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