Publications

Featured Articles

Robust avoidance of edge-localized modes alongside gradient formation in the negative triangularity tokamak edge
Nelson, A. O., Schmitz, L., Paz-Soldan, C., Thome, K. E., Cote, T. B., Leuthold, N., Scotti, F., Austin, M. E., Hyatt, A. & Osborne, T., Physical Review Letters, 131, 195101 (2023).

Prospects for H-mode inhibition in negative triangularity tokamak reactor plasmas
Nelson, A. O., Paz-Soldan, C. & Saarelma, S., Nuclear Fusion 62, 096020 (2022).

Highest Fusion Performance without Harmful Edge Energy Bursts in Tokamak
Kim, S. K., Shousha, R., Yang, S. M., Hu, Q., Hahn, S. H., Jalalvand, A., Park, J.-K., Logan, N. C., Nelson, A. O., Na, Y.-S., Nazikian, R., Wilcox, R.Hong, R., Rhodes, T., Paz-Soldan, C., Jeon, Y. M., Kim, M. W., Ko, W.H., Lee, J.H., Battey, A., Bortolon, A., Snipes, J. & Kolemen, E., Nature Communications, 15, Article number: 3990 (2024).

First Author Publications

First Access to ELM-free Negative Triangularity at Low Aspect Ratio
Nelson, A. O., Vincent, C., Anand, H., Lovell, J., Parisi, J. F., Wilson, H. S., Imada, K., Wehner, W. P., Kochan, M., Blackmore, S., Guizzo, S., Rondini, L., Freiberger, S., Paz-Soldan, C. and the MAST-U Team, Nuclear Fusion, 64, 124004 (2024).

Characterization of the ELM-free Negative Triangularity Edge on DIII-D
Nelson, A. O., Schmitz, L., Cote, T., Parisi, J. F., Paz-Soldan, C., Thome, K.E., & Austin, M.E., Scotti, F., Barr, J.L., Hyatt, A., Leuthold, N., Marinoni, A., Neiser, T., Osborne, T., Richner, N., Welander, A.S., Wehner, W.P., Wilcox, W., Wilks, T.M. & Yang, J., Plasma Physics and Controlled Fusion, 66, 105014 (2024).

Implications of Vertical Stability Control on the SPARC Tokamak
Nelson, A. O., Garnier, D. T., Battaglia, D. J., Paz-Soldan, C., Stewart, I., Reinke, M., Creely, A., & Wai, J., Nuclear Fusion 64, 086040 (2024).

Vertical Control of DIII-D Discharges with Strong Negative Triangularity
Nelson, A. O., Hyatt, A., Wehner, W., Welander, A., Paz-Soldan, C. & Anand, H., Plasma Physics and Controlled Fusion 65, 044002 (2023).

Prospects for H-mode inhibition in negative triangularity tokamak reactor plasmas
Nelson, A. O., Paz-Soldan, C. & Saarelma, S., Nuclear Fusion 62, 096020 (2022).

Interpretative SOL modeling throughout multiple ELM cycles in DIII-D
Nelson, A. O., Xing, Z. A., Izacard, O., Laggner, F. M. & Kolemen, E., Nuclear Materials and Energy 26, 100883 (2021).

Time-dependent experimental identification of inter-ELM microtearing modes in the tokamak edge on DIII-D
Nelson, A. O., Laggner, F. M., Diallo, A., Smith, D. R., Xing, Z. A., Shousha, R. & Kolemen, E., Nuclear Fusion 61, 116083 (2021).

Setting the H-mode pedestal structure: variations of particle source location using gas puff and pellet fueling
Nelson, A.O., Laggner, F. M., Groebner, R. J., Grierson, B. A., Izacard, O., Eldon, D., Shafer, M., Leonard, A. W., Shiraki, D., Sontag, A. C. & Kolemen, E., Nuclear Fusion 60, 046003 (2020).

Experimental evidence of ECCD-based NTM suppression threshold reduction during mode locking on DIII-D
Nelson, A. O., Logan, N., Choi, W., Strait, E. J. & Kolemen, E., Plasma Physics and Controlled Fusion 62, 094002 (2020).

