Continuation of XP442 Scoping Study of Ohmic Hmodes: An Opportunity

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Continuation of XP442 - Scoping Study of Ohmic
H-modes An Opportunity
Columbia U Comp-X General Atomics INEL Johns
Hopkins U LANL LLNL Lodestar MIT Nova
Photonics NYU ORNL PPPL PSI SNL UC Davis UC
Irvine UCLA UCSD U Maryland U New Mexico U
Rochester U Washington U Wisconsin Culham Sci
Ctr Hiroshima U HIST Kyushu Tokai U Niigata
U Tsukuba U U Tokyo JAERI Ioffe
Inst TRINITI KBSI KAIST ENEA, Frascati CEA,
Cadarache IPP, Jülich IPP, Garching U Quebec
C.E. Bush, et al. Oak Ridge National Laboratory
NSTX Research Forum Sept. 22-24, 2004 Princeton,
NJ
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Results for Ohmic H-mode Scoping Study

• One-half run day mini-scans in Bt and Ip
• Some OH-H-modes randomly on other days
• H-modes at 600 to 900 kA, 3.0 to 4.5 kG TF
• Short H-mode at Ip 600 kA, Bt 3 kG
• OH H-modes obtained for 1st time ever on NSTX
  last run
• Most readily obtained after hot boronization
• Alternating helium conditioning shots seem to
  help
• Obtained both double null (DN) and lower single
  null (LSN) divertor
• Most short duration, some with ELMs and some
  ELM-free
• Peaked Central ne
• ELMy Small high frequency ELMs (?) keep ears
  from developing
• ELM-free have ears, but edge peak lower than
  central ne
• No turbulence measurements made in core of OH
  H-mode
• Some edge reflectometer fluctuation data Some
  GPI, no L-H

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PLOSS for NBI and OH Hmodes
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Edge measurements (ERD) in Ohmic H-modes show Er
and Vp change prior to L-H transition
Shot 113350
Ip (MA)
H-mode

• Er and Vp begin to change 10 to 20 ms before L-H
  transition (here at t 0.220 sec)

Er (kV/m)
VT (km/s)
Vp (km/s)
Time (s)
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Main Work to be Done

• Obtain longer duration Ohmic H-modes
• Procedure established last run
• Make core and edge turbulence measurements
• Use full set of key diagnostics
• Determine effect of divertor configuration
• The 1/2 day last run allowed only LSN operation
• Need data for double null (DND)
• Determine applications of OH H-modes
• Early injection
• Target for creating ITB/ETB plasma
• L-H physics the same for OH H-mode as for NBI?

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EXTRAS
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OHH-mode with Dithers (DND)
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ELM-Free OHH-mode (LSN)
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Concerns

• Obtaining OHH-mode at desired time
• Optimize time of transition for application (DND)
  -
• Parameter Scans (DND)
• Ip scan 600 kA, 900 kA
• Bt scan 0.30 T, 0.45 T
• Repeat B. and C. above for LSN -
• Application (Need NBI at this point could be
  another day)
• Early injection using best results above
  (determine NBI) 5 shots
• Combined Edge and Core Barriers - use best
  results above 6 shots
• Need available - 100 kV (heat core), 60 kV (other
  heat)
• Different from early injection shots