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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 ----> MHD stability –High self-driven current ----> Bootstrap current –Sufficiently good particle and energy confinement ----> Plasma transport –Plasma edge that allows particle and power handling ----> 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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Transport Safety factor Pressure profileCurrent profile (bootstrap) LHCD, FWCD, NBCD, ECCD, HHFW NBI rotation Pellet injection Plasma shaping Impurity injection RWM feedback NTM feedback Divertor pumping plasma Ion/electron heating Alpha heating Appreciating the plasma’s integrated behavior is helping us learn to control it
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Next Step Devices Must Provide the Basis for Advanced Tokamak Reactor Regime FIRE Inductive AT KSTAR FIRE AT is approaching the reactor AT regime Present tokamak experiments are pushing the envelope
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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 thermal conductivity temperaturesdensity&velocity magnetic field twist centeredgeASDEX-U
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Theory and Experiments Show That Powerful MHD Instabilities Can Be Controlled HBT-EP, Columbia Univ. DIII-D, General Atomics
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Impurities Can Control Where Power from the Plasma is Deposited Power radiated onto high heat flux surfaces Power radiated more uniformly throughout vessel
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Large Plasma Self-Driven Current Fractions are Being Attained 60-90% of the plasma current is driven by the plasma itself, from its pressure gradient ASDEX-U, Germany DIII-D,USA Japan
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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, q>2 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 Analysis :Determine 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
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