Program Overview (2003-2008)

Program Advisory Committee MeetingFebruary 20, 2003

presented by E. S. Marmaron behalf of the C-Mod Group

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Physicsand

TechnologyTransport Edge/Divertor RF MHD

IntegratedThrusts

Advanced Tokamak Burning Plasma Support

NextStep(s)

High Bootstrap, High βNQuasi-Steady State High Field, High Pressure

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C ModAlcator

−Unique Capabilities

⇒ Address Key Questions

• Unique long pulse capability (relative to skin and L/R times)• highly shaped, diverted, high pressure plasma

• 5 second pulse length at B = 5 T→ Quasi-steady lower hybrid driven AT scenarios

• fully relaxed current profiles• High performance, compact, high field capability

→Next Step Burning Plasma issues• Tight e-i coupled regimes• H-mode threshold• Pedestal regulation• Reactor-like normalized neutral mean free path (λ0/a)• Prototypical disruption forces• Reactor level pressure (disruption mitigation)

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Unique Capabilities⇒ Address Key Questions

• Exclusively RF driven– Heating decoupled from particle sources (most like α-

heating)– No external momentum sources; strong rotation in H-

Mode→Reactor-relevant regimes for Transport, MHD, AT studies

• Unique dimensional parameters; comparable to larger tokamaks in dimensionless plasma parameters– Key points on scaling curves – Test sensitivities to non-similar processes (radiation,

neutrals, etc.)• Very high scrape-off layer power density (>0.5 GW/m2);

Metal plasma-facing materials– Unique divertor regimes, ITER and reactor prototypical– Unique recycling properties

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−Program Contributes to all 4 IPPA MFE Goals

Emphasis on Goals 1 and 3

• Long Pulse AT– IPPA 3.1 steady state; 3.2 high performance

• Compact, High Field– 3.2 high performance; 3.3 burning plasma

• RF Driven– 1.3 wave-particle interactions; 4.1 plasma technologies; 1.1

turbulence and transport; 1.2 macroscopic stability; 3.3 burningplasma

• Unique Dimensional parameters– 1.1 turbulence and transport; 1.4 multiphase interfaces; 3.3

burning plasma; 1.2 macroscopic stability• Very High Boundary Power Density, Long Pulse

– 1.4 multiphase interfaces• Advanced Materials

– 4.1 plasma technologies; 1.4 multiphase interfaces

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Collaborations are Significant in all Aspects of the Program

Domestic Institutions

Princeton Plasma Physics LabU. Texas, AustinU. AlaskaUCSDColorado School of MinesDartmouth U.GAU. IdahoLLNLLehigh U.LodestarLANLU. MarylandNotre Dame U.ORNLSNLAU. WashingtonU. Wisconsin

International Institutions

Budker Institute, NovosibirskC.E.A. CadaracheChalmers U., SwedenC.R.P.P. LausanneCulham LabEcole Royale Militaire, BrusselsIGI PaduaIPP GreifswaldIPP GarchingJET/EFDAJT60-U/JAERIKeldysh InstituteKFA JülichLHD/NIFSPolitecnico di TorinoU. TorontoHebrew U.

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−C-Mod has Prominent Role in Education

• Typically have ~20 graduate students doing their Ph.D. research on C-Mod– Nuclear Engineering, Physics and EECS– Collaborators also have students working at the

facility• MIT undergraduates participate through UROP

program (~5 at any time)• Host National Undergraduate Fusion Fellows every

summer (4 in 2002)

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−Advanced Tokamak Research Thrust

• Goals– Current Profile Control via Lower

Hybrid Current Drive, at reactor relevant densities

• Extend pulse length to multiple current relaxation times, ~τL/R with fully non-inductive current drive (LHCD + Bootstrap)

– Understanding, control and sustainment of Internal Transport Barriers, with τei<<τEand no momentum input

– Attain and optimize no-wall βlimits (βN≥3); explore means to achieve higher values

Pulse-length allows full current relaxation

Integrated target: βN=3, H89≈2.5, noninductive, fbs>.7, I=0.85 MA, t=τL/R

C-Mod(5s)

JET(50s)DIII-D(10s)

AUG(10s)

ITER(1000s)

Pul

se le

ngth

/rel

axat

ion

time

Major Radius (m)0 1 2 3 4 5 6 7

10.0

1.0

0.1

Relaxation Times:

