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Anton Jansen van Vuuren (Swiss Plasma Center, EPFL)28/09/2026, 09:10
Energetic particles (EPs) are essential for plasma heating and current drive in present and future fusion devices, but their confinement can be degraded by Alfvén eigenmodes (AEs) and related instabilities [1]. Developing robust methods for AE control is therefore important for preserving EP confinement and reducing fast-ion losses in reactor-relevant regimes [2]. Recent experiments on the...
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Ken McClements (UKAEA)28/09/2026, 09:45
Spontaneous, strongly supra-thermal ion cyclotron emission (ICE) at or close to multiple ion cyclotron harmonics has been detected in many magnetically-confined plasmas, and is usually attributed to velocity space inversion in an energetic ion population. It thus provides a passive diagnostic of these ions that can be combined with other measurements to enhance understanding of their...
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Pablo Oyola (Princeton Plasma Physics Laboratory)28/09/2026, 10:10
Fast ions generated by neutral beam injection (NBI) or radio-frequency (RF) heating can resonantly interact with background plasma and excite Alfvénic eigenmodes (AEs), in turn leading to enhanced fast-ion transport and potential damage to reactor components [1]. The combined use of RF and NBI heating exhibits mixed effects on AE activity—mitigating or enhancing mode excitation in NSTX(-U)...
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Prof. LIU CHEN (UNIVERSITY OF CALIFORNIA, IRVINE)28/09/2026, 11:00Invited
We have further extended previously derived expressions for zonal electromagnetic fields (ZFs) beat driven by reversed shear Alfvén eigenmode (RSAE) [L. Chen et al., Nucl. Fusion 65 (2025) 016018] to the case of toroidal Alfvén eigenmode (TAE). It is found that the expression of zonal current (i.e., the zonal component of the parallel vector potential) remains robust. The expression of the...
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Riccardo Stucchi28/09/2026, 11:35
Simulations and experiments have shown that zonal flows can play a crucial role in the regulation of turbulence. In the context of energetic particles physics for magnetic confinement devices, it is then interesting to study how the interplay of energetic particles and Alfvén eigenmodes can affect the dynamics of zonal flows, and more in general zonal structures, and potentially impact the...
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Phillip Bonofiglo (PPPL - Princeton Plasma Physics Laboratory (US))28/09/2026, 12:00
This report presents experimental and modeling studies on the interaction between energetic particles, Alfvén eigenmodes (AEs), and thermal plasma turbulence in neutral-beam-heated MAST-U spherical tokamak plasmas. These studies address the nonlinear coupling between fast-ion-driven MHD activity and microturbulence, with emphasis on the impact of energetic particles on turbulence regulation...
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Yuehao Ma (University of Science and Technology of China)28/09/2026, 12:25
In tokamaks, it is well established that sheared flows mitigate turbulence that drives heat and particle transport, thereby providing a direct pathway to improved confinement. In particular, achieving the ITER steady-state and long-pulse high-performance operation relies on the internal transport barrier (ITB), a narrow region of steep pressure gradients that improves core plasma...
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Antti Snicker (VTT Technical Research Centre of Finland Ltd.)28/09/2026, 16:15
Fast-ion interactions with plasma-facing components remain an important open question for ITER, particularly after the recent transition to a full tungsten first wall. Tungsten sputtering is expected to be mostly caused by the thermal plasma, but lost fast ions such as fusion-born alpha particles may contribute to tungsten sputtering. The extent of fast ion contribution depends on both the...
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Roman Ochoukov (IPP - Max-Planck-Institut für Plasmaphysik (EU))28/09/2026, 16:50
This study is motivated by the observation of a macroscopic (~10 cm in scale) carbon tile failure in the ion cyclotron range of frequencies (ICRF) limiter structure during a hydrogen minority ion cyclotron heating scenario in D plasma on ASDEX Upgrade (AUG). In this discharge (#42762): the on-axis magnetic field is 2.65 T, the plasma current is 0.36 MA, the core plasma electron density is...
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Fabio Camilo de Souza (UKAEA)28/09/2026, 17:15
Future tokamak power-plant prototypes will rely on alpha heating to sustain burning-plasma conditions. However, the transport and loss of a minority of energetic alpha particles can lead to significant heat loads on plasma-facing components (PFCs), which must withstand unprecedented steady-state particle and power fluxes during operation.
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The development and validation of reliable workflows... -
Don Spong (Oak Ridge National Laboratory)29/09/2026, 09:00
Recently stellarators have made significant progress with respect to improvements in the classical guiding center energetic particle confinement via shape optimization [1]. However, as has been observed with tokamaks once the neoclassical confinement is reduced to a low level, the confinement properties of energetic particle (EP) populations may be more dominated by instability-induced...
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Ryosuke SEKI (National Institute for Fusion Science)29/09/2026, 09:35
In magnetic confinement fusion devices, there are multiple fast-ion species such as fusion product (i.e., α particles) and fast deuterons produced by neutral beam injection. These fast ions may induce MHD instabilities such as Alfvén Eigenmodes (AEs) which can enhance fast-ion transport and losses. The study of fast-ion-driven MHD instabilities is one of the important topics for fusion...
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Dr Panith Adulsiriswad (adulsiriswad.panith@qst.go.jp)29/09/2026, 10:00
The tokamak hybrid scenario is a candidate for long-pulse, sawtooth-free operation in ITER. This sawtooth-free state is attributed to its robust, near-flat q≳1 core safety factor profile, maintained by the long-lived MHD-driven current redistribution that hinders the peak current profile. A notable example is the long-lived m/n=1/1 quasi-interchange mode. However, this m/n=1/1 mode leads to...
