The%20UW%20Plasma%20Physics%20Group

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The UW Plasma Physics Group

• Clint Sprott, Paul Terry, Ellen Zweibel, Stas
  Boldyrev, Dalton Schnack, Cary Forest, Stewart
  Prager
• Presented to
• Introductory Seminar for New Graduate Students
• on September 6, 2007

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Plasma Physics

• What is a Plasma?
• Ionized gas (kT gt a few eV)
• The fourth state of matter
• 99 of the universe
• History of Plasma Physics
• 1920s - Langmuir (vacuum tubes)
• 1930s - Appleton (ionosphere)
• 1950s - Nuclear Fusion
• 1960s - Solar wind, stellar interiors
• 1980s - Industrial applications

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Wisconsin Plasma Physics Program

• Began in 1962 by Donald W. Kerst
• Present Physics Faculty
• Clint Sprott (computational dynamics)
• Paul Terry (theory)
• Ellen Zweibel - joint with Astronomy (theory)
• Stas Boldyrev (theory)
• Dalton Schnack part-time (computational)
• Cary Forest (experimental)
• Stewart Prager (experimental)
• Plasma Research in other UW Departments
• Stellarator/Torsatron (ECE)
• Spherical Tokamak (EP)
• Fusion Technology Institute (EP)
• Plasma Theory Computation (EP)
• Plasma Processing (EP)

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Plasma Physics Group

• Composition
• 7 faculty
• 11 scientists
• 9 postdocs
• 28 graduate students
• 27 support staff
• frequent and long-term visitors
• gt 80 people total
• Funding (8M year)
• 80 Ph.D. graduates over 40 years
• 50 at National Labs
• 25 at Universities
• 25 in Industry
• http//plasma.physics.wisc.edu/

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Nuclear Fusion

• D T ? 4He (3.5 MeV) n (14 MeV)
• Inexhaustible Source of Energy
• D2 in oceans will last 3 x 108 years
• 1 gal H2) 1/8 g D2 300 gal gasoline
• Must contain DT plasma _at_ kT gt 10 keV for n? gt
  1020 sec/m3 (Coulomb barrier)
• Scientific Feasibility Essentially Proven
• Much Work Remains
• Physics
• Technology

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What to do if Interested

• Come around and get Acquainted
• Take Plasma Courses
• 525 introduction
• 526 plasma lab (EP)
• 527 confinement devices
• 528 plasma processing
• 724 waves instabilities
• 725 plasma kinetic theory
• 726 magnetohydrodynamics
• Plasma Seminar 1205 Mon (1227 Engr)
• Group Meeting 400 Thurs (5280 Ch)
• Summer Jobs Available
• Pass Qualifiers

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Paul Terry
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Turbulence in fusion and astrophysics

• Interests (organizing principles)
• Physics of coherent structure formation in
  turbulence
• Role of symmetry-breaking waves
• Role of strongly inhomogeneous background
• (e.g., shear flow)
• Applications
• Transport in fusion plasmas
• Interstellar medium

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Ellen Zweibel
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Stas Boldyrev
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Why to Study Plasma Physics?
Controlled fusion practically infinite source
of energy!
Almost all Galactic volume and Universe volume
are filled with a plasma!
It is just fun astrophysical plasma flows
exhibit regimes that have never been
investigated in terrestrial experiments!
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What is special about plasma?

• Very hot, ionized gas.
• How to confine it?
• Plasma consists of electrons and ions weakly
  interacting with each other. Can sustain currents
  -gt can interact with magnetic fields.

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Plasma in Magnetic Field
Magnetized plasma is usually unstable and
turbulent
Good confiment
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Plasma Turbulence
Solar wind
MST, UW-Madison
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Plasma Turbulence
Interstellar medium
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Plasma Turbulence

• One of the main topics of our theoretical group.
  
• Goals
• Explain turbulence in MST experiment
• turbulence in the Solar wind
• turbulence in the Interstellar Medium

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Dalton Schnack

• Computational Physics
• Fluid models of plasmas
• Plasmas in astrophysics

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Research Interests

• Magnetohydrodynamics (MHD)
• Extended MHD (2-fluid/FLR effects)
• Fluid models for tokamak plasmas (closures)
• Plasma relaxation/dynamo
• Large scale computations for fluid plasmas
• MHD/RF interactions
• Anomalous angular momentum transport in
  magnetized plasmas
• Structure and heating of the solar corona
• Accretion disk coronae

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Cary Forest
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The MST Experiment(Madison Symmetric Torus)
a reversed field pinch (RFP)
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MST
minor radius 0.5m current lt 0.5 kA, T 107 k,
n 1013 cm-3
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The confining magnetic field is weak

• Plasma is relatively unstable an advantage for
  fusion energy
• Magnetic fluctuations are large need to reduce
  energy loss
• Energy is lost rapidly

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The purpose of MST research

• Fundamental plasma physics
• The RFP as a fusion concept
• Fundamental plasma physics in common with
  astrophysics

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Magnetic self-organization MST
magnetic fluctuations
toroidal magnetic flux
dynamo
heat flux (MW/m2)
energy transport
rotation (km/s)
momentum transport
ion temperature (keV)
ion heating
time (ms)
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• for fusion energy
• learn to suppress magnetic self-organization
• for astrophysics
• understand magnetic self-organization common
• to lab and cosmos

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Plasma properties measured with

• Lasers
• Neutral atom beams
• Ion beams
• Spectroscopy
• and more

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plasma controlled with

• EM waves
• Induced electric fields
• Neutral beams

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Graduate student research on MST

• MST is a team effort with strong scientific and
  technical interactions very dynamic
• Many mentors available for graduate students
• Each student owns a physics problem
• Many physics and instrumentation opportunities

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Stewart Prager
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The NSF Center for Magnetic Self-Organization in
Laboratory and Astrophysical Plasmas

• Purpose
• To understand major plasma physics problems
  critical to
• laboratory and astrophysical plasmas
• Unites
• Laboratory and astrophysical scientists
• Experiments, theory, and computation
• Tests
• Astrophysical ideas that can be studied in the
  lab

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Magnetic Self-Organization

• Magnetic field (and related quantities)
  spontaneously rearranges itself

Solar surface
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Physics Topics

• Dynamo
• Magnetic reconnection
• Angular momentum transport
• Ion heating
• Magnetic chaos

Spans plasma phenomena in solar wind, sun,
accretion disks, galactic clusters
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Institutions

• The University of Wisconsin
• Princeton University
• The University of Chicago
• Science Applications International Corp
• Swarthmore College
• Lawrence Livermore National Laboratory
• Los Alamos National Laboratory
• University of New Hampshire
• Includes experiments at UW, Princeton, Livermore,
  Swarthmore