CMPD March 2005

The Center for Multiscale Plasma DynamicsThe Center for Multiscale Plasma Dynamics

MarylandMarylandUCLAUCLA

PrincetonPrincetonMITMITTexasTexasDartmouthDartmouthBerkeleyBerkeleyMichiganMichiganGeneral AtomicsGeneral Atomics

CMPD

The Broad ContextThe Broad Context

• DOE announced a national competition for two Fusion Science Centers in DOE announced a national competition for two Fusion Science Centers in 2004. There were a dozen or so serious contenders.2004. There were a dozen or so serious contenders.

• We proposed to work on plasma physics problems for which the evolution We proposed to work on plasma physics problems for which the evolution of dynamics on disparate spatio-temporal scales is tightly coupledof dynamics on disparate spatio-temporal scales is tightly coupled

• We know how to derive first-principles models for some critical aspects (turbulence, reconnection) of We know how to derive first-principles models for some critical aspects (turbulence, reconnection) of various problems -- but how can we get at the big picture (transport, system evolution)?various problems -- but how can we get at the big picture (transport, system evolution)?

• What do experiments tell us we need to know? And how do we come to understand experimental data?What do experiments tell us we need to know? And how do we come to understand experimental data?

• Maryland and UCLA won this compeition, with funding from 2004-2009 Maryland and UCLA won this compeition, with funding from 2004-2009 and the possibility of a five-year extension. Total 5-year funding is and the possibility of a five-year extension. Total 5-year funding is approximately $7.5 million. approximately $7.5 million.

March 2005

CMPD

Why a Center for Multiscale Plasma Dynamics?Why a Center for Multiscale Plasma Dynamics?

• The development of multiscale techniques in plasma physics has been inhibited by The development of multiscale techniques in plasma physics has been inhibited by the traditional programmatic boundaries between macro- and micro-scale physicsthe traditional programmatic boundaries between macro- and micro-scale physics

• The Center brings together three key elements:The Center brings together three key elements:

– Applied mathematicsApplied mathematics• Powerful new techniques are revolutionizing the approach to multiscale problemsPowerful new techniques are revolutionizing the approach to multiscale problems

– Traditional adaptive mesh refinement techniques cannot address the huge separation in Traditional adaptive mesh refinement techniques cannot address the huge separation in time scales and the range of physics phenomenatime scales and the range of physics phenomena

– Need new ideas, like equation-free projective integration and patch dynamicsNeed new ideas, like equation-free projective integration and patch dynamics

– Computation/theoryComputation/theory• Members of Center played a central role in developing the current physics Members of Center played a central role in developing the current physics

understanding of microturbulence and reconnectionunderstanding of microturbulence and reconnection

• Tactical advantage: we can build on these tools and theoretical insightsTactical advantage: we can build on these tools and theoretical insights

– ExperimentExperiment• Experimental observations motivate and guide development of physics modelsExperimental observations motivate and guide development of physics models

• Benchmarking is crucial to ensure that dominant physical processes are includedBenchmarking is crucial to ensure that dominant physical processes are included– Basic experiments in simple geometries - LAPD, VTF, LDXBasic experiments in simple geometries - LAPD, VTF, LDX

– Complex experiments in the most advanced fusion facilities - DIII-D, NSTX, JET, C-ModComplex experiments in the most advanced fusion facilities - DIII-D, NSTX, JET, C-Mod

March 2005

CMPD

Annulus, Islands and TurbulenceAnnulus, Islands and TurbulenceMultiscale for NTMs and SawteethMultiscale for NTMs and Sawteeth

Space Scales.Island size > 1cmTurbulent Eddy size ~ 1cmElectron Layer ~ 0.025cmBanana width ~ 1cmEigenfunction width ~ 1m

Timescales - NTM Turbulent correlation time ~ 10sTransport relaxation timeacross island region ~ 1msIsland rotation times ~1msIsland growth time >1s

Critical Kinetic Physics Bootstrap currentTurbulent vs parallel transport

March 2005

CMPD

The Transport ProblemThe Transport Problem

• Self-consistent modeling of fusion plasma evolutionSelf-consistent modeling of fusion plasma evolution– Small scale turbulence (structures << device size)Small scale turbulence (structures << device size)– Stiff, offset-nonlinear transport fluxes well-establishedStiff, offset-nonlinear transport fluxes well-established– Self-consistent heating in next-generation machines leads to strongly Self-consistent heating in next-generation machines leads to strongly

coupled system; small scale dynamics determines system evolutioncoupled system; small scale dynamics determines system evolution• Brute force calculations require > 10,000 petaflops (SCALES report)Brute force calculations require > 10,000 petaflops (SCALES report)

These structures are ~ 1 ion gyroradius across, compared to a machine size of more than 1000 ion gyroradii

March 2005

CMPD

Transport: A multiscale challengeTransport: A multiscale challenge

• Use patch dynamics scheme of Kevrekidis Use patch dynamics scheme of Kevrekidis and Gearand Gear

