XP720: EBW BXO mode coupling in Hmode discharges

1
XP-720 EBW B-X-O mode coupling in H-mode
discharges

• Investigate collisional effects on B-X-O mode
  coupling
• LPI conditioning has shown increase in EBE
• Gas valve near antennas available will be used
  for remaining run time
• Bootstrap current from pressure gradient at
  H-mode pedestal may change field pitch at UHR
• Wide acceptance angle antenna to detect EBE
  outside steered antenna field of view
• Investigate effects of plasma
  parameters on B-X-O coupling
• Initial outer gap scan has shown
  small
  increase in emission
• Vertical position scan started
• Only -2.8 cm scan achieved
• Proposed at least 3 cm
  

2
Preliminary H-mode results show increase in
B-X-O coupling with Li conditioning

• Reference shot (123148) Te(0)1 keV,
  ne(0)4-6x1013 cm-3, Ip1MA
• 3.4 mg Li pellet injection (LPI) into ohmic He
  L-mode plasma for conditioning
• 1st shot after LPI, 123153,
  exhibited 2x increase
  
  in EBE
• 2nd shot after LPI,
  123154,
  EBE reverted
  to pre-Li conditions
  
  

Reference shot 1st after 3.4 mg LPI 2nd after 3.4
mg LPI
Li conditioning reduces ELM's and increases edge
Te - possibly reducing effects of EBW
collisional damping. EBE modeling ongoing.
3
Preliminary H-mode results show good fce and 2fce
B-X-O coupling in high ?, fBS plasmas

• Target plasma (with LITER) Ip0.8 MA, k2.5,
  Te1 keV, ne(0)2-4x1013 cm-3
• Preliminary experimental
• B-X-O coupling efficiency
• 30-50 for fce18 GHz, 2fce28 GHz
• EBE simulation work is ongoing

t0.3 s
shot 123544
2fce28 GHz
L-H transition
More near-term experiments to focus on studying
this target plasma. Antenna location will be
scanned to optimize emission.
4
Remaining run time focused on optimizing
B-X-O coupling in H-mode plasmas

• Excellent H-mode target identified scans
  required to optimize emission and understand
  coupling physics
• Target - 123544 Ip0.8 MA, Te(0)1keV,
  ne(0)2-4x1013 cm3, k2.5 with LITER
  conditioning
• Shot Description
• 1-2 Shot development
• 3-12 Antenna scan
• 13-15 Vertical position scan - at least 3 cm
• 16-17 Outer gap scan - 1 cm and - 3 cm
• Required diagnostics
• EBW radiometers
• Thomson scattering
• Reflectometer