Overview of Initial Operation of NSTX-U Devon Battaglia On behalf - - PowerPoint PPT Presentation

1 TOFE 2016, Overview of Initial Operation of NSTX-U, D.J. Battaglia, August 22, 2016

Devon Battaglia

On behalf of the NSTX-U Team

Overview of Initial Operation of NSTX-U

TOFE Conference Philadelphia, PA August 22, 2016

2 TOFE 2016, Overview of Initial Operation of NSTX-U, D.J. Battaglia, August 22, 2016

• NSTX-U mission toward advancing magnetic

confinement fusion development

• Highlights from the first NSTX-U experimental

campaign

• Initial operations with plasma control and digital coil

protection systems on NSTX-U

Outline

3 TOFE 2016, Overview of Initial Operation of NSTX-U, D.J. Battaglia, August 22, 2016

• Explore unique ST parameter

regimes to advance predictive capability

• Develop solutions for the

plasma-material interface challenge

• Advance ST Fusion Nuclear

Science Facility (FNSF) and reactor concepts

NSTX Upgrade advances the spherical tokamak (ST) concept and complements larger aspect ratio devices

4 TOFE 2016, Overview of Initial Operation of NSTX-U, D.J. Battaglia, August 22, 2016

• National Spherical Tokamak operated 1999 - 2010
• New center column: double toroidal magnetic field,

triple solenoid V-s

– Access to 2 × higher temperatures, lower collisionality – Pulse lengths increase 1 à 5 seconds

• Second neutral beam injection system added

– Doubles NBI heating and increases flexibility in heating profile – More tangential injection triples NBI current drive and increases current profile control capability

• Increased flexibility in divertor field to support

innovative configurations

NSTX completed multi-year upgrade to increase field, heating and pulse length

TF OD = 40cm

Previous center-stack

TF OD = 20cm

New 2nd NBI

Present NBI

New center-stack

5 TOFE 2016, Overview of Initial Operation of NSTX-U, D.J. Battaglia, August 22, 2016

• NSTX-U mission toward advancing magnetic

confinement fusion development

• Highlights from the first NSTX-U experimental

campaign

• Initial operations with plasma control and digital coil

protection systems on NSTX-U

Outline

6 TOFE 2016, Overview of Initial Operation of NSTX-U, D.J. Battaglia, August 22, 2016

• First plasma August 10, 2015

– Signified completion of major construction

• First experimental run from December,

2015 to June, 2016

– Commissioned control, heating and diagnostic systems – Began physics assessment of new capabilities – Run ended early due to an internal short within a divertor coil

§ Currently removing coil for inspection and defining corrective actions

• Next campaign slated to begin mid-2017

following coil replacement

– Restart with new capabilities, including full- field operation at 1 Tesla

NSTX-U recently completed its first experimental campaign

202822 451ms

One of the first H-mode discharges on NSTX-U January 13, 2016 (second week of operation)

7 TOFE 2016, Overview of Initial Operation of NSTX-U, D.J. Battaglia, August 22, 2016

Majority of commissioning activities were completed or nearing completion at the end of the campaign

• XMP-101: Breakdown Optimization
• XMP-102: Gas Flow Rate Calibration
• XMP-106: Magnetics Calibration
• XMP-126: IP and R Control
• XMP-105: Software Tests for n=0 Control
• XMP-115: ISOFLUX Commissioning
• XMP-116: Initial H-Mode Access
• XMP-127: Neutral Beam Commissioning
• XMP-107: Neutron Calibration Transfer
• XMP-120: Strikepoint & X-Point Control
• XMP-128: Increase L-Mode Elongation
• XMP-132: Fast Rampdown Sequence Commissioning
• XMP-137: Increase κ and IP in L- and H- Mode
• XMP-138: Improved Vertical Control Checkout
• XMP-121: SPA & RWM Control Checkout
• XMP-140: PF-5 Proportional EFC Test
• XMP-141: Proportional EFC Tests
• XMP-111: MPTS Commissioning
• XMP-142: Reduced MHD H-Mode Development
• XMP-146: Higher-Order Feed Forward EFC in L-Mode
• XMP-147: Integrate control improvements in L-Mode fiducial
• XMP-148: Between-Shot TRANSP Validation
• XMP-110: ssNPA & FIDA checkout
• XMP-150: He Density Scan for Zeff Calibration
• XMP-151: L-Mode Development for Core and Boundary XPs
• XMP-152: Improved dr-sep and rtEFIT Control
• XMP-153: H-mode Access and Rampup Control Development
• XMP-154: Inner Gap Control Development
• XMP-114: CHERS Modulation Study
• XMP-125: MSE-CIF 2nd NB Interference Study
• XMP-130: Granule Injector Commissioning
• XP-1506: Low Beta n=1 EFC