– Use a few thin annular domains (flux tubes)Use a few thin annular domains (flux tubes)• Compute fully nonlinear microscale Compute fully nonlinear microscale

dynamics in this regiondynamics in this region

– Evolve coupled flux tubes on transport time Evolve coupled flux tubes on transport time scalescale

• Requires finding gradient as a function of Requires finding gradient as a function of flux (done)flux (done)

March 2005

CMPD

The Sawtooth Crash ProblemThe Sawtooth Crash Problem

• Periodic instability of the core of tokamak plasmasPeriodic instability of the core of tokamak plasmas– Loss of central plasma confinementLoss of central plasma confinement– Times scales of 50-100 Times scales of 50-100 sec are much shorter than the resistive MHD sec are much shorter than the resistive MHD

theorytheory– Central value of Central value of qq remains below unity implying incomplete reconnection remains below unity implying incomplete reconnection

of the core magnetic fieldof the core magnetic field• But core energy is expelled without reconnection. Why?But core energy is expelled without reconnection. Why?• Not seen in MHD modelNot seen in MHD model

Yamada, et al., 1992

March 2005

CMPD

Sawtooth: A multiscale challengeSawtooth: A multiscale challenge• Critical non-MHD physicsCritical non-MHD physics

– Fast crashFast crash• Coupling to dispersive kinetic Alfven wavesCoupling to dispersive kinetic Alfven waves• Anomalous resistivityAnomalous resistivity

– Partial reconnectionPartial reconnection• Development of kinetic turbulence in steep Development of kinetic turbulence in steep

gradients around x-linegradients around x-line• Propagation of turbulent front into corePropagation of turbulent front into core

– Production of energetic particlesProduction of energetic particles

March 2005

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EducationEducation

• > 70% of center money is to be spent on new talent> 70% of center money is to be spent on new talent

• Gap in training at the advanced student/post-doc levelGap in training at the advanced student/post-doc level

• Winter school on advanced plasma theory every year Winter school on advanced plasma theory every year

(2005 in conjunction with the IPAM workshop) (2005 in conjunction with the IPAM workshop) – Include the worldwide communityInclude the worldwide community

– Gyrokinetics, turbulence, HED plasma theory, etc. Gyrokinetics, turbulence, HED plasma theory, etc.

– An event where the next generation of plasma and fusion scientists An event where the next generation of plasma and fusion scientists meet and interactmeet and interact

• Develop an advanced curriculumDevelop an advanced curriculum– video conference lectures and seminarsvideo conference lectures and seminars

– review articles and booksreview articles and books

Aim: To attract and train a new cadre of plasma physicistsAim: To attract and train a new cadre of plasma physicists

March 2005

CMPD

Effort SummaryEffort Summary (budget includes 15% matching)(budget includes 15% matching)

Year 1Year 1 Year 2Year 2 Year 3Year 3 Year 4Year 4 Year 5Year 5

Educational Educational activitiesactivities

Winter Winter schoolschool

Winter Winter schoolschool

Winter Winter schoolschool

Winter Winter schoolschool

Winter Winter schoolschool

Senior Senior (faculty)(faculty)

1.91.9 2.32.3 1.91.9 1.71.7 1.7 1.7

PostdocsPostdocs 66 66 77 66 66

Grad Grad studentsstudents

44 55 66 66 66

CostCost $1,324 k$1,324 k $1,466 k$1,466 k $1,609 k$1,609 k $1,472 k$1,472 k $1,487 k$1,487 k

Ambitious center scientific program leverages existing efforts

March 2005

CMPD

Budget overviewBudget overview (includes 15% matching)(includes 15% matching)

Year 1Year 1 Year 2Year 2 Year 3Year 3 Year 4Year 4 Year 5Year 5 TotalTotal

UMDUMD $575 K$575 K3p 2g 1f3p 2g 1f

$575 K$575 K3p 2g 1f3p 2g 1f

$575 K$575 K3p 2g 1f3p 2g 1f

$575 K$575 K3p 2g 1f3p 2g 1f

$575 K$575 K3p 2g 1f3p 2g 1f

$2,875K$2,875K

UCLAUCLA $490 K$490 K2p 1g 0.5f2p 1g 0.5f

$529 K$529 K2p 2g 0.5f2p 2g 0.5f

$669 K $669 K 3p 2g 0.5f3p 2g 0.5f

$680 K$680 K3p 2g 0.5f3p 2g 0.5f

$692 K$692 K3p 2g 0.5f3p 2g 0.5f

$3,062K$3,062KWinter sch.Winter sch.

PrincetonPrinceton $114K$114K1p 0.1f1p 0.1f

$115K$115K1p 0.1f1p 0.1f

$115K$115K1g 0.1f1g 0.1f

$115K$115K1g 0.1f1g 0.1f

$115K$115K1g 0.1f1g 0.1f

$577K$577K

MichMich $75K$75K0.3f0.3f

$175K$175K0.7f0.7f

$175K$175K1p 0.2f1p 0.2f

$25K$25K0.1f0.1f

$25K$25K0.1f0.1f

$475K$475K

MITMIT $70K$70K1g1g

$72K$72K1g1g

$75K$75K1g1g

$77K$77K1g1g

$80K$80K1g1g

$376K$376K

March 2005