Publications

2023

  1. C. J. McDevitt, X. Z. Tang, C. J. Fontes, P. Sharma, and H. K. Chung. The constraint of plasma power balance on runaway avoidance. Nuclear Fusion, 63:024001. 2023.
  2. G. A. Wimmer and X. Tang. Structure preserving transport stabilized compatible finite element methods for magnetohydrodynamics. submitted. 2023.
  3. G. A. Wimmer, B. S. Southworth, T. J. Gregory, and X. Tang. A fast algebraic multigrid solver and accurate discretization for highly anisotropic heat flux I: open field lines. submitted. 2023.
  4. B. Zhu, X.-q. Xu, and X.-Z. Tang. Electromagnetic turbulence simulation of tokamak edge plasma dynamics and divertor heat load during thermal quench. submitted. 2023.
  5. Y. Li, B. Srinivasan, Y. Zhang, and X.-Z. Tang. The plasma-sheath transition and Bohm criterion in a high recycling divertor. Physics of Plasmas, 30:063505. 2023.
  6. Z. Jorti, Q. Tang, K. Lipnikov, and X.-Z. Tang. A mimetic finite difference based quasi-static magnetohydrodynamic solver for force-free plasmas in tokamak disruptions. submitted. 2023.
  7. J.-U. Chen, S. Kang, T. Bui-Thanh, and J. N. Shadid. UNIFIED HP-HDG FRAMEWORKS FOR FRIEDRICHS' PDE SYSTEMS. Computers & Mathematics with Applications, submitted. 2023.
  8. J. Li, Y. Zhang, and X.-Z. Tang. Staged cooling of a fusion-grade plasma in a tokamak thermal quench. Nuclear Fusion, 63:066030. 2023.
  9. Y. Zhang, Y. Li, B. Srinivasan, and X. Z. Tang. Resolving the mystery of electron perpendicular temperature spike in the plasma sheath. Physics of Plasmas, 30:033504. 2023.
  10. Y. Zhang and X. Z. Tang. On the collisional damping of plasma velocity space instabilities. Physics of Plasmas, 30:030701. 2023.
  11. Y. Zhang, J. Li, and X. Z. Tang. Cooling flow regime of a plasma thermal quench. Europhysics Letters, 141:54002. 2023.
  12. J. Rudi, M. Heldman, E. M. Constantinescu, Q. Tang, and X.-Z. Tang. Scalable Implicit Solvers with Dynamic Mesh Adaptation for a Relativistic Drift-Kinetic Fokker-Planck-Boltzmann Model. submitted. 2023.
  13. M. M. Crockatt and J. N. Shadid. A Non-neutral Generalized Ohm's Law Model for Magnetohydrodynamics in the Two-Fluid Regime. Physics of Plasmas,, 30:053902. 2023.
  14. M. Maier, J. N. Shadid, and I. Tomas. Local-in-time structure-preserving finite-element schemes for the Euler-Poisson equations. Communications in Computational Physics,, to appear. 2023.
  15. S. Muralikrishnan, S. Shannon, T. Bui-Thanh, and J. N. Shadid. A multilevel block preconditioner for the HDG trace system applied to incompressible resistive MHD. Computer Methods in Applied Mechanics and Engineering, 404. 2023.

