TORIC and AORSA are being used to design flow drive experiments on Alcator C-Mod - PowerPoint PPT Presentation

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TORIC and AORSA are being used to design flow drive experiments on Alcator C-Mod

Work by Myra, Jaeger et al. [PRL, 2003] demonstrated significant shear flow generation is possible in fast wave to ion cyclotron wave (ICW) mode conversion experiments on C-Mod [Melby et al., PRL, 2003]:

Mechanism relies on mode converted ICW damping at ion resonance as wave propagates back toward the tokamak LFS.
TORIC and AORSA are being used to identify C-Mod scenarios (multi-ion species) where cyclotron absorption is maximum and electron damping of ICW is minimized.
Code comparisons [J.C. Wright et al., PoP, 2004] are a critical feature of these studies to cross-check high resolution TORIC simulations against integral conductivity operator of AORSA.

Field solvers employing different conductivity models give very similar results

TORIC at 240Nr x 255 Nm

J. Wright, PSFC, PoP, 2004

ICW

IBW

FW

AORSA at 230Nx x 230 Ny

E.F. Jaeger, PRL, 2003

RF SciDAC Project is Providing Critical Input to ITPA For ICRF Code Benchmark Activity

ICRF Simulations of 2WT Heating in the ITER Device Are Being Performed using AORSA and TORIC:

Calculations use ELMY H-Mode Parameters (ITER Scenario 2).
Include energetic fusion alpha particle population.

Initial Comparisons Between AORSA and TORIC are Favorable

Power balance - TORIC

P(2T) = 50 %

P(ELD) = 35%

P(D) = 1.8%

P(alpha) = 14 %

Bi-Maxellian for f(v)

Teff=1.6 MeV

Power balance – AORSA2D

P(2T) = 45 %

P(ELD) = 38%

P(D) = -0.5%

P(alpha) = 17 %

Slowing down distribution for f(v)

Calculations using exact f(v) from CQL3D are in progress

TORIC Results for ICRF Absorption (Nm=127, NR=480)Don and Fred – Below Please Insert a Comparison Figure From AORSA !

Injected fast wave electric fields

exhibit strong focusing

Antenna coupling for impedance calculations under way using TOPICA3 + 2D Wave Solver - TORIC– to be completed in 4 weeks

Review the relationship between H and E on the LFS and to develop the final form of the reaction integrals in the spectral domain -Torino, done.
Find the best way to approximate the aperture and transform to the spectral domain -Torino, done.
Code a subroutine implementing the aperture transform in 2)-Torino to do.
Code changes to TORIC solver and output routines to do impedance calculation for individual nf M{n} and mq b{m}– MIT to do.
Combine with per mode loading from TOPICA to get total loading and fields consistent with that loading in postprocessing step– MIT/Torino to do.

Toric stiffness matrix, M, is fctn of nf, boundary vector; b is a fctn of antenna mode pair. Solution, x, is one column in impedance matrix, Ym,m', which is closely related to M-1

TOPICA3 was recently coupled to the 1D Wave Code FELICE and used to simulate loading in the Alcator C-Mod “E” Antenna (R. Maggiora et al., APS, 2005)

Computed Loading

Computations and Code Implementation on the MIT Beowulf Cluster – Using the measured density profiles in the C-Mod SOL.

Plasma shot

Measured Loading

Free boundary MHD simulations and ideal stability analysis with self-consistent current profile control

RF simulator with driven RF current electron response will soon be available [CQL3D+TORIC and CQL3D + AORSA]:

Current density source terms due to LHCD, FWCD, or MCCD.

Plan to couple the driven current source term to a free boundary MHD solver and iterate [ACCOME code - Bonoli, Ramos, Kessel et al., PPCF, 1997]:

Resulting MHD equilibrium and current density source terms are then consistent with each other.

MHD equilibrium can then be tested for ideal stability (ballooning and low-n external kink modes) by coupling to a stability package [PEST-II].
As a first step, the ACCOME code has been successfully implemented and tested on the MIT Beowulf cluster.