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Miguel Calvo Carrera (Massachusetts Institute of Technology)29/09/2026, 10:25
Alpha particles typically exhibit collisionless dynamics throughout most of their phase space. However, their motion can be very sensitive to collisions under resonant conditions. The collision operator is required to resolve the singular behavior around resonances, allowing the formation of a collisional boundary layer, where a perturbed distribution function forms and drives radial...
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James Oliver (UKAEA)29/09/2026, 11:20
The Joint European Torus (JET) recently completed historic deuterium-tritium (D-T) campaigns, which provided unique opportunities to study burning plasma physics. Alfvén eigenmodes were excited by fusion-born α particles [1] in several high-performance plasmas with fusion power > 8 MW externally heated only by neutral beam injection at up to 32 MW [2]. These modes were absent in pure deuterium...
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Emma Devin (Princeton University)29/09/2026, 11:55
The kinetic destabilization of gap modes, e.g., toroidal Alfvén eigenmodes, results in both diffusive and convective transport of energetic particles [1]. In scenarios where fast relaxation events result in very rapid redistribution of fast ions or rapid changes to the mode resonance conditions, a mode can be excited in a regime far from the instability threshold. For example, strong Alfvén...
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Dr Jari Varje (Tokamak Energy Ltd)29/09/2026, 12:20
ST40 is a high-field spherical tokamak with a major radius up to 0.55 m and toroidal magnetic field up to 2.1 T, operating at plasma currents ranging from 0.2-1.0 MA. It is equipped with two neutral beam injectors (NBI) with 1.0 MW at 55 keV and 0.8 MW at 24 keV. Across the wide toroidal field range the fast ions from NBI can range from sub- to super-Alfvénic, driving a variety of Alfvénic...
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Rui Coelho (Instituto Superior Tecnico - IPFN)29/09/2026, 16:00
Future fusion power plants will operate in the burning plasma regime, where a substantial fraction of the plasma heating is provided by fusion-born alpha particles produced in DT reactions. Understanding the generation, slowing down and confinement of these energetic particles is therefore essential and remains a major objective of present experimental, theoretical and modelling efforts in...
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Philipp Lauber (MPG IPP Garching)29/09/2026, 16:35
In next-step fusion devices, the physics of energetic particles (EP) will play a prominent role in distinct ways. For fusion power plants, such as DEMO-type or first-of-a-kind devices [1, 2], the self-organization of an alpha-particle heated plasma strongly depends on the transport and cross- scale coupling properties of the EP-driven meso- and background-driven micro-scale fluctuations...
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Alex Tinguely29/09/2026, 17:00
This talk will describe recent progress in modeling and diagnosing energetic particles in the SPARC tokamak, specifically DT-fusion alpha particles and runaway electrons (REs). First, alpha-driven MHD instabilities (such as Toroidal Alfven Eigenmodes) are simulated with several linear and nonlinear hybrid kinetic-MHD codes, including M3D-C1; these show good agreement in predicting a “most...
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A. LeViness (Commonwealth Fusion Systems)29/09/2026, 17:25
The ARC tokamak, currently under design by Commonwealth Fusion Systems, is expected to produce over 1 GW of fusion power in a deeply burning plasma regime with Q > 50.[1] Fusion-produced alphas will carry over 200 MW of power and act as the dominant source of heating in ARC, and if poorly confined, can cause melting or sputtering of the first wall. This work presents an overview of alpha...
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Mr Seongbin Hong (POSTECH)30/09/2026, 09:00
Energetic-ion redistribution and loss induced by MHD activity are critical issues for present fusion experiments and future burning plasmas [1,2]. In future fusion power plants, energetic-particle diagnostics must operate in reactor-relevant environments where access, neutron/gamma radiation, and the use of active beam-based measurements may be limited. Radio-frequency diagnostics are...
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Andong Xu (Peking University)30/09/2026, 09:35
This report presents an overview of the experimental results and data processing advancements in fast-ion diagnostics using neutron emission spectroscopy (NES) on the EAST tokamak.
The EAST NES system comprises multiple spectrometers arranged along four lines of sight (LOS), including a time-of-flight enhanced diagnostic (TOFED), a stilbene crystal, three liquid scintillators, a CLYC, a...
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Dr Vasili Kiptily (UKAEA, United Kingdom)30/09/2026, 10:00
Studying the mechanisms of energetic α-particle slowing down, redistribution and the development of optimal plasma conditions for their confinement is a priority task for burning fusion reactors. The harsh radiation environment of deuterium-tritium (D-T) fusion reactors makes realisation of this task extremely difficult since a restricted set of plasma diagnostics will be available. In this...
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Taeuk Moon (Korea Institute of Fusion Energy)30/09/2026, 10:25
Modern devices such as KSTAR and ITER are crowded with heating ports, cooling channels, and diagnostics, and rely on auxiliary heating such as neutral beam injection (NBI), so that beam power deposition and the resulting plasma-facing component (PFC) heat loads are governed by real, non-axisymmetric engineering geometry that idealized toroidally symmetric models cannot capture....
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Dr Kyle Callahan (UCI)30/09/2026, 11:20
An empirical method for inferring MHD-induced anomalous fast ion transport from normalized Electron Cyclotron Emission (ECE) temperature fluctuation measurements is reported. The model developed infers a time-dependent, spatially varying anomalous fast ion diffusion profile directly from normalized temperature fluctuations such that $D_{fast} \propto dT/T$. The model is coupled to the Monte...
