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Your search keyword '"McMillan, B.F."' showing total 8 results
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8 results on '"McMillan, B.F."'

1. Magnetic shaping effects on turbulence in ADITYA-U tokamak.

Author

Singh, Amit K., Choudhary, S., Gopal Krishna, M., Mahapatra, J., Bokshi, A., Chowdhury, J., Ganesh, R., Hayward-Schneider, T., Lanti, E., Mishchenko, A., McMillan, B.F., and Villard, L.

Subjects
PLASMA turbulence, TOKAMAKS, WAVENUMBER, TURBULENCE, HEAT flux, COLLISIONLESS plasmas, ION temperature
Abstract

The work reported in this paper addresses two aspects. In the first part, numerical simulations are conducted to examine the impact of magnetic equilibrium shaping (elongation and triangularity), on both conventional Ion Temperature Gradient (ITG) modes and Short Wavelength ITG modes. This analysis is performed considering the experimental profiles and parameters of the ADITYA-U tokamak, employing the nonlinear global gyrokinetic Particle-in-Cell code ORB5. The linear and nonlinear collisionless electrostatic simulation of these modes are carried out with kinetic ions and adiabatic electrons. From the linear results, it has been observed that the magnetic equilibrium shaping slighty reduced the growth rates and widened the spectrum, and the maxima of growth rate curve is shifted to higher toroidal wave number. We find that the heat flux is reduced by a significant ≃ 35 % for the true circular magnetohydrodynamic magnetic equilibrium as compared to ad hoc concentric circular equilibrium reported in Singh et al (2023 Nucl. Fusion 63 086029). A further ≃ 10 % reduction in the heat flux is seen with magnetic equilibrium shaping. In the second part, linear collisionless electrostatic simulation studies of ITG coupled with fully kinetic electrons (both trapped and passing electrons are treated kinetically) using a drift-kinetic ordering is performed. It can be seen from the linear results that, in presence of kinetic electrons, the growth rate and real frequency of the ITG mode are increased significantly for ADITYA-U parameters and a mode propagating in the electron diamagnetic direction is identified at high toroidal wavenumbers. [ABSTRACT FROM AUTHOR]

Published
2024
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4. Global nonlinear electromagnetic simulations of tokamak turbulence

Author

Bottino, A., Scott, B., Brunner, S., McMillan, B.F., Tran, T.M., Vernay, T., Villard, L., Jolliet, S., Hatzky, R., and Peeters, A.G.

Subjects
Electric waves -- Analysis, Electromagnetic radiation -- Analysis, Electromagnetic waves -- Analysis, Monte Carlo method -- Usage, Plasma devices -- Design and construction, Tokamaks -- Analysis, Business, Chemistry, Electronics, Electronics and electrical industries
Published
2010

7. Rapid Fourier space solution of linear partial integro-differential equations in toroidal magnetic confinement geometries

Author

McMillan, B.F., Jolliet, S., Bottino, A., Angelino, P., Tran, T.M., and Villard, L.

Abstract

Abstract: Fluctuating quantities in magnetic confinement geometries often inherit a strong anisotropy along the field lines. One technique for describing these structures is the use of a certain set of Fourier components on the tori of nested flux surfaces. We describe an implementation of this approach for solving partial differential equations, like Poisson''s equation, where a different set of Fourier components may be chosen on each surface according to the changing safety factor profile. Allowing the resolved components to change to follow the anisotropy significantly reduces the total number of degrees of freedom in the description. This can permit large gains in computational performance. We describe, in particular, how this approach can be applied to rapidly solve the gyrokinetic Poisson equation in a particle code, ORB5 (Jolliet et al., (2007) ), with a regular (non-field-aligned) mesh. [Copyright &y& Elsevier]

Published
2010
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8. A global collisionless PIC code in magnetic coordinates

Author

Jolliet, S., Bottino, A., Angelino, P., Hatzky, R., Tran, T.M., Mcmillan, B.F., Sauter, O., Appert, K., Idomura, Y., and Villard, L.

Subjects
*TURBULENCE, *FLUCTUATIONS (Physics), *MECHANICAL movements, *PLASMA gases, *SYSTEMS design
Abstract

Abstract: A global plasma turbulence simulation code, ORB5, is presented. It solves the gyrokinetic electrostatic equations including zonal flows in axisymmetric magnetic geometry. The present version of the code assumes a Boltzmann electron response on magnetic surfaces. It uses a Particle-In-Cell (PIC), δf scheme, 3D cubic B-splines finite elements for the field solver and several numerical noise reduction techniques. A particular feature is the use of straight-field-line magnetic coordinates and a field-aligned Fourier filtering technique that dramatically improves the performance of the code in terms of both the numerical noise reduction and the maximum time step allowed. Another feature is the capability to treat arbitrary axisymmetric ideal MHD equilibrium configurations. The code is heavily parallelized, with scalability demonstrated up to 4096 processors and 109 marker particles. Various numerical convergence tests are performed. The code is validated against an analytical theory of zonal flow residual, geodesic acoustic oscillations and damping, and against other codes for a selection of linear and nonlinear tests. [Copyright &y& Elsevier]

Published
2007
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