1 ebw & hhfw research - g. taylor pac-19 2/23/06 ebw & hhfw research (including ebw...

1 EBW & HHFW Research - G. Taylor PAC-19 2/23/06

EBW & HHFW Research EBW & HHFW Research (Including EBW Collaborations with MAST & (Including EBW Collaborations with MAST &

PPEGASUSEGASUS))

Gary TaylorGary Taylorpresented on behalf of thepresented on behalf of the

NSTX Research TeamNSTX Research Team

NSTX Program Advisory Committee MeetingNSTX Program Advisory Committee Meeting(PAC-19)(PAC-19)

February 23, 2006February 23, 2006


OutlineOutline

• NSTX EBW Research (including MAST & NSTX EBW Research (including MAST &

PPEGASUSEGASUS ) )

• NSTX HHFW ResearchNSTX HHFW Research

• SummarySummary


NSTX EBW ResearchNSTX EBW Research(including MAST & P(including MAST & PEGASUSEGASUS))

• EBW research is directed towards…EBW research is directed towards…


Deposition similar for 14 GHz & 28 GHz and ~ 20-

40%CQL3D/GENRAY

NSTXBt(0) = 3.5

kG

• Need ~100 kA RFCD between Need ~100 kA RFCD between = 0.4 & = 0.4 & = = 0.8; 0.8; CD localization is not criticalCD localization is not critical

CurrentDensity(A/cm2)

EBWCD Needed to Sustain EBWCD Needed to Sustain > 20 % Non-Inductive > 20 % Non-Inductive NSTX PlasmasNSTX Plasmas

• Need resilient Need resilient coupling coupling to EBWsto EBWs for viable for viable EBWCD scheme EBWCD scheme

• Large trapped Large trapped particle particle fraction on low field fraction on low field side side enables off-axis enables off-axis Ohkawa Ohkawa EBWCD EBWCD

G. Taylor et al., Phys. Plasmas G. Taylor et al., Phys. Plasmas 1111, , 4733 (2004)4733 (2004)


Strong Diffusion Near Trapped-Passing Boundary Strong Diffusion Near Trapped-Passing Boundary EnablesEnables

Efficient Ohkawa EBWCDEfficient Ohkawa EBWCD

Contours of Quasilinear RF Velocity Contours of Quasilinear RF Velocity Space Diffusion OperatorSpace Diffusion Operator

Unorm = 30 keV

Trapped-PassingBoundary

Uperp /Unorm

UparaUnorm

10

1

0-1

= 0.7

ElectronDiffusion

GENRAY/CQL3DGENRAY/CQL3D


Synergy with Bootstrap Current Modifies EBWCD Synergy with Bootstrap Current Modifies EBWCD Current Profile & Enhances CD Efficiency by ~ Current Profile & Enhances CD Efficiency by ~

10% 10%

R.W. Harvey & G. Taylor, Phys. Plasmas R.W. Harvey & G. Taylor, Phys. Plasmas 1212, , 051509 (2005)051509 (2005)

NSTX NSTX = 40% = 40%, PPEBWEBW = 1 MW, Co- = 1 MW, Co-EBWCDEBWCD

Normalized Radius, 0.80.60.40.2

0

ParallelCurrentDensity

J(A/cm2)

5

10

15

-5

1.00.0

EBWCD + SynergyBootstrap Current

Synergy BootstrapCurrent

EBWCD Current

GENRAY/CQL3DGENRAY/CQL3D

• Synergistic bootstrap current Synergistic bootstrap current results from EBW-induced pitch results from EBW-induced pitch angle scattering into trapped angle scattering into trapped electron populationelectron population

• Radial diffusion broadening is Radial diffusion broadening is marginally important for marginally important for = 40% = 40% case: case: ~ 0.05 @ ~ 0.05 @ ~ 0.7~ 0.7

• CD modeling assuming diffusion CD modeling assuming diffusion constant in velocity space, being constant in velocity space, being performed for range of NSTX performed for range of NSTX conditionsconditions

• CQL3D being upgraded to improve radial transport CQL3D being upgraded to improve radial transport calculation, icalculation, including ncluding possible self-consistent anti-pinch effect of Ohkawa possible self-consistent anti-pinch effect of Ohkawa EBWCD & its effect on EBWCD & its effect on bootstrap current bootstrap current


Measured 80% B-X-O Coupling in L-Mode Edge Measured 80% B-X-O Coupling in L-Mode Edge Plasmas, Consistent with ModelingPlasmas, Consistent with Modeling