Electron cyclotron emission based q-profile measurement and concept for equilibrium reconstruction
Nelson, A. O., Austin, M. E. & Kolemen, E., Plasma Physics and Controlled Fusion 61, 085013 (2019).

Simultaneous detection of neoclassical tearing mode and electron cyclotron current drive locations using electron cyclotron emission in DIII-D
Nelson, A. O., La Haye, R. J., Austin, M. E., Welander, A. S. & Kolemen, E., Fusion Engineering and Design 141, 25–29 (2019).

New experimental capability to investigate the hypervelocity micrometeoroid bombardment of cryogenic surfaces
Nelson, A. O., Dee, R., Gudipati, M. S., Horányi, M., James, D., Kempf, S., Munsat, T., Sternovsky, Z. & Ulibarri, Z., Review of Scientific Instruments 871, 24502–24502 (2016).

Advanced designs for non-imaging submillimeter-wave Winston cone concentrators
Nelson, A. O. & Grossman, E. N., Proceedings of SPIE 9102, 91020U (2014).

Thesis

Comprehensive dynamic analysis of the H-mode pedestal in DIII-D
Nelson, A. O. PhD thesis, Princeton University, Available from ProQuest Dissertations & Theses Global (2021)

Co-Author Publications

2025

Accelerating Discoveries at DIII-D With the Integrated Research Infrastructure
Bechtel Amara, T., Smith, S. P., Xing, Z. A., Neiser, T. F., Simpson, C., Nelson, A. O., Denk, S., Colmenares, J., DeShazer, E., Antepara, O., Deshpande, A., Clark, M., Lestz, J., Tyler, N., Ding, P., Kostuk, M., Dart, E. Nazikian, R., Osborne, T., Williams, S., Uram, T. & Schissel, D. A. Frontiers of Physics, in press.

Achievement of highly radiating plasma in negative triangularity and effect of reactor-relevant seeded impurities on confinement and transport
Casali, L., Eldon, D., Odstrcil, T., Mattes, R., Welsh, A., Lee, K., Nelson, A. O., Paz-Soldan, C., Khabanov, F.,Cote, T., McLean, A. G., Scotti, F. & Thome, K. E., Plasma Physics and Controlled Fusion, in review.

Application of the Scrape-Off-Layer Fast Ion (SOLFI) code to assess particle motion in mirrors and tokamaks
Zhang, X., Lopez, N. A., Nelson, A. O., Rondini, L. & Poli, F. M., Fusion Engineering and Design, in review.

Characterization and controllability of radiated power via extrinsic impurity seeding in strongly negative triangularity plasmas in DIII-D
Eldon, D., Casali, L., Bykov, I., Chrystal, C., Erickson, K., Hyatt, A. W., Leonard, A. W., Moser, A. L., Nelson, A. O., Odstrcil, T., Paz-Soldan, C., Pederson, T., Scotti, F., Shen, H., Thome, K. E., Wang, H. Q., Welsh, A. & Wilks, T. M., Plasma Physics and Controlled Fusion, 67 015018 (2025).

Characterization of Turbulence Properties in Negative Triangularity DIII-DPlasmas
Stewart, S., McKee, G., Chrystal, C., Cote, T., Geiger, B., Khabanov, F., Nelson, A. O., Qin, X., Paz-Soldan, C., Schmitz, L., Thome, K. E. & Yan, Z., Plasma Physics and Controlled Fusion, in review.

First observations of edge instabilities in strongly shaped negative triangularly plasmas on DIII-D Cote, T. B., Yu, G., Nelson, A. O., Leuthold, N., Richner, N., Stewart, S., Khabanov, F., Zhu, Paz-Soldan, C., Schmitz, L., Thome, K. E., Austin, M. E. & Scotti, F., Plasma Physics and Controlled Fusion, in review.

Multimodal Super-Resolution: Discovering hidden physics and its application to fusion plasmas
Jalalvand, A., Curie, M., Kim, S., Seo, J., Hu, Q., Curie, M., Steiner, P., Nelson, A. O., Na, Y.-S & Kolemen, E., Science, in review.