2022

  1. R. M. Park, W. Kupets, M. C. Zammit, J. Colgan, C. J. Fontes, B. S. Scheiner, E. Timmermans, X. Z. Tang, L. H. Scarlett, D. V. Fursa, I. Bray, and N. A. Garland. Anisotropic angular scattering models of elastic electron-neutral collisions for Monte Carlo plasma simulations. Plasma Sources Science and Technology, 31:065013. 2022.
  2. K. Lee, H. C. Elman, C. E. Powell, and D. Lee. Enhanced alternating energy minimization methods for stochastic Galerkin matrix equations. BIT Numerical Mathematics, 62:965–994. 2022.
  3. B. Sousedik, H. C. Elman, K. Lee, and R. Price. On surrogate learning for linear stability assessment of Navier-Stokes equations with stochastic viscosity. Applications of Mathematics, 67:727–749. 2022.
  4. C. J. McDevitt and X.-Z. Tang. Runaway electron current reconstitution after a non-axisymmetric magnetohydrodynamic flush. submitted. 2022.
  5. Y. Li, B. Srinivasan, Y. Zhang, and X.-Z. Tang. Bohm criterion of plasma sheaths away from asymptotic limits. Physical Review Letters, 128:085002. 2022.
  6. Y. Li, B. Srinivasan, Y. Zhang, and X.-Z. Tang. Transport physics dependence of Bohm speed in presheath–sheath transition. Physics of Plasmas, 29:113509. 2022.
  7. N. A. Garland, R. Maulik, Q. Tang, X. Z. Tang, and P. Balaprakash. Efficient data acquisition and training of collisional-radiative model artificial neural network surrogates through adaptive parameter space sampling. Machine Learning: Science and Technology, 3:045003. 2022.
  8. J. J. Lee, T. Bui-Thanh, U. Villa, and O. Ghattas. Forward and inverse modeling of fault transmissibility in subsurface flows. Computers and Mathematics with Applications, 128:354–367. 2022.
  9. A. H. Boozer. Local analysis of fast magnetic reconnection. Physics of Plasmas, 29:052104. 2022.
  10. I. Fekete, S. Conde, and J. N. Shadid. Embedded pairs for optimal explicit strong stability preserving Runge–Kutta methods. Journal of Computational and Applied Mathematics, 412:114325. 2022.
  11. P. Ohm, T. A. Wiesner, E. C. Cyr, J. J. Hu, J. N. Shadid, and R. S. Tuminaro. A monolithic algebraic multigrid framework for multiphysics applications with examples from resistive MHD. Electronic Transactions on Numerical Analysis, 55:365–390. 2022.
  12. A. H. Boozer. Magnetic field evolution and reconnection in low resistivity plasmas. Submitted. 2022.
  13. M. M. Crockatt, S. Mabuza, J. N. Shadid, S. Conde, T. M. Smith, and R. P. Pawlowski. An implicit monolithic AFC stabilization method for the CG finite element discretization of the fully-ionized ideal multifluid electromagnetic plasma system. Journal of Computational Physics, 464. 2022.
  14. M. G. Yoo, W. X. Wang, E. Startsev, C. H. Ma, S. Ethier, J. Chen, and X. Z. Tang. The 3D magnetic topology and plasma dynamics in open stochastic magnetic field lines. Physics of Plasmas, 29. 2022.
  15. T. Bui-Thanh, Q. Li, and L. Zepeda-Nunez. Bridging and Improving Theoretical and Computational Electric Impedance Tomography via Data Completion. SIAM Journal on Scientific Computing, 44:B668–B693. 2022.
  16. N. A. Garland, H. K. Chung, M. C. Zammit, C. J. McDevitt, J. Colgan, C. J. Fontes, and X. Z. Tang. Understanding how minority relativistic electron populations may dominate charge state balance and radiative cooling of a post-thermal quench tokamak plasma. Physics of Plasmas, 29. 2022.
  17. A. H. Boozer. The rapid destruction of toroidal magnetic surfaces. Physics of Plasmas, 29. 2022.
  18. Q. Tang, L. Chacón, T. V. Kolev, J. N. Shadid, and X. Z. Tang. An adaptive scalable fully implicit algorithm based on stabilized finite element for reduced visco-resistive MHD. Journal of Computational Physics, 454. 2022.
  19. H. C. Elman, J. Liang, and T. Sánchez-Vizuet. Surrogate approximation of the Grad–Shafranov free boundary problem via stochastic collocation on sparse grids. Journal of Computational Physics, 448. 2022.