Completed In progress Planned

8 TOFE 2016, Overview of Initial Operation of NSTX-U, D.J. Battaglia, August 22, 2016

• Rapid development of high-performance discharges in first 10

weeks of operation

– Operated routinely at BT0 = 0.65T, greater than maximum NSTX field – Wall conditioning: Helium GDC + boronization – Many diagnostics available at first plasma

Commissioning activities developed discharges to support planned experiments

NSTX%U' NSTX' NSTX%U' NSTX'

117742% 204082%

Time%(seconds)% Plasma%current%(Mega%amps)% Toroidal%magne<c%field%(Tesla)%

• Stationary L-mode pulse length ~ 4

times longer than NSTX

– Supported first experiments on error fields, transport, current drive and fast-ion physics

• H-mode discharges comparable to

NSTX performance for Ip < 1.0 MA

L-mode with 1MW NBI

9 TOFE 2016, Overview of Initial Operation of NSTX-U, D.J. Battaglia, August 22, 2016

Neutral beam injection using the new beam line immediately demonstrated exciting results

• Plasma instabilities are driven

by neutral beam heating

– Instabilities can increase the transport of thermal energy – Example at right, instabilities start with when NBI heating is increased

• Tangential injection suppresses

fast ion instabilities

– Unique result to observe instabilities go away after adding more power – Significant tool for improving energy confinement

Frequency (MHz)

shot 203980 hf n= 9 n=10 n=11 n=12 n=13 n=14 1.6 1.7 1.8 1.9 2.0

Injected Power NBI #1 (MW) Injected Power NBI #2 (MW)

4 2 1

Toroidal mode number of instabilities detected using magnetic sensors

10 TOFE 2016, Overview of Initial Operation of NSTX-U, D.J. Battaglia, August 22, 2016

Steady progress in error field correction, plasma control and NBI heating improved H-mode performance

WMHD (kJ) Dα (AU) PNBI (MW) IP (MA)

EFIT02 204112 0.898000 s EFIT02 202946 0.697000 s

202946 February 204112 April 202946 Feb – no EFC 203679 March – EFC v1 202112 April – EFC v2 202118 April – EFC v2

Control development EF correction

11 TOFE 2016, Overview of Initial Operation of NSTX-U, D.J. Battaglia, August 22, 2016

• Scenario matches best NSTX

performance at Ip = 0.9 MA

– Progress toward larger Ip and longer pulses was interrupted by coil failure

H-mode scenario achieved with H98y,2 > 1 and βN ≥ no-wall stability limit

Plasma Current [MA] Volume Average Pressure [kPa]

NSTX-U, Boronized NSTX, Lithium NSTX, Mixed NSTX, Boronized Future NSTX-U

• perations up to 2MA
• 10 weeks

10 years

Shot 204112, n=

0.2 0.4 0.6 0.8 1.0 20 40 60 80 100

high-n array

1 2 3 4 Composite%no,wall%limit%model%

100 80 60 40 20 1.2 1.0 0.8 0.6 0.4 6 5 4 3 2 1

Mode frequency (kHz) H98y,2 βN

12 TOFE 2016, Overview of Initial Operation of NSTX-U, D.J. Battaglia, August 22, 2016

• NSTX-U mission toward advancing magnetic

confinement fusion development

• Highlights from the first NSTX-U experimental

campaign

• Initial operations with plasma control and digital coil

protection systems on NSTX-U

Outline

13 TOFE 2016, Overview of Initial Operation of NSTX-U, D.J. Battaglia, August 22, 2016

Shape control challenges due to increased aspect ratio (A) of NSTX-U were successfully addressed

Higher-A operation challenges …

• Vertical stability

– Improved detection of vertical plasma motion – Achieved comparable elongation to NSTX at matched li

• Controlling inboard gap without inboard PF coils

– Coil actuator sharing algorithm (MIMO): find solution that best matches target shape when # control points > # PF coils Modify the plasma shape to achieve the best match 8 plasma shape target points (including inboard gap) with

• nly 7 PF coils.

