XP627: Non-solenoidal Rampup with HHFW and NBI
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XP627: Non-solenoidal Rampup with HHFW and NBI
C. Kessel, J. Hosea, D. Mueller, P. Ryan, R. Wilson
Princeton Plasma Physics Laboratory
NSTX Results Review, 7/26/2006
Supported byOffice ofScience
Ip
timeCHI HHFW HHFW+NBI
Basic NSTX Plan for Non-solenoidal Rampup
CHI for plasma initiation and early ramp
HHFW for low Ip rampup
NBI for higher Ip rampup
At low Ip: Establish NICD capability of HHFW, via bootstrap and FWCD Establish NICD capability of NB, via bootstrap and NBCD Determine ability to use HHFW and NB together
Discharges• 120016-120025, Ip = 600 kA, BT = 4.5 kG, NB sources A and B @ 70 keV
– Best shots 120019, 120020, 120021• 120026-120032, Ip = 500 kA, BT = 4.5 kG, NB sources A and B and C @ 70 keV
– Best shots 120027, 120028, 120029, 120030, 120031• 120033-120035, Ip = 400 kA, BT = 4.5 kG, NB sources A and B @ 70 keV
– Best shots 120033, 120034
• 120286-120295, control setting did not allow Ip below 300 kA, lost shots• 120296-120300, Ip = 250 kA, BT = 4.5 kG, HHFW 14 m-1 heating
– Best shots 120297• 120301-120307, Ip = 275 kA, BT = 4.5 kG, HHFW 14 m-1 heating
– Best shots 120301, 120306
• 121541-121547, Ip = 400 kA, BT = 5.5 kG, HHFW -7 m-1 co-CD– Best shots 121541, 121543, 121544, 121545, 121546, 121547
• 121548-121550, Ip = 400 kA, BT = 5.5 kG, HHFW -7 m-1 co-CD, NB source A @ 70 keV
– Best shots 121550• 121551-121552, Ip = 300 kA, BT = 5.5 kG, HHFW -7 m-1 co-CD
XP627 Part B: Inject NB’s into Low Ip Plasmas (run 1/2 day)
Source A@70 keV
Ip = 600, 500, 400 kA
Similar Vloop, so higher Wth compensates for higher Ip
Ip = 600 kA has lower li
XP627 Part B: Inject NB’s into Low Ip Plasmas (1/2 run day)
TRANSP analysis of same discharges indicate that 600 and 500 kA cases give NICD ≈ 250 kA, while 400 kA case is noticeably lower in NBCD and BS due to strong NB losses
600 kA
500 kA
400 kA
XP627 Part B: Inject NB’s into Low Ip Plasmas (1/2 run day)
Sources A+B@70 keV
Ip = 600, 500, 400 kA
Lowest Vloop at 500 kA, li clearly lowest for 600 kA inferring higher BS, but profiles show localized profile modification, higher Pped
XP627 Part A: HHFW Injection into Low Ip Plasmas (1/4 run day)
High pressure discharges from 2005 were not reproduced in 2006 at Ip = 250 kA 2005 2006
2005 2006 2006
14 m-1 heating
XP627 Part A: HHFW Injection into Low Ip Plasmas (?? run day)
Comparison of NB only (A@70keV), HHFW only (7 m-1 co-CD), and HHFW (7 m-1 co-CD) & NB (A@70 keV)
BT = 5.5 kG BT = 5.5 kGBT = 4.5 kG
t = 385 ms
Observations• Low Ip NBI case indicate that the non-inductive current drops
strongly at 400 kA, compared to 500 kA, is this the limit for using NBI in rampup?– This means the HHFW only phase must deliver a 500 kA plasma
100% non-inductive current to the HHFW+NBI phase
• Lowest loop voltage for NB shots was about 0.1 V at 500 kA with 140 kJ and source A+B @ 70 keV– Need to examine this case with TRANSP to see what the non-
inductive current breakdown is between BS and NBCD
• HHFW injection at low Ip was disappointing this year due to insufficient run time to establish good RF coupling discharges
• Higher BT HHFW discharges may make the 7 m-1 phasing more useful but still could not sustain H-mode, similar to 2005
• Combination of NB into HHFW plasmas at low Ip was hampered by MARFEs(?) or some other strong drops in stored energy -- these discharges will determine how high Ip can be sustained non-inductively
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