ABSTRACTS

Please submit your abstract for oral talks and poster presentations using this Google Form: https://forms.gle/yjtAcGnoxdup5Quu6 

Abstract submission will close on 7/19/2026.

Invited Speaker Abstracts: 

Jeff Lestz — University of California, Irvine

Experimental Evidence of Helicon Wave Heating and Current Drive in DIII-D 

J.B. Lestz, B. Van Compernolle, R.I. Pinsker, S.X. Tang, A. Dupuy, A.M. Garofalo, L. McAllister, C.P. Moeller, C.C. Petty, M. Porkolab, M.P. Ross, G. Rutherford, and A. Torrezan

Helicon current drive is an attractive solution for driving off-axis current to sustain steady state tokamak operation in reactor conditions. Dedicated DIII-D experiments have been conducted with a MW-level helicon system and successfully demonstrated core power deposition and current drive with helicon waves launched via a traveling wave antenna. The profile of the measured electron temperature response to helicon power injection is in good agreement with time-dependent integrated modeling that incorporates ray tracing and the effects of thermal transport simultaneously. The absorption is observed to scale with the normalized electron pressure βe, as theoretically predicted by Landau damping for single pass absorption. When the helicon is injected continuously to drive co-Ip current, the reconstructed safety factor profile flattens significantly faster and sawteeth are triggered earlier than in comparison shots where the helicon is replaced by a similar amount of electron cyclotron heating. Calculation of the non-inductive current profile due to helicon waves yields a peaked profile in the core, consistent with the observed power deposition profile, and in good agreement with ray tracing predictions. Taken together, these experimental results represent strong evidence for the first definitive observation of auxiliary current drive due to helicon waves on any device.

Shreekrishna Tripathi — University of California, Los Angeles

Destabilization of Ion Cyclotron Emission and EMIC Waves by a Proton Beam in a Large Magnetized Plasma Shreekrishna Tripathi — Physics and Astronomy, UCLA

The resonant interaction between energetic ions and plasma waves is a fundamental topic in space and laboratory plasma physics (e.g., the interaction of protons and alpha particles with ion-cyclotron and Alfvén waves in the solar wind, aurora, and magnetic fusion plasmas). Electromagnetic Ion Cyclotron (EMIC) waves propagate into distinct bands based on the number of ion species and relative concentration ratios. In the magnetosphere, these waves are destabilized by energetic protons (10-100 keV) through Doppler-shifted cyclotron resonance. Ion Cyclotron Emission (ICE) is observed at harmonics of the fast-ion gyro-frequency. The role of resonant processes in destabilizing these waves is examined with unprecedented detail in 3D using unique capabilities of the Large Plasma Device (LAPD). In these experiments, a proton beam (15 keV, 10 A) is injected into a large magnetized plasma (n ≈ 10¹⁰–10¹³ cm⁻³, Te ≈ 5.0–15.0 eV, B = 0.6–1.8 kG, He⁺ and H⁺ ions, 19 m long, 0.6 m diameter) for performing fast-ion studies. The beam forms a helical orbit (pitch angle ≈ 7°–55°) and propagates with an Alfvénic speed (beam-speed/Alfvén-speed = 0.2–3.0). The mode structure of waves and relevant plasma parameters are recorded using a variety of diagnostic tools (retarding-field energy analyzer, three-axis magnetic-loop, Dipole, and Langmuir probes). Experimental results demonstrate that the Doppler-shifted cyclotron resonance with energetic protons is efficient in generating broad spectra of Alfvén, EMIC, and ion cyclotron waves. These experiments have identified specific regimes of resonant interactions, in which beam-destabilized waves scatter protons over a wide range of pitch angles, suggesting a fascinating interplay between plasma waves and energetic protons in a laboratory plasma experiment.

Ehab Hassan — Oak Ridge National Laboratory

Integrated Modeling as a Pathway for Designing, Optimizing, and Controlling Next Generation of Tokamaks and Stellarators by Coupling Plasma Physics to Engineering Constraints Ehab Hassan, S. De Pascuale, C.S. Collins, G.M. Staebler, and J.M. Park — Fusion Energy Division, Oak Ridge National Laboratory