G. Taylor et al., , Phys. Plasmas Phys. Plasmas 1212, , 052511 (2005) 052511 (2005) J. Preinhaelter et al., AIP Proc. J. Preinhaelter et al., AIP Proc. 787787, , 349 (2005)349 (2005)

• 3-D ray tracing & full wave3-D ray tracing & full wave EBW mode conversion model EBW mode conversion model using EFIT magnetic equilibriumusing EFIT magnetic equilibrium & Thomson scattering T& Thomson scattering Tee & n & nee

f =16.5 GHz

NSTX Shot 113544

CalculatedEBW Trad

NSTX Shot 113544EBW Frequency = 16.5 GHz

Te of EBWEmission Layer

Time-AveragedMeasuredEBW Trad

1.5

1.0

0

Trad & Te(keV)

1.5

1.0

R (m)

0 0.3 0.6

Radius of EBWEmission Layer

RLCFS

Raxis

TIME (s)

0.5

Frequency = 16.5 GHz, Bt(0) = 4.5 kG

1.2

-1

0

1

1.6

fce 2fce

Z(m)

R(m)0.80.4

UHR

LCFSEBWRays

2fce

xO

kperp

O-Mode

UpperHybrid

Resonance

RadiusxL

Slow X-Mode

EBWElectromagnetic

Antenna


~ 30% B-X-O Coupling in H-Modes Consistent with ~ 30% B-X-O Coupling in H-Modes Consistent with Collisional 3fCollisional 3fcece EBE Damping at Upper Hybrid EBE Damping at Upper Hybrid

LayerLayer

Trad ~ Te(R=1m) Te

R(m)1.0 1.2 1.4 1.6

0

1.0

Te(keV)

fUHR

2fce

3fceFreq. (GHz)

25 GHz

0

20

40

60

AxisLast ClosedFlux Surface

Measured Trad

Simulated Trad with Zeff = 3 at UHRSimulated Trad with Zeff = 5 at UHRSimulated Trad with no EBW damping at UHR

Trad(keV)

1000

Time (s)

Shot = 117970f = 25 GHz

00 0.6

•TTee~ 20 eV at UHR, near ~ 20 eV at UHR, near foot of foot of H-mode pedestal H-mode pedestal

• EBW collisional damping EBW collisional damping sensitive sensitive to Z to Zeffeff for T for Te e < 30 eV< 30 eV• Measured TMeasured Tradrad behavior behavior consistent consistent with EBE only from 3f with EBE only from 3fce ce

off-axisoff-axis

• Li conditioning may significantly Li conditioning may significantly improve B-X-O improve B-X-O coupling from H-modes by increasing T coupling from H-modes by increasing Tee at UHR at UHR

Trad ~ Te(R=1.3 m)


M. CarterORNL

AORSA-1DNSTX = 40%Bt(0) = 3.5 kGf = 28 GHz

Remotely-steered B-X-O Antennas, Covering 8-40 GHz, will Remotely-steered B-X-O Antennas, Covering 8-40 GHz, will Test EBW Coupling Efficiency Predictions from Models Test EBW Coupling Efficiency Predictions from Models

• Experiments will Experiments will study study L- & H-mode L- & H-mode plasmas plasmas and effect of Li and effect of Li pumpingpumping on EBW edge on EBW edge couplingcoupling

• Scanning frequency & antenna Scanning frequency & antenna viewing angle viewing angle provides key information on provides key information on angle of peak angle of peak EBW coupling & emission EBW coupling & emission polarizationpolarization • EBW coupling study critical for EBW coupling study critical for assessing assessing technical feasibility of EBWCD technical feasibility of EBWCD in FY06in FY06

• Supports EBW TSupports EBW Tee(R,t) diagnostic (R,t) diagnostic developmentdevelopment

npol

ntor

0.6

0.6-0.6-0.6

18-40 GHzQuad Ridged

Antenna

LensEBW

Emission

Plasma

VacuumWindows

Lens

8-18 GHzQuad Ridged

Antenna

Dual Channel18-40 GHzRadiometer

Dual Channel8-18 GHz

Radiometer


MAST EBW CollaborationMAST EBW Collaboration

• EBWCD benchmarking between EBWCD benchmarking between GENRAY/CQL3D GENRAY/CQL3D & BANDIT & BANDIT shows reasonably good agreement for shows reasonably good agreement for = 40% NSTX = 40% NSTX case:case:

