Dettrick_APSDPP2017_poster_final
P. 1

LReqMI
Multi ion species force balance
Initial condition
neutral fluid; external coils, end biasing; synthetic experimental diagnostics
KSOL*
Kinetic Electron dynamics
in Scrape Off Layer
Q2D and GTC domains
ANC domain
Equilibrium and Stability
Whole Device Modeling of Compact Tori: Stability and Transport Modeling of C-2W
Sean Dettrick1), Daniel Fulton1), Calvin Lau2), Zhihong Lin2), Francesco Ceccherini1), Laura Galeotti1), Sangeeta Gupta1), Marco Onofri1), Toshiki Tajima1,2) and the TAE team
1) TAE Technologies, Inc., 19631 Pauling, Foothill Ranch, CA 92610
2) University of California, Irvine
Summary
n TAE is working towards catalysing a community-wide collaboration to develop a Whole Device Model (WDM) of Compact Tori.
n We have many components of the WDM in-house, with some partial specialization to FRC geometry
n The WDM includes Equilibrium, Stability and Transport codes, which will propose operating points for the new C-2W device, under commissioning at TAE
Status of Whole Device Model
n Models couple through a reduced global transport model
n Timescales of models
Physics Questions
n How do equilibrium, stability, and global transport depend on plasma parameters?
n Low magnetic field region:
n How does current drive with neutral beams work?
n What determines confinement when π’π’Œπ‘©π‘» ≫ π‘©πŸ/𝟐𝝁𝟎 ?
n Electron heat transport and expander physics – can we
achieve high Te as in the Gas Dynamic Trap (GDT) [3]?
n Control of equilibrium profiles and shape – can we have stable (or controlled) long, shallow equilibria?
n Heating by RF and NB – can we decouple heating and fueling?
n Multiple ion species effects on all of the above?
Transport
n C-2W constitutes an FRC inside a mirror machine with expander divertors
n Perpendicular and Parallel transport are coupled [4] n Observations and Insights:
n Expander divertors isolate hot electrons from cold ends n Magnetic mirrors and electrostatic sheath create
trapped/passing boundaries in phase space
n Electrode biasing in divertor affects electron outflow
n Kinetic microturbulence causes perpendicular transport n 𝛁𝐏 and 𝛁𝐁 point in opposite directions in FRC
n Short field line length inside separatrix, cf tokamak
n Ion orbit size comparable to FRC size
n Fast ions sample closed and open field regions
n Tools:
n KSOL computes parallel electron heat transport using
1D2V Fokker-Planck
n GTC computes parallel electron heat transport using PIC
n GTC and ANC simulate kinetic microturbulence using 3D3V PIC with fully kinetic ion orbits
n Q2D couples parallel and perpendicular losses through reduced global transport model. Allows rampup studies including source and sink terms, and β€œWhole Device” model for comparison against experiment
C-2W beam-driven FRC
n In the C-2U beam driven FRC experiment, energy confinement appeared to improve with inverse collisionality [5], similar to NSTX [6,7] and MAST [8].
n Main goal of C-2W is to increase electron temperature, to study energy confinement scaling at higher Te
n Supporting goals are to master stability, control, and plasma rampup
Model Validation on C-2W
n Models validated against C-2U. To continue on C-2W. n Turbulence code validation against reflectometry
(DBS) (L. Schmitz, BP11.00057)
n Fast Ion physics validation against neutronics, proton detectors, neutral particle analyzer, bolometry, FIDA
n Equilibrium, Stability, and Global Transport validation against comprehensive plasma state inferred by Bayesian methods (J. Romero, BP11.00056)
n Validated codes will help design future FRC reactors. References
1. S. Gupta, et al, Phys. Plasmas, 23 (2016) 052307
2. M. Onofri et al, Phys. Plasmas, 24 (2017) 092518
3. E. Soldatkina et al., Phys. Plasmas, 24 (2017) 022505 4. L. Steinhauer et al, submitted to Phys. Plasmas (2017) 5. M. Binderbauer, et al., Phys. Plasmas, 22 (2015) 56110 6. S. Kaye, et al. Nucl. Fusion, 47 (2007) 499
7. S. Kaye, et al. Nucl. Fusion, 53 (2013) 63005
8. M. Valovič, et al. Nucl. Fusion, 51 (2011) 73045
DEGAS2
Kinetic thermal neutral model
MC
Kinetic neutral beam and fast ion model
Coupled on orbit timescale
Q2D* Global Transport
Coupling of MHD, fast ions, SOL
n Domains of models Confinement
vessel
Expander
Electrodes
(optional)
Mirror
To be coupled on profile relaxation timescale
ANC* and GTC* codes Kinetic Microturbulence
n Observations and Insights:
n C-2W has a real time control system for plasma position and
separatrix shape
n FRC separatrix shape also depends on radial pressure profile
n Tilt, Interchange, Tearing modes can each be avoided by choice of plasma profiles and shape. What is allowed parameter region?
n Neutral Beam Fast Ions can stabilize or de-stabilize modes. What are best parameters?
n End-biasing affects rotation and rotation shear. Can it be used as a control?
n Tools:
n LR_eqMI equilibrium code predicts FRC shape given coil currents and assumed profiles. Fast ion species from neutral beam are included kinetically by coupling to MC code
n Semi-analytic tools to evaluate interchange, tearing, tilt stability
n 3D PIC code FPIC to evaluate kinetic stabilization, wave/particle resonances, and to perform virtual experiments in feedback and control
(* See other posters at this meeting)
n Dimensionality of Models
n 0D – Power balance interpretation (E. Trask et al)
n 1D – Interchange & tearing stability models
n 1D – KSOL parallel electron dynamics (S. Gupta, BP11.00062)
n 1D – Q1D perpendicular transport [1]
n 1D – LSP beam driven modes (S. Nicks, BP11.00065)
n 2D – HHFW electron heating (F. Ceccherini, BP11.00066)
n 2D – Q2D global transport [2](M. Onofri, BP11.00063)
n 3D – GTC parallel transport (J. Bao, BP11.00060)
n 3D – ANC and GTC kinetic microturbulence (D. Fulton, BP11.00058; C. Lau, BP11.00059)
n 3D – FPIC global kinetic stability code
physics
KSOL domain


































































































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