the nstx research program and collaboration opportunities
DESCRIPTION
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 - PowerPoint PPT PresentationTRANSCRIPT
1
Supported by
Columbia UComp-X
General AtomicsINEL
Johns Hopkins ULANLLLNL
LodestarMIT
Nova PhotonicsNYU
ORNLPPPL
PSISNL
UC DavisUC Irvine
UCLAUCSD
U MarylandU New Mexico
U RochesterU Washington
U WisconsinCulham Sci Ctr
Hiroshima UHIST
Kyushu Tokai UNiigata U
Tsukuba UU TokyoIoffe Inst
TRINITIKBSI
KAISTENEA, Frascati
CEA, CadaracheIPP, Jülich
IPP, GarchingU Quebec
E.J. SynakowskiPPPL
Alcator C-Mod Ideas ForumDecember 2, 2004
The NSTX Research Program and Collaboration
Opportunities
2
Theory-experiment
coupling
Experimentalcollaboration
Unique NSTX plasma properties provide scientific leverage in all major areas of toroidal confinement research
Core transport
& turbulenc
eMHD: stability & helicity injection
Wave/particle interactions
Strengthen the scientific basis for
fusion energy
Edge transport & stability
Test theory by isolating important physics and challenging models at their extremes of applicability
3
Assess high low A physics with passive control
Strengthen physics basis with advanced
measurements & control at high &
low A
Optimize long-pulse, high
Strengthen physics
understanding
• Take maximal scientific advantage of ST plasma characteristics through novel diagnostics and new control tools, and targeted inter-device studies
focus for FY
‘05-‘07
NSTX research is entering a phase of advanced diagnostic implementation and advanced control
Innovative diagnostics
Control tools to test physics &
increase operating space
enablingInter-device
studies
scienceHigh impact onturbulence, waves, MHD
Unique edge B structureLarge super-
Alfvénic ni
High Vflow/VAlfvén
4
• NBI + EBW CD.
• Mode control + rotation are key
• Fast ion transport & MHD important for understanding JNB
• Turbulence studies to form basis for confinement understanding
• Edge optimization & particle control required
• Successful HHFW w/ NBI ==> more JBS. Also
high value in NI-startup
40% T with ~100% INI, pulse >> skin, demands development of new tools and understanding their underlying physics
Kessel, TSCIAEA 2004
NBCD
bootstrap EBW
psi
bootstrap
NBCDEBW grad-pth
q(0)q(min)
Ongoing partnership with MIT
Common elements with error field & RWM research
Complementary *AE research with very different Vion/VAlfvén?
Build on joint edge studies, towards high k studies in the core.
Pedestal studies with very different edges. C-Mod originated Li studies at PPPL
Wave physics opportunity?
40% T , INI = 100%, pulse >> skin
5
MHD & macroscopic plasma behavior
Passive stability limits & mode
characterization
C-Mod/NSTX opportunities include
• Error field studies
• Fast ion physics
• Edge stability (discussed later)
Active feedback coils
Strong shapingenabling Helicity injection
Physics of active control
Expand operating space
scienceFlows
NTM physicsNonlinear fast
ion MHDDynamo physics
Optimize stability of high
Develop startup techniques
Deepen physics understanding of
stability & reconnection
Relevant physics attributes
• Strongly driven vs. low rotation (Vflow/VA
1 on NSTX)
• Vfast ion/VA > 1 always true on NSTX.
• Different means of generating fast ions
6
Rotation effects are strong in NSTX plasmas
W. Park, J. Menard
Rotational shear also strong candidate for internal mode saturation
7
Differences & similarities in plasma parameters may allow comparative studies in mode control & mode locking
• Compared to C-Mod,
– ~ similar sound speed, C-Mod has smaller VAlfvén. NSTX has Larger Vflow/Valfvén.
Implications for mode damping/locking?
– At lower A, higher n modes expected to be more important --> benchmark RWM theories
• Likely source of complementarity: error field and mode locking studies
Columbia U.
Feedback coils
Contact [email protected], [email protected]: camera image & DCON code
8
9
NSTX’s large population of super-Alfvénic fast particles enables an important branch of nonlinear
MHD physics to be studied• Vfast ion/VAlfvén ~ 3, similar to ITER
values of ~ 2.
