Phys 5931 Introduction to Plasma Physics

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Phys 5931Introduction to Plasma Physics

• Alfonso G. Tarditi
• alfonso.g.tarditi1_at_jsc.nasa.gov
• Ph. [phone]

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What you will learn about
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Fusion Reactions (Deuterium-Tritium)
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Controlled Fusion Experiments
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The Tokamak
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The Plasma in the Stars
The Sun a very old fusion reactor
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The Sun-Earth Connection
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Earth Ionosphere
The Sun
Galactic Cosmic Rays
Ionospheric plasma interactions
Earth Magnetosphere
Detectors on ISS
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Fusion/Plasma Propulsion
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Particle motions in Magnetic Fields

• Magnetic Mirror charged particles (protons and
  electrons) move in helical orbits at their
  cyclotron frequency

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Fluid Plasma Simulation
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Particle Simulation
Basic Algorithm Summary
Initial particle loading
Compute interparticle forces
ttDt
Solve particle equation of motion
Update particle positions and velocities
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Syllabus

• Object of Plasma Physics
• Plasma Physics Fundamentals
• Applied Plasma Physics theory, simulation and
  experiments

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I. Object of Plasma Physics

• 1. Characterization of the Plasma State
• 1.1 Definition of the Plasma State
• 1.2 Historical Perspective
• 1.3 Transition to the Plasma State
• 1.4 Examples
• 2. Plasmas in Nature
• 2.1 Astrophysical Plasmas
• 2.2 Space Plasma
• 2.3 The Ionosphere
• 3. Plasmas in the Laboratory
• 3.1 Relevance of Plasma Physics in Science and
  Technology
• 3.2 Nuclear Fusion
• 3.3 Industrial Plasmas
• 3.4 Space Propulsion

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II. Plasma Physics Fundamentals

• 4. Particle Picture
• 4.1 Unmagnetized Plasmas
• 4.2 Magnetized Plasmas
• 5. The Kinetic Theory
• 5.1 The Distribution Function
• 5.2 Moments of the Plasma Distribution Function
  
• 6. The Fluidodynamic Description of a Plasma
• 6.1 Fluid Variables
• 6.2 The Fluid Equation of Motion
• 6.3 MHD
• 6.4 Fluid drifts in presence of Magnetic Fields
• 7. Plasma Waves
• 7.1 Dispersion Relation
• 7.2 Classification of Waves in Plasmas

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III. Applied Plasma Physics theory, simulation,
experiments

• 8. The Plasma Laboratory     
• 8.1 Plasma Generation
• -         8.2 Plasma Confinement
• -         8.3 Plasma Heating
• 8.4 Plasma Diagnostic
• 9. Nuclear Fusion
• -         9.1 Inertial Confinement
• -         9.2 Magnetic Confinement
• 9.3 Electrostatic Confinement
• 10. Industrial Plasmas
• 10. 1 Plasma Processing
• 10. 2 Plasma Torches
• 11. Advanced Space Plasma Propulsion
• 11.1 Electric Plasma Propulsion
• 11.2 The VASIMR Experiment
• 12. Space and Astrophysical Plasmas
• 12.1 The Ionosphere
• 12.2 The Stars
• 13.1 Space Plasmas

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Part I
BACK

• Object of Plasma Physics

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I. Object of Plasma Physics

• 1. Characterization of the Plasma State
• 2. Plasmas in Nature
• 3. Plasmas in the Laboratory

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1. Characterization of the Plasma State
BACK

• 1.1 Definition of the Plasma State
• 1.2 Historical Perspective
• 1.3 Transition to the Plasma State
• 1.4 Examples

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1.1 Definition of the Plasma State
BACK

• 1.1.1 Atomic Physics Brush-Up
• 1.1.2 Ionized Gases
• 1.1.3 From Ionized Gas to Plasma
• 1.1.4 The Fourth State of the Matter
• 1.1.5 Debye Shielding
• 1.1.6 Solid State Plasmas

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1.1.1 Atomic Physics Brush-Up
BACK
How do atoms really look like?
Atoms in a Silicon crystal as seen through a
Scanning Tunnel Microscope
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Looking at an Atom

• An electron cloud

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Looking inside an Atom

• Inside the electron cloud Electrons, Protons
  and Neutrons

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The real proportions inside an atom
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1.1.2 Ionized Gases
BACK

• An ionized gas is characterized, in general, by a
  mixture of neutrals, (positive) ions and
  electrons.
• For a gas in thermal equilibrium the Saha
  equation gives the expected amount of ionization
• The Saha equation describes an equilibrium
  situation between ionization and (ion-electron)
  recombination rates.

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Example Saha Equation

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Backup The Boltzmann Equation
The ratio of the number density (in atoms per
m3) of atoms in energy state B to those in
energy state A is given by NB / NA ( gB / gA )
exp -(EB-EA)/kT where the g's are the
statistical weights of each level (the number of
states of that energy). Note for the energy
levels of hydrogen gn 2 n2 which is just the
number of different spin and angular momentum
states that have energy En.
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1.1.3 From Ionized Gas to Plasma
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• An ionized gas is not necessarily a plasma
• An ionized gas can exhibit a collective
  behavior in the interaction among charged
  particles
• An ionized gas could appear quasineutral if the
  charge density fluctuations are contained in a
  limited region of space
• A plasma is an ionized gas that presents a
  collective behavior and is quasineutral

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1.1.4 The Fourth State of the Matter
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• The matter in ordinary conditions presents
  itself in three fundamental states of
  aggregation solid, liquid and gas.
• These different states are characterized by
  different levels of bonding among the molecules.
• In general, by increasing the temperature
  (average molecular kinetic energy) a phase
  transition occurs, from solid, to liquid, to gas.
  
• A further increase of temperature increases the
  collisional rate and then the degree of
  ionization of the gas.

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The Fourth State of the Matter (II)
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• The ionized gas could then become a plasma if the
  proper conditions for density, temperature and
  characteristic length are met (quasineutrality,
  collective behavior).
• The plasma state does not exhibit a different
  state of aggregation but it is characterized by a
  different behavior when subject to
  electromagnetic fields.