Why Is There Vacuum? (The sequel to Bill Cosby’s “Why Is There Air?”) Matthew C. DeLong University of Utah OptoElectronic Materials Laboratory 7 January.

Slides:



Advertisements
Similar presentations
Pressure 1 atmosphere ~ 1 bar ~ 760 mm Hg ~ 760 torr ~ 100,000 Pa Ion gauges read in mbar i.e. 1x mbar = 1x atm. Sometimes ion gauges read.
Advertisements

MPA 2010, Braga HIGH VACUUM PLANTS FOR REACTIVE SPUTTER DEPOSITION OF MULTI-LAYER STACKS Milko Angelov Milko Angelov Consulting Co Ltd., Plovdiv, Bulgaria.
Pressure measurement From Wikipedia, the free encyclopedia Manometer: a pressure measuring instrument, usually limited to measuring pressures near to atmospheric.
Overview of Vacuum Systems Tejas Deshpande 24 July, 2014.
Center for Materials for Information Technology an NSF Materials Science and Engineering Center Vacuum Fundamentals Lecture 5 G.J. Mankey
Vacuum increases the mean-free-path of gas molecules.mean-free-path Vacuum prevents chemical reaction. Vacuum removes contaminants from surfaces.contaminants.
Chapter 13: States of Matter Kinetic-Molecular Theory: Explains the motions and behavior of a gas. The theory has three components: 1. Particle Size: Gas.
Vacuum equipment. Pumps Rotary vane pumps Rotary piston pumps Roots pumps Turbo molecular pumps Diffusion pumps Getter pumps –Sublimation pumps.
Vacuum systems Electron beam – mean free path: Gun – column - sample Signal detection – electron and X- ray collection: Scattering of emitted electrons.
Why Is There Vacuum? (The sequel to Bill Cosby’s “Why Is There Air?”) Matthew C. DeLong University of Utah OptoElectronic Materials Laboratory 5 March.
Pressure Sensors.
Pressure Measurement Muhajir Ab. Rahim
Barometer Vacuum Height of column in. (76 cm) Air pressure Mercury.
Photoelectron Spectroscopy Lecture 5 – instrumental details –General spectrometer design –Vacuum generation and measurement.
PRESSURE MEASUREMENT Low pr ( Below 1 mm of Hg)- manometer and low pr gauges Medium and low ( between 1mm of Hg 1000 atm)- Bourdon gauge and Diaphragm.
High-Vacuum Technology Course
Pressure 1 atmosphere ~ 1 bar ~ 760 mm Hg ~ 760 torr ~ 100,000 Pa Ion gauges read in mbar i.e. 1x mbar = 1x atm. Sometimes ion gauges read.
Solar Cell conductive grid and back contact
Ch. 13 States of Matter Need Need I to I to Know Fuzzy Learn Know Fuzzy Learn 1. Describe the assumptions of the kinetic theory as it applies to solid,
States of Matter Ch. 10. The Nature of Gases 10-1.
The Nature of Gases Regardless of their chemical identity,
Chapter 4 Equipment of Freeze-drying
Vacuum Techniques Arijit Chowdhuri.
Vacuum science.
Reference book: Building Scientific Apparatus A practical guide to design and construction by John H. Moore, C. C. Davis and M. A. Coplan 2ed or 3rd edition.
Methods and Tehniques in Surface Science Prof. Dumitru LUCA “Alexandru Ion Cuza” University, Iasi, Romania.
Vacuum Fundamentals 1 atmosphere = 760 mm Hg = kPa 1 torr = 1 mm Hg vacuum range pressure range low 760 ~ 25 torr medium 25~ high ~ 10.
PHYSICS 225, 2 ND YEAR LAB VACUUM TECHNOLOGY G.F. West Thurs, Jan. 12.
Techniques of Vacuum and Basics of High Voltage (2/3) Pauli Heikkinen Jyväskylä University.
