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Electron and ion ITB with fast ramp

Electron and ion ITB with fast ramp. 100. 100. c e. c i. 10. 10. c e. 1. 1. c i. c i NC. c i NC. TRANSP q(r). c using outboard gradients. 4. 0.2. 0.4. 0.6. 0.8. 0.2. 0.4. 0.6. 0.8. 8. 4. 8. 4. q. q. 4. 2. 4. 2. w EXB. w EXB. 0.2. 0.4. 0.6. 0.8. 0.2. 0.4.

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Electron and ion ITB with fast ramp

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  1. Electron and ion ITB with fast ramp 100 100 ce ci 10 10 ce 1 1 ci ciNC ciNC TRANSP q(r) c using outboard gradients 4 0.2 0.4 0.6 0.8 0.2 0.4 0.6 0.8 8 4 8 4 q q 4 2 4 2 wEXB wEXB 0.2 0.4 0.6 0.8 0.2 0.4 0.6 0.8 r/a r/a Fast ramp Slow ramp c (m2/s) c (m2/s) 105/s 105/s • TRANSP also computes stronger negative shear with fast ramp • wExB comparable transport changes due to magnetic shear

  2. NSTX L-mode Microtearing Investigation • Vary LT and Ls to see effects on long  drift modes for slow ramp case112996 at r/a=0.35 • Find kinetic ballooning, microtearing and ITG/TEM modes, but not always all, in each of ~100 cases examined. • Case based on experimental T not symmetrical in s, because of hybridization with other long wavelength modes • T=0, no ITG or microtearing, some kinetic balloooning modes • Reversal of TiTe at s=1 causes icrotearing to change to ITG • Ballooning approximation breaks down, global code needed many additional runs needed for low shear cases. Spurious modes found at s~0; high growth rates; Microtearing destabilized: T scaled by 1/2,1,2 Not for negative T scaling. • Why does fastest growing mode shift: tearing to ITG and back as shear changes from 0.5 to 1 to 2? • What is physics behind three peaked ITG mode eigenfunctions? • First identification of kinetic ballooning mode in modelling • experimental plasma

  3. Microtearing mode destabilization by magnetic shear and temperature gradient

  4. ITG mode destabilization by magnetic shear and temperature gradient

  5. Kinetic ballooning mode destabilization by magnetic shear and temperature gradient

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