Conveners - E. Synakowski (PPPL), R. Waltz (GA)
P4 Sections of Snowmass Report
- P4 introduction (PDF file)
- Flexibility and Transport (PDF file)
Snowmass Appendix documents and vugraphs contributing to the P4 Snowmass Report
- Waltz performance (PDF file)
- Synder pedestal stability (PDF file)
- Hubbard magnetic configurations and pedestals (PDF file)
- Staebler density peaking and rotation (PDF file)
- Bateman performance (PDF file)
- Waltz "Pedestals & Confinement vugraphs (PDF file)
- Cordey pedestal vugraphs (PDF file)
- Waltz H vs L vugraph (PDF file)
- Waltz F,Q,H performance sensitivity vugraph (PDF file)
- HammettFIRE-confinemnt (PDF file)
- Romanelli.FTU (PDF file)
- Perkins y2 and gyroBohm scaling (PDF file)
Charter
The primary goal of the Transport Group (P4) is to provide
a uniform assessment of the confinement performance (projected Q)
for the proposed ITER-FEAT, FIRE and IGNITOR designs. Empirical
scaling laws and theory based transport models benchmarked
to existing plasma discharges, will be used in this assessment.
Using these exercises as a basis, these models will also be
used to identify the transport science that may emerge in
the integration of turbulence, transport, and self-heating.
As part of the assessment, the flexibility required to achieve
a range of Q values and to permit a study of this transport
science will be evaluated.
The tasks for this subgroup to be performed for the proposed experiments are:
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Perform standard target performance projections from global confinement data
and dimensionally similar demonstration discharges.
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Perform target performance projections using transport models with H-mode
temperature pedestals given.
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Clarify the range of possible H mode temperature pedestal heights and
characterize their uncertainties.
-
Assess the H mode access requirements in terms of power and edge parameters.
-
Characterize range the of possible scenarios, flexibility requirements, and
pressure profile dynamics affecting performance.
-
Identify transport physics to be addressed in the base program to reduce
uncertainties for BP performance and operating space.
Work Outline
TASK 1
Perform standard target performance projections from global
confinement data and dimensionally similar demonstration discharges.
-
Use latest H- (or L-) mode scaling from the "global confinement database" group
to predict nTtau for standard target from each machine.
-
A subtask here is to make rho_star projections from "demonstration discharges"
to nTtau values.
TASK 2
Perform target performance projections using transport models.
-
Goal: Generate Q (and nTtau) plots versus T_pedestal for standard targets from
each machine.
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Use several transport models GLF23, MMModel, IFS/PPPL and any others which
have documented statistical fits to the ITER database.
-
This activity includes benchmarking of the codes to existing data, especially
demonstration discharges that have been created on existing devices.
TASK 3
Clarify the range of possible H mode temperature pedestal
heights and characterize their uncertainties.
-
Generate predictions of T_pedestal given n_pedestal
constrained by the operating density limit of the targets.
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We will need close co-ordination with the Boundary
Working Group P5 to make sure we are provided concrete T_pedestal
formulas (or predictions) however provisional they may be.
Clarify how the target Q's (or nTtau's) vary with changes in the "targets"
themselves (e.g., operating density and profiles, input aux. power) and also
assign some uncertainty (error bars) on the projections.
Relationship with other tasks: Task 3 needs to be folded with
Task 2 to get a projected nTtau (or Q) and compared with Task
1 empirical projection. The Q plots (from empirical and theory
models) will result in the "front table" or bottomline assessment
to go in the executive report. It also will provide key input
into Task 5 (below).
TASK 4
Assess the H mode access requirements in terms of power and
edge parameter and estimate uncertainties.
-
Compare power requirements for proposed devices for
entering H mode using dominant scaling expressions and alternatives.
-
Extrapolate uncertainties in power requirements for
H mode access from existing spread in threshold database.
-
Identify desired flexibility to help ensure success
of obtaining L-H transitions to ensure access margin and compare
to flexibility of proposed experiments.
-
Explore access likelihood using edge transport models.
TASK 5
Characterize range of possible scenarios, flexibility requirements,
and possible pressure profile dynamics.
-
Work will be performed in close contact with the Integration group (E4).
-
Key importance is to assess the likelyhood of bifurcations
to internal transport barriers (rotational shear vs Shafarnov
shift stabilization), flow shear control tool possibilities
and control tool development needs, flexibility of design
for reversed shear, aligned bootstrap current, AT, MHD stability,
burn control, etc.
-
Nonlinear dynamics of the pressure profile evolution
will be studied first from the point of view identifying the
requirements for obtaining a stable operating point. This
includes identifying needs for external flow shear generation
as a control tool for managing the plasma pressure profile
and bootstrap current.
-
Identify programmatic elements, including diagnostic
requirements, that will enable key assessments of transport
and turbulence dynamics.
-
Identify transport control tool needs.
Additional comments:
The modeling will be directed towards identifying new transport dynamics that
may emerge in a strongly alpha-dominated heating environment. Modeling
exercises will be performed under various assumptions including a range of
H mode pedestal heights, as determined by Task 3, and core transport
assumptions. The latter include those implicit in microstability calculations
built into the predictive models, as well as various assumptions determined
from experimental studies of transport.
TASK 6
Identify transport physics that must addressed in the base program
to reduce the uncertainties for BP performance and operating space.
Deliverables/Schedule
January 31
- Complete definition of tasks for confinement projections based on empirical scaling.
Mid-February
- Identify common tasks with Integrated Modelling Group for scenario assessment (E2).
Mid-March
- Group conference call regarding progress, refining tasks on empirical scaling.
April 1
- Finalize results on baseline performance from empirical projections and modeling.
Mid-point assessment regarding scenario exploration: density profile peaking, prospects for ITB's, etc.
April 3-6
- Discuss flexibility requirements, scientific opportunities for a BP at TTF Meeting
April 23
- R. Waltz presents summary of results on performance projections at Sherwood.
April 30
- Finalize scenario explorations.
Assignments
Task 1
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Rip Perkins, Craig Petty
Task 2
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Jon Kinsey (GLF23), Glenn Bateman (Multimode model),
Bob Budny (predictive TRANSP with various models),
Doug McCune (TRANSP support)
Task 3
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Phil Snyder, Amanda Hubbard, Martin Greenwald, Rich Groebner
Task 4
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Rich Groebner, Amanda Hubbard, Martin Greenwald
Task 5
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Bob Budny, Jon Kinsey, Gary Staebler, Lang Lao, Masanori Murakami, Holger St. John
Documents presented at Sherwood 2002
- Snowmass P4 Summary at Sherwood, 23 April 2002 (PDF file)
- Kinsey Sherwood talk (PDF file)
- Onjun Sherwood poster pedestal (PDF file)
- Kritz Sherwood poster pedestal (PDF file)
- Bateman Sherwood poster pedestal (PDF file)
- Snyder Sherwood poster pedestal stability (PDF file)