Inboard gap X-point radius Outer squareness

14 TOFE 2016, Overview of Initial Operation of NSTX-U, D.J. Battaglia, August 22, 2016

Plasma Shutdown scheme routinely used to initiate controlled rampdown of NSTX-U discharges

• NSTX: No means of detecting a disruption, or

ramping down the plasma current based on events.

• NSTX-U: State machine orchestrates the

shutdown.

– Examples of events triggering shutdown:

§ Ohmic coil approaching current limit (loss of control) § Loss of vertical stability (example at right) § Plasma current missing target § Insufficient plasma current for control

– Routinely used in NSTX-U discharges to avoid disruptions

• Supports future research into reactor-relevant

disruption avoidance schemes

– Disruption avoidance may be critical to future divertor material testing on NSTX-U

0.0 0.2 0.4 0.6 0.8 1.0 100 200 300 400 500 600 700 202926 0.0 0.2 0.4 0.6 0.8 1.0

• 1.0
• 0.5

0.0 0.5 1.0 0.0 0.2 0.4 0.6 0.8 1.0

• 1

1 2 3 4 5 0.0 0.2 0.4 0.6 0.8 1.0 time [s]

• 1.0
• 0.5

0.0 0.5 1.0

IP IP Request

(including asynchronous transition to rampdown)

ZP(dZP/dt) ZP(dZP/dt) threshold Normal Fast IP Rampdown Insufficient IP ZP from EFIT “State”

15 TOFE 2016, Overview of Initial Operation of NSTX-U, D.J. Battaglia, August 22, 2016 0.0 0.2 0.4 0.6 0.8 1.0 100 200 300 400 500 600 700 IP [kA]

202912

0.0 0.2 0.4 0.6 0.8 1.0

• 20
• 10

10 20 IOH [kA] 0.0 0.2 0.4 0.6 0.8 1.0

• 5

5 10 15 20 IPF-1aL [kA] 0.0 0.2 0.4 0.6 0.8 1.0 time [s]

• 40
• 20

20 40 FZ,PF-1aL [klbs.]

• DCPS developed to protect

coils from exceeding force and thermal limits

– 400 real-time force and stress calculations using coil and plasma currents – Fault detection triggers all power supplies to remove voltage from coils

• System designed for every-

shot protection

– Redundant systems with multiple layers of system status checking and fault tracing

• DCPS successfully avoided

exceeding force limits during

• ff-normal events

Digital coil protection system (DPCS) successful in avoiding coil force and heating limits

Vertical force on PF1A

EFIT01 202912 0.889000 s

+ IPF1A

• IOH

16 TOFE 2016, Overview of Initial Operation of NSTX-U, D.J. Battaglia, August 22, 2016

• NSTX-U is now the most capable spherical tokamak in the world

fusion program

– NSTX-U will evaluate the ST design for future burning plasma devices and complement conventional tokamak experiments

• Initial operations made rapid progress in discharge scenario

development and commissioning heating and diagnostic systems

– Long (> 1.5 s) L-mode discharges supported first experimental results – Progress in H-mode scenario enabled by progress in error field correction, shape control and heating power availability

• New plasma control and coil protection systems were commissioned

to support NSTX-U operations

– Many of the new capabilities applicable to present and future tokamak devices

Summary

17 TOFE 2016, Overview of Initial Operation of NSTX-U, D.J. Battaglia, August 22, 2016

• Thermal and structural performance evaluation of the NSTX-U high-z divertor

– Art Brooks 18403 Monday Poster Session

• NSTX-U 2nd Neutral Beam Relocation

– Neway Atnafu 18167 Monday Poster Session

• NSTX-U Bake-Out Simulations and Evaluations

– Peter Titus 18220 Monday Poster Session

• Design and operation of the electrical noise suppression system for CHI on NSTX

and NSTX-U

– Zhi Gao 18163 Tuesday Poster Session

• Studies of Next-Step Spherical Tokamaks Using High-Temperature Superconductors

– Jon Menard 18205 Tuesday AM Invited Talk

Please come tour NSTX-U on Tuesday evening!

NSTX-U Talks and Posters at TOFE 2016