second switching power amplifier (spa) upgrade physics considerations discussion s.a. sabbagh 1, and...

Second Switching Power Amplifier (SPA) Upgrade Second Switching Power Amplifier (SPA) Upgrade Physics Considerations DiscussionPhysics Considerations Discussion

S.A. Sabbagh1, and the NSTX Research Team

1Department of Applied Physics, Columbia University, New York, NY, USA

NSTX ARRA Meeting

May 20, 2009

PPPL

College W&MColorado Sch MinesColumbia UComp-XGeneral AtomicsINELJohns Hopkins ULANLLLNLLodestarMITNova PhotonicsNew York UOld Dominion UORNLPPPLPSIPrinceton UPurdue USandia NLThink Tank, Inc.UC DavisUC IrvineUCLAUCSDU ColoradoU MarylandU RochesterU WashingtonU Wisconsin

Culham Sci CtrU St. Andrews

York UChubu UFukui U

Hiroshima UHyogo UKyoto U

Kyushu UKyushu Tokai U

NIFSNiigata UU Tokyo

JAEAHebrew UIoffe Inst

RRC Kurchatov InstTRINITI

KBSIKAIST

POSTECHASIPP

ENEA, FrascatiCEA, Cadarache

IPP, JülichIPP, Garching

ASCR, Czech RepU Quebec

NSTXNSTX Supported by

v1.0

NSTXNSTX Second SPA Upgrade - discussion (S.A. Sabbagh) 2May 20th, 2009

Second Switching Power Amplifier Planned for NSTXSecond Switching Power Amplifier Planned for NSTX

Part of NSTX 5-year Plan (2012-2013) “Implement 2nd switching power amplifier (SPA) to allow

independent control of all 6 midplane RWM coils”

Engineering meeting held in parallel to March ReNeW workshop at PPPL

Existing Status (bullets from Raki’s talk 3/18/09) The Six RWM coils are grouped in pairs Each Pair is fed from one sub-unit of SPA which has 3 sub-units Each coil has two turns. Maximum of 3.33kA Pulsed power feed. Three dedicated ckts. & power loops for RWM Coils exist

Proposed Change Each RWM coils are to be individually fed Each coil to be fed from one sub-unit of SPA


Some physics program considerations for 2Some physics program considerations for 2ndnd SPA SPA

More flexible RWM feedback capability n = 2 (and n = 3) field for rotation control during n = 1 RWM feedback Could begin multi-mode RWM control studies, n = 2 with n = 1 RWM

feedback Greater spectrum for dynamic error field correction

More flexible rotation control capability Simultaneous odd/even n field spectrum for NTV rotation control Greater rotation control flexibility for real-time rotation control

More flexible field generation for ELM control independent n = 1, 2, 3 amplitude and phase control for RMP studies (with

n=1 RWM feedback)

Independent use for CHI Run CHI absorber and n=1, 3 control simultaneously


Design work for upgraded non-axisymmetric control capabilities has begun

Capabilities Non-axisymmetric

control coil (NCC) – at least four applications• RWM stabilization

(n > 1, higher N)

• DEFC with greater field correction capability

• ELM control (n = 6)

• n > 1 propagation, increased Vcontrol)

• Similar to proposed ITER coil design

• Consider design to allow moderate 3-d shaping for mode control

• In incremental budget Addition of 2nd SPA

power supply unit for simultaneous n > 1 fields

Non-magnetic RWM sensors; advanced RWM active feedback control algorithms

PrimaryPP option

Secondary PP option

Existingcoils

Proposed Internal Non-axisymmetric Control Coil

(NCC)(initial designs - 12 coils toroidally)

RWM with n > 1 RWMobserved

0.22 0.24 0.26 0.28t(s)

-20-10010200

100200300010

20300102030400204060

02

46

0.18 0.20 0.22 0.24 0.26 0.28t(s)

-20-10010200

1002003000

10

20010

20300102030

02

46

114147

FIG. 1

114452

N

FP

|Bp|(n=1)

(G)(G)

(G)

|Bp|(n=2)

|Bp|(n=3)

Bp(n=1)(deg)

|Br|(n=1)(ext.)

