 Turbo Pump
 Ion Pump
 Pirani Gauge
 Penning Gauge
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3. INTRODUCTION
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4. HIGH VACUUM: HIGH VACUUM IS VACUUM WHERE THE MEAN FREE PATH OF RESIDUAL
GASES IS LONGER THAN THE SIZE OF THE CHAMBER OR OF THE OBJECT UNDER TEST. IT
USUALLY REQUIRES MULTI-STAGE PUMPING AND ION GAUGE MEASUREMENT.
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High vacuum
FIGURE: High Vacuum

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Ultra High Vacuum
Ultra High Vacuum : British and German standards define ultra high vacuum as pressures
below 10-7 Pa. Ultra high vacuum requires backing the chamber to remove trace gases and
other special producers.
FIGURE: Ultra-High Vacuum

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https://en.wikipedia.org/
wiki/Vacuum_pump

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Pressure range (See note below)
'Degree of vacuum'Pascal
(absolute mode)
Pascal
(absolute mode)
1×105 to 3×103 100 000 to 3 000 low vacuum
3×103 to 1×10-1 3 000 to 0.1 medium vacuum
1×10-1 to 1×10-4 0.1 to 0.000 1 high vacuum
1×10-4 to 1×10-7 0.000 1 to 0.000 000 1 very high vacuum
1×10-7 to 1×10-10 0.000 000 1 to 0.000 000 000 1 ultra-high vacuum (UHV)
<1×10-10 <0.000 000 000 1 extreme-ultrahigh vacuum (EHV or XHV)
Pressure ranges

8. CHARACTERISTICS OF HIGH VACUUM
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9. CHARACTERISTICS OF ULTRA HIGH VACUUM
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10. Need of HV & UHV :
High vacuum is needed in a variety of processes and devices. Its first use was in the incandescent light
bulb to protect the filament from chemical degradation. The chemical inertness produced by a vacuum
is also useful for electron beam welding, cold welding , vacuum packing and vacuum frying.
Ultra high vacuum is used in the study of automatically clean substrates as only a good vacuum
preserves atomic-scale clean surfaces for reasonably long time. High to ultra high vacuum removes the
obstruction of air allowing particle beams to deposit or remove materials without contamination. UHV
is also used for particle accelerators, gravitational wave detectors, atomic physics and microscopy.
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11. Principle of pumping system
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12. Terminology used in vacuum technology :
 Absorption
 Adsorption
 Backing Pump
 Compression Ratio
 Desorption
 Final Pressure
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14. Diffusion pump is an oil-based vacuum pump, that is used for obtaining different levels of vacuum – even high
vacuum of 10 -9 Pascal. In this system the oil is boiled by a heating with a heater.
The system consists of
 Multistage nozzles
 Overheating protection
 Oil reservoir
 Boiler
 Foreline baffle
 Water-cooled body
 Outlet
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Diffusion Pump

15. Diffusion pumps work by spraying hot oil from nozzles close to the vacuum chamber down
to a reservoir at the base of the pump. When the oil encounters an air molecule, it tends to
deflect it towards the bottom of the pump. Near the bottom of the pump there is a exhaust
line connected to a backing pump which removes the gas molecules accumulated by the oil
spray from the system. To avoid oil getting into the main vacuum system, it is necessary to
use a cold trap which condenses the oil vapor. The oil then drips back into the main
pumping system.
Diffusion pumps are by nature very messy and fairly temperamental, but they are quite
simple and inexpensive compared to turbo molecular pumps. Diffusion pumps are limited
in pressure by the presence of oil vapors and molecules derived from the chemical
decomposition of the pump oil.
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Diffusion Pump

16. Uses of Diffusion Pump :
An oil diffusion pump is used to achieve higher vacuum (lower pressure) than is possible by use of positive
displacement pumps alone. Although its use has been mainly associated within the high-vacuum range (down to
10−9 mbar), diffusion pumps today can produce pressures approaching 10−10 mbar when properly used with
modern fluids and accessories. 21

17. Rotary pump is an oil sealed mechanical
vacuum pump.
The outlet valve is oil-sealed.The inlet valve
is designed as a vacuum safety valve that is
always open during operation.The working
chamber is located inside the housing. Rotor
and vanes divide the working chamber into
two separate spaces having variable
volumes. As the rotor turns, gas flows into
the enlarging suction chamber until it is
sealed off by the second vane.The enclosed
gas is compressed until the outlet valve
opens against atmospheric pressure. Oil is
used as a lubricant, coolant and gas sealant
for the vanes. Single-stage rough rotary vane
pumps have ultimate pressures around 10-2
Torr range while two stage pumps reach 10-3
Torr.
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Rotary Pump

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Turbo pump is the most common type of pump for
high vacuum processes which reduces the pressure
from about 10-3 Torr to about 10-7 Torr.
Turbo Pump
A cutaway view of a turbo molecular high
vacuum pump

19. Ion pump is a vacuum pump or high vacuum to achieve the ionization of the gas.
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Ion Pump

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21. Pirani gauge is a device use to measure low
vacuum between the range.
There are three modes of operation for a pirani
gauge:
i. Constant current and measure voltage
ii. Constant resistance
iii. Constant voltage
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Pirani Gauge

22. Penning gauge is also known as cathode gauge which
uses an ion current to measure pressure. In this
gauge, a much higher voltage (2kV) is used but there
is no heating to the cathode. The gauge is formed
from two cathode plates with a wire loop anode
halfway between the two.
An electron emitted from the cathode is accelerated
towards the positive anode, and due to the magnetic
field it also accelerated perpendicular to its direction
of motion. This results in a helix trajectory of the
electron and can have a length of several meters.
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Penning gauge

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Penning gauge

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