- both predict Ohkawa EBWCD, peaked at r/a ~ 0.7- both predict Ohkawa EBWCD, peaked at r/a ~ 0.7- BANDIT: 26 kA/MW, GENRAY/CQL3D: 37 kA/MW- BANDIT: 26 kA/MW, GENRAY/CQL3D: 37 kA/MW- BANDIT includes EBW coupling at UHR, GENRAY did - BANDIT includes EBW coupling at UHR, GENRAY did

notnot - In 2006, will include EBW coupling in GENRAY - In 2006, will include EBW coupling in GENRAY

• 28 GHz EBW I28 GHz EBW Ipp initiation/ramp-up system will be initiation/ramp-up system will be tested on MAST tested on MAST in late 2006 (installation in summer 2006): in late 2006 (installation in summer 2006): - collaborate with 28 GHz startup/ramp-up - collaborate with 28 GHz startup/ramp-up experiments in 2006-7experiments in 2006-7

- possible 28 GHz B-X-O experiments in 2007-8- possible 28 GHz B-X-O experiments in 2007-8

• B-X-O coupling measurements from spinning mirror EBE B-X-O coupling measurements from spinning mirror EBE diagnostic diagnostic (March 2006) will (March 2006) will contribute to FY06 decision on contribute to FY06 decision on technical feasibility of technical feasibility of EBWCD on NSTX EBWCD on NSTX


2.45 GHz EBW Experiments on P2.45 GHz EBW Experiments on PEGASUSEGASUS will Study will Study Coupling, Propagation, Heating & CDCoupling, Propagation, Heating & CD

• Existing 2.45 Existing 2.45 GHz GHz PLT equipment to PLT equipment to bebe used for 0.9 MWused for 0.9 MW EBW systemEBW system

• Demonstrate EBW Demonstrate EBW coupling at coupling at significant significant power via O-X-B power via O-X-B & X-B& X-B

• Study nonlinear Study nonlinear EBW EBW coupling effects coupling effects

• Validate ray Validate ray tracing, tracing, demonstrate demonstrate electron electron heatingheating

• Measure EBWCD Measure EBWCD


Frequency = 2.45 GHz, Poloidal Angle of Antenna Location = 15 deg.

Normalized Minor Radius0

00.1 0.30.2

PowerDensity(W/cm3)

12Prf = 200 kW

Rod Current90 kA

120 kA150 kA

Normalized Minor Radius

CurrentDensity(A/cm2)

0

80

0 0.1 0.30.2

• Initial modeling completed for PInitial modeling completed for PEGASUSEGASUS 2.45 GHz EBW heating 2.45 GHz EBW heating & CD system for I& CD system for Irod rod = 90-150 kA= 90-150 kA

- CD efficiency ~ 20-25 kA/MW ; - CD efficiency ~ 20-25 kA/MW ; - Fisch-Boozer CD dominates on axis for I- Fisch-Boozer CD dominates on axis for Irod rod = 90-150 kA= 90-150 kA- I- Irodrod ~ 210-240 kA may allow dominant off-axis Ohkawa CD ~ 210-240 kA may allow dominant off-axis Ohkawa CD

• 200-400 kW EBW experiments could begin on P200-400 kW EBW experiments could begin on PEGASUSEGASUS in 2008-9 in 2008-9

Near Midplane EBW Launch Provides Significant EBW Near Midplane EBW Launch Provides Significant EBW Electron Heating & Current Drive Near AxisElectron Heating & Current Drive Near Axis


EBW Models & Emission Coupling Studies on NSTX EBW Models & Emission Coupling Studies on NSTX Being Significantly Improved in FY06Being Significantly Improved in FY06

• NSTX & MAST EBW emission studies will contribute to NSTX & MAST EBW emission studies will contribute to FY06 technicalFY06 technical assessment of EBWCD:assessment of EBWCD:

- NSTX remotely steered antennas will study B-X-O- NSTX remotely steered antennas will study B-X-O coupling from L- & H-mode & effect of Li coupling from L- & H-mode & effect of Li conditioning conditioning

- MAST spinning mirror diagnostic will study B-X-- MAST spinning mirror diagnostic will study B-X-O couplingO coupling

• 2.45 GHz EBWCD modeling of P2.45 GHz EBWCD modeling of PEGASUSEGASUS plasmas plasmas at Iat Irod rod > > 200 kA to 200 kA to identify scenarios with dominant Ohkawa CDidentify scenarios with dominant Ohkawa CD