Multi‑fidelity Whole Device Modeling (WDM) frameworks integrate physics and engineering tools to design, evaluate, and optimize fusion reactors. These frameworks comprise multiple coupled subsystems that perform coordinated physics and engineering analyses within integrated workflows. WDM is being applied to re‑assess and optimize poloidal‑field (PF) and toroidal‑field (TF) coil designs and to develop non‑inductive, high‑fusion‑gain plasma scenarios in conceptual fusion devices such as the Fusion National Science Facility (FNSF) and the Compact Advanced Tokamak (CAT). The FreeGSNKE MHD free‑boundary equilibrium code has been used to reduce PF‑coil stresses by optimizing coil placement and structural design for FNSF and CAT, and to simulate time‑dependent full‑pulse evolution in tokamaks. In parallel, IPS‑FASTRAN has been used to develop MHD‑stable, non‑inductive operating scenarios with high fusion gain, a large bootstrap‑current fraction, and strong energy confinement. For stellarators, full‑pulse scenario development can be pursued by coupling equilibrium (VMEC), transport (ASTRA/GX), and heating/current‑drive models to evolve plasma profiles self‑consistently. After an optimal tokamak plasma scenario is identified, an additional engineering optimization layer is carried out to reduce thermal loads on plasma facing components. Overall, reactor performance can be maximized through self‑consistent integration and joint optimization of the physics and engineering components. WDM frameworks, combined with advanced actuators, also provide the foundation for digital‑twin capabilities for tokamaks and stellarators, which require real‑time prediction and control of plasma behavior. To enable real‑time applications, machine‑learning and neural‑network surrogate models are being developed to replace computationally expensive high‑fidelity codes, accelerating simulations and supporting real‑time control in fusion devices. These advances are expected to shorten the path to deploying fusion power on the electrical grid.

Jalaan Avritte — Auburn University

Analysis of Mixed Modes of Filament Morphologies in the MDPX Device Through a Convolutional Neural Network

To study the magnetic effects on dusty plasmas, magnetic fields, |B| ≥ 1 Tesla are often required. When these fields are applied to the capacitively coupled plasmas that are typically used to these systems, the uniformity of the plasma is disrupted. Past experiments have shown that the plasma will form self-organized, magnetic field aligned structures that are referred to as "filaments". A previous study categorized these filaments as singular "types" and their correlation with the degree of magnetization through the ion-Hall parameter. This talk expands on this previous work by classifying these filaments as azimuthal modes m similar to Archimedean spirals. Under this new classification, filament transformations and mixed modes are permitted to exist. By using a Convolutional Neural Network (CNN) to quantify these modes, the m = 1 mode is shown to be valuable in identifying filament transformations and mixed mode states. Lastly, future applications utilizing these morphologies to gain a deeper understanding of temporal and spatial plasma dynamics like electric field and transport are discussed.

Ben Antognetti — University of Wisconsin–Madison

Interactions between Bursts of High-Frequency Waves and Runaway Electrons in MST Tokamak Plasmas B.R. Antognetti, A.F. Almagri, B.E. Chapman, N.C. Hurst, M. Poulos, J.S. Sarff, M.A. Thomas, C.B. Forest — University of Wisconsin–Madison; M. Poulos — CompX

Non-thermal particle distributions can resonantly exchange energy with waves in magnetospheric, astrophysical, and laboratory plasmas. In tokamak fusion devices, this process may help to passively mitigate the harmful effects of high-energy runaway electrons (RE). We present results from low-density tokamak plasmas in the Madison Symmetric Torus where an internal B-dot probe is used to study waves driven by runaway electrons at high frequencies near and above the electron cyclotron frequency. Periodic bursts of waves are detected primarily in three frequency bands centered on 35 MHz, 1.3 GHz, and 3.2 GHz, and x-rays are simultaneously observed with energy 10–100 keV, likely due to RE striking the wall. The experiments are carried out with toroidal field BT = 0.13 T, average electron density 3×10¹⁷ m⁻³, edge safety factor 1.5–2.5, and background electron temperature Te = 100 eV. The bursts coincide with sawtooth-like MHD behavior which may serve to both accelerate the RE and drive them to the wall. Spatially-separated coils on the B-dot probe are used to measure the toroidal and poloidal wavenumbers. The data show that waves arrive in packets with varying wavenumbers. Ray-tracing simulations from the GENRAY code show that the waves may be confined, allowing them to gain energy from the RE over many orbits. Further properties of the waves and possible resonances inferred by the B-dot data are discussed. These novel results show that resonant wave-particle interactions with RE in tokamaks can be directly studied at high frequencies using internal probes, with applications to space/astrophysics and fusion energy.