2021

  1. H. Goh, S. Sheriffdeen, J. Wittmer, T. Bui-Thanh, J. Bruna, J. S. Hesthaven, and L. Zdeborova. Solving Bayesian Inverse Problems via Variational Autoencoders. Proceedings of Machine Learning Research, 145:386–425. 2021.
  2. W. Zhang, G. Rossini, T. Bui-Thanh, and M. Sacks. The integration of structure and high-fidelity material models in heart valve simulations using machine learning, International Journal for Numerical Methods in Biomedical Engineering. International Journal for Numerical Methods in Biomedical Engineering, 37:e3438. 2021.
  3. H. Nguyen and T. Bui-Thanh. Model-Constrained Deep Learning Approaches for Inverse Problems. submitted. 2021.
  4. T. Bui-Thanh. The Optimality of Bayes' Theorem. SIAM News. 2021.
  5. N. A. Garland, R. Maulik, Q. Tang, X.-Z. Tang, and P. Balaprakash. Efficient training of artificial neural network surrogates for a collisional-radiative model through adaptive parameter space sampling. Submitted. 2021.
  6. S. Liu, Q. Tang, and X. Z. Tang. A parallel cut-cell algorithm for the free-boundary Grad-Shafranov problem. SIAM Journal on Scientific Computing, 43:B1198–B1225. 2021.
  7. A. Myers, A. H. Thiéry, K. Wang, and T. Bui-Thanh. Sequential ensemble transform for Bayesian inverse problems. Journal of Computational Physics, 427. 2021.
  8. M. G. Yoo, W. X. Wang, E. Startsev, C. H. Ma, S. Ethier, J. Chen, and X. Z. Tang. Collisionless plasma transport mechanisms in stochastic open magnetic field lines in tokamaks. Nuclear Fusion, 61. 2021.
  9. S. Kang and T. Bui-Thanh. A scalable exponential-DG approach for nonlinear conservation laws: With application to Burger and Euler equations. Computer Methods in Applied Mechanics and Engineering, 385. 2021.
  10. J. Wittmer and T. Bui-Thanh. Data-Informed Regularization for Inverse and Imaging Problems. Handbook of Mathematical Models and Algorithms in Computer Vision and Imaging, 1–38. 2021.
  11. B. Zhu, H. Seto, X. qiao Xu, and M. Yagi. Drift reduced Landau fluid model for magnetized plasma turbulence simulations in BOUT++ framework. Computer Physics Communications, 267. 2021.
  12. M. Crockatt and J. Shadid. Development, Implementation, and Verification of Partially-Ionized Collisional Multifluid Plasma Models in Drekar. Sandia National Laboratories Technical report, SAND2021–7427. 2021.
  13. A. H. Boozer. The interaction of the ITER first wall with magnetic perturbations. Nuclear Fusion, 61. 2021.
  14. P. Cagas, A. H. Hakim, and B. Srinivasan. A boundary value "reservoir problem" and boundary conditions for multi-moment multifluid simulations of sheaths. Physics of Plasmas, 28. 2021.
  15. N. M. Li, X. Q. Xu, R. J. Goldston, J. Z. Sun, and D. Z. Wang. Impact of plasma density/collisionality on divertor heat flux width. Nuclear Fusion, 61. 2021.
  16. J. W. Burby, Q. Tang, and R. Maulik. Fast neural Poincaré maps for toroidal magnetic fields. Plasma Physics and Controlled Fusion, 63. 2021.
  17. A. H. Boozer. Plasma steering to avoid disruptions in ITER and tokamak power plants. Nuclear Fusion, 61. 2021.
  18. I. Tomas, J. Shadid, M. Crockatt, M. Maier, J.-L. Guermond, and R. Pawlowski. Final report of activities for the LDRD-express project #223796 titled: “Fluid models of charged species transport: numerical methods with mathematically guaranteed properties”, PI: Ignacio Tomas, Co-PI: John Shadid. Sandia National Laboratories Technical report, SAND2021–11481. 2021.
  19. J. H. Chaudhry, A. E. Rappaport, and J. N. Shadid. An a Posteriori error analysis for the equations of stationary incompressible magnetohydrodynamics. SIAM Journal on Scientific Computing, 43:B354–B380. 2021.

2020

  1. R. Maulik, N. A. Garland, J. W. Burby, X. Z. Tang, and P. Balaprakash. Neural network representability of fully ionized plasma fluid model closures. Physics of Plasmas, 27. 2020.
  2. S. Mabuza, J. N. Shadid, E. C. Cyr, R. P. Pawlowski, and D. Kuzmin. A linearity preserving nodal variation limiting algorithm for continuous Galerkin discretization of ideal MHD equations. Journal of Computational Physics, 410. 2020.
  3. S. Kang, F. X. Giraldo, and T. Bui-Thanh. IMEX HDG-DG: A coupled implicit hybridized discontinuous Galerkin and explicit discontinuous Galerkin approach for shallow water systems. Journal of Computational Physics, 401. 2020.
  4. N. A. Garland, H. K. Chung, C. J. Fontes, M. C. Zammit, J. Colgan, T. Elder, C. J. McDevitt, T. M. Wildey, and X. Z. Tang. Impact of a minority relativistic electron tail interacting with a thermal plasma containing high-atomic-number impurities. Physics of Plasmas, 27. 2020.
  5. Z. PENG, Q. TANG, and X. Z. TANG. An adaptive discontinuous petrov-galerkin method for the grad-shafranov equation. SIAM Journal on Scientific Computing, 42:B1227–B1249. 2020.
  6. S. Muralikrishnan, T. Bui-Thanh, and J. N. Shadid. A multilevel approach for trace system in HDG discretizations. Journal of Computational Physics, 407. 2020.
  7. N. M. Li, X. Q. Xu, J. W. Hughes, J. L. Terry, J. Z. Sun, and D. Z. Wang. Simulations of divertor heat flux width using transport code with cross-field drifts under the BOUT++ framework. AIP Advances, 10. 2020.
  8. I. Ambartsumyan, W. Boukaram, T. Bui-Thanh, O. Ghattas, D. Keyes, G. Stadler, G. Turkiyyah, and S. Zampini. Hierarchical matrix approximations of hessians arising in inverse problems governed by PDEs. SIAM Journal on Scientific Computing, 42:A3397–A3426. 2020.
  9. L. Wang, X. Q. Xu, B. Zhu, C. Ma, and Y. A. Lei. Deep learning surrogate model for kinetic Landau-fluid closure with collision. AIP Advances, 10. 2020.
  10. A. H. Boozer. Flattening of the tokamak current profile by a fast magnetic reconnection with implications for the solar corona. Physics of Plasmas, 27. 2020.
  11. C. Ma, B. Zhu, X. Q. Xu, and W. Wang. Machine learning surrogate models for Landau fluid closure. Physics of Plasmas, 27. 2020.

