3. Introduction
Vacuum
The vacuum is a partially empty space in which some of the air and other gases have been removed from a gas-
filled volume. A vacuum is defined as any volume that has a lower particle density and gas pressure than the
surrounding outer atmosphere. Thus, a gaseous environment with pressures lower than the atmosphere is called a
vacuum.
Vacuum ranges
GV = Rough vacuum (Atmospheric Pressure …1m bar)
FV = Medium vacuum (𝟏𝟎−𝟑… 1 m bar )
HV = High vacuum (𝟏𝟎−𝟑… 𝟏𝟎−𝟖m bar )
UHV = Ultra-high vacuum (𝟏𝟎−𝟖… 𝟏𝟎−𝟏𝟏m bar )
4. Units of measurement
The units that are most frequently used are Pascal (Pa) and bar.
100 Pa = 1 hPa , 1 hPa = 1 mbar , 1 mbar = 0.001 bar
Vacuum systems
Vacuum systems are equipment designed to create and maintain a low-pressure
environment by removing gases and fluids from a specific area. They utilize suction and
negative pressure to achieve this.
Vacuum systems are utilized in various industrial sectors, including manufacturing,
packaging, medical applications, and material handling, for depositing and characterizing
thin films using pumps, tubing, valves, and gauges.
5. Vacuum Technology
Vacuum technology is based on the creation of an environment in which the
needed process, the deposition of thin films, may be carried out.
Vacuum technology removes atmospheric components, reduces molecular effects,
and extends particle movement distance, preventing contamination and collisions,
thereby ensuring the safety of prepared surfaces and preventing particle collisions.
Different kind of vacuum pumps have different ranges where they are effective
and so to go from atmospheric pressure.
To the ultra-high vacuum of a microscope column, you employ different kinds of
pumps one after another.
6. Vacuum Pump
A vacuum pump is a machinery that creates a vacuum when the chamber pressure is lower
than the surrounding systems or atmosphere.
The history of a vacuum pump
Otto von Guericke undoubtedly invented the first vacuum pump, in the sense of a machine
that could gradually remove air from a closed vessel, around 1650.
8. Components and operation
A vacuum evaporation system for metals uses
a multistage oil diffusion pump and rotary
mechanical pump.
The system has a dual vacuum pumping circuit
with three valves. The high-vacuum and roughing
valves are closed during cold start, and the
foreline valve is opened.
9. Types of vacuum pumps
Gas transfer
pumps
Positive
Displacement
pumps
Rotary
mechanical
pumps
Root pumps
Kinetic
Vacuum
pumps
diffusion
pumps
Turbomolecul
ar
pumps
Entrapment
pumps
Cryogenic
pumps
Sputtering
pumps
Adsorption
pumps
10. Positive displacement pumps
positive displacement pumps:
Positive displacement pumps create an
additional volume, this volume allows the gas
to transfer into it then the pump confine the
gas and empty it.
Rotary vane pumps:
11. Oil diffusion pumps
A heated oil diffusion pump is mounted below the
electron and uses baffles to deflect oil molecules,
causing them to bounce downward.
The cold edges of the pump maintain a cold
environment, causing the oil to condense and drip
back into the reservoir.
Gas molecules from the column enter the pump,
eventually being knocked down and exhausted
before being passed to a holding tank pumped by a
rotary pump.
13. Turbo- molecular pump
Turbo-molecular pump: Molecular turbopump As gas molecules come down from the
column, they'll get inside between one of these propellers, and as the propellers spin round
and round, they bat the molecules down and out, and as the pressure drops lower and lower,
these vanes spin faster and faster.
14. Entrapment pumps
Cryogenic Vacuum Pump: This kind
of vacuum pump operates by
lowering the gas's temperature to
the freezing or condensation point.
Cryogenic pumps are capable of
generating a very clean vacuum in
the pressure range of 10 -3 to 10 -10
torr
15. Vacuum leak
No vacuum apparatus is absolutely vacuum tight and, however, is that the leak rate be small
and not influence the required working pressure, gas content, or ultimate system pressure
16. What is a pressure gauge?
A pressure gauge is an instrument for measuring fluid intensity
in a pressure powered machine. This fluid intensity is specified
by the force that the fluid would exert on a specific unit area.
Typical pressure gauge intensity measurement units are
pounds per square inch (psi), or newtons per square meter
called the pascal, or torr
18. Direct pressure gauges
Direct reading gauges are so called because they measure
pressure directly :
by measuring the force exerted by a gas over an area.
Direct reading gauges exist that can measure accurately
from atmospheric pressure down to the range of 10-5 torr.
Popular direct reading gauge technologies are capacitance
manometers
A major advantage of direct reading gauges is that they
can be gas independent; that is, accuracy is not impacted
by the type of gas being measured.
19. Capacitance manometers
What makes them different?
Highly accurate Operates over a wide
temperature range
Insensitive of gas
composition
20. How does it works?
A pressure sensor measures pressure by deforming a diaphragm.
A capacitance gauge converts pressure-modulated movement into an
electrical signal.
The sensor is exposed to pressure and an electrode, typically a ceramic
disc, is mounted in the reference cavity.
Pressure differences cause capacitance variations, which are amplified by
electronics and controlled using communication protocols.
21.
22. Indirect pressure gauges
As pressure drops, indirect reading gauges are used to measure
gas force, such as thermal conductivity or density.
Pirani gauges, based on thermal conductivity, are most accurate
in 10¯⁴ tor range.
23.
24. Residual gas analysis
The RGA sensor filters ions based on their mass to charge ratio,
generating an output current.
This current is measured at the detector using a Faraday cup or
Secondary Electron Multiplier.
25. conclusion
Vacuum systems significantly enhance industrial
efficiency by improving productivity, safety, and cost
reduction through careful selection and maintenance.
Vacuum systems are crucial in industries like
semiconductor manufacturing, pharmaceutical
production, and food packaging, enabling precise control
and enhancing product quality.
26. References
Marquardt, N., Introduction to the Principles of Vacuum. CERN European Organization for Nuclear
Research Reports, Dortmund, 1999.
Festo, A. and C. KG, Basic principles of vacuum technology, brief overview. 2015.
Ohring, M., Materials Science of Thin Films: Depositon and Structure. 2001: Elsevier.
https://www.iqsdirectory.com/articles/vacuum-pump.html.
Bozzola, J.J. and L.D. Russell, Electron microscopy: principles and techniques for biologists. 1999:
Jones & Bartlett Learning.
https://www.antsalliance.com/pump/oil-diffusion/hot-sale-high-quality-oil-Diffusion-Pump.html
https://www.vacuumscienceworld.com/blog/residual-gasanalysers-explained
https://vacuu-lan.com/vacuum-measurement-direct-indirectgauges/
https://realpars.com/pressure-gauge/
https://www.goodreads.com/author/show/615381.Milton_OhriNg
Rotary Vane Pump Animation – YouTube