Bz(G

) (f<40 kHz, odd-n)

n=2,3

n=1 no-wall unstable

0.240.22 0.26 0.28t(s)

(Sabbagh, et al., Nucl. Fusion 46, 635 (2006). )


VALEN RWM predictions for new control coils behind passive plates (PP)

10-1

100

101

102

103

104

4.5 5 5.5 6 6.5 7 7.5NSTX.07.2007

g P=Cu,S=Cu)g ideal Cu Cug Gp=e7g Gp=5e6 BS (Cu,Cu)g Gp=5e6 BP (Cu,Cu)

10-1

100

101

102

103

104

4.5 5 5.5 6 6.5 7 7.5NSTX.07.2007

g (P=SS,S=Cu)g (P=Cu,S=SS)g P=Cu,S=Cu)g Gp=e7g Gp=5e6 BSppg Gp=5e6 BPppg ideal Cu Cu

coils behind copper passive plates perform

worse than existing external RWM

change copper passive plates to SS RWM

performs better than existing external RWM

n

gro

wth

ra

te

[1

/s]

passive

Idea

l w

all

lim

it

copper PP

Coils behind Cu secondary PP

Coils behind Cu primary PP

exte

rnal

sys

t em

n•

gro

wth

ra

te

[1

/s]

passive

Idea

l w

all

lim

it

partial steel PP

Coils behind SS secondary PP

Coils behind SS primary PP

exte

rnal

sys

tem

J. Bialek


Proposed NSTX upgrade, coils on plasma side of passive plates

Possible upgrades:

coils on plasma side of passive plates

we examine only one such coil system at a time

we approach the ideal wall limit with either coil system

new coils plasma side primary passive

plates

new coils plasma side secondary passive

plates


New control coils on plasma side of NSTX copper passive plates (PP) stabilize to C>99%

10-1

100

101

102

103

104

4.5 5 5.5 6 6.5 7 7.5NSTX.08.2008

g passive CU,CUg ideal CU,CUg Gp=e7g Gp=e8 FS, CU,CUg Gp=e8 FP, CU,CU

10-1

100

101

102

103

104

6.9 6.95 7 7.05 7.1 7.15 7.2NSTX.08.2008

g passive CU,CUg ideal CU,CUg Gp=e7g Gp=e8 FS, CU,CUg Gp=e8 FP, CU,CU

passive

exis

tin

g c

oils

Idea

l wal

l lim

it

Idea

l wa l

l lim

itexisting coils

n n

gro

wth

ra

te

[1/

s]

gro

wth

ra

te

[1/

s]

coils on plasma side Cu secondary PP stabilize to n = 7.04

coils on plasma side Cu primary PP stabilize to n = 7.05

Ideal wall limit n = 7.06

J. Bialek


Recent ELM mitigation results show promising results with NCC

n = 6 configuration

Higher q95 shows best results

T. Evans, GA


Consider a more capable power supply upgrade to best support future non-axisymmetric field upgrades?

Investment to support future upgrades JEM: “2nd SPA would be needed for any future RMP/RWM/EF

control coils, so this is a good investment” JEM: “More coils are next in line as a possible major facility upgrade”

Consider a power supply that will best support internal NCC coil upgrade

Internal RWM coil upgrade will allow expanded physics studies that is best supported by faster power supplies RWM stabilization up to the with-wall beta limit (growth < 1 ms) Greater control capability for RWMs with fast growth (growth < 1 ms) Potential for control of NTMs at large R (f ~ n*10 kHz) Potential for non-resonant increase of plasma rotation (f ~ n*10 kHz)

second switching power amplifier (spa) upgrade physics considerations discussion s.a. sabbagh 1, and...

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