• Access to multimode Alfvénic turbulence in nearly every NBI discharge on NSTX
• MSE commissioned, with goal of routine EFIT constraints next run
• Features for scientific leverage between C-Mod & NSTX include– similar shape, different R/a– Different driving mechanisms
Already joint XPs with DIII-D. Contact [email protected]
10
Transport & turbulence (core)
Global scalings
Local
Edge turbulence
Confinement optimization
Role of + Er in & turbulence
Optimize confinement +
JBS in long-pulse, high
Extend physics understanding of turbulence
to unity
NSTX transport physics
• Role of : onset of electromagnetic effects broadens theory/experiment comparisons
• Electron transport: Broad range of k for theory tests
enablingParticle control: lithium
q profile & reverse shear
scienceElectron thermal transport: High k
scattering
Ion, electron transport: low k
imaging
e-m effects, low & hi k
C-Mod/NSTX research opportunities
• High k comparisons at low & high and the onset of e-m effects
• Core ITBs with RF
• Dimensionless similarity?
NB vs HHFW heating
11
Understanding electron thermal transport will be a focus for ‘05 - ‘07
• The dominant energy loss channel & a topic of broad importance to fusion & burning plasmas, including ITER.
• Potentially important for RF & CD
• While e transport is rapid, it can be modified– Why the flat center?
• Collaborative core transport similarity experiments through ITPA (MAST, DIII-D)
Faster Ip ramp
Te
ch
ang
e (%
)
t (ms)
137.5 cm
134 cm
131 cm
127 cm
R0=101 cm
Stutman, JHU
LeBlanc, R. Bell, Kaye
Rapid cold pulse propagation following ELM
12
High k scattering measurements will be developed in FY’ 05
• Initial system will allow range of k measurements in select locations (2 - 20 cm-1) with good spatial resolution & ∆n/n < 0.01%
• Major installation this opening.
High k scattering
Luhmann (UC Davis), Munsat (U. Colorado) Mazzucato, Park, Smith (Princeton U.)
1.0 10k (cm-1)
Contact [email protected]
13
Waves & energetic particles
HHFW heating, phasing, & CD
EBW emissions
Coupling startup techniques to ramp-up
Wave physics in overdense plasmas
Reduce V-s through JBS
and direct CD
Extend physics understanding
of waves in overdense plasmas
NSTX wave-particle physics
• HHFW, EBW: wave coupling, propagation & deposition for overdense plasmas (for ST, RFP)
• EBW: Ohkawa current drive with high trapping fraction
scienceHHFW wave physics from
antenna to core
EBW physics: mode conversion & f(v)
modification
Super-Alfvénic particles &
MHD
enabling
EBW tube. Launcher
development
Heat low Ip plasmas for
ramp-up
NBI at modest B
Opportunities with MIT/ C-Mod program
• Strong RF theory & modeling effort at present, including ongoing EBW theory research
• Direct measures of fast wave deposition
14
HHFW Absorption Depends on Antenna PhasingHHFW modulated to assess % absorption
k||=14 m-3 80% 7 m-1 (ctr) 75% -7 m-1 (co) 40% 3 m-1 10%
Edge ion heating, parametric decay of HHFW
Evidence for parametric absorption processes found in spectroscopy, RF probes
Absorption
Hot component
Cold component
Biewer, APS invited 2004
Contact [email protected]@pppl.gov
15
Can overdense C-Mod plasmas be created so that fast waves can be launched and
diagnosed?
• Need for NSTX: validate fast wave physics– Core deposition to be sampled with modified edge
reflectometer (ORNL) up to ne = 6x1012 cm-3
• Opportunity for C-Mod program: Clarify & test FW deposition theory with PCI deeper into the core– Perhaps 80 MHz, high density operation will yield
an appropriate overdense condition for the RF?
16
ST properties and recent experiments make EBW attractive & high priority
• Ongoing research effort with MIT theory
• EBW current drive takes advantage of high ST electron trapping fraction via Ohkawa effect. The ST is perfect for exploring this science.
• Recent NSTX emissions evaluating EBW coupling are promising
• Modeling indicates efficient off-axis current drive
Compx Genray/CQL3D
Contact [email protected]
17
C-Mod/NSTX opportunities
• Different edge Bp/B T
• Different values of B, ne, Te…
Plasma boundary interfaces
Power balance
Heat flux scaling
Pedestal & ELM character
Lithium pellets & coatings
Fueling studies
SOL transport
Optimize high , long pulse
regimes through pedestal
modification
Assess boundary
control needs for steps
beyond NSTX
Boundary physics opportunities
• Advanced heat and particle flux management techniques relevant to all toroidal confinement concepts
• SOL transport: intermittency & shear Alfvénic turbulence
Lithium studies for influx control
Optimize ELMs
Radiative divertor regimesenabling
Pedestal-core connection
Pedestal stability at low A
SOL transport & turbulence
science L-H transition physics
18
Improved diagnostics are allowing details of ELM characteristics to emerge
• Diagnostics (e.g. fast camera) now allow detailed documentation of ELM dynamics, tests of theory
• On NSTX, Type V ELMs: small, with little change in stored energy– So far, found in high
ne regimes– Possible platform for
comparitive study with benign regimes on C-Mod
Type V Type I
Small, filamentary, perturbation
Larger low n perturbation
Contact [email protected]@pppl.gov
19
NSTX capability for pedestal studies will be improved in ‘05
• MPTS: additional channels added in edge and core.