L/R TimeSlowest Eigenmode

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−Advanced Tokamak Research

• Requirements– Efficient off-axis current drive

(r/a ≥≥≥≥ 0.7)– Confinement (control of edge +

internal transport)– Impurity Control

• L-mode or EDA/ELMy H-Mode edge

• High heat-flux divertor– Efficient heating (ICRF + LH)– Density and density profile

control• Active pumping, RF control

ACCOME scenario: Fully non-inductive, 70% bootstrap fraction, H89P

≈ 2.5Ip = 0.86 MA Ilh = 0.24 MA fbs = 0.7

j (M

A/m

2), q

(r)

r/a

Tot

BS LH

q

seed

PLH = 3 MW

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−Burning Plasma Support Thrust Objectives

• Identify, characterize and understand optimized Edge Relaxation Mechanisms (ELMs, EDA)

• High power operation with acceptable divertor heat loads, steady-state density; understand extrapolations to BPX

• RF core heating in BPX relevant scenarios (D(3He), LH)• Control of Neoclassical Tearing Modes with localized RF

current drive (LHCD + MCCD)• Develop, test, model High Performance scenarios• Develop, model Disruption Mitigation technique(s)

Integrated Target: B=8T, I=2MA, P≥6MW, H89 ≥2, Zeff<1.5

Goals:

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−Dimensionless Similarity Scaling to Next Steps

Example matching β and νi/ω*e for ρ* scaling of NTM physics

2.44.34.81ρ* factor

1345.7100P (MW)

.74.247.0753.22ττττ89 (s)

.80.236.0673.5τH (s)

6.73.74.817T (keV)0.540.420.330.85n/ng

0.820.733.51n (1020 m-3)3.91.61.615I (MA)

0.910.540.222.0a (m)32.15.35.3B0 (T)

JETDIII-DC-ModITER-FEAT

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−Science Goals: Transport

• Marginal stability & turbulence– Quantitative understanding of non-linear

physics setting ∇ Ti near marginal stability– Origin and role of Zonal/GAM flows

• Momentum transport– Self-generated flows– RF flow drive

• Particle transport– Characterize, detailed comparisons with

theory– Correlation with fluctuations

• Electron transport (τei<< τE)– Small scale turbulence and effects on

electron channel• Transport barriers (core & edge)

– Understand threshold or trigger conditions– Understanding & predictive capability for

H-mode pedestal (including relaxation)

BOUT Simulations may Identify EDA QC mode

Xu & Nevins, LLNL

-10 0 10 20-20k (1/cm)θ

8

6

4

2

10

0QC mode

Drift Alfven mode

Freq

uenc

y (M

Hz)

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Science/Technology Goals: Edge/Divertor

• Edge Turbulence and Transport– Expand turbulence measurements: locations,

(’03-’07)– Improve poloidal characterization of radial ion fluxes

(’03-06)– Understand relationship between turbulence and

macroscopic profiles (’04-’08)• Neutral Dynamics & Fueling

– Wall recycling, Neutral flows, Co-deposition (’03-’06)• Impurity Sources & Transport

– Improved diagnosis of sources and ion fluxes– RF induced impurity effects (ICRF ’03, +LH ’03-06)

• Power & Particle Control– Expanded IR measurements (’04)– Tungsten brush (Tiles ’03, Module ’05, BPX

prototype ’07-’08)– Mitigation: detachment, strike point sweeping (’03-

’08)– Active pumping (’04-’08)

t=0-4µs t=4-8µs

t=8-12µs t=12-16µs

t=16-20µs t=20-24µs

Edge of Hot Confined Plasma

2 cm

Ultra-fast Imaging of Edge Fluctuations��n, T

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−Science/Technology Goals: RF

• ICRF– Load-tolerant 4-strap antenna (10 MW/m2, fast-

matching)– Predictive capability for near-field antenna-wave-

plasma interactions– D(3He) absorption physics at 8T– Mode-Conversion poloidal flow drive– Mode-Conversion current drive– Fast wave e-heating & current drive ω<ωci

• Lower Hybrid RF– Coupling efficiency and power handling– Fast electron generation and impurity dynamics– LHCD current profile control; compare with

theoretical predictions– Symbiotic effects with two couplers: compound

spectrum• ICRF-LHRF synergies

– Interaction of mode converted waves with LH deposition location

R - R0 (cm)

Z (cm

)

-6 -4 -2 0 2 4 6-15

-10

-5

0

5

10

15

TORIC simulations of Mode Conversion to ICW; seen experimentally with PCI

LHCD Coupler

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−Science Goals: MHD

• Disruption studies– Extend to 2 MA, 8 T; improved

halo/eddy/strain diagnostics– High pressure gas-jet mitigation– Locked-modes; control coils