2024

Assessment of vertical stability for negative triangularity pilot plants
Guizzo, S., Nelson, A. O., Hansen, C., Logak, F., & Paz-Soldan C., Plasma Physics and Controlled Fusion 66, 065018 (2024).

Characterizing the negative triangularity reactor core operating space with integrated modeling
Wilson, H., Nelson, A. O., McClenaghan, J., Rodriguez Fernandez, P., Parisi, J. & Paz-Soldan, C., Plasma Physics and Controlled Fusion, in review (2024).

Eﬀect of rotation on negative triangularity plasmas in DIII-D
Chrystal, C., Austin, M. E., Odstrcil, T., Paz-Soldan, C., Thome, K. E., Marinoni, A,. Boyes, W., Osborne, T., and Logan, N., and Hyatt, A. W. & Nelson, A. O., Plasma Physics and Controlled Fusion 66, 105004 (2024).

Examining transport and integrated modeling predictive capabilities fornegative-triangularity scenarios
McClenaghan, J., Marinoni, A., Nelson, A. O., Neiser, T., Lao, L. L., Staebler, G. M., Smith, S. P., Meneghini, O. M., Lyons, B. C., Snyder, P. B. & Austin, M., Plasma Physics and Controlled Fusion 66, 115008 (2024).

A Gaussian Process Guide for Signal Regression in Magnetic Fusion
Michoski, C., Oliver, T. A., Hatch, D. R., Diallo, A., Kotschenreuther, M., Eldona, D., Wallerb, M., Groebnera, R. & Nelson, A. O., Nuclear Fusion, in press (2024).

High performance power handling in the absence of an H-mode edge in negative triangularity DIII-D plasmas
Scotti, F., Marinoni, A., McLean, A. G., Paz-Soldan, C., Thome, K. E., Zhao, M., Allen, S., Austin, M., Burke, M. G., Eldon, D., Fenstermacher, M.,Hyatt, A., Lasnier, C. J., Leonard, A., Lore, J., Nelson, A. O. , Osborne, T., Sauter, O., Truong, D., Van Zeeland, M. A., Wang, H. Q. & Wilcox, R., Nuclear Fusion 64, 094001 (2024).

Kinetic-Ballooning-Bifurcation in Tokamak Pedestals Across Shaping and Aspect-Ratio
Parisi, J. F., Nelson, A. O., Gaur, R., Kaye, S., Parra, F., Berkery, J., Barada, K. K., Clauser, C., Creely, C., Diallo, A., Guttenfelder, W., Hughes, J., Kogan, L., Kleiner, A., Kuang, A., Lampert, M., Macwan, T., Menard, J. & Miller, M. A., Physics of Plasmas 31, 030702 (2024).

Kinetic-Ballooning-Limited Pedestals in Spherical Tokamak Plasmas
Parisi, J. F., Guttenfelder, W., Nelson, A. O., Gaur, R., Kleiner, A., Lampert, M., Avdeeva, G., Berkery, J., Clauser, C., Curie, M., Diallo, A., Dorland, W., Kaye, S. M., McClenaghan, J. & Parra, F. I., Nuclear Fusion 64, 054002 (2024).

Novel intrinsic helical cores and MHD dynamo flux pumping evidence in DIII-D
Boyes, W., Turco, F., Hanson, J., Navratil, G., Turnbull, A., Hyatt, A., Luce, T., Meyer, W., Nelson, A. O., Odstrcil, T.,Osborne, T., Scotti, F., Welander, A. & Wingen, A., Nuclear Fusion 64, 124005. (2024).

