UTPA STEM/CBI Courses/Materials/Thin Films

Course Title: Thin Films and Surface Engineering

Lecture Topic: Vacuum

Instructor: Dr. Dorina Mihut

Institution:University of Texas Pan American

Backwards Design

Course Objectives

• Primary Objectives- By the next class period students will be able to:
  • Understand the concept of vacuum and why vacuum is necessary for Thin Films and Surface Engineering
  • Know how vacuum can be created
  • Know different vacuum levels and the technology required to create it

• Sub Objectives- The objectives will require that students be able to:
  • Solve problems involving gases' kinetics
  • Solve problems that help identify the best pumps (type, parameters) to use for creating a certain vacuum level in a given chamber

• 
  Kolben Luft Pump

• Difficulties- Students may have difficulty:
  • Remembering and Using Physics' relationships governing gases' kinetics
  • Using resources beside the text book to identify the best equipments

• Real-World Contexts- There are many ways the students can use this material in the real-world, such as:
  • Understanding different behavior of gases in vacuum conditions (e.g. difference Earth - Moon)
  • Understanding how different tools in Materials' investigation area work, e.g. SEM, TEM (tools that require the use of vacuum)

Model of Knowledge

• Concept Map
  • Kinetic Theory of Gases
  • Molecular Velocities

• The Most Probable Velocity
• Average Velocity
• Mean Square Velocity

• Pressure, Gas Pressure, Unit Systems
  • Mean Free Path
  • Gas impingement on Surfaces
  • Gas Transport and Pumping

• Gas Flow Regimes
• Conductance
• Pumping Speed

• Content Priorities
  • Enduring Understanding
    • Understand the concepts of high pressure and low pressure
    • Understand the concepts of viscous flow and molecular flow regimes
  • Important to Do and Know
    • Know how to calculate the conductance in a vacuum system
    • Know how to calculate the pumping speed for different pumps and chambers
    • Calculate the characteristic contamination time
  • Worth Being Familiar with
    • Mean Free Path, Particle collision calculations
    • Steady state distribution of molecular velocities
    • Gas impingement flux, frequency with which molecules impinge or collide with a surface

Assessment of Learning

• Formative Assessment
  • In Class (groups)
    • Projects
    • Quizes
  • Homework (individual)
    • Questions during the class
• Summative Assessment
  • Midterm Exams
  • Final Exam
  • Project

Legacy Cycle

OBJECTIVE

By the next class period, students will be able to:

• Understand the concept of kinetic of gases, pressure
• Understand the relationship between gas flow regimes and pressure regimes

The objectives will require that students be able to:

• Calculate the working parameters for a vacuum system in a molecular flow gas regime
• Find the best scheme of components for a vacuum system

THE CHALLENGE

Question:

Imagine yourself in a room filled with things such as: books, tables, glasses, pencils, clothes, balls. Imagine those things are not static but are floating around with a certain velocity. The room has one door and you have an emergency and need an imediate exit through the door. What it will happen to you trying to move towards the exit door? How can you exit the door the fastest possible way? What would you do to be able in the future to exit the room or just move around in the room easier?

GENERATE IDEAS

• Students will describe the air composition and what conditions are determining it
• Why is important to have the current air composition
• Where is it important to create vacuum and how can we change the air composition
• What is it going to be different in vacuum and what it will remain the same

MULTIPLE PERSPECTIVES

• Students will perform a research using journal articles, textbooks, web sites on vacuum subject

RESEARCH & REVISE

• After all data are collected the most important results will be presented in the class, gathered knowledge and new ideas will be discussed.

TEST YOUR METTLE

• Students will compare their observations and draw conclusions.

GO PUBLIC

• Students will offer a Power Point presentation to the class on new research related to vacuum.

Pre-Lesson Quiz

1. What is vacuum?
2. Identify few places where you can find more or less vacuum?
3. Is vacuum useful/dangerous? - Explain what you think in each situation.

Test Your Mettle Quiz

1. Describe the behavior of gases in a closed system.
2. Describe the distribution of molecules' velocities in a system.
3. How is the pressure related to the velocity of molecules?
4. What is the mean free path and what is the condition for one collision to occur?
5. What is the gas impingement flux?
6. What is the molecular and the viscous flow regime?
7. What is the conductance in a molecular flow system; what type of conductance will ensure a good functioning?
8. What is the pumping speed relationship to pressure and conductance?
9. What is the intrinsic speed at the pump inlet and what is the ultimate pressure of the pump?
10. How should be the ducts between the pump and the chamber to ensure the best performance of a vacuum system?
11. Which are the main types of pumps?
12. Which is the pressure regime for a rotary mechanical pump?
13. Which is the pressure regime for a turbomolecular pump?