2019

  1. H. Goh, S. Sheriffdeen, J. Wittmer, and T. Bui-Thanh. Solving Bayesian Inverse Problems via Variational Autoencoders. Submitted. 2019.
  2. S. Sheriffdeen, J. C. Ragusa, J. E. Morel, M. L. Adams, and T. Bui-Thanh. Accelerating PDE-constrained Inverse Solutions with Deep Learning and Reduced Order Models. Submitted. 2019.
  3. X. Q. Xu, N. M. Li, Z. Y. Li, B. Chen, T. Y. Xia, T. F. Tang, B. Zhu, and V. S. Chan. Simulations of tokamak boundary plasma turbulence transport in setting the divertor heat flux width. Nuclear Fusion, 59. 2019.
  4. Z. Guo, C. McDevitt, and X. Tang. Toroidal effect on runaway vortex and avalanche growth rate. Physics of Plasmas, 26. 2019.
  5. N. Alger, V. Rao, A. Myers, T. Bui-Thanh, and O. Ghattas. Scalable matrix-free adaptive product-convolution approximation for locally translation-invariant operators∗. SIAM Journal on Scientific Computing, 41:A2296–A2328. 2019.
  6. T. Wildey, S. Muralikrishnan, and T. Bui-Thanh. Unified geometric multigrid algorithm for hybridized high-order finite element methods. SIAM Journal on Scientific Computing, 41:S172–S195. 2019.
  7. W. X. Wang, T. S. Hahm, E. A. Startsev, S. Ethier, J. Chen, M. G. Yoo, and C. H. Ma. Self-driven current generation in turbulent fusion plasmas. Nuclear Fusion, 59. 2019.
  8. L. Wang, B. Zhu, X. Q. Xu, and B. Li. A Landau-fluid closure for arbitrary frequency response. AIP Advances, 9. 2019.
  9. C. J. McDevitt, Z. Guo, and X. Z. Tang. Spatial transport of runaway electrons in axisymmetric tokamak plasmas. Plasma Physics and Controlled Fusion, 61. 2019.
  10. C. J. McDevitt and X. Z. Tang. Runaway electron generation in axisymmetric tokamak geometry. EPL, 127. 2019.
  11. J. G. Chen, X. Q. Xu, and Y. A. Lei. Extension of Landau-fluid closure to weakly collisional plasma regime. Computer Physics Communications, 236:128–134. 2019.
  12. C. J. McDevitt, Z. Guo, and X. Z. Tang. Avalanche mechanism for runaway electron amplification in a tokamak plasma. Plasma Physics and Controlled Fusion, 61. 2019.
  13. J. J. Lee, S. J. Shannon, T. Bui-Thanh, and J. N. Shadid. Analysis of an hdg method for linearized incompressible resistive MHD equations. SIAM Journal on Numerical Analysis, 57:1697–1722. 2019.

2018

  1. C. J. McDevitt, Z. Guo, and X. Z. Tang. Relation of the runaway avalanche threshold to momentum space topology. Plasma Physics and Controlled Fusion, 60. 2018.
  2. Z. Guo, C. J. McDevitt, and X. Z. Tang. Control of runaway electron energy using externally injected whistler waves. Physics of Plasmas, 25. 2018.