• MHD at high β, AT profiles– Study stability near no-wall limit– Stabilization of NTM: profile mod./sawtooth

stab.– Active MHD feedback– Assess potential for “steady-state” high fb

operation above no-wall limit using RWM feedback; Implement if feasible

• Pedestal stability– effects of higher δ– Understanding ELM regimes: comparisons

with theory/simulation– Compare single/double null

B~

Active MHD Coils

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• LHCD experiments begin in CY2003– 3 MW source @ 4.6 GHZ + 8 MW source ICRF (03)– 4 MW source @ 4.6 GHz + 8 MW source ICRF (05)

• Add second LH launcher, new 4-strap ICRF antenna (05)• New facility and diagnostic upgrades (partial list)

– Locked-mode coils; Cryopump (ne control); Divertor upgrades (advanced materials); Real-time antenna matching; Long-pulse DNB; New ports; High-P Gas Puff (disruption mitigation); Active wall (RWM)

– Thomson upgrades (SOL, spatial res.); Hard X-ray, non-thermal ECE (LHCD); Reflect. upgrades (higher ne); Polarimetry (j(r)); MSE & CXRS upgrades; PCI upgrades (spatial coverage, ρe scale); Scattering diag (long & short λ fluct.); Ultra-fast Imaging ( ); Erosion/deposition divertor diagnostics

• Full utilization of the facility (25 weeks/year operation)

New Tools enable New Discoveries

��n, T

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IPPA Goal 1: Advance fundamental understanding and enhance predictive capability through comparison of well-diagnosed experiments, theory and simulation.

Theory/Modeling accomplished mainly through collaborations• ICRF

– Jaeger, Myra and D’Ippolito: ICRF Flow Drive– Brambilla, D’Azevedo, Batchelor and J. Wright: Fast wave and

Bernstein waves in toroidal geometry– McCune, C.K. Phillips, Brambilla and J. Wright: Full-wave/Fokker

Planck minority heating simulations– R. Maggiora (Torino): TOPICA modeling of antenna-plasma system

• Lower Hybrid– Dumont, C.K. Phillips and J. Wright: 1D full wave simulations– Peysson, Bers: Fokker Planck LHCD efficiency and distribution

functions– Harvey: 2D LHCD Fokker Planck simulations– Bernabei and Dumont: Scenario development– Bernabei: Launcher design and coupling simulations– McCune and C.K. Phillips: Integration of ACCOME into TRANSP

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−Theory and Modeling Collaborations

• Transport,Turbulence and MHD– Xu and Nevins: EDA H-mode QCM, Edge fluctuations– Ramos, Snyder and Wilson: Edge MHD phenomena– Carreras, Antar, : SOL turbulence analysis– Hallatschek and Rogers: Theory and modeling– Diamond: Theory– Mikkelsen and Dorland: Critical gradient – Non-linear stability– Redi, Ernst and Dorland: GS2 microturbulence modeling– Bateman and Kritz: Baldur transport simulations– McCune, C.K. Phillips: TRANSP– Chang, Chan, Coppi, Perkins, White: Transport, RF induced rotation

• Impurity and Particle Dynamics– Stangeby, Lisgo, Elder: OSM-Eirene neutral modeling– Stotler: DEGAS II neutral transport– Pigarov and Krasheninnikov: Edge atomic processes– Scott and Wan: Radiation transfer

20032002

Cryopump/Up. Div.Inner Div Up

Adv. Tok.n-control, power, long pulse

ITB Studies

Overview Schedule (February 2003)

)(Operations

RFX Beam CXRS, MSE, BES

Calendar Year 200620052004

Long Pulse Beam

Edge Fluctuation ImagingHard X-Ray Imaging

Alcator C-Mod

Tang. HIREX Add Horiz Ports

Outer Divertor Up

W Brush Proto

Burn PlasmaSupport

PCI Upgrade

LHCD

Reflectometry Up. Polarimetry

20082007

Double Null

5 sec Active StabActive n-control, j-control

3 sec

Advanced Materials BP Prototype

fboot ≥ 0.7, βn=3, H89~2.5

Inner-Wall limited2MA, 8T Dimensionless Scaling

I-rise opt Sawtooth/NTM stabPower/Part Handling

Active MHD Ant.

Facility

3 MW LH 2nd Launcher, 4 MW LH8 MW ICRF, 3 Antennas 2nd Quad ICRF Antenna

Ultra-fast CCD Camera

Thomson Up. MSE Up. ECE Up.

