Alcator C-ModProgram Overview

Presented to the C-ModProgram Advisory Committee

February 6, 2002

E. S. Marmar

Physicsand

TechnologyTransport Edge/Divertor RF MHD

IntegratedThrusts

Advanced TokamakBurning Plasma Support

NextStep(s)

High Bootstrap, High βNQuasi-Steady State

Advanced Tokamak Research

• Target scenario– High Bootstrap Fraction– High βN– Non-inductive current sustainment ττττ

>>>>>>>> ττττCR– All RF driven

• No particle or momentum sources– Ti ≈ Te

• Requirements– Confinement (control of edge + internal transport)– Impurity Control

• L-mode or EDA/ELMy H-Mode edge– Efficient ICRF heating– Density and density profile control– Efficient off-axis current drive– Rotation?

Advanced Tokamak Research Thrust

• Highest Priority Topics for next 8 Years– Current Profile Control via Lower Hybrid Current Drive, at

reactor relevant densities– Understanding, control and sustainment of Internal Transport

Barriers, with Ti ≈ Te and no momentum input– Extend pulse length to multiple current relaxation times with

fully non-inductive current drive– Increase β through profile optimization to MHD limit

• Phase I LHCD experiments begin in CY2003– 3 MW source @ 4.6 GHZ + 8 MW source ICRF

• Phase II LHCD (2005)– 4 MW source @ 4.6 GHz + 8 MW source ICRF

• requires second launcher, new 4-strap antenna

Burning Plasma Support Research Thrust

• High Priority Topics– H-Mode Pedestal Physics– Power and power handling at high plasma and power

densities– RF physics and technology (ICRF, Lower Hybrid) for

heating, current drive and plasma control• Builds on strong base of results and facility capabilities

– Progress highly constrained by limited resources and run-time

Develop and Validate Physics Basis for Tokamak Burning Plasma Experiments

Develop and Demonstrate Scenarios for BPX Optimization

20032002

Facility Mag Insp 2 MA/High δ

DivertorCryopumpInner Div Up

ICRF2 Dipole + 1 Quad Antenna, 8 MW

Diagnostics

Adv. Tok.

Eng Fab Install

n-control, power, long pulse

ITB Studies, Flow drive

3 MW LH Ops

2nd LH Launcher

Overview Schedule (February 2002)

)(Operations

RFX Beam CXRS, MSE, BES

Calendar Year 200620052004

2nd Quad Antenna

Long Pulse Beam

Edge Fluctuation ImagingHard X-Ray Imaging

Alcator C-Mod National Facility

RT Tuning: Proto; 3 additional

Alt Insp

Tang. HIREX

Add Horiz Ports

Longer Pulse

Outer Divertor Up

W Brush Proto

Burn PlasmaSupport

PCI Upgrade

Lower Hybrid4 MW

LHCD

Reflectometry Polarimetry

20082007

Double Null

5 sec Active stab?Active n-control, j-control

3 sec

Advanced Materials BP Proto Tests

fboot>0.7, βn=3

Inner-Wall limited2MA, 8T Dimensionless Scaling

I-rise opt NTM stabPower/Part Handling

Electron Scale Turbulence

Active MHD Ant.

FY2002 Plans

• 8 Week Campaign in 2002– Highest priority to:

• AT: ITB physics, density control issues, diagnostics• ICRF: Reliable high power heating, flow drive• Burning Plasma Support: High current, double null• Transport: Pedestal physics, ELMy/EDA regimes• Edge/Divertor: Edge turbulence and transport• MHD: NTM physics, pedestal stability

– Can only begin to address highest priority issues

Significant Increase in Facility Utilization Planned for FY2003

• Tremendous pressure building from deferred ideas and mini-proposals across all research areas– Approximately 120 run days for proposed experiments

already in the queue• 21 weeks of operation divided into 2 campaigns

– Fall campaign (~12 weeks)– Summer campaign (~9 weeks)

• First Lower Hybrid Current Drive experiments• Targeted upgrades and expanded diagnostic capabilities will

greatly enhance the productivity of operations in FY2003 and beyond

• Staffing increases required in scientific and engineering/technical areas

Science Goals: Advanced Tokamak

• Understand trigger mechanism for RF-generated ITBs in C-Mod (’03)

• Determine the influence of current profile on formation of, and energy and particle transport in,ITBs (’04)

• Evaluate MHD stability and transport in reversed shear discharges having high (~50%) bootstrap fraction (’04-’05)

• Understand and control core particle and energy transport so as to maintain MHD stable, steady-state barrier regimes (’06)

• Assess physical limits to bootstrap fraction in steady-state discharges (’06-’08)

Science Goals: Burning Plasma Support

• Assess ρ* scaling for FIRE, ITER-FEAT, Ignitor model discharges (same β, ν*, shape, configuration, etc) to testgyroBohm extrapolation hypothesis (’03-’04)

• Evaluate variation in divertor heat load, particle flux as function of SSEP, triangularity (’03)

• Quantify trade-offs between heat removal, particle and impurity control, and core confinement for dissipative/detached divertor (’04-’05)

