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Masa Ono

Masa Ono. Questions to be discussed will be how much we should glow (if any of what type for how long) and/or the degree of lithium deposition prior to the run. Unofficial Start-up Plan. Duplicate March start-up (as close as possible) 5% Lithium fill (1 day)

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Masa Ono

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  1. Masa Ono • Questions to be discussed will be how much we should glow (if any of what type for how long) and/or the degree of lithium deposition prior to the run.

  2. Unofficial Start-up Plan • Duplicate March start-up (as close as possible) • 5% Lithium fill (1 day) • Evaporate Lithium from E-H? Will that form LiC? • He glow before to clean plates? Or dirty them? • XMP064 to evaluate • Argon glow, more lithium to solve problems. • Revisit LLD with 50% fill in June with better conditioned machine, proper personnel and modified XP1000 • Proceed with “high triangularity” experiments until revisit of LLD. • Then, during/before a partial or full maintenance week, heat the LLD again to evaporate the Lithium and start over with 3-4 days of Lithium evaporation and go into a modified XP1000 as discussed at the last LR-TSG meeting.

  3. Vlad Soukhanovskii comments • I am surprised to hear that the LLD experiment is considered for the week of May 24th, when the PSI conference is taking place,and when we are all gone to San Diego. • I think a bigger concern is the NSTX start-up XMP064 after several argon vents. These vents had a potential to introduce water and oxygen into the vacuum vessel and minimize the bake-out effect and oxidize the lithium already deposited. • I fully agree with Henry’s plan • 1) In the week of May 24th, use medium LITER rates, run high triangularity fiducials, carefully evaluate machine conditions aka XMP064 and then have a discussion on how to proceed (He/ D /Ar GDC, more LITER ?) • 2) Run XP1000/ XP1001 sometime in late June, when LLD, LITER ready and more diagnostics may be on-line. To quantify the LLD pumping or non-pumping, introduce elements of XP1001 into the LLD experiment.

  4. JEM concerns/questions • Concerned that multiple Ar vents have: • Allowed *oxides from H2O/air to form on plasma facing surfaces • Allowed too much Ar to bond (loosely) to surface • JEM worried we will inadvertently burry Ar and/or oxides with 1 day Li, which will later be liberated in uncontrolled ways  irreproducible shots • How much Ar is in the machine? • How much is acceptable? • Have bad memories of M. Bitter Ar injection experiments in middle of previous decade – recall increased H-mode threshold, radiation, reduced pulse length… • If problematic, is He glow to remove Ar advisable? • And didn’t we already have Ne glow, so perhaps any impact on LLD would be comparatively minor anyway? • JEM personal opinion uninformed by data (and subject to ridicule!): • If Ar level in vessel is noticeably higher than usual, should run ½ hr He glow to see if Ar level is reduced. If some reasonable clean-up is observed, continue He glow until Ar is reduced to 2-3x normal pre-run levels (or lower). • Positive side effect is additional removal of oxides by He (+Ar?) glow • Risk is sputtering C onto LLD. Any diagnostics to know if this is a problem? • Then, try to make plasmas with normal LITER ops (20-40mg/min) • If that fails, try 1 day LITER method, then if that fails assess if oxide or Ar issue

  5. XP Scheduling

  6. and into week 9 ...

  7. Rajesh Maingi • Li deposition - agree with Henry that we should fill LLD to at least 50% • Mechanism to look for reduced LLD pumping and reduced density: we should re-introduce modest ELMs so that the particle confinement is not very large, which makes comparison difficult. This implies some expts. with lowish IP ~ 0.7-0.8 MA and n=3 triggered ELMs as part of Henry's assessment • GDC - haven't followed closely enough to render a good opinion

  8. Hosea: GA FDR conflicts week of June 7,switch with June 14 w/ Phil Ryan approval? • Kolemen: At a conference week of May 31st • Solomen: On vacation week of June 12. • Rajesh: Swap June 2 and June 11? • Vlad: Waiting for DIMS, expected mid-June

  9. Rajesh Maingi • The temperature profiles look rather good, and one can see a change in the single color temps as compared to 2-color right at the melting/freezing point (180), where 2 color gives the right answer and single color ones deviate (lower). • So technique seems to be working ok and correcting emissivity differences, as hoped. • Its a high priority to turn these into heat fluxes routinely, and I think we'll get that soon, hopefully some time next week just after PSI drafts are sent for co-author review.

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