Active Wall

Transport

Edge/Divertor

RF

MHD RWM2MA DisruptionsPed. Stab. NTM

MCICW/MCIBW/MCCD Load-Tol Ant. ω < ωci ICCD

LH Propagation LHCD Compound Spect LH/IC Synergies

IWS Probe

6MW, H89 ≥ 2, Zeff ≤ 1.5

Te, ne Fluct. Inner SOL Fluct. Impurity Sources & Transp.

Neutral Physics Pumping/Particle Control Power Handling

Transient Transp. Shear/Flows Self Org. Crit. Zonal/GAM flows Momentum Transp. Reynold's StressElectron Transp.Barrier Physics

Flow Drive

Locked-Modes

PCI 2nd View

Real-time matching 8 MW Tunable

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−Budget Profiles

22,569

96

427

1,934

20,112

FY04

28,78729,45028,61027,48025,250National Project Total

137130125120110LANL

630610585560540U Texas

2,9202,8102,7002,6002,500PPPL

25,10025,90025,20024,20022,100MIT

FY08FY07FY06FY05FY04Institution

Guidance 5 Year Proposal

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−Status of PAC 2002 Recommendations

• Efforts should be made to have a more permanent PPPL presence at C-Mod– Steve Scott joined the collaboration this year

• On-site full time at MIT• Integrated AT modeling: we encourage you to enter discussions with

the CALTRANS and TRANSPp predictive code development and application efforts– Liptac, Tang, Parker, Bonoli using TRANSP in predictive mode; 2

APS papers• Coordinated experiments: work with international community to

identify common phenomena and establish common physics principles– Expanded edge and core dimensionless identity experiments

with ASDEX-U, JET and DIII-D– Detailed coordinated experiments with DIII-D/JET on edge

particle transport

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−PAC 2002 Recommendations (cont’d)

• Ideas forum: We strongly recommend continuing the ideas forum annually– Because of limited run time in 2002, plan to hold

next ideas forum in summer, 2003– Before first operations with Lower Hybrid

• Goals and metrics: by sharpening your descriptions of research goals and identifying clear metrics, program planning can be more useful– Have explicit goals and intermediate objectives in

each of the thrust and science areas in the 5 year proposal

C-MOD FIVE YEAR PROPOSAL

Table 3.1: AT Goals

Goal Intermediate Objectives Date

Demonstrate, anddevelop predictivemodels for fullnon-inductive currentdrive using LH andICRF waves, in a highdensity regime(> 1020m−3) for pulselengths long comparedto current relaxationtimes

Produce some optimized target plasmas for LH studies 2003Commission LHCD Phase I and measure coupling,power handling properties

2004

Measure profile of fast electrons with x-ray camera 2004Measure CD efficiency and localization in L-mode, H-mode and ITB regimes, and determine upper densitylimit for effective use.

2005

Demonstrate 50% current drive, possibly at reduceddensity, for 3 second pulses

2005

Compare to ACOME, CQL3D and full wave models 2004-06.Commission LHCD Phase II and assess CD localiza-tion with multiple N‖ spectrum

2006

Maximize and document LH driven current as a func-tion of target density profile

2006

Combine LHCD with bootstrap current produced byITBs, optimizing to maximize total non-inductive CD

2006-08

Extend pulse length to five seconds 2007-08Produce, understandand control coretransport barriers inLH and ICRF drivenregimes with stronglycoupled electrons andions

Measure core χ, D with off and on axis ICRH, over arange of Ip, BT and ne

2003

Conduct gyrokinetic simulations of several cases, com-pare with experiment.

2003-04

Assess influence of reduced or reversed shear (pro-duced by LH) on ITB formation, location

2005

Test whether barriers form spontaneously with re-versed shear, with on-axis ICRH. Compare χi, χe andD and assess impurity accumulation

2006

Optimize profiles and transport for steady state, withmaximum off-axis bootstrap current (target 70%).

2007-08

Attain and optimizeno-wall β limits, withβN of at least three,and explore means ofachieving higher values

Use ICRH power to increase β in inductive discharges,and measure MHD growth rates using active MHDantennas.

2003-04

Compare observed growth rates with stability codes 2004Explore MHD properties of reversed shear discharges 2005Use control of current and pressure profile to optimizeno- wall beta limits, guided by modelling

2006-07

Conduct feasibility and design studies of conformalwall and active MHD coils

2004-05

If studies show feasibility, and if warranted by demon-strated high β, fabricate and install MHD controlhardware. Full exploitation would likely extend tonext five-year period.