• Based on considerations of pedestal/edge transport, MHDstability, RF coupling, identify optimized pedestal relaxation/control for core confinement, particle control, powerexhaust (’06)

• Test feedback stabilization of NTM in high performance H-Mode plasma with LHCD &/or MCCD (’07)

Science Goals: Transport

• Physics of H-Mode Pedestal Width (and Height)– Role of neutrals (’02-’03)– Plasma Physics details (’04-’07)

• Marginal stability — Quantitative understanding of non-linear physics setting ∇Ti near marginal stability (’03-’05)

• Characterize particle and impurity transport and make detailed comparisons with theory (’03-’06)

• ELM/EDA physics — Sufficient understanding of pedestal relaxation mechanisms to predict/control H-mode regime (’05-’06)

• Electron transport — Characterize small scale turbulence and its effect on electron transport (’05-’08)

• Rotation — Understand origin of rotation w/o direct momentum source (’06-’08)

Science/Technology Goals: Edge/Divertor

• Edge Turbulence and Transport– Identify underlying physics & compare with numerical

models• “Bursty” far SOL (’03)• SOL ne, Te profiles (’04)• Scaling of SOL transport, including density limit (’05-’08)

– Relationship between plasma flows & SOL turbulence (’04-’08)

– SOL plasma interactions with LH (’04)– Optimize SOL profiles for LHCD (’05-’08)

• Neutral Dynamics & Fueling– Main chamber recycling: understanding & control (’02-’03)– Active pumping control & optimization (’04-’08)

• Impurity Sources & Transport (ICRF ’02-’03, LH ’03-’06)• Advanced divertor materials technology

– Tungsten Brush (Tile ’03, Module ’05, Full prototype ’07-’08)

Science/Technology Goals: RF

• MCIBW poloidal flow drive — Evaluate and assess underlying physics (’03)

• Investigate and model D(3He) absorption physics (’03)• Evaluate coupling efficiency and power handling capability of

first lower hybrid antenna (’03-’04)• Evaluate and assess the underlying physics of coupling LH

waves at high density (’04)• Assess the interaction of MCIBW and LH waves (’05)• Evaluate symbiotic effects of launching LH waves with two

couplers (’05-’06)• Assess and model fast wave current drive below all cyclotron

frequencies (’05-’06)• Investigate current profile control with LHCD and compare with

theoretical predictions and models (’03-’06)

Science Goals: MHD

• NTM physics– Extend NTM stability database to unique non-dimensional

parameters; compare with/validate theoretical models (’04-’05)

– Evaluate current drive stabilization of NTM using eitherLHCD or MCCD (’05-’06)

• Macroscopic stability of AT profiles– Assess potential of active MHD spectroscopy to sense

proximity to instability (’04)– Evaluate evolution of AT plasma stability up to no-wall limit

as j(r) relaxes to “steady-state” (’05-’06)– Extend “steady-state” high fb operation above no-wall limit

using RWM feedback (’08)• Sawtooth Stabilization — Demonstrate 1/1 mode control using

RF (’05)

Status of 2001 PAC Recommendations

• New AT task force should be created …• AT Task Force created; Amanda Hubbard leads

– Issues identified, plans made for upcoming campaign

– Responsible for long-range planning and coordination

• RF tools• Diagnostics• Facility upgrades• Modeling

Research Priorities

• Program should hold internal review to assess research priorities

• Extensive internal discussions held during current shut down– Highest priorities agreed on for AT and Burning

Plasma Support thrusts• AT has higher overall priority

– Near-term run allocations reflect prioritizations– Upgrades consist with highest priority needs

• Process continuing as plans for the 5-year proposal are solidified and elaborated

Advanced Tokamak Theory

• … establish closer contact with the AT theory community• Strong Connections in RF areas

– LHCD (Dumont, Phillips, Harvey)– Lower Hybrid Scenario Development (Bernabei, Dumont)– MCCD, Flow Drive (Brambilla, D’Azevedo, Batchelor)

• Transport– TRANSP/Predictive Scenario Modeling (McCune, Phillips

and Redi)– GS2 (Redi and Ernst, Dorland)– Transport induced rotation (Chang, Chan, Perkins, White,

Coppi)– Critical gradient physics – IFS-PPPL, MM, GLF32

(Mikkelsen, Dorland)• Will continue outreach efforts

ICRF

• If present remedial actions are not sufficient …• Substantial improvement in antenna performance in 2001

campaign– Stripline arcing solved– One remaining place with high E || B (modifying)– Exposed BN-Metal interfaces being eliminated

• Major redesign to coax feeds not needed• Tests on current drive phasing not done (runtime)

– Scheduled for last week of FY2002 campaign– Continue in FY2003

• Continue Increasing the on-site RF technical staff– Hired senior RF engineer + post-doc

DNB and Associated Diagnostics

• A senior research staff member should be assigned oversight responsibility …

• Bob Granetz assigned DNB/Diagnostics oversight responsibility– Weekly meetings with all involved– Assessment from 2001 campaign

