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XP Review Plasma Transport With Varying Fractions of P HHFW and P NBI

XP Review Plasma Transport With Varying Fractions of P HHFW and P NBI. C. Kessel with B. Le Blanc, R. Wilson, P. Ryan, T. Biewer, R. Bell, E. Synakowski, and anyone else…. March 16, 2004. Transport With Varying P HHFW and P NBI. Goals and Motivation

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XP Review Plasma Transport With Varying Fractions of P HHFW and P NBI

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  1. XP ReviewPlasma Transport With Varying Fractions of PHHFW and PNBI C. Kessel with B. Le Blanc, R. Wilson, P. Ryan, T. Biewer, R. Bell, E. Synakowski, and anyone else…. March 16, 2004

  2. Transport With Varying PHHFW and PNBI • Goals and Motivation • Examine transport regimes under HHFW, NBI, and HHFW+NBI • HHFW L-mode, Te(0) = 2-4 keV, Ti(0) = 0.7-1 keV, peaked core Te, more peaked n • HHFW H-mode, Te(0) = 1-1.5 keV, Ti(0) = 0.7-1 keV, T pedestal, peaked core Te, very broad n • NBI H-mode, Te(0) = 1 keV, Ti(0) = 1.5-2 keV, T pedestal?, broad core T, very broad n • HHFW + NBI ??? • Power absorption depends on presence of NBI • HHFW power expected to have strong fast ion absorption, NPA expt. observed, theory indicates off axis • Theory predicts that when Ti/Te > 1 off axis thermal ion absorption will also be strong, this condition is established in NBI only discharges, not observed yet • Otherwise electron absorption should be good (no NBI, and Ti < Te) • Current drive from HHFW will depend on power absorption channels and background transport (electron temperature) • Relevant to ITPA goals: TP-3, characterize transport at Te ≈ Ti; TP-4, characterize transport with low momentum input

  3. Transport With Varying PHHFW and PNBI • Ip = 600-800 kA • Flattop = 300 ms • BT = 0.45 T • n(0) ≈ 3  1019 /m3 in 1st HHFW • DN, diverted • HHFW heating step in rampup to slow V-s consumption • Maximum power = 4 MW • Phases in flattop: • HHFW only, 100 ms • HHFW+NBI, 100 ms • HHFW only, 100 ms • Heating phasing • Co-CD phasing • Ctr-CD phasing Illustration of discharge, I made it up

  4. Transport With Varying PHHFW and PNBI • Heating Phasing,  k||=5.5 m-1 ----> 9 shots • PHHFW = 4, 4, 4 MW, PNBI = 0, 0, 0 MW • PHHFW = 4, 2, 4 MW, PNBI = 0, 2, 0 MW • PHHFW = 4, 0, 4 MW, PNBI = 0, 4, 0 MW • Co-CD Phasing,  k||=5.5 m-1 ----> 9 shots • PHHFW = 4, 4, 4 MW, PNBI = 0, 0, 0 MW • PHHFW = 4, 2, 4 MW, PNBI = 0, 2, 0 MW • PHHFW = 4, 0, 4 MW, PNBI = 0, 4, 0 MW • Ctr-CD Phasing,  k||=5.5 m-1 ----> 9 shots • PHHFW = 4, 4, 4 MW, PNBI = 0, 0, 0 MW • PHHFW = 4, 2, 4 MW, PNBI = 0, 2, 0 MW • PHHFW = 4, 0, 4 MW, PNBI = 0, 4, 0 MW • NBI-only shot ----> 2 shots • PNBI = 4 MW

  5. Transport With Varying PHHFW and PNBI • Want to use the lowest Ip that can sufficiently confine A and B beam sources • 800 kA is conventional wisdom for NBI confinement • V-s for 800 kA is probably too high, even with a preheat, to allow 300 ms flattop • Also want to avoid sawteeth • Egedal analysis of beam confinement indicates • 105917, Ip = 1.0 MA, BT = 0.45 T, source A - 79%, source B - 78% • 105582, Ip = 0.8 MA, BT = 0.45 T, source A - 78%, source B - 77% • 105631, Ip = 0.6 MA, BT = 0.45 T, source A - 76%, source B - 76% • Beam blips into HHFW-only plasmas must be kept to 10 ms or they will perturb the transport • If HHFW H-modes not produced reliably, go to L-mode ---> or if DN not working, use LSN • Difficulties with lower k||, go to higher values, say 7 m-1 • Density control would improve experiment ALOT, but may not be available • Desired Expts to precede this one: HHFW H-mode (LeBlanc), HHFW CD (Ryan), HHFW+NBI (LeBlanc)

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