Work supported by U.S. DOE award DE-SC0018266 and NSF award PHY 1828159

Krishan Kumar — West Virginia University

Role of Laser Polarization in Quantum Beat Spectroscopy for Magnetic Field Measurements in Plasmas

Magnetic fields exert a strong influence on plasma behavior, highlighting the need for diagnostic techniques that can measure magnetic fields with high accuracy while minimizing plasma perturbation. Quantum Beat Spectroscopy (QBS), recently demonstrated by Gilbert et al. [Plasma Sources Sci. and Technol. 34 025020 (2025)], is a laser-based optical diagnostic that provides Doppler-free, near single-shot measurements of magnetic field strength in laboratory plasmas. In this work, the effect of laser polarization on the QBS signal is investigated using a femtosecond laser in an argon plasma. The experiments are performed in a tabletop six-way cross vacuum chamber. A pair of Helmholtz coils mounted on a rotational stage keeps the chamber centered between the coils, allowing precise control over the orientation of the applied magnetic field. This study evaluates the feasibility of using polarization-resolved QBS measurements to determine both the magnitude and orientation of the magnetic field.

Cameron Kuchta — University of Wisconsin–Madison

Measurement of Electron Pressure Anisotropy during Laboratory Magnetic Reconnection

The Terrestrial Reconnection EXperiment (TREX) at the Wisconsin Plasma Physics Laboratory (WiPPL) studies collisionless magnetic reconnection using a cylindrically symmetric architecture. We have developed a pressure anisotropy probe that can measure plasma flows and temperature anisotropies during reconnection. With a three coil driving system, magnetic reconnection in our machine is in the collisionless kinetic regime in which we expect electron anisotropy effects to dominate the physics of the ion diffusion regime. Embedded jets, seen in laboratory data, are driven into the outflow as expected from spacecraft observation of the magnetosphere, theory, and simulations. Additionally, we have measured pressure anisotropy in the laboratory with the pressure anisotropy probe that validates prior results.

Tommy Steinberger — West Virginia University

Non-Perturbative Mapping of Inverted Sheaths in Low-Temperature Plasmas Using Planar LIF and QBS T.E. Steinberger and J.W. McLaughlin — Department of Physics and Astronomy, West Virginia University, Morgantown, WV

Plasma sheaths are among the most widely studied plasma phenomena because of their central role in regulating particle fluxes and energy deposition at plasma-facing boundaries. Despite this importance, key aspects of sheath formation remain poorly understood, particularly when the boundary emits electrons. In the classical picture, electrons and ions are lost from the plasma bulk to a surface such that the net current to a floating plasma-facing component is zero. This balance is significantly modified when the boundary emits electrons through thermionic emission or secondary electron emission. With increasing electron emission, a classical sheath can transition to a space-charge-limited sheath and, under sufficiently strong emission, to an inverted sheath. In the inverted sheath regime, ion current to the boundary is suppressed, and ions are no longer accelerated through a presheath from the plasma bulk to the sheath edge. Although inverted sheaths have been investigated extensively through computational and theoretical studies, direct experimental confirmation of these potential structures remains limited. In this talk, we describe recent developments of a plasma facility designed to systematically control electron emission from a boundary and access the transition from classical to inverted sheath structures. We also present emerging laser spectroscopic approaches for nonperturbative measurements of ion dynamics and electric potentials from the plasma bulk to the plasma-facing boundary.

Lingling Zhao — University of Alabama in Huntsville

Multiscale Interaction Between Solar Wind Turbulence and Shocks

Collisionless shocks in the solar wind are embedded within a turbulent plasma environment where fluctuations spanning a broad range of scales both influence and are modified by the shock transition. Understanding the coupling between shocks, turbulence, waves, and particles is essential for describing energy transfer and dissipation in heliospheric plasmas. We investigate turbulence-shock interactions through a combination of theoretical modeling and in-situ spacecraft observations. We present a theoretical framework in which pre-existing turbulence modifies shock structure, alters energy partition, and enables non-adiabatic energy conversion across scales. We then examine observations from Parker Solar Probe, Solar Orbiter, and Wind to characterize the multiscale plasma processes associated with collisionless shocks in the inner heliosphere. The analysis reveals the generation of ion-scale waves near shocks, systematic evolution of proton temperature anisotropy across shock transitions, and significant changes in turbulence properties and polytropic behavior downstream of shocks. These results support a multiscale picture in which collisionless shocks act not only as sites of energy dissipation but also as sources of waves and turbulence that regulate particle distributions and energy transfer.

Shea Hess-Webber — Stanford University & COFFIES Science Center

Connecting Laboratory Plasmas to the Solar Interior Presenting Author: Shea A. Hess-Webber, Stanford University & COFFIES Science Center Collaborators: Mel Abler, SSI; JT Stefan, NJIT; Nat Mathews, Paris Observatory; Bibhuti Kumar Jha, SwRI; Andrés Muñoz-Jaramillo, SwRI; Sushant Mahajan, Stanford University; Todd Hoeksema, Stanford University

Laboratory plasma experiments have been used extensively to study the necessarily-remote physics of the solar atmosphere and heliosphere in detail for decades. The coupling of these scientific disciplines comes naturally out of the accessible conditions of the plasma environment and the direct observations above the photospheric optical depth (τ=1). While experiments exist to investigate high plasma-beta physical regimes, it is more challenging to replicate solar surface/interior conditions. This is due to both the conditions required within the laboratory setting as well as the lack of directly comparable observations within the opaque solar surface. However, current solar surface and interior techniques — including MHD theory, flux transport models, and helioseismology — can greatly benefit from the measurements and insights that laboratory plasma physics can provide. In this talk, I will discuss some recent work in solar surface/interior, including machine-learning efforts, that would benefit from lab plasma collaborations, some proposed work that we are hoping to do in the near future, and some broader ideas about where our disciplines might be able to cross-pollinate.