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Sergei Sharapov (UK Atomic Energy Authority, UK)30/09/2026, 11:55
The MAST-U spherical tokamak [1] with aspect ratio R/a [m] = 0.8/0.5, max B=0.72 T at 0.8 m, elongation up to 2.5, operated at 1 MA currents recent two years and delivered high D-D fusion beam-plasma performance. This performance was achieved with two deuterium NBI sources, one of which was on-axis, and the other - off-axis (shifted by 65 cm from the magnetic axis up). Of particular interest...
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Klara Bogar (Institute of Plasma Physics of the CAS, Prague, Czech Republic)30/09/2026, 12:20
Fast neutral beam injection into magnetically confined plasmas produces pairs of fast ions and electrons at their ionization location. While the electrons remain close to the ionization flux surface, fast ions experience substantially larger drift orbits, resulting in a radial displacement between positive and negative charges. This charge separation contributes to the formation of a radial...
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Dr Juan Ruiz ruiz (University of York (EU))01/10/2026, 09:00
We report Doppler backscattering (DBS) measurements and gyrokinetic simulations of alternating Alfvénic bursts in a JET plasma previously analysed by Ruiz Ruiz et al. [Phys. Rev. Lett. 134, 095103 (2025)]. The DBS measurements show that fluctuation power in the ITG-turbulence frequency range is anticorrelated with the fluctuation power of modes in the gaps of the Alfvénic spectrum, with the...
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Xiaodi Du (GAT - Fusion Energy Research General Atomics (US))01/10/2026, 09:35
The suppression of ion temperature gradient (ITG) turbulence by the nonlinear evolution of toroidicity-induced Alfvén eigenmodes (TAEs) is demonstrated in the DIII-D tokamak [1]. Systematic measurements of plasma parameters reveal that this phenomenon is characterized by: (1) a reduction in the poloidal correlation length of ITG from 5 cm to 2 cm and a 30% decrease in the radial correlation...
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Ruirui Ma01/10/2026, 10:10
Achieving good confinement in tokamak advanced scenarios requires understanding and controlling Alfvénic instabilities driven by energetic particles (EPs). Reversed-shear Alfvén eigenmodes (RSAEs) [1, 2] are commonly observed in plasmas with nonmonotonic safety-factor profiles and can cause substantial EP transport and losses, making their nonlinear saturation mechanisms critical for...
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William Heidbrink01/10/2026, 10:35
Alfvén eigenmodes (AE) create a regime in the DIII-D tokamak where zonal flows and currents strongly suppress ion-temperature-gradient (ITG) turbulence. This oral focuses on the differences between AEs in the strongly suppressed ITG regime and “normal" AEs in unsuppressed plasmas. Strongly suppressed cases are compared to closely matched reference shots at several stages: (1) before the...
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Jialei Wang (National Institute for Fusion Science)01/10/2026, 11:20
Recurrent bursting Alfvénic instabilities can severely degrade energetic-particle (EP) confinement and impose transient loads on plasma-facing components. We recently reported the first comprehensive simulations of ICRF-heated tokamak plasmas on the slowing-down timescale with the kinetic-MHD hybrid code MEGA, where shear Alfvén wave induced minority ion transport is self-consistently retained...
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Eric Bass01/10/2026, 11:55
A new self-saturation regime for energetic particle (EP) driven Alfvén eigenmodes (AEs) at reactor-like ρ is identified using the CGYRO [1] gyrokinetic flux-tube code. This new saturation regime could markedly reduce the predicted impact of AEs in future reactors. Previous nonlinear gyrokinetic flux-tube studies [2,3] of fast ion-driven AEs at higher values of ρ associated with modern...
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Dr Pengjuan Su (Key Laboratory of Frontier Physics in Controlled Nuclear Fusion and Institute of Plasma Physics, Chinese Academy of Sciences)01/10/2026, 12:20
Energetic particles (EPs) from fusion reactions and auxiliary heating can drive symmetry-breaking shear Alfvén wave (SAW) instabilities, including AEs and EPMs, via resonant wave-particle interactions, and understanding their nonlinear evolution is critical for understanding the alpha particle confinement in next-generation devices like ITER and CFEDR.
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In our previous work [1], nonlinear... -
Michael Fitzgerald (UKAEA)01/10/2026, 16:15
It has long been understood that alpha particle equilibrium in tokamaks relies on the existence of approximate symmetries in time, gyroangle and toroidal angle. Violation of these symmetries in tokamaks leads to energetic particle losses observed in simulation and experiment. This behaviour is well modelled in terms of collisionless particle trajectories.
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In stellarators, a chief concern for... -
Jacobo Varela Rodriguez (Institute for Fusion Studies UT-austin)01/10/2026, 16:50
Core density collapses (CDC) events observed in the Large Helical Device (LHD) are a major concern for the performance of future Stellarator reactors, particularly for quasi-symmetric magnetic field configurations with weak magnetic shear. CDC severely restrict the maximum β of LHD outward shifted magnetic axis configurations, strongly fueled by pellets and heated by neutral beam injector...
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Alexandra Lachmann (Columbia University)01/10/2026, 17:25
Modulations in amplitude and phase of Alfvénic eigenmodes (AEs) may occur due to wave particle interactions with energetic particle (EP) distribution functions [1]. Damping can shrink the resonance with the mode, creating a hole-clump pair in the region of the shrunken resonance [1]. Hole-clump pairs in phase space are associated with phase modulations (chirps) of modes and propagate through...
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Alexander Battey (Ecole Polytechnique Federale de Lausanne (EPFL), Swiss Plasma Center (SPC), CH-1015 Lausanne, Switzerland)02/10/2026, 09:00
Wave–particle interactions have emerged as a promising pathway for directly affecting runaway electron (RE) dynamics and enabling new mitigation strategies in tokamaks. Recent experiments on the DIII-D tokamak explored both externally launched and self-generated waves that resonantly interact with the RE population.
