The ideas behind these proposals : 2'5 run days

1
Four Proposals to Exploit the Unconditioned-to-Li
Conditioned Transition D. K.
Mansfield, H. Kugel, L. Roquemore, R. Maingi, et
al

• The ideas behind these proposals (2.5 run days)
• Normally, NSTX only gets to make the
  unconditioned-to-Li conditioned
• transition once per run year. This transition
  represents an opportunity to learn
• about SOLs, ELMs, Zeff and Li conditioning.
• The first three proposals comprise an attempt to
  exploit that opportunity to the
• greatest possible extent by making the transition
  twice.
• The fourth proposal assumes the successful
  suppression of Zeff and radiation
• by Li aerosol during the previous XPs.
• These proposals involve two types of H-mode
  plasmas

2
The First Three XPs and the Two Types of Plasmas
Involved (Depends on Li powder Injection
Before LITER is Used)
1st XP Powder into ELMS 129019 1/2 day Nude
Walls
2nd XP Repeat Powder into 130389 - 1 day Nude
Walls
3rd XP LITER Slowly into 129012 1/2 day Nude
Walls

Very Little Li Used to This Point
Recover Nude Wall
3
1st XP Injection of Lithium Powder into
High-Recycling ELMy Plasma Run on
Lithium-Free Divertor Surfaces - Finish XP 828
1st XP Powder into ELMS 129019 1/2 day Nude
Walls
Can Aerosol Reduce / Pace ELMS ?

• Establish ELMy discharge
• Inject Li aerosol (25 mg/s early)
• Monitor effect on ELMS
• Monitor effect on other parameters
• Good comparison shot 129038
• Can we inject more Li than D ?
• Germane to LLD loading
• Li (_at_ 40 mg/s) D2 (_at_ 54 TL/s)
• Total 15 - 20 shots 1/2 day
• Very little Li used walls still nude

Can Li Aerosol Resupply LLD ?
4
2nd XP Documentation of Lithium Powder Effects
on Moderate Elongation Plasma Run on
Lithium - Free Divertor Surfaces
2nd XP Repeat Powder into 130389 - 1 day Nude
Walls
Reproduce 130989 with no residual Li ?

• Establish fiducial
• Inject Li Aerosol (10 mg/s early)
• Monitor effect on plasma parameters
• Monitor impurity radiation
• Monitor early profile shapes
• Monitor OH consumption
• Increase influx as appropriate
• Eliminate CS gas puff
• Good comparison shot 130389
• Total 25 - 35 shots 1 day
• Very little Li used Walls still Nude

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6
Early Lithium Injection Flat ne, Te and Pe
Profiles

• Continuous Aerosol Injection Starting Before
  Plasma Breakdown

7
3rd XP Initial Use of Dual LITER in 2009,
Effects of Lithium Conditioning on
Moderate Elongation ELMy Discharge
3rd XP LITER Slowly into 129012 1/2 day Nude
Walls
How does Li change standard fiducial ?
(Compared with previous XP 827)

• Establish fiducial
• LITER at 16 mg/min (5 10 shots)
• Monitor effects on ELMs (shot by shot)
• Monitor effect on plasma parameters
• Good comparison shot 129064
• Total 10 - 15 shots 1/2 day
• Walls no longer nude

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10
4th XP Active Suppression of Impurities by Li
Aerosol
4th XP Powder into Radiating LITER Plasma - 1/2
day
Can Li aerosol reduce impurity influx ?
(Induced by LITER / No ELMs)

• Establish radiating LITER discharge
• Inject Li powder early (15 -20 mg/s)
• Monitor effects on metallic radiation
• Monitor effect on plasma parameters
• Good comparison shots 129064/130389
• Total 10 - 15 shots 1/2 day
• Walls no longer nude

11
Comparison Zeff(0) from Metals
No Li 700 mg LITER 7mg Early Li Aerosol
Estimated Contribution of Metals to Zeff
0.6
LITER
0.4
Dimensionless
Aerosol Injection
0.2
No Li
0
0
0.2
0.4
0.6
0.8
S. Paul
Time (sec)
12
Extra Slides
13
Shot 130389 Early Injection of Li Powder

• Nominal aerosol trajectories shown by red
  vertical lines

Plasma Encounters Aerosol Particles
X-Point Established (H-mode _at_ 180 ms)
Stored Energy Steady State
Li1 Rings Observed (Fig 12)
25 ms
509 ms
102 ms
80 ms
58 ms
14
Camera View of Early Li Aerosol InjectionTaken
at t 60 ms
15

16
The Subtle Difference Between 130386 and 130389
130386 _at_ 85 ms No Li
130389 _at_ 85 ms Early Powder