• CQL3D/GENRAY modeling of EBE from non-thermal CQL3D/GENRAY modeling of EBE from non-thermal electron distributionselectron distributions

• Include EBW mode conversion model in GENRAYInclude EBW mode conversion model in GENRAY

• Benchmark CQL3D/GENRAY(with EBW MC) & BANDIT for NSTX Benchmark CQL3D/GENRAY(with EBW MC) & BANDIT for NSTX casescases

• Improve user interface to "Prague" EBW emission Improve user interface to "Prague" EBW emission modeling code modeling code

• CQL3D/GENRAY EBWCD calculations assuming constant CQL3D/GENRAY EBWCD calculations assuming constant diffusion in diffusion in velocity space (consistent with TCV results) for a velocity space (consistent with TCV results) for a range NSTX conditions range NSTX conditions


EBW Priorities for FY 2007-2008EBW Priorities for FY 2007-2008

• Complete detailed study of EBE coupling with NSTX remotely Complete detailed study of EBE coupling with NSTX remotely steered antennassteered antennas

• Collaborate with 28 GHz startup/ramp-up experiments in 2006-7Collaborate with 28 GHz startup/ramp-up experiments in 2006-7& possibly 28 GHz B-X-O experiments in 2007-8& possibly 28 GHz B-X-O experiments in 2007-8

• Upgrade radial transport calculation in the CQL3DUpgrade radial transport calculation in the CQL3D

• Examine possible role of self-consistent anti-pinch effect in Examine possible role of self-consistent anti-pinch effect in Ohkawa EBWCD and its effect on bootstrap currentOhkawa EBWCD and its effect on bootstrap current

• Analytical study of EBAnalytical study of EBWCDWCD and scenarios for optimizing the and scenarios for optimizing the current drive efficiencycurrent drive efficiency

• Possible collaboration on NSTX ~1 MW, 28 GHz EBW experimentsPossible collaboration on NSTX ~1 MW, 28 GHz EBW experiments

• Implement ~ 400 kW, 2.45 GHz EBW heating & CD capability on Implement ~ 400 kW, 2.45 GHz EBW heating & CD capability on PPEGASUSEGASUS


NSTX HHFW ResearchNSTX HHFW Research• HHFW research is directed towards… HHFW research is directed towards…


• Field pitch angle may explain differences between Field pitch angle may explain differences between co & counterco & counter

k//(m-1) % Power absorbed

14 80+7 70-7 55+3 < 20

• Parametric decay into surface waves may explain some Parametric decay into surface waves may explain some of of the power absorption dependence on k the power absorption dependence on k////

HHFW Power Modulation Experiments HHFW Power Modulation Experiments Show Decreasing RF Absorption with Decreasing Show Decreasing RF Absorption with Decreasing

kk////


• Ion heating through parametric decay was observed in 2004 & Ion heating through parametric decay was observed in 2004 & confirmed with improved time resolution in 2005confirmed with improved time resolution in 2005

• Waves in the surface can cause power deposition in sheaths and in Waves in the surface can cause power deposition in sheaths and in the plasma periphery through collisionsthe plasma periphery through collisions

• For lower kFor lower k// // , fast waves propagate at lower , fast waves propagate at lower density and reachdensity and reach much higher much higher kk at a given density at a given density

• Wave fields in the edge are enhanced at lower kWave fields in the edge are enhanced at lower k// //

and should and should contribute to greater power loss via parametric contribute to greater power loss via parametric decay, sheathdecay, sheath damping & collisions damping & collisions

Possible HHFW Power Loss in Plasma Edge via Parametric Decay & Waves in the Periphery


• Edge ion heating via parametric decay increases Edge ion heating via parametric decay increases with wavelength:with wavelength:

16% @ k|| = 14 m-1, 23% @ k|| = -7 m-1

• Represents lower limit estimate of power loss by Represents lower limit estimate of power loss by this processthis process

0.20

0.15

• Significant RF power required to sustain large Significant RF power required to sustain large temperature difference temperature difference between edge ions and electrons between edge ions and electrons

Parametric Decay Accounts for Significant Parametric Decay Accounts for Significant Fraction of RF Power Losses at kFraction of RF Power Losses at k|||| = 14 m = 14 m-1-1 & &