Experiments utilizing externally launched electron cyclotron (EC) waves...
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Boris Breizman (The University of Texas at Austin)02/10/2026, 09:35
Energetic-particle-driven instabilities in plasmas commonly modify the particle distribution function to establish a balance between the instability drive and the wave-damping rate. This balance can last long in the presence of particle sources and sinks. In such situations, a stationary spectrum of turbulence and the distorted distribution of particles need to be determined self-consistently....
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chenxi luo02/10/2026, 10:00
Multiple low-frequency beta-induced Alfvén eigenmodes (BAEs, 10 - 20 kHz) and a high-frequency toroidal Alfvén eigenmode (TAE, 120 - 145 kHz) driven by runaway electrons are simultaneously observed in the EAST low-density Ohmic discharges. A new high-frequency mode (HFM, 100 - 170 kHz), generated by nonlinear coupling between BAEs and TAE, are conclusively identified.
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The experiments were... -
Tong Liu (Dalian University of Technology)02/10/2026, 10:25
High-energy relativistic runaway electron (RE) beams emerge during plasma disruptions in tokamaks through avalanche multiplication processes. This phenomenon arises from the synergistic interplay of Dreicer acceleration and knock-on collisions, potentially jeopardizing plasma-facing components through localized energy deposition exceeding 10 MJ/m². Advanced MHD simulations have revealed that...
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Mario Podesta02/10/2026, 11:20
Projecting fast ion dynamics from present devices to a fusion reactor requires a combination of experimental results and numerical models. Confidence in the models relies on their extensive validation to ensure that the underlying physics is correct, as well as to assess their range of validity and possible limitations. Experiments on TCV have revisited the physics of well-known instabilities...
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Mr Quentin Kernel (EPFL - Swiss Plasma Center)02/10/2026, 11:45
Energetic-particle-driven instabilities can induce strong fast-ion redistribution and losses, thereby degrading plasma heating and confinement. This is a key concern for future burning plasmas such as ITER, where fusion-born alpha particles are expected to drive resonant wave-particle interactions. To limit these, it is important to understand the associated phase-space transport [1] and, more...
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Francesco Porcelli (Politecnico di Torino)02/10/2026, 12:20
An overview on Vertical Displacement Oscillatory Modes driven by fast ions is presented. These modes have been identified by analytic work in 2022 [1,2] and their existence for realistic tokamak geometry has been confirmed by numerical simulations using the NIMROD code [3]. Together with Global Alfvén Eigenmodes (GAE), VDOM are a candidate to explain the observation of axisymmetric, saturated...
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Prof. Yasushi Todo (National Institute for Fusion Science)Poster session IPoster
We have developed a two-fluid model of the energetic-particle-driven geodesic acoustic mode (EGAM) in magnetically confined toroidal plasmas by applying fluid models to the bulk plasma and energetic particles separately. Analysis of the theoretical model reveals two EGAM solutions with high and low frequencies. In the high-frequency mode, the pressure perturbations of the two components...
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Andrea Valentini (University of Milano Bicocca)Poster session IPoster
In this work, we show an alternative approach for calculating energy spectra of particles generated via fast ions in magnetized plasmas reacting with a finite temperature bulk. While numerical methods account for all degrees of freedom involved, recently developed analytical methods [1-3] disregard the temperature of the bulk plasma in favor of faster calculations. Here, we still make use of...
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Seppo Sipilä (Aalto University)Poster session IPoster
The Monte Carlo orbit-following code ASCOT /1/ is a widely used tool for simulating fast ion minority populations in toroidal devices, featuring source modules for fusion products (AFSI) and neutral beam injection (BBNBI) as well as modelling of ion cyclotron resonance heating (RFOF). In addition to its capability to simulate the formation of hot ion tail distributions from various sources in...
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Jeff Lestz (University of California Irvine)Poster session IPoster
Several reduced models exist for predicting anomalous energetic particle (EP) transport that may be induced by instabilities such as Alfven Eigenmodes, spanning a wide spectrum of fidelity and computational cost. However, these models have typically been validated against isolated experimental discharges instead of databases, providing an incomplete assessment of their reliability and...
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Eamon Hartigan-O'Connor (Princeton University)Poster session IPoster
Instabilities driven by energetic particles are central to the physics of a burning plasma. The majority of kinetic simulations and reduced models assume that the unstable distribution is already fully established when energetic-particle-driven modes grow unstable. In realistic scenarios, however, energetic particles may accumulate in the resonance on an effective timescale comparable to the...
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100. Consistent workflow for evaluating beam-target fusion rate with the orbit-following code ASCOT5Joona SissonenPoster session IPoster
Volumetric neutron sources (VNS) are being developed to produce 14 MeV DT neutrons for fusion materials testing. To limit the size and cost of such VNS, beam-driven systems utilising beam-target fusion reactions are widely studied [1]. Accurate prediction of the beam-target fusion rate is therefore essential for VNS design. Beam-target fusion rates are typically evaluated by first calculating...
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Anton Tykhyy (Institute for Nuclear Research, Kyiv, Ukraine)Poster session IPoster
Mechanisms of destabilization of toroidal Alfvèn eigenmodes (TAE) in tokamaks are analyzed with the aim to reveal those leading to modes propagating in the direction opposite to plasma current, i.e. counter-propagating modes (ctr-TAE). Plasmas with fast-ions sources [such as neutral beam injection (NBI), ion cyclotron resonance heating (ICRH), fusion reactions] and without them (Ohmic...
