Advanced Tokamak Plasmas and the Fusion Ignition Research Experiment

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Advanced Tokamak Plasmas and the Fusion Ignition
Research Experiment

• Charles Kessel
• Princeton Plasma Physics Laboratory
• Spring APS, Philadelphia, 4/5/2003

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What is an Advanced Tokamak?

• The advanced tokamak plasma simultaneously
  obtains
• Stationary state
• High plasma kinetic pressure ----gt MHD
  stability
• High self-driven current ----gt Bootstrap
  current
• Sufficiently good particle and energy confinement
  ----gt Plasma transport
• Plasma edge that allows particle and power
  handling ----gt Boundary condition between hot
  core plasma and vacuum/solid walls
• The advanced tokamak is a recognition that the
  tokamak is an integrated system and requires
  control to succeed
• The advanced tokamak is a tough nut to crack

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Appreciating the plasmas integrated behavior is
helping us learn to control it
RWM feedback
Pellet injection
NBI rotation
Alpha heating
Transport
Safety factor
NTM feedback
Divertor pumping
plasma
Pressure profile
Current profile (bootstrap)
Plasma shaping
Impurity injection
LHCD, FWCD, NBCD, ECCD, HHFW
Ion/electron heating
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Next Step Devices Must Provide the Basis for
Advanced Tokamak Reactor Regime
AT
FIRE AT is approaching the reactor AT regime
FIRE
KSTAR
Present tokamak experiments are pushing the
envelope
Inductive
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Local Reduction of Energy, Particle, and Momentum
Transport in Plasmas By Manipulating Magnetic
field distribution Momentum injection Electron/ion
heating Current distribution Impurity
injection D Pellet injection we are learning to
control the location and width of the transport
reduction
temperatures
densityvelocity
thermal conductivity
magnetic field twist
center
edge
ASDEX-U
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Theory and Experiments Show That Powerful MHD
Instabilities Can Be Controlled
DIII-D, General Atomics
HBT-EP, Columbia Univ.
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Impurities Can Control Where Power from the
Plasma is Deposited
Power radiated more uniformly throughout vessel
Power radiated onto high heat flux surfaces
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Large Plasma Self-Driven Current Fractions are
Being Attained
ASDEX-U, Germany
60-90 of the plasma current is driven by the
plasma itself, from its pressure gradient
Japan
DIII-D,USA
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FIRE Has Adopted the AT Features Identified by
ARIES Reactor Studies

• High toroidal field
• Double null
• Strong shaping
• Internal vertical position control coils
• Wall stabilizers for vertical and kink
  instabilities
• Very low toroidal field ripple
• ICRF/FW on-axis CD

• LH off-axis CD
• NTM stabilization from LHCD, ECCD, qgt2
• Tungsten divertor targets
• Feedback coil stabilization of RWMs
• Burn times exceeding current diffusion times
• Pumped divertor/pellet fueling/impurity control
  to optimize plasma edge

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FIRE is Aggressively Pursuing AT Control Tools
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AT Physics Control Capability on FIRE
Strong plasma shaping and control Pellet
injection Divertor pumping Impurity
injection ICRF/FW (electron heating/CD) on-axis
ICRF ion heating on/off-axis LHCD (electron
heating/CD) off-axis ECCD off-axis (Ohkawa
current drive) RWM MHD feedback
control t(flattop)/t(curr diff)
1-5 Diagnostics
MHD J-Profile P-profile Flow-profile
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FIRE Pushes to Self-Consistently Simulate
Advanced Tokamak Modes
0-D Systems AnalysisDetermine viable operating
point global parameters that satisfy constraints
Plasma Equilibrium and Ideal MHD Stability
(JSOLVER, BALMSC, PEST2, VALEN), Determine
self-consistent stable plasma configurations to
serve as targets Heating/Current Drive (LSC,
ACCOME, PICES, SPRUCE, CURRAY), Determine current
drive efficiencies and deposition
profiles Transport(GLF23 and pellet fueling
models to be used in TSC) Determine plasma
density and temperature profiles consistent with
heating/fueling and plasma confinement Integrated
Dynamic Evolution Simulations (Tokamak
Simulation Code, WHIST, Baldur) Demonstrate
self-consistent startup/formation and control
including transport, current drive, fueling and
equilibrium Edge/SOL/Divertor(UEDGE) Find
self-consistent solutions connecting the core
plasma with the divertor
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FIRE AT Integrated Simulations Show Attractive
Features
Q 5
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Advanced Tokamaks --- We Want to Have It Our Way

• The advanced tokamak is characterized by the
  features we need for a viable fusion power plant
• Access to this regime requires control of the
  plasma and we are learning how by penetrating its
  coupled physics
• FIRE is a next step burning plasma device
• Utilizing experimental advanced tokamak
  accomplishments
• Adopting design features of advanced tokamak
  reactor designs
• Applying integrated simulation tools to project
  the advanced tokamak performance
• FIRE can bridge the AT physics gap from present
  experiments to the reactor regime