MANTA: A Negative-Triangularity NASEM-compliant fusion pilot plant
The MANTA Collaboration, Rutherford, G., Wilson, Haley S., Saltzman, A., and Arnold, D., Ball, J., Benjamin, S., Bielajew, R., De Boucaud, N., Calvo Carrera, M., Chandra, R., Choudhury, H., Cummings, C., Corsaro, L., DaSilva, Nigel., Diab, R., Devitre, A., Ferry, S., Frank, S., Hansen, C., Jerkins, J., Johnson, J., Lunia, P., Van De Lindt, J., Mackie, S., Maris, A., Mandell, N., Miller, M., and Mouratidis, T., Nelson, A. O., Pharr, M., Peterson, E., Rodriguez-Fernandez, P., Segatin, S., Tobin, M., Velberg, A., Wang, A., Wigram, M., Witham, J., Paz-Soldan, C. & Whyte, D., Plasma Physics and Controlled Fusion 66, 105006 (2024).

Overview of results from the 2023 DIII-D Negative Triangularity campaign
Thome, K. E., Austin, M. E., Hyatt, A. W., Marinoni, A., Nelson, A. O., Paz-Soldan, C., Scotti, F., Boyes, W. S., Casali, L., Chrystal, C., Ding, S., Du, X., Eldon, D., Ernst, D. R., Hong, R., McKee, G. R., Mordijck, S., Sauter, O., Schmitz, L., Barr, J. L., Burke, M. G., Coda, S., Cote, T., Fenstermacher, M. E., Garofalo, A. M., Khabanov, F., Kramer, G. J., Lasnier, C., Logan, N., Lunia, P., McLean, A. G., Okabayashi, M., Shiraki, D., Stewart, S. D., Takemura, Y., Truong, D., Osborne, T. H., Van Zeeland, M. A., Victor, B. S., Wang, H. Q., Watkins, J., Wehner, W. P., Welander, A. S., Wilks, T., Yang, J., Yu, G. & Zeng, L., Plasma Physics and Controlled Fusion 66, 105018 (2024).

Power handling in a highly-radiative negative triangularity pilot plant
Miller, M. A., Arnold, D., Wigram, M., Nelson, A. O., Witham, J., Rutherford, G., Choudhury, H., Cummings, C., Paz-Soldan, C. & Whyte, D. G.,. Plasma Physics and Controlled Fusion 66, 125004 (2024).

Simultaneous access to high normalized current, pressure, density, and confinement in strongly-shaped diverted negative triangularity plasmas
Paz-Soldan, C., Chrystal, C., Lunia, P., Nelson, A. O., Austin, M. E., Cote, T. B., Hyatt, A. W., Marinoni, A., Osborne, T. H., Pharr, M., Sauter, O., Scotti, F., Thome, K. E., Wilks, T. M. & Wilson, H. S., Nuclear Fusion 64, 094002 (2024).

Stability and Transport of Gyrokinetic Critical Pedestals
Parisi, J. F., Nelson, A. O., Guttenfelder, W., Gaur, R., Berkery, J., Kaye, S., Barada, K., Clauser, C.,; Diallo, A., Hatch, D., Kleiner, A., Lampert, M., Macwan, T., Menard, J., Nuclear Fusion 64, 086034 (2024).

TokaMaker: An open-source time-dependent Grad-Shafranov tool for the design and modeling of axisymmetric fusion devices
Hansen, C., Stewart, I. G., Burgess, D., Pharr, M., Guizzo, S., Logak, F., Nelson, A. O. & Paz-Soldan, C., Computer Physics Communications 298, 109111 (2024).

Toroidal injection angle dependence of EC assisted plasma initiation at DIII-D
Yang, J., Sips, A., De Vries, P., Sinha, J., Kim, H., Glass, F., Austin, M., Van Zeeland, M., Herfindal, J., Shafer, M., Nelson, A., Marini, C. & Yoo, M., Nuclear Fusion 64, 126065 (2024).

2023

Geometric dependencies of the mean E × B shearing rate in negative triangularity tokamaks
Singh, R., Diamond, P. & Nelson, A. O., Nuclear Fusion, 63 126053 (2023).

Understanding the negative triangularity ELM trigger and ELM free state on DIII-D with ECE-imaging
Yu, G., Li, Z., Kramer, G., Scotti, F., Nelson, A. O., Diallo, A., Lasnier, C., Austin, M. E., Qin, X., Chen, Y., Zheng, Y., Zhu, Y. & Luhmann, N. C., Physics of Plasmas 30 062505 (2023).