Anna Tenerani — University of Texas at Austin

3D Spherically Polarized Alfvén Waves

The solar wind originating from coronal holes is made of Alfvén waves propagating away from the Sun. Despite the large amplitude of these magnetic fluctuations — sometimes producing field reversals known as switchbacks — the total magnetic field magnitude (B) remains remarkably constant. Geometrically, this property corresponds to spherical polarization, which is observed from near-Sun regions out to beyond 1 au, together with negligible density fluctuations. These characteristics motivate the common assumption in turbulence models that compressible effects play a minor role in the nonlinear dynamics of Alfvénic fluctuations. A longstanding question is whether fully three-dimensional, smooth magnetic field configurations can satisfy the constant-B constraint, and how such fields can be constructed analytically or numerically. Here we present a numerical method to construct magnetic field configurations that are exactly spherically polarized, reproducing key features of solar wind fluctuations. Within this framework, we demonstrate that, in three-dimensional geometry, discontinuities must develop where such solutions cease to exist. This result implies that continuous field rotations can preserve the constant-B condition only in limited regions of space, separated by discontinuities where magnetic compressibility cannot be neglected.

Yevgeny Raitses — Princeton Plasma Physics Laboratory

Electron-Beam-Generated E×B Plasmas and Their Applications: User and Host Team Research at the Princeton Collaborative Research Facility (PCRF) Yevgeny Raitses — Princeton Plasma Physics Laboratory, Princeton, NJ

There is growing interest in electron-beam (e-beam) generated low-temperature plasmas for atomic-scale materials processing with applications in microelectronics and quantum technologies. In these systems, the plasma (electron density ~10⁹–10¹² cm⁻³ and electron temperature ~0.1–10 eV) is produced by injecting an energetic electron beam (10²–10⁴ eV) into a low-pressure (10⁻¹–10² mTorr) background gas along an applied magnetic field (10–10³ G). The magnetic field confines the electron beam as it propagates through the plasma source, while an electric field applied perpendicular to the magnetic field enables control of the cross-field ion flux. This crossed electric and magnetic field (E×B) configuration allows selective generation of ions and reactive species while maintaining a spatially uniform flux of low-energy particles to large-area substrates, such as semiconductor wafers, located at the plasma periphery. These unique characteristics make e-beam-generated E×B plasmas highly attractive for low-damage materials processing. This talk will present an overview of theoretical, experimental, and computational studies of e-beam-generated magnetized plasmas conducted at the Princeton Collaborative Research Facility (PCRF). Topics will include electron and ion kinetics in e-beam plasmas, beam–plasma instabilities, plasma chemistry, applications to gentle processing of two-dimensional materials and diamond for quantum technologies, and advanced plasma diagnostics.

Kristopher Klein — University of Arizona

The Oblique Drift Instability: A Route to Ion Heating via Drifts in Magnetically Dominated Plasmas

Weakly collisional magnetized plasmas can store significant free energy in multi-component velocity distributions (VDFs), exhibited as temperature anisotropies and relative drifts between components or species. These instabilities can, in turn, impact the thermodynamics of the system in which they are embedded. Given the abundance of relative drifts in the solar wind, a quintessential collision-poor plasma in which VDFs can be measured in situ, we focus on oblique drift instability (ODI) in magnetically dominated plasmas driven by secondary ion populations. These instabilities convert ion drift energy into electromagnetic fluctuations which is subsequently transformed to heating of the proton core distribution. Motivated by Parker Solar Probe observations of typical plasma conditions, we show that this mechanism can regulate both the minimum attainable proton plasma β through proton heating and the maximum relative drift between alpha particles and core protons. ODI is shown to be able to alter the plasma kinetics at ion timescales — equivalent to MHz in most plasma devices — developing non-linear saturations during the lifetime of the plasma flow in a chamber. These results provide a laboratory-relevant, potentially testable, example of how kinetic instabilities mediate energy exchange, constrain distribution functions, and produce effective relaxation in weakly collisional multi-ion or multi-component plasmas.