• Decision to replace beam• Repair MSE/BES optics• Purchase high throughput CXRS spectrograph

– Actively pursuing alternative diagnostic techniques• Pellets, tomography: new results in 2001• Faraday rotation polarimetry (under assessment)• Adding tangential ports for improved x-ray doppler profiles in

2002 (Ti, vφ)

X-Ray Tomography Promising as q Profile Diagnostic

Increasing Experimental Interactions with DIII-D

• Strong participation in C-Mod Ideas Forum– Ideas from Leonard, Mahdavi, Perkins (3), Whyte, Moyer (2),

La Haye– Covered a number of topical areas

• H-Mode Pedestal Physics; ELMs; Dimensionless Scaling (Burning Plasma Support); Advanced Tokamak (100% Bootstrap Fraction); MHD

• Very successful joint experiments on Edge Pedestal similarity; more to come

• Coordinated experiments on recycling/wall pumping• Phase Contrast Imaging (Porkolab/Rost)• Fluctuation physics (Texas collaborations)• Discussions on density limit experiments

Connections with other Experimental Groups

• JET– joint expts on edge turbulence and density limit– joint edge similarity studies– wall recycling studies, poloidal boundary flows– small ELM regimes, EDA H-Mode– Active MHD experiments– LHCD+ICRF experiments with ITB’s

• JT60-U– Wall recycling studies– Impurity source rate comparisons

• ASDEX-Upgrade: H-Mode pedestal and threshold comparisons• Tore-Supra: Imaging hard x-ray spectrometer diagnostic

collaboration• NSTX: Joint turbulence imaging studies• RFX: Joint experiments on DNB/Diagnostics

International Participation Through ITPA

• C-Mod team members are very active in the ITPA• 10 physicists distributed across 6 topics

– Rice, Fiore, Hubbard, C.K. Phillips, Nazikian,Bonoli, Granetz, Snipes, Mikkelsen, Lipschultz

• Excellent forum for exchanges to, and connections with, all the major tokamak programs in the world

Extensive Theory and Modeling Collaborations

• Transport,Turbulence and MHD– Xu and Nevins: EDA H-mode QCM– Carreras, Antar, : SOL turbulence analysis– Hallatschek and Rogers: theory and modeling– Redi and Ernst: GS2 microturbulence modeling– Bateman and Kritz: Baldur transport simulations– McCune, Phillips and Redi: TRANSP analysis (esp. ITB)– Mikkelsen and Dorland: Critical Gradient – Non-linear Stability (ifs-pppl,

mm, glf23)– Chang, Chan, Coppi, Perkins, White: Transport and RF induced rotation– Snyder and Wilson: Edge MHD phenomena

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

Strong RF Theory and Modeling Collaborations

• ICRF– Jaeger, Myra and D’Ippolito: ICRF Flow Drive– Brambilla, D’Azevedo and Batchelor: Fast wave and Bernstein

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

minority heating simulations• Lower Hybrid

– Dumont and C.K. Phillips: 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

C-Mod is a Major Player in theNational Fusion Collaboratory

• Goal is to lower technical barriers to collaboration– access to: data, physics codes, post-processing

tools, visualization• MIT participates along with GA, PPPL, and computer

scientists from LBNL, ANL, U. Utah, Princeton U.• Funded through DoE Office of Advanced Scientific

Computing Research (SciDAC program)

Budget Increment in FY2003 Presents Excellent Opportunities

0

5

10

15

20

25

Fiscal Year1999 2000 2001 2002 2003

Budg

et (2

002

M$)

C-Mod National Budget (Inflation Adjusted)

17,57417,954Grand Total

17,37017,749Alcator Project Total

9595LANL Research

925925U. Tx. FRC Total

5858Equipment

200200Operations

668668Research

2,3002,355PPPL Total

0468Equipment

500501Lower Hybrid

230149Operations

1,5701,237Research

14,25414,579Co-op Agreement Total

149150MDSplus

5555JET Collaborations

14,05014,374MIT C-Mod Total

7101,347Lower Hybrid

8,2018,291Operations

5,1394,736Research

FY02FY01

MIT

PPPL

UTx

C-Mod National Budgets

FY03 Presidential

(Feb 4, 2002)

Research 8,500

Operations 13,800

_______________

Total 22,300

C-Mod Will Make Major Contributions to the Fusion Sciences Program

• Broad and strong science program, focussed technology developments in support of the major thrusts

• With current funding, concentrate on Advanced Tokamak Thrust and supporting science and technology– Important tools being developed

• LHCD begins in 2003• Diagnostics & Facility upgrades being implemented• Goal: fully relaxed non-inductive current, with high fboot and βN

in next 5 year grant period (2004-2008)• Burning Plasma Support thrust has had lower priority: selected

contributions• All aspects of the program will be greatly strengthened by

increased funding (FY03 and beyond)– Diagnostics and facility upgrades will be phased in sooner– Exciting experiments presently deferred for lack of run time

• Expanded opportunities in all areas; especially so for Burning Plasma Support thrust