2022

Accelerated Workflow for Advanced Kinetic Equilibria
Bechtel, T. A., Nelson, A. O., Lao, L. L., Xing, Z. A., Smith, S. P., Nazikian, R., Flanagan, S., Schissel, D., Stephey, L., Thomas, R., Williams, S., Antepara, O., Dart, E., Koleman, E. & Tang, W., Proceedings of the First Combined International Workshop on Interactive Urgent Supercomputing CIW-IUS, 1-5 (2022).

A survey of pedestal magnetic fluctuations using gyrokinetics and a global reduced model for microtearing stability
Curie, M., Larakers, J. L., Hatch, D., Nelson, A. O., Diallo, A., Hassan, E., Guttenfelder, W., Halfmoon, M., Kotschenreuther, M., Hazeltine, R. D., Mahajan, S. M., Groebner, R. J., Chen, J., Perez von Thun, C., Frassinetti, L., Saarelma, S., Giroud, C. & Tennery, M., Physics of Plasmas 29, 042503 (2022).

DIII-D research advancing the physics basis for optimizing the tokamak approach to fusion energy
Fenstermacher, M. E. et al., Nuclear Fusion 62, 042024 (2022).

Radiative pulsed L-mode operation in ARC-class reactors
Frank, S., Perks, C. J., Nelson, A. O., Qian, T., Jin, S., Cavallaro, A. J., Rutkowski, A., Reiman, A. H., Freidberg, J. P., Rodriguez-Fernandez, P. & Whyte, D. G. . Nuclear Fusion 62, 126036 (2022).

Gyrokinetic analysis of inter-edge localized mode transport mechanisms in a DIII-D pedestal
Halfmoon, M. R., Hatch, D. R., Kotschenreuther, M. T., Mahajan, S. M., Nelson, A. O., Kolemen, E., Curie, M., Diallo, A., Groebner, R. J., Hassan, E., Belli, E. A. & Candy, J., Physics of Plasmas 29, 112505 (2022).

Identifying Microtearing Modes in the pedestal of DIII-D H-modes in Gyrokinetic Simulations
Hassan, E., Hatch, D. R., Halfmoon, M. R., Curie, M., Kotschenreuther, M. T., Mahajan, S. M., Merlo, G., Groebner, R. J., Nelson, A. O. & Diallo, A., Nuclear Fusion 62, 026008 (2022).

Alfvén eigenmode classification based on ECE diagnostics at DIII-D using deep recurrent neural networks
Jalalvand, A., Kappatou, A. A., Garcia, A. V., Nelson, A. O., Abbate, J., Austin, M., Verdoolaege, G., Brunton, S. L., Heidbrink, W. W. & Kolemen, E., Nuclear Fusion 62, 026007 (2022).

Optimization of 3D controlled ELM-free state with recovered global confinement for tokamak fusion plasmas
Kim, S. K., Shousha, R., Hahn, S. H., Nelson, A. O., Wai, J., Yang, S. M., Park, J. K., Nazikian, R., Jeon, Y. M., In, Y., Lee, J. H., Kim, J., Na, Y.-S. & Kolemen, E., Nuclear Fusion 62, 026043 (2022).

To dee or not to dee: costs and benefits of altering the triangularity of a steady-state DEMO-like reactor
Schwartz, J. A., Nelson, A. O. & Kolemen, E., Nuclear Fusion 62, 076006 (2022).

Design and experimental demonstration of Feedback Adaptive RMP ELM Controller towards complete long pulse ELM suppression on KSTAR
Shousha, R., Kim, S. K., Erickson, K. G., Hahn, S. H., Nelson, A. O., Yang, S. M., Park, J.-K., Wai, J., Jeon, Y. M., Lee, J. H., Jang, J., Seo, D. C. & Kolemen, E., Physics of Plasmas 29, 032514 (2022).