-7 m-7 m-1-1


k|| = 3m-

1

7m-1

14m-1

• Density onset is Density onset is function function of ~ of ~ B*kB*k||||

22

• Propagation is Propagation is very close very close to wall at 7 mto wall at 7 m-1-1 and on the and on the wall at 3 m wall at 3 m-1-1

• Losses in surface Losses in surface should should be higher for be higher for lower klower k||||

• Strong motivation Strong motivation for for antenna antenna modification tomodification to provide 14 mprovide 14 m-1-1 directeddirected launch launch

Fast Wave Propagation Begins at Lower Density at Lower k||

B = 4.5kG

k

0

60

ne [x 1012 cm-3]0 5


• PDI instability observed at 4.5 kG, PDI should be weaker at higher PDI instability observed at 4.5 kG, PDI should be weaker at higher magnetic fieldmagnetic field

• Onset density for propagation of HHFW is approximatelyOnset density for propagation of HHFW is approximately proportional to magnetic field at a given kproportional to magnetic field at a given k|||| : :

- waves propagate further from plasma edge at higher field- waves propagate further from plasma edge at higher field

• Wave propagation into core faster with increased magnetic field:Wave propagation into core faster with increased magnetic field:- surface fields decrease with increasing magnetic field- surface fields decrease with increasing magnetic field

• In 2006 will measure HHFW power loss properties as function of magnetic In 2006 will measure HHFW power loss properties as function of magnetic field at constant q:field at constant q:

- New RF probes will detect waves propagating in periphery- New RF probes will detect waves propagating in periphery

- Important for projections to the higher field regime of - Important for projections to the higher field regime of ITER & ST CTF; even 5-10% loss significant with ~ 20 MW ITER & ST CTF; even 5-10% loss significant with ~ 20 MW

RF powerRF power

Higher Magnetic Field Should Yield Higher HHFW Heating Efficiency


• New antenna voltage New antenna voltage feedback feedback algorithm to reduce RF algorithm to reduce RF power power as voltage on antenna as voltage on antenna increases increases

This Year Early Solenoid-Free IThis Year Early Solenoid-Free IPP Ramp-up Ramp-up Experiments using HHFW Heating will Benefit from Experiments using HHFW Heating will Benefit from

Antenna Voltage FeedbackAntenna Voltage FeedbackIP = 300 kA, k|| = 7 m-1 co-CDIP = 250 kA, k|| = 14 m-1 heating

Time (s) 0.60

• Need to avoid RF tripping for Need to avoid RF tripping for 14 m 14 m-1-1 to get relaxation to get relaxation

• 14 m14 m-1-1 shows robust H-mode shows robust H-mode 7 m7 m-1-1 does not does not


• Magnetic field dependence of RF power loss, PDI ion Magnetic field dependence of RF power loss, PDI ion heating and surface wave propagation & dampingheating and surface wave propagation & damping

• If reversed BIf reversed Btt & I & Ipp campaign, will conduct HHFW campaign, will conduct HHFW experiment to elucidate coupling physics using experiment to elucidate coupling physics using reversed fieldsreversed fields

• Effect of Li on HHFW antenna couplingEffect of Li on HHFW antenna coupling

• Non-inductive current ramp up using HHFWNon-inductive current ramp up using HHFW

• Heat CHI discharges with HHFWHeat CHI discharges with HHFW

• Early HHFW heating to reduce volt-seconds consumption Early HHFW heating to reduce volt-seconds consumption in a long pulse dischargein a long pulse discharge

HHFW Experiments in 2006 Continue Exploring Coupling Physics & Application of HHFW to ST’s


HHFW Priorities for FY 2007-2008

• HHFW applications during current ramp-up phase of HHFW applications during current ramp-up phase of

discharge:discharge:

- Bridge gap between CHI initiation and NBI heating Bridge gap between CHI initiation and NBI heating to high performanceto high performance

• Improve understanding and performance of HHFW power Improve understanding and performance of HHFW power coupling to the core plasma:coupling to the core plasma:

- Modify antenna to provide directed spectra at 14 mModify antenna to provide directed spectra at 14 m--

1 1 for better CD efficiency (depending on results for better CD efficiency (depending on results from FY2006 studies) and for higher power operationfrom FY2006 studies) and for higher power operation

• HHFW system will support driven CAE mode studiesHHFW system will support driven CAE mode studies

• Use improved coupler for HHFW-CD applicationsUse improved coupler for HHFW-CD applications

1 ebw & hhfw research - g. taylor pac-19 2/23/06 ebw & hhfw research (including ebw...

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