Development and Analysis of Gas Puff CXRS in SOL

1
Development and Analysis of Gas Puff CXRS in SOL

• Motivation
• Develop an alternative edge rotation measurement
• Inner wall measurement
• Alternative to beam CXRS
• Confirm probe flow measurements
• Potentially used to determine flow shear and
  electric field profile
• H-mode and momentum transport studies
• Current status
• He gas puff used for cross-beam measurement of
  HeII at inner wall
• He ions appear to not equilibrate before being
  completely ionized
• Leads to velocity measurements that appear too
  low
• Leads to unreliable temperature measurements
• Trends based on probe measurements confirmed but
  differences in flow magnitude and direction leads
  to the belief that the He puff is locally
  perturbative

2
BV CXRS measurement looks promising

• Current status (continued)
• BV CXRS also done at the inner wall with gas puff
  for neutral beam
• B5 ions at separatrix sampled and Ti 80 eV
  (so it appears they are well-equilibrated)
• Few measurements and dont know the limits of its
  use (how far inside the separatrix, density
  range)

3
Development and Analysis of Gas Puff CXRS in SOL

• Experiments
• Vary plasma density
• By varying the density we can explore the limits
  and dependence of the rotation measurement on
  density. We can also test the range of puff
  duration so as not to perturb the local plasma
  density, but still localize emission.
• Vary the location of the innermost viewing chord
  in the plasma to identify how far inside the
  separatrix that this technique gives a decent
  signal.
• BV emission becomes significant near the
  separatrix (50 eV) and presumably further into
  the core. By varying the size of the inner gap
  we can build up a profile both across our fibers
  as well as into the plasma. We will explore the
  limitation of neutral penetration from the puff
  into the plasma pedestal region.
• Expectations
• Analysis to determine if further implementation
  is warranted
• New spectrometer for better resolution?
• Additional views at the outside edge?
• Poloidal measurements for electric field analysis?