Course detail

# Electrovacuum instruments and cryogenic technique

Gas, steam, pressure. Ideal gas laws. Principles of kinetic theory of gases. Pumping processes. Special electronic circuits for electro-vacuum devices. Devices based on measuring of macroscopic properties of gas (vacuometers,
mass flowmeters), on control of charged particles trajectories (mass spectrometers, electron microscopes) and on exploitation of cryogenic technology (cryogenic and cryosorption pumps). Devices based on exploitation of gas discharges ( plasma deposition and plasma etching devices, ionic pumps).

Learning outcomes of the course unit

Based on the verification of the student's knowledge and skills in seminars, laboratory work and in the written exam, after completing the course the student is able to:

Interpret the ideal gas laws: Boyle-Mariott, Gay-Lussac (Charles´s) and Dalton laws.
Derive and interpret the Equation of state of ideal gas.
Define conditions for modeling the processes in gases using the Kinetic theory of gases.
Calculate the number of incident molecules per unit time per unit area.
Calculate the mean free path of particles in the gas and discuss its impact on the processes in vacuum.
Define and explain the Maxwell-Boltzmann velocity distribution of particles in the gas.
Calculate the mean velocity, root mean square velocity and most probable velocity of particles in a gas.
Describe and discuss the volume and transport phenomena in gas - particle diffusion, viscosity and thermal conductivity of gas.
Describe and discuss surface processes in vacuum - adsorption, desorption, formation of monomolecular and multi-molecular layers.
Define and explain the basic adsorption isotherms - Langmuir, Henry and BET isotherms.
Define vapor pressure and saturated vapor pressure.
Interpret Clausius-Clapeyron relation and August equation.
Discuss how the processes associated with the vapor pressure and saturated vapor pressure influence the vacuum devices and technological processes in vacuum.
Define resistance and conductivity of the vacuum pipe.
Define mechanisms of respective gas flow and calculate and measure the conductivity of a vacuum pipe for different types of the gas flow - turbulent gas flow, viscous flow, molecular flow and effusion flow.
Define nominal and effective pumping speed of the vacuum pump.
Define the continuity equation and interpret its meaning for pumping of vacuum equipments.
Describe the processes and mechanisms that are used for pumping of vacuum devices.
Describe and discuss the influence of vacuum leakage and desorption processes.
Calculate the ultimate pressure of vacuum equipment.
Calculate the required pumping speed pumps with regard to the arrangement of the apparatus.
Calculate the time of exhaustion to the desired pressure.
Measure the pumping speed of the pump using a constant pressure and constant volume methods.
Describe and explain the operation of transport pumps - rotary oil pump, Roots pump, turbomolecular pump, jet-ejector and an oil diffusion pump.
Describe and explain the operation of sorption pumps - titanium sublimation pump, diode ion pump, triode ion pump, cryopump and cryosorption pump.
Define and explain methods for measuring the vacuum-pressure.
Describe and explain the operation of Torricelli tube and U-tube.
Describe and explain the operation of thermal vacuum gauges – Piranni vacuum gauge and thermocouple vacuum gauge.
Describe and explain the operation of Penning ionization vacuum gauge.
Describe and explain the operation of triode vacuum gauge including typical application areas.
Explain the principle and the use of special electronic circuits for Electro-vacuum devices - high-voltage generators, high frequency generators and circuits for electrical isolation.
Describe and explain the technology of vacuum brazing and electron beam welding.
Explain the function of devices based on trajectories of charged particles - mass spectrometers and electron microscopes.
Explain the function of devices based on the use of cryogenic equipments- cryosorption and cryogenic pumps.
Define and explain superconductivity and discuss the use of superconductors for the construction of superconducting solenoids.
Explain the function of devices based on the use of gas discharges - Titanium discharge pumps and ion pumps.
Explain the use of technologies based on gas discharges - cathode sputtering, plasma enhanced chemical vapor deposition and dry etching.

Prerequisites

The subject knowledge on the secondary school level is required.

Co-requisites

Not applicable.

Recommended optional programme components

Not applicable.

Fikes,L.: Fyzika nízkých tlaků, SNTL, Praha, 1991. (CS)
Pátý,L.: Vakuová technika, ČVUT, Praha, 1990. (CS)
Grozskowski J.: Technika vysokého vakua, SNTL, Praha, 1981 (CS)
Roth A.: Vacuum Technology, 3rd ed., North-Holland, Amsterdam (1990) ISBN: 0-444-88010-0
John F. O'Hanlon : “User's guide to vacuum technology”, 3rd ed., New Jersey, John Wiley, 2003. xviii,516p. ISBN : 0-471-27052-0

Planned learning activities and teaching methods

Teachning methods include mutually interlaced lectures, numerical exercises and practical laboratories. Course is taking advantage of e-learning (Moodle) system.

Assesment methods and criteria linked to learning outcomes

Laboratorní cvičení - 30 bodů; minimum 20 bodů.
Závěrečná zkouška - 70 bodů; minimum 30 bodů.

Language of instruction

English

Work placements

Not applicable.

Course curriculum

Gas, vapour, pressure. Basic principles and laws for the ideal gases. Kinetic theory of gases - basic principles. Mean free path of gas molecules. Thermal velocity of gas molecules, Maxwell-Boltzmann statistic.
Pumping processes. Gas transport through vacuum pipes, gas conductance of vacuum pipes. Influence of leakage and desorption. Surface processes. Different types of gas transport - turbulent, viscose, molecular and effusion.
Basic principles of gas transport - transport and getter pumps. Mechanical pumps, Roots blowers, turbo pumps. Diffusion pumps. Getter pumps.
The basic principles of vacuum equipment design. Basic technologies in the vacuum equipment production.
Electronic circuits for electro-vacuum instruments. High voltage power sources, high frequency generators. Circuits for very low current measurement. Circuits for the potential isolation, electronic protection circuits.
Devices based on gas volume and gas particle properties. Thermocouple gauges, Pirani gauges, mass flow-meters. Ion gauges.
Devices based on trajectory control of charged particles thermal emission, ionization, electromagnetic and electrostatic deflection.
Devices based on trajectory control of charged particles mass spectrometers.
Devices based on trajectory control of charged particles electron microscopes.
Devices based on usage of cryogenic technology - cryogenic technology in electro-vacuum technology, cryogenic and cryosorption pumps.
Devices based on usage of cryogenic technology - superconductivity, exploitation of superconductivity.
Devices based on usage of gas dicharges - types of discharges, examples of their exploitation. Plasma parameters, measurement of plasma parameters.
Devices based on usage of gas dicharges - cathode sputtering, plasma deposition from gas phase, plasma etching. Titanium discharge pump, ionic pump.

Aims

Acquirement of the knowledges about modern vacuum technics for use in electronics, in electrotechnical and mechanical industry

Specification of controlled education, way of implementation and compensation for absences

Laboratory practicum. Numerical practicum.

Classification of course in study plans

• Programme EEKR-BC Bachelor's

branch BC-MET , 3. year of study, summer semester, 5 credits, optional specialized

#### Type of course unit

Lecture

26 hours, optionally

Teacher / Lecturer

Fundamentals seminar

12 hours, compulsory

Teacher / Lecturer

Laboratory exercise

14 hours, compulsory

Teacher / Lecturer

eLearning