Dettrick_APSDPP2018_poster_v5

Summary
n Equilibrium and Global Stability of a Field Reversed Configuration (FRC) can be influenced by external actuators, three of which are:
1. external magnetic field shapes 2. neutral-beam injection (NBI)
3. concentric electrode biasing.
n Flexible control systems for all three of these actuators are available on the C-2W experiment, so we study their effects on FRC Equilibrium and Global Stability
Equilibrium
TAE Technologies, Inc., 19631 Pauling, Foothill Ranch, CA 92610 Equilibrium with NBI Fast Ions
Global Stability
Deuterium
Hydrogen
n Tool used is the LReqMI equilibrium code [1]: n Multiple ion fluid, with rotation
n Fast Ions have a slowing down distribution
n Fast ion pressure may be very significant while fast ion
density is still small
8
Once the arbitrary surface functions are assigned, the code uses
n Solves simultaneously the equations
them to calculate the equilibrium problem unknowns
n To address the role of the electron pressure term the equilibrium has been generated taking into account a very low electron temperature (2 eV)
ABCDABCD Stability Questions
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?
References
1. L. Galeotti et al, PoP, 18, 082509 (2011)
2. A.F. Lifshitz et al, Nucl. Fus., 44, 1015 (2004)
3. F. Ceccherini et al. CP10.00087, APS-DPP 2016
4. S. Dettrick et al. PP11.00097, APS-DPP 2018
5. E. Belova et al, Physics of Plasmas 13.5 (2006): 056115
6. Y. A. Omelchenko, Physical Review E 92 (2015) 023105
This is done solving simultaneously the equations:
Ɵ component of (momentum equation for the ion species “i”)
quasi-neutrality
Bernoulli's functions
coupled with the Ampere's law
Presenter: Francesco Ceccherini
(momentum
Deuterium
Hydrogen
n Inputs are coil currents and choices of conducting or insulating boundary
n Constraints are separatrix radius and radial profile functions for temperatures and rotation rates
n Recent extensions to the equilibrium code :
a. Optimizer to reconstruct equilibrium from experimental data
New flux loop measurements on C-2W make it possible to impose magnetic scalar flux as a Dirichlet condition. Least squares Cost Function is then built from comparison between synthetic and experimental diagnostics
b. From multi-fluid to hybrid fluid/kinetic operation
Fast Ions from NBI are treated as Kinetic species by coupling the LReqMI solver to TAE’s full orbit Monte Carlo code. Similar procedure may have been performed by [2].
An award of computer time was provided by the Innovative and Novel Computational Impact on Theory and Experiment (INCITE) program. This research used resources of the Argonne Leadership Computing Facility, which is a DOE Office of Science User Facility supported under Contract DE-AC02-06CH11357.
Ɵ component of equation for electrons)
surface variable for the ion species “i”
A
B
Very different for p and B11
Privileged and Confidential
Deuterium
Hydrogen
Simulation of FRC Equilibrium and Global Stability
Sean Dettrick, Francesco Ceccherini, Laura Galeotti, Kevin Hubbard, Dan Barnes, and the TAE team
n Fast ion pressure may be strongly anisotropic, depending on NB injection parameters. Changing neutral beam injection
n Tool used is the FPIC Ohm’s law Hybrid PIC code [3,4]: n Ampere’s law to obtain Jtot from B
n Fully kinetic ion push to obtain Je from Jtot – Jion
n Ohm’s law to obtain E from B, Je, ne,
n Faraday’s law to update B from E.
n Similar physics model to HYM [5] and HYPERS [6]
n Implementation
n 3D, Cartesian Yee mesh, Cut-cells for shaped boundary
n Recent extensions to the stability code:
n Multiple ion species, domain decomposition, periodic
boundaries, boundary virtual particles
n Example
C-2W-like equilibrium with 83% deuterium and 17% hydrogen.
angle changes the FRC length by increasing P
zz
relative to P . rr
C
D
Thermal equilibrium
Thermal +20° beams
Thermal +45° beams
Deuterium
Hydrogen