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S.A. Sabbagh, J.M. Bialek, S.P. Gerhardt, R.E. Bell, J.W. Berkery, B. LeBlanc, J.E. Menard, et al. - PowerPoint PPT Presentation


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slide1

Supported by

Columbia U

Comp-X

General Atomics

INEL

Johns Hopkins U

LANL

LLNL

Lodestar

MIT

Nova Photonics

NYU

ORNL

PPPL

PSI

SNL

UC Davis

UC Irvine

UCLA

UCSD

U Maryland

U New Mexico

U Rochester

U Washington

U Wisconsin

Culham Sci Ctr

Hiroshima U

HIST

Kyushu Tokai U

Niigata U

Tsukuba U

U Tokyo

JAERI

Ioffe Inst

TRINITI

KBSI

KAIST

ENEA, Frascati

CEA, Cadarache

IPP, Jülich

IPP, Garching

U Quebec

XP1023:Optimized RWM control for high <bN>pulseat low collisionality and li

S.A. Sabbagh, J.M. Bialek, S.P. Gerhardt, R.E. Bell, J.W. Berkery, B. LeBlanc, J.E. Menard, et al.

Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY, USA

Princeton Plasma Physics Laboratory

NSTX Physics Meeting

April 26th, 2010

Princeton Plasma Physics Laboratory

V1.0

xp1023 optimized rwm feedback control for high b n pulse at low collisionality and l i
XP1023:Optimized RWM feedback control for high <bN>pulseat low collisionality and li
  • Motivation
    • Next-step ST devices (including the planned upgrade of NSTX) aim to operate at plasma collisionality and li below usual NSTX levels
    • 2009 XP948 showed significantly higher RWM activity, lower bN limit, in reduced li plasmas (li ~ 0.45 and below)
  • Overall Goal
    • Improve reliability of RWM stabilization at low li, understand impact of reduced plasma collisionality using new LLD capability
  • Progress
    • Generated reduced li target plasmas
    • Generated unstable RWMs without manipulating plasma rotation
    • Utilized new bN feedback, new RWM control algorithms
    • Insufficient tE to complete XP, but developed target for XP1020
slide3

bN/li

ARIES ST (DEMO)

13

12

11

10

ST-CTF

bN

NSTX

database

DCON bNno-wall

XP948

Uncontrolled RWM

Stable / controlled RWM

li

NSTX XP948 operated very low li, with high probability of RWM – can these plasmas be better controlled?
  • Advancement in bN/li toward targets
    • 2006 value: 11
    • XP948 (2009): 13
    • ST-CTF: 16
  • Uncontrolled growing RWM occurred in about 50% of shots
    • ST-CTF target must be sustained indefinitely
  • What value of li is the current-driven kink limit (unstable any b)?
    • DCON n = 1 no-wall limit for 135111 low: bN = 2.8 (li = 0.38)

XP948: S.P. Gerhardt

xp1023 unstable rwm created in low l i target plasma
XP1023: unstable RWM created in low li target plasma
  • Clear unstable RWMs produced
    • Although tE was low, unstable RWM generated without n = 3 braking

137722

unstable RWM

RWM rotation

xp1023 new low l i targets generated with reduced n 1 ideal no wall beta limit
XP1023: new low li targets generated with reduced n = 1 ideal no-wall beta limit
  • Ip = 1.0 and 1.1 MA target plasmas
  • No-wall beta limit significantly reduced
    • Ip = 1.1MA target: DCON n = 1 no-wall limit low for 137722: bN < 2.8 (li ~ 0.4)
    • With single LITER, this target was not reliably reproduced last Thursday to use in XP1020

bN/li

ARIES ST (DEMO)

13

12

11

10

“usual” n = 1

bNno-wall limit

ST-CTF

bN

Reduced bNno-wall < 2.8

Filled = over

the no-wall limit

(Ip = 1.1 MA)

li

xp1023 new low l i targets generated with reduced n 1 ideal no wall beta limit1
XP1023: new low li targets generated with reduced n = 1 ideal no-wall beta limit
  • Ip = 1.0 and 1.1 MA target plasmas
  • No-wall beta limit significantly reduced
    • Ip = 1.1MA target: DCON n = 1 no-wall limit low for 137722: bN < 2.8 (li ~ 0.4)
    • Ip = 1.0MA target: DCON n = 1 no-wall limit low for 137804: bN = 3.4 (li ~ 0.5)
  • Unstable RWM without n = 3 braking
    • Ip = 1.0 target was reliable: moved on and used it in XP1020

bN/li

ARIES ST (DEMO)

13

12

11

10

“usual” n = 1

bNno-wall limit

ST-CTF

bN

Ip = 1.0 MA

bNno-wall = 3.4

Ip = 1.1 MA

bNno-wall < 2.8

Filled = over

the no-wall limit

li