• CHERS: resolution surpasses carbon ion gyroradius at the edge
• Edge reflectometry for ne
Contact: [email protected]
20
Imaging & probe measurements provide a powerful test bed for edge turbulence codes
• Already a strong collaborative effort with the C-Mod program
• L-H transition physics, turbulence structure and dynamics are all possibilities
• NSTX may be revealing new class of turbulence not seen in DIII-D or C-Mod– BOUT simulations point to “electrostatic
shear Alfvén eigenmodes” (Umansky, LLNL).
• Can we better understand the limits of edge codes through this sort of comparative study?
L mode
BOUT simulations underway based on measured profiles & NSTX geometry (preliminary)
Umansky, LLNL
Zweben
Probes: Boedo
21
Lithium edge flux control studies start with pellets, and may culminate in a powerful edge control approach
• Li coatings: localized, 1000 Å before every shot
e-beam for Li coatings in ‘06
Liquid lithium module: decision following coatings studies
• Under ALIST group of VLT• Would represent a revolutionary
solution for both power and particle handling
Li pellets: injector commissioned in ‘04
• Develop deposition techniques in ‘05
Contact [email protected], [email protected]@fusion.gat.com
22
NSTX research run plan extends to 18 run weeks
• Scheduled to start in late winter
• Contacts: myself, Jon Menard (this run’s run coordinator), ET leaders, Stan Kaye, Mike Bell– MHD: Steve Sabbagh, Dave Gates– Transport: Stan Kaye, Dan Stutman– Boundary: Bob Kaita, Jose Boedo– HHFW/EBW: Cynthia Phillips, Randy Wilson– Integrated scenarios: Rajesh Maingi, Chuck
Kessel
23
There are many opportunities for additional, high leverage collaborative research
• A key aspect of our research approach is to use similarities & differences between different devices to challenge theories & models at their extremes
• Scientific progress is colinear with demonstrations of advanced scenarios
• Improved diagnostics and control capability will enable more sophisticated comparative studies this run
• We welcome this as part of a continuing constructive dialogue between the two programs
24
25
FESAC Theme: Understand & control the processes that govern confinement of heat, momentum, and particles
FESAC Theme: Learn to use energetic particles & e-m waves to
sustain and control high temperature plasmas
FESAC Theme: Understand the role of magnetic structure on confinement, & plasma pressure limits
Microscopic ion, electron, and tearing turbulence measurement & theory comparison over wide range in , flows, and magnetic shear, with good average curvature and high trapping
Stability pressure limits & magnetic reconnection vs. A, shape, profile, q & flows, for internal & external modes with Vflow/VA < 0.4 & unity ; helicity transport
EM waves in overdense plasma; Phase space manipulation with high electron trapping; energetic ions with large orbits; Alfven eigenmodes and turbulence with Vfast/VA >> 1
FESAC Theme: Learn to control the interface
between a 100 million degree plasma and its
room temperature surroundings
Physics of ELMs, pedestal, SOL turbulence & high
divertor heat flux, with large in/out asymmetry; Li
coatings & liquid surface interactions with plasma.
NSTX research for ‘05 - ‘07 is well aligned with the fusion program’s scientific priorities and supports strategic goals
NSTX
_
Demonstrate Feasibility with Burning Plasmas
Develop Understanding and Predicitve Capability
Determine Most Promising Configurations
Develop New Materials, Components, & Technologies
26
Plasma flows will be a focal point of research through ‘07
• Understanding momentum transport a national transport priority
• Motivated by observations– Counter-directed flow with co-
injection – V, V with HHFW & prior to
ohmic H modes
• Needed to reconstruct Er & profile
• V measurements deeper in the core will be developed for ‘06
R. Bell
27
NSTX research led to an expansion of operating space in 2004
Reduced latency improved vertical control at high-, high-T
Capability for higher allowed higher IP/aBT
Significantly more high-T
(N=6.8 %mT/MA achieved)
More routine high Longer current flattop duration pulse = (>0.85 Ip,max)
Time of peak T