2021

Effect of n=1 RMP-driven Turbulence on Ion Pedestal and its role in Adaptive ELM control in KSTAR
Kim, S. K., Shousha, R., Hahn, S. H., Nelson, A. O., Wai, J., Yang, S. M., Park, J. K., In, Y., Lee, J. H., Kim, J. & Kolemen, E., Proceedings of 47th EPS Conference on Plasma Physics P4, 1067. (2021)

Neural Dynamical Systems: Balancing Structure and Flexibility in Physical Prediction
Mehta, V., Char, I., Neiswanger, W., Chung, Y., Nelson, A. O., Boyer, M. D., Kolemen, E. & Schneider, J., 2021 60th IEEE Conference on Decision and Control (CDC), 3735–3742 (2021).

Electromagnetic torque measurements in DIII-D using internal/external magnetic field decomposition
Strait, E. J., Munaretto, S., Sweeney, R. M., Logan, N. C. & Nelson, A. O., Review of Scientific Instruments 92, 043516 (2021).

CAKE: Consistent Automatic Kinetic Equilibrium reconstruction
Xing, Z., Eldon, D., Nelson, A. O., Roelofs, M. A., Eggert, W. J., Izacard, O., Glasser, A., Logan, N., Meneghini, O., Smith, S. P., Nazikian, R. & Kolemen, E., Fusion Engineering and Design 163, 112163 (2021).

2020

Offline Contextual Bayesian Optimization for Nuclear Fusion
Chung, Y., Char, I., Neiswanger, W., Kandasamy, K., Nelson, A. O., Boyer, M. D., Kolemen, E. & Schneider, J., Machine Learning and the Physical Sciences Workshop at the 33rd Conference on Neural Information Processing Systems (NeurIPS), 1–12. (2020).

An improved theory of the response of DIII-D H-mode discharges to static resonant magnetic perturbations and its implications for the suppression of edge localized modes
Fitzpatrick, R. & Nelson, A. O., Physics of Plasmas 27, 072501 (2020).

Real-time pedestal optimization and ELM control with 3D fields and gas flows on DIII-D
Laggner, F. M., Eldon, D., Nelson, A. O., Paz-Soldan, C., Bortolon, A., Evans, T. E., Fenstermacher, M. E., Grierson, B. A., Hu, Q., Humphreys, D. A., Hyatt, A. W., Nazikian, R., Meneghini, O., Snyder, P. B., Unterberg, E. A. & Kolemen, E., Nuclear Fusion 60, 076004 (2020).

Infrared Constrained Equilibria and Application to Snowflake Divertor Studies
Wai, J. T., Vail, P. J., Nelson, A. O., Xing, Z. A., Lasnier, C. & Kolemen, E., Nuclear Materials and Energy 25, 100835 (2020).

2019 and prior

Sputtering of lithium and lithium compound films under deuterium and helium ion bombardment
Buzi, L., Nelson, A. O., Yang, Y., Kaita, R., Krstić, P. S. & Koel, B. E., Nuclear Materials and Energy 19, 411–415 (2019).

Offline Contextual Bayesian Optimization
Char, I., Chung, Y., Neiswanger, W., Kandasamy, K., Nelson, A. O., Boyer, M. D. & Kolemen, E., Advances in Neural Information Processing Systems 32, 4629–4640 (2019).

Post exposure time dependence of deuterium retention in lithium and lithium compounds
Yang, Y., Buzi, L., Nelson, A. O., Kaita, R. & Koel, B. E., Nuclear Materials and Energy 19, 161–165 (2019).

Hydrogen retention in lithium and lithium oxide films
Buzi, L., Yang, Y., Domínguez-Gutiérrez, F. J., Nelson, A. O., Hofman, M., Krstić, P. S., Kaita, R. & Koel, B. E., Journal of Nuclear Materials 502, 161–168 (2018).

Non-Imaging Winston Cone Concentrators for Submillimeter-Wave, Overmoded Waveguide
Grossman, E. N., Friedman, O. D. & Nelson, A. O., IEEE Transactions on Terahertz Science and Technology 4, 65–74 (2014).