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XP-310 – Electron Heating with HHFW

XP-310 – Electron Heating with HHFW. David Swain, Dan Stutman, Randy Wilson and the usual suspects HHFW Group Meeting Dec 16, 2003. Power Deposition XP. Issues: Where is the power deposited? How does it change as rf parameters (e.g., phasing) are changed?

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XP-310 – Electron Heating with HHFW

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  1. XP-310 – Electron Heating with HHFW David Swain, Dan Stutman, Randy Wilson and the usual suspects HHFW Group Meeting Dec 16, 2003

  2. Power Deposition XP • Issues: • Where is the power deposited? • How does it change as rf parameters (e.g., phasing) are changed? • How does it change as plasma parameters (e.g., ne, Ip) are changed? • Efficiency? How much winds up in the core? • Technique: • Modulate rf, look at changes in Te, ne, Prad,... with modulation • Brief trial run done in 2003, saw very small change in Te • Shot 110016, CD, 500 kA, 4.5 T, He, LSN • Square-wave modulation of rf 50%, 10-ms period • Low-energy USXR detectors saw modulation in outer 1/2 of plasma, probably density or impurity modulation • Modulation of Te(0) ≤ 1%

  3. Generic modulation experiment setup • P = 2 – 3 MW (want reproducible shots) • Modulate rf: ~50% square-wave with ~10-ms period (need to check; try 20 and 30-ms periods also) • Diagnostics: • Need USXR set for full spectrum measurements (from Stutman): • Bay J Top, E > 0.4 keV, • Bay G Top, H_up, H-down E > 1.4 keV for tomography • Bay G_bottom E =0.3 keV / bolometry, for C influx. • FIRETiP data as much as possible (how many channels, what’s time resolution?) • Bolometry, impurity lines,.... • Thomson scattering • Ion temperature measurements: • How necessary are they? • Argon Ti? • Beam blip?

  4. Plasma conditions to try • Would like to try as many of these as possible in piggy-back mode before dedicated run day for modulation experiments. Want to see HHFW shot where Te appears to equilibrate after PRF is applied. • Heating case: • High Ip (≥ 800 kA), LSN (DN?) • 0π0π0π , 00ππ00, or CD phasing • Density: medium? • CD case: • Low Ip (≤ 500 kA), CD phasing • Beam-heated case: • ≥ 800 kA, LSN? • Try w. C source (≈ 1.5 MW) early to get good Te, quiescent (Stutman) • Other suggestions?

  5. Things probably NOT covered in this XP • Study of H-mode threshold or operation • For high power may be difficult to avoid • Run in He to avoid H-mode? • ITB formation • Run time for this XP is 1 day, plus 1 day later. • Don’t have time to study these topics, unless H-mode or ITB operation is established by other XP’s.

  6. Strawman run plan • First day (in Feb?) operation depends on results of piggy-back experiments • IF no good shots found, then may try: • Replicate 110016 • He, 0.45T, 500 kA, ~2e19, LSN • Phasing -90° • Try heating at higher current (sim. to 107873?) • He, 0.45T, 800 kA, ~2E19, LSN (shot was actually D2) • 0π0π0π phasing • With beams (107872?) • Add beam early

  7. Trying to make modulation experiments easier • New power and phase modulation widget developed: • RF amplitude with • finite ramp turn-on • two power levels • Phase with two levels • Power modulation: • “One-click” on/off • Easy adjustment of modulation frequency and amplitude, start and stop times Power, no modulation Power with modulation

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