Vacuum system.
Vacuum Fundamentals 1 atmosphere = 760 mm Hg = kPa 1 torr = 1 mm Hg vacuum range pressure range low 760 ~ 25 torr medium 25~ high ~ 10.
High-Vacuum Technology Course
Introduction to Fluid Mechanics Engineering 1h Prof Bill Easson.
Center for Materials for Information Technology an NSF Materials Science and Engineering Center Vacuum Systems Lecture 6 G.J. Mankey
Turbomolecular pump Vahid Bahrami Yekta MBE LAB UVIC.
KNUDSEN PUMP. WHAT IS IT? Vacuum pump Principal of thermal transpiration temperature gradient causing the gas molecules to move from one side of the tube.
ION PUMPS By: Nima Moghimian. Why pump? Why vacuum? What is a good vacuum?
Vacuum Technology.
Dr. Kamel Mohamed Guedri Umm Al-Qura University, Room H1091
Top Down Method Vacuum Applications in Nanomanufacturing Author’s Note: Significant portions of this work have been reproduced and/or adapted with permission.
I. Physical Properties Gases Gases. A. Kinetic Molecular Theory b Particles in an ideal gas… have no (very small) volume. have elastic collisions. are.
Pressure measurements related to the fluid systems are the topic of this chapter. Absolute pressure refers to the absolute value of the force per unit.
Solar Cells need a top side conductor to collect the current generated They also need a conductive film on the backside.
Particle Theory of Matter
Lecture 4. Pressure. 4.1 Pressure and it units Pressure = “the normal (perpendicular) force per unit area” Pressure at the bottom of the static (nonmoving)
Vacuum Technology and Components for Cryogenics
Pacific school of Engineering Sub: I.P.C Topic: Pressure measurement Guided by Piyush modi Mayani Chintak Sudani Dhrutik Bhikadiya.
Properties of Gases Kinetic Molecular Theory: 1.Small particles (atoms or molecules) move quickly and randomly 2.Negligible attractive forces between particles.
MEASUREMENT OF PRESSURE.. Shantilal shah engineering college. NAME:SARIYA ARTI ENROLL.NO: SUB:FLUID MECHANICS. BRANCH :CIVIL. SEM: 3 rd.
Jari Koskinen 1 Thin Film Technology Lecture 2 Vacuum Surface Engineering Jari Koskinen 2014.
Gas Notes. Physical Properties of all gases  Gases have mass  Gases are easily compressed –Air in you car tires, air in a basketball  Gases will expand.
Vacuum Systems for Electron Microscopy Constraints on Specimens Specimens placed in the electron microscope must be able to withstand very high vacuum.
Pressures and Pumps Andy Therrien 1/9/17.
Pressure Pressure is defined as the force exerted by a fluid per unit area. Units in SI are Pa=N/m2. The pressure unit Pascal is too small for pressure.
Gases.
I. Physical Properties (p )
Ch.12- Gases I. Physical Properties.
I. Physical Properties (p )
I. Physical Properties (p )
V. Measurement pressure gauges, flow meters
I. Physical Properties (p. 303 – 312 in school)
Electron Probe Microanalysis EPMA
Electron Probe Microanalysis EPMA
Electron Probe Microanalysis EPMA
VIII. Production of Vacuum
BASIC VACUUM PRACTICE.
Chapter 7-1, 7-2.
States of Matter Chapter 13.
Pressure Measurements
Electron Probe Microanalysis EPMA
Presentation transcript:

Why Is There Vacuum? (The sequel to Bill Cosby’s “Why Is There Air?”) Matthew C. DeLong University of Utah OptoElectronic Materials Laboratory 7 January 2008

Ranges of Vacuum Low: 1 atm to 1 Torr Medium: ( 1  m) to 1 Torr High: to Torr Ultra High: to Torr Extreme: < Torr Note: low vacuum ↔ high pressure Drying, drinking straws Sputtering Thermal evaporation, e- gun, SEM STEM, FIM, AES, SIMS Anti-particle accumulators, space simulation

Pressure: Units of Measure Pressure exerted by a column of fluid: P ≡ F/A = mg/A =  ghA/A =  gh  h 1 Atm (mean sea level) = 760 Torr = 1013 mBar = 1.01x10 5 Pa = kPa = 14.7 psi = 34 ft. water Average atmospheric pressure in SLC is about 635 Torr, 12.3 psi, 28.4 ft water…

“Kinds of Pressure” Gauge Pressure: measured with respect to ambient. Absolute pressure: measured with respect to vacuum Car tires, basketballs, boilers, LN2 tanks, JFB compressed air supply… Vacuum systems, cathode ray tubes, light bulbs, barometers

Measurement Techniques Low Medium High Ultra High Extreme Mechanical (Bourdon), Hg column, capacitance Thermocouple, Pirani Ionization [hot and cold (Penning) cathode] Ionization (hot cathode: Bayard-Alpert) Modulator Bayard-Alpert

Bourdon Gauge (Mechanical)

Capacitance Manometer A = Annular electrode D = Disk electrode S = Substrate G = Getter (in vacuum space) Differential capacitance between annulus and disk depends on pressure difference between Test Chamber and “Getter”.

Heat Transfer of Gases Conductivity is linear in pressure over about 2 orders of magnitude. Molecular flow regime Pirani and thermocouple gauges

Ionization gauges Hot cathode: more sensitive; less forgiving Cold cathode: less sensitive; more forgiving

Chambers et al. P.84

Mean Free Path in Gases With sufficient accuracy for approximate calculations we may take: λ = 7 x /p mbar-cm λ = 5 x /p Torr-cm λ = 5/p μmHg-cm

Roughing pump comparisons: Oil Sealed Pumps TypeAdvantagesDisadvantages Rotary vaneLow ultimate pressure. Low cost Long pump life. Backstreams oil. Produces hazardous waste. Rootes LobeVery high pumping speed Frequent maintenance. Requires a purge gas. Requires a backing pump. Must be absolutely horizontal. Rotary pistonHigh volume Low cost Noise. Vibration Safety Valve.

Roughing pump comparisons: Dry Roughing Pumps ScrollClean. Low "dry" ultimate pressure. Easily serviceable Quiet. Technology is well known. Limited bearing life. Limited scroll life. Permeable to small gases. Not hermetically sealed. Clean applications only. DiaphragmLow cost. Quiet. Easily serviced. Low pumping speed. High ultimate pressure. Frequent service required. Hook and Claw No backstreaming. Low ultimate pressure Expensive Screw rotorLow ultimate vacuum. Less maintenance than hook & claw Expensive Dry pistonLow ultimate pressureExpensive SorptionCleanRequires LN2.

Rotary Vane Mechanical Pump Robust Inexpensive Operates to ambient pressure Single stage and two stage

Sorption Pump Clean: no oil Very inexpensive: 170,000 Torr-liters for $ l LN2 Requires LN2 Air adsorbs onto zeolite at 77K Torr capability

Oil Vapor Diffusion Pump Vacuum system Robust (silicone oil!) Low maintenance: no moving parts Requires backing – Torr

Turbomolecular Pump Requires backing: Operates only <1 Torr Clean: no oil Expensive: Approximately triple the cost of a rotary vane mechanical pump and oil diffusion pump Limited lifespan

Getter pump Low maintenance: no moving parts – Torr Requires backing Clean: no oil Based on chemical reaction of “air” with very reactive metals

Vac-Ion Pump (Sputter/Getter) Clean: no oil – Torr Not cheap! Require backing

References A. Chalmers, B.K. Fitch, and B. S. Halliday, Basic Vacuum Technology, IOP Publishing, Bristol (1998). TJ/940/C45/1998. D. Hucknall, Vacuum Technology and Applications, Butterworth-Heinemann, Oxford (1991). TJ/940/H83 (1991). Vacuum Equipment, Granville-Phillips Co., Boulder CO. TJ/940/G7. R. R. LaPelle, Practical Vacuum Systems, McGraw-Hill, New York (1972). David Joy, “New Lecture 3” on course website.