2006-08

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−PAC 2002 Recommendations (cont’d)

• DNB: group must develop plans for a permanent DNB this year– Excellent progress on

diagnostics with RFX beam

– Have quote from Budker for 1.5 second beam, 55 kV, 8 Amp ion current, 6 cm FW@1/e ($600k)

14 month delivery; need to commit very soon to have beam in time to replace RFX beam (returning to Padua spring 2004).

Beam On Beam Off

Fre

quen

cy (

kHz)

0.70 0.72 0.74 0.76 0.78 0.800

100

200

300

400

Time (s)

BES Detection of QCM in EDA H-Mode

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−PAC 2002 Recommendations (cont’d)

• continue to evaluate metal-wall issues, especially issues like hydrogenic gas retention– Quartz Microbalance, Elastic Recoil, Rutherford

Backscattering in plans (new collab with D. Whyte)• Theory coordination: consider identifying an individual to

help facilitate experiment-theory collaborations– Not done: believe that our approach based on person-to-

person contacts is working well– addition of John Wright and Darin Ernst to MIT theory has

significantly increased local experiment/theory interactions

• special encouragement should be given to MPs that include clear connections to theory/computation– MPs meeting the criterion received 21 of 57 run days in

2002

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MPs with strong connections to theory/computations (2002)

• Formation and Decay of Ohmic H-mode ITB – 2 run days• ITB - Access Conditions and Hysteresis – 1 run day• Density Limits, Transport and Turbulence – 2 run days• High Bootstrap Fraction Regimes - Based on bootstrap simulations (TRANSP) – 1

run day• Spatial Dependence of Edge Turbulence Statistics - Connection to SOC models – 1

run day• Ohmic H-modes - Test of models of rotation w/o momentum sources, momentum

diffusion – 3 run days• Instrumented Divertor Leakage Experiments – test, benchmarking of divertor neutral

transport simulations – 1 run day• Evaluate Btor-sweep method of measuring ∇ T scale length – development of

experimental technique in suppport of theoretical simulations/analysis – 2 run days• ITB Study with Expanded Diagnostic Set – provide improved profiles, including

rotation, for input into TRANSP and GS2 – 3 run days• Experimental/Theoretical Comparisons of SOL Turbulence – 1 run day• ITB Formation with 2-Freq. ICRF in Optimized Shear Plasmas with Ip Ramp –

significant data for transport modelers (GS 2, TRANSP, etc.) – 3 run days• Develop low ne EDA H-mode targets for LHCD - Experiment based on ACCOME

simulations; provide important data for AT modelling – 1 run day

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−LHCD Diagnostics

• current drive diagnostics needed to quantify performance:

• j(r)– initial MSE results encouraging; strong

collaboration with PPPL– Polarimeter/interferometer in plan (initial

feasibility tests in 2002 successful)• Rotation profiles

– Added tangential views for soft x-ray doppler

– CXRS under evaluation; improved beam in plan

• Fast electrons– Hard X-Ray imaging spectrograph under

construction– Non-thermal ECE in plan

.70 .75 .80 .85 .900

2

4

6

10

8

q

Major Radius (m)

Unconstrained EFITMSE Constrained

q Profile using MSE

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−Five-Year Renewal Recommendations

• highlight those research areas where C-Mod will make unique contributions; articulate clearly why they are so important for progress in our field– Chapter 2 of proposal devoted to these issues; thrust and

science chapters address this for each topic• AT target should incorporate enhanced confinement produced by

inducement of transport barriers– AT target can only be reached with enhanced confinement– Explicitly added H89P≈2.5 into the target

• include tests of MCCD for AT scenarios, development of AT scenarios that challenge the “reactor” divertor problem, examinemetal-wall solutions, highlight and explain the importance of transport studies in discharges without particle and momentum sources– All are in the proposal

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C-Mod is Positioned to Make Major Contributions to the Fusion Sciences Program

• Broad and strong science program, focused technology developments

• Diagnostics & Facility upgrades being implemented• Advanced Tokamak

– Current profile control experiments begin in 2003– Integrated Goal: fully relaxed non-inductive current,

with high fboot, βN, and confinement.• Burning Plasma Support

– Study regimes prototypical of next steps– Integrated Goal: High performance plasmas, Ip ≥≥≥≥ 2MA,

Pin ≥≥≥≥ 6 MW, H89 ≥≥≥≥ 2, Zeff ≤≤≤≤ 1.5, ⟨⟨⟨⟨P⟩⟩⟩⟩v ≈ 4 Atm.