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Avigdor Veksler (Columbia University)Poster session IPoster
Understanding the interactions between the energetic particle (EP) distribution function with waves is critical for burning plasma operation in future reactor-scale stellarators. We develop a quasilinear theory for nonlinear alpha particle-AE interactions in stellarators, building on a resonance-broadened quasilinear model for tokamaks [1] in action-angle coordinates. Action-angle coordinates...
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Massimo Nocente (Instituto Nazionale di Fisica Nucleare (EU))Poster session IPoster
Following the end of the operations of the Joint European Torus (JET) and the recent development of a new baseline for ITER, future tokamaks will be based on a high Z first wall material and will no longer use beryllium. New developments in fast ion generation scenarios and neutron and gamma-ray diagnostics are necessary to provide both the instruments and the knowledge base required in...
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Alex Reyner Viñolas (University of Seville)Poster session IPoster
A. Reyner-Viñolas1,2, J. Galdon-Quiroga1, J.M. Ordonez-Jimenez1, J. Gonzalez-Martin3, J. Rueda-Rueda4, Ye.O. Kazakov5, R. Ochoukov6, R. Bilato6, W. Suttrop6, S. Sipilä7, L. Sanchis1, the ASDEX Upgrade teama and the WPTE teamb
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1. Department of Atomic, Molecular and Nuclear Physics, University of Seville, 41012 Seville, Spain
2. CNA (U. Sevilla, CSIC, J. de Andalucia), Sevilla,... -
Yunpeng Zou (Institute of Plasma Physics, Chinese Academy of Science)Poster session IPoster
The kinetic-magnetohydrodynamic hybrid code, MEGA, is employed to study the effect of energetic particle (EP) distribution on reversed shear Alfvén eigenmodes (RSAEs). Focusing on the most unstable (n=2) RSAE in an EAST discharge, the EP distribution is represented as a linear sum of multiple Gaussian functions, following Gorelenkov [Nucl. Fusion 45, 226 (2005)] and Liu [Phys. Plasmas 21,...
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Dr Guanming YANG (Southwestern Institute of Physics, Chengdu, China)Poster session IPoster
ITER plans to conduct the D-T fusion experiment in 2039. Effects of the resistive internal kink mode (IK) and fishbone instabilities on the redistribution and the transport coefficients of alpha particles in ITER 15 MA baseline scenario are numerically investigated using the particle tracing code PTC. The results of scanning the perturbation amplitude shows that the IK can result in alphas...
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Michael Van Zeeland (GAT - Fusion Energy Research General Atomics (US))Poster session IPoster
Localized electron cyclotron heating (ECH) can have a dramatic effect on neutral beam driven toroidicity induced Alfvén eigenmode (TAE) activity in DIII-D plasmas. In these experiments, ECH with varied current drive phasing was deposited at large radius near the location of TAEs that have been recently reported to locally stabilize ITG turbulence through the generation of sheared flows [1]....
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Dr Xiao-Long Zhu (Southwestern Institute of Physics)Poster session IPoster
In HL-3 H-mode plasma discharges, two new MHD instabilities have observed and identified. Both instabilities are localized in the outer region or the pedestal region of the plasma. The first is a low-frequency instability with f=0–50 kHz, exhibiting rapid frequency chirping and a toroidal mode number of n=3. It propagates in the ion diamagnetic drift direction, displays energetic-particle...
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Wei Chen (SWIP)Poster session IPoster
In HL-3 H-mode plasma discharges, two new MHD instabilities have observed and identified. Both instabilities are localized in the outer region or the pedestal region of the plasma. The first is a low-frequency instability with f=0–50 kHz, exhibiting rapid frequency chirping and a toroidal mode number of n=3. It propagates in the ion diamagnetic drift direction, displays energetic-particle mode...
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Mervi Mantsinen (Barcelona Supercomputing Center (EU))Poster session IPoster
Energetic-particle observations of second harmonic tritium heating in JET DTE3 and comparison with H-minority heating
M.J. Mantsinen $^{1,2}$, P. Jacquet$^{3}$, D. Gallart$^{1}$, K. Kirov$^{3}$, E. Lerche$^{3,4}$, D. Taylor$^{3}$, C.D. Challis$^{3}$, E. Delabie$^{5}$, A. Kappatou$^{6}$, D. Keeling$^{3}$, D. King$^{3}$, V. Kiptily$^{3}$, M. Nocente$^{7,8}$, E. Parr$^{3}$, S....
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Dr Henrik Järleblad (Department of Physics, Technical University of Denmark)Poster session IPoster
In future fusion power plants, to ensure safe and reliable operation, it will be necessary to be able to accurately and efficiently measure the distribution of energetic particles[1]. Since the fast-ion distribution cannot be measured directly, we need to reconstruct it from diagnostic measurements[2]. The problem of reconstructing the fast-ion distribution given measurements is an...
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Dr Chenyu Pan (Institute of Plasma Physics, Hefei Institutes of Physical Science Chinese Academy of Sciences, Hefei 230031, China)Poster session IPoster
Ion cyclotron resonance heating (ICRH) is a key auxiliary heating method for fusion reactors[1], supporting multiple heating schemes including minority, harmonic, and three-ion heating. These schemes generate fast ions that can efficiently drive Alfvén eigenmodes (AEs)[2], which can induce fast-ion redistribution or loss, potentially impacting plasma-wall interactions and first-wall...
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Feng Wang DLUT (Dalian University of Technology (CN))Poster session IPoster
Fast-ion transport in EAST plasmas is studied using a particle-tracing method for two cases: edge-localized-mode (ELM) electromagnetic perturbations alone and coexisting ELM and tearing-mode (TM) perturbations. The ELM perturbations are obtained from nonlinear BOUT++ simulations first and then mapped onto the triangular equilibrium mesh used in the Particle orbit Tracing Code (PTC). When ELM...
