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"Multimachine analysis of intermittent fluctuations in the