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Elizabeth Paul (Columbia University)Poster session IPoster
FIRM3D is an open-source Python/C++/CUDA software suite for modeling energetic particle dynamics in 3D magnetic fields. The core guiding-center integration routines grew out of SIMSOPT (Landreman et al., 2021), but have been extended to include additional physics and diagnostics not typically required in the stellarator optimization context. This standalone framework enables focused...
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Andreas Bierwage (QST)Poster session IPoster
Computationally inexpensive integrated codes simulating interactions between Alfvén waves and fast ions in tokamak plasmas make use of perturbative models for the intermediate and slow processes of instability growth, saturation, chirping and busting, and associated fast ion transport. Meanwhile, the processes by which an Alfvén mode's spatiotemporal structure forms are assumed to have been...
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Lina Velarde (Universidad de Sevilla)Poster session IPoster
Instabilities such as Edge Localised Modes (ELMs) can degrade confinement in tokamak plasmas [1, 2]. Externally applied Magnetic Perturbations (MPs) are used to suppress these instabilities [3]. This technique is still under investigation in many tokamaks, and its understanding is crucial for future fusion devices, as applying these perturbations can also have a detrimental effect on fast-ion...
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Cosmo GallaroPoster session IPoster
Gyrokinetic Simulations for Spherical Tokamak Energetic Particle-Turbulence Experiments
C. Gallaro¹†, T. Barberis¹, T. Adkins¹, P. J. Bonofiglo¹, and V. N. Duarte¹
¹Princeton Plasma Physics Laboratory, Princeton, New Jersey, USA
†cgallaro@pppl.govRecent experiments on the MAST-U spherical tokamak investigated the multi-scale coupling between energetic particles, Alfvénic eigenmodes...
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Charlson Kim (SLS2 Consulting)Poster session IPoster
Linear (n=1) hybrid kinetic-MHD simulations have been performed with the NIMROD code to investigate energetic particle effects on (m=1,n=1) stability in SPARC plasmas. Understanding energetic particle-driven instabilities is critical for burning tokamaks, where fusion-born alphas can strongly modify the stability of MHD modes, impacting plasma confinement and performance. Using the SPARC...
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Dr Hanzheng Li (National Institute for Fusion Science)Poster session IPoster
We develop a full-orbit delta-f energetic-particle model in the hybrid kinetic-MHD code MEGA and apply it to nonlinear simulations of a beam-driven, sub-cyclotron global Alfven eigenmode (GAE) in a low-field DIII-D plasma. The equilibrium and beam parameters are based on the NSTX-similarity DIII-D discharge reported by Heidbrink et al. (Nucl. Fusion 46, 324, 2006), for which the observed...
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Runzhe Zhang (University of Science and Technology of China)Poster session IPoster
Synergistic heating using Ion Cyclotron Range of Frequencies (ICRF) waves and Neutral Beam Injection (NBI) can produce fast ions (FIs) with energies significantly higher than those of the beam ions. The effects of NBI-ICRF synergy (NIS) FIs on NBI-fast-ion-driven fishbone instabilities are investigated using the M3D-K code. The FIs distribution function contains a slowing-down distribution and...
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Olivier Panico (Ecole Polytechnique Fédérale de Lausanne (EPFL), Swiss Plasma Center (SPC), Lausanne)Poster session IPoster
Electromagnetic modes are routinely observed in tokamaks during runaway electron (RE) experiments [1-3]. These modes lie in both the Alfvénic and the lower hybrid frequency ranges. Theory and recent experiments suggest that such modes can enhance the pitch-angle scattering of REs [4], help reduce their maximum energy [5] and enhance their radial transport.
These modes therefore play a dual...
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Wei Shen (Institute of Plasma Physics, Chinese Academy of Science)Poster session IPoster
Numerical investigation of mode transition induced by fast particle transport in phase space on the EAST tokamak has been carried out by the global kinetic-magnetohydrodynamic (MHD) code M3D-K. Firstly, based on the fishbone instabilities observed on EAST, linear simulations show that the fishbone instability is excited at experimental value of beam ion pressure. When the beam ion pressure is...
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Prof. Gyungjin ChoiPoster session IPoster
The rigorous evaluation of magnetically trapped particle dynamics in 3D perturbed magnetic fields in toroidal magnetized plasmas remains a fundamental theoretical challenge. Standard bounce-averaging methods are often too rough or produce artificial singularities near the turning points due to the distortion of magnetic surfaces. This mathematical difficulty becomes a crucial physical issue...
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Dr Jose Rueda Rueda (Postdoctoral Researcher)Poster session IPoster
Resonant energy exchange between waves and particles is a fundamental concept in plasma physics. It was previously measured in satellite and basic laboratory experiments but has never been measured in the core of a magnetic fusion device. Now, however, thanks to DIII-D’s diagnostic suite, resonant energy exchange between energetic particles and Alfvén waves has been measured. This work...
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Amelia ChamblissPoster session IPoster
The impact of $\alpha$ heating on collisional transport of thermal species and the influence of Alfv\'en waves on fast ion transport are crucial mechanisms driving reactor-scale physics, though both remain important open questions for stellarator fusion power plants (FPPs). To better understand the latter, we compute the linear growth rates of Alfv\'en eigenmodes (AEs) in a reactor scale...
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Deyong Liu (General Atomics)Physics of energetic particle modes and transport IVOral
Sawtooth oscillations and the associated fast ion transport play a critical role in plasma stability, heating efficiency, and fusion performance. Despite general similarities, sawteeth show a broad variance in characteristics, such as sawtooth crash time, amplitude, and period, depending on the safety factor q, plasma current, plasma beta, plasma shape, and collisionality. The improved...
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Otso Hyvärinen (University of Helsinki)Poster session IPoster
Achieving burning fusion plasmas relies on the confinement of energetic fast ions, yet this remains challenging due to the gaps in our understanding of the fast-ion distribution function. However, the reconstruction of high-dimensional fast-ion distribution function is a severely ill-posed inverse problem. As a result, to find physically meaningful solutions, the experimental data must be...
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DEBABRATA BANERJEE (POLITECNICO DI TORINO)Poster session IPoster
Axisymmetric modes (toroidal mode n=0) have been observed in recent experiments on TCV with both co-current and counter-current directions injection of neutral beam [1]. These energetic particle driven global modes, prominently the GAE (Global Alfven Eigenmode), and the VDOM (Vertical Displacement Oscillatory Modes) [2], could potentially be driven by fusion alpha particles in future fusion...
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Xin WangPoster session IPoster
Frequency chirping of Alfvénic modes is a ubiquitous signature of the nonlinear phase-space dynamics of energetic particles (EPs) in tokamaks [1], and the chirping rate carries direct information on the resonant EP redistribution that limits fast-ion confinement [1]. Recent work shows that the nonlinear dynamics of the thermal plasma — beat-driven zonal fields and zonal currents together with...
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Dr Haider Rizvi (Korea Institute of Fusion Energy)Poster session IPoster
Most nonlinear simulations of Alfvén Eigenmode (AE) stability study one toroidal mode family at a time, yet in a real tokamak discharge several toroidal mode numbers $n$ are unstable simultaneously. When these families coexist, they compete for the same free energy, couple through three-wave interactions, and collectively drive zonal flows, none of which a single-$n$ model can describe. To...
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Simone Cavallero (Polytechnic of Turin, Princeton University)Poster session IPoster
Axisymmetric (n=0) perturbations in magnetically confined plasmas include distinct global oscillatory modes occurring in the Alfvénic frequency range, such as Global Alfvén Eigenmodes and Vertical Displacement Oscillatory Modes, both of which can couple resonantly to energetic particles and undergo nonlinear saturation in the presence of fast-ion drive. This is particularly relevant in NBI or...
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Dr Jian Bao (Institute of Physics, Chinese Academy of Sciences)Poster session IPoster
Recent fusion experiments have observed significant improvement in plasma confinement in the presence of fusion-born alpha particles [1,2], with Alfven eigenmodes playing a central role in regulating drift-wave microturbulence. First-principles gyrokinetic theory has proposed two mechanisms: direct three-wave interaction [3] and indirect interaction mediated via zonal fields or phase-space...
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Xiangfeng Wu (Dalian University of Technology)Poster session IPoster
The synergy between neutral beam injection (NBI) and ion cyclotron range of frequencies (ICRF) heating provides an effective route for tailoring fast-ion distribution functions and enhancing non-thermal fusion reactivity in tokamak plasmas. In this work, NBI–ICRF synergistic fast-ion physics in an EAST plasma scenario is investigated using complementary TRANSP and PTC simulations. NBI-only and...
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Yufan Qu (Southewestern Institute of Physics)Poster session IPoster
We report the analogous experimental observation of the nonlinear mode coupling preceding sawtooth crashes on HL-2A and HL-3 tokamaks. In this experiment, nonlinear mode coupling between m/n = 1/1 internal kink mode (where m and n are poloidal and toroidal mode number respectively) and energetic particle modes (EPMs) is conclusively identified by MEGA analysis, and the mode coupling is...
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Ningfei Chen (Max-Planck Institute for Plasma Physics)Poster session IPoster
The confinement and slowing-down of energetic particles (EPs) generated by fusion reaction and/or neutral beam injection (NBI) are essential topics in achieving self-sustained burning plasma [1]. Alfvén instabilities, which can be driven unstable by EPs [2], can induce significant EPs transport [3], among which the toroidal Alfvén eigenmode (TAE) is an important component due to its minimal...
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Lars-Göran Eriksson (Chalmers University of Technology, Gothenburg, Sweden)Poster session IPoster
There is evidence that axisymmetric modes can be driven by alpha particles in tokamaks [H. J. C. Oliver, Phys. Rev. Lett. \textbf{136}, 055101 (2026)]. It is therefore of interest to investigate the main mechanism behind the drive of the modes. When the distribution function of the non-thermal ions, $f_h$, is given as a function of the invariants of the unperturbed motion energy ...
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Daniil Kabirov (University of Seville)Poster session IPoster
In magnetically confined fusion devices, energetic particles produced by external heating systems such as neutral beam injectors (NBI) or ion cyclotron resonance heating (ICRH) may excite MHD instabilities such as Alfven Eigenmodes (AEs) which can degrade confinement in tokamak plasmas and potentially damage the plasma facing components [1]. Externally applied 3D Magnetic Perturbations (MPs)...
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Dmitry Moseev (IPP Greifswald)Poster session IPoster
Due to the 3D geometry, the toroidal canonical momentum is not an adiabatic invariant in stellarators. Typically, this leads to higher losses of fast ions in comparison with tokamaks. Wendelstein 7-X, an optimized stellarator, is predicted to have improved confinement of isotropically distributed fast ions in equilibria with high beta. Whether this property of the optimized equilibrium can be...
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Erik Eidsvig (IPP - Max-Planck-Institut für Plasmaphysik (EU))Poster session IPoster
For operation of future tokamak scenarios, a high pressure gradient favours the bootstrap mechanism, but also makes the plasma prone to MHD instabilities [1]. One of these instabilities is the fishbone instability, which is a 𝑚=𝑛=1 internal kink mode driven unstable by energetic particles [2]. It has been reported by both experimental and
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numerical studies that the fishbone instability is not... -
xiaoxi zhangPoster session IPoster
The interaction between fusion-born alpha particles and resistive MHD modes is a key stability concern for burning plasmas such as ITER. The neoclassical tearing mode — one of the most performance-limiting instabilities in these regimes — is itself driven by the helical perturbation of the bootstrap current associated with pressure flattening inside magnetic islands, which makes the perturbed...
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Mirko Salewski (Technical University of Denmark (ZZ))Poster session IPoster
Collective Thomson scattering (CTS) diagnostics have been installed at several machines and will be primary alpha-particle diagnostic at ITER. CTS measurements are sensitive to the projection of the local velocity distribution function in a measurement volume. The thermal ions with low projected velocities dominate the low-Doppler-shift part of CTS spectra whereas the fast ions with high...
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Francesco Palermo (UKAEA)Poster session IPoster
Spherical tokamaks (STs) represent one of the most promising research pathways towards fusion energy. Owing to their low aspect ratio, devices such as the Mega Amp Spherical Tokamak Upgrade (MAST-U) allow access to high-β plasma regimes, potentially offering a route towards more compact and efficient fusion reactors.
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In spherical tokamaks such as MAST-U, Alfvén Eigenmodes (AEs) can play an... -
Thomas Hayward-Schneider (Max Planck Institute for Plasma Physics, Garching)Poster session IPoster
We present recent progress of applying global electromagnetic gyrokinetics (GK) to future fusion devices. Results shown from the global GK particle-in-cell (PIC) code ORB5 [E. Lanti et al., CPC, 2020] include simulations of the EUROfusion Volumetric Neutron Source (VNS) [see also Ph. Lauber, this conference], for which simulations of Alfvén eigenmodes have been performed as well as for...
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Tommaso Barberis (Princeton Plasma Physics Laboratory)Poster session IPoster
We present a reduced framework to describe the multiscale interaction between thermal plasma microturbulence, energetic particles generated by auxiliary heating, and the macroscopic instabilities that these particles can drive. Our approach focuses on how microturbulence regulates the saturation amplitude of energetic-particle-driven modes, such as shear Alfvén waves, through...
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Mads Rud Larsen (École Polytechnique Fédérale de Lausanne)
A thorough understanding of the resonant interactions between fast
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ions and plasma instabilities is vital for the successful operation of burning plasmas in future devices, such as ITER. It is well described that fast ions can drive instabilities, causing confinement degradation or, alternatively, turbulence suppression [1]. Measuring the fast-ion distribution function from experimental data... -
Dr Pavel Aleynikov (Max-Planck-Institut für Plasmaphysik)Poster session IPoster
Stellarators are among the leading concepts for future fusion reactors, with a key advantage over tokamaks being their practical immunity to large-scale disruptions. The work [1] shows that a rapid shutdown of stellarator coil currents - leading to fast dissipation of poloidal magnetic flux - can nonetheless generate a strong toroidal electric field and drive a runaway-electron avalanche, even...
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Weixin Guo (Huazhong University of Science and Technology)Poster session IPoster
Future D–T burning plasmas generate energetic alpha particles that gradually evolve into thermalized helium ash. The resulting helium ions modify turbulence through dilution effects, while turbulence simultaneously regulates helium-ion transport. Understanding this mutual interaction is essential for predicting both confinement performance and helium-ash exhaust in future fusion reactors.
A...
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Dr Hao Wang (National Institute for Fusion Science)Poster session IPoster
Energetic particles (EPs) include fusion alpha particles and the fast ions from auxiliary heating. These particles can drive instabilities in a toroidal plasma. The instabilities then push the EPs outward. This lowers the heating efficiency and raises the heat load on the first wall.
These instabilities are studied with the MEGA code. MEGA is a hybrid code: the bulk plasma is a nonlinear...
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Edward Parr (UKAEA, Abingdon, Oxfordshire, UK)Poster session IPoster
The Charged Fusion Product Detector (CFPD) is a fast-ion diagnostic employing solid-state detectors to measure energies and production rates of charged fusion products [in particular p (3.02 MeV) and t (1.01 MeV) from D-D fusion] primarily from fast-ion induced reactions. Results obtained during the recent MU04 and MU05 (2024-26) MAST-U campaigns will be presented. The current diagnostic is an...
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Arkaprava Bokshi (UKAEA)Poster session IPoster
Transport of alpha-particles born in deuterium-tritium (D-T) nuclear fusion reactions is a key issue for magnetic fusion. Wave-particle resonant interactions – between Alfvén waves and alpha-particles born at super-Alfvénic energy – could induce significant radial re-distribution of alpha-particles, affecting both the self-heating efficiency and integrity of the first wall [1].
The effect...
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Huisan Cai (University of Science and Technology of China (CN))Poster session IPoster
Energetic particles (EPs) are essential for sustaining burning plasmas through self-heating, but they can also drive global instabilities that degrade EP confinement, making quantitative prediction of EP transport crucial for achieving high fusion performance. Among these instabilities, fishbone modes are particularly important because their macroscopic mode structures can induce significant...
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Abdullah Hyder (Columbia University)Poster session IPoster
Energetic particle (EP)-driven Alfvénic instabilities have been shown to play an important role in stellarators, as demonstrated by neutral beam fast ions in the W7-AS [1] and TJ-II [2] experiments. Alfvénic instabilities may be similarly important in fusion power plants driven by fusion-born alpha particles. However, a comprehensive numerical study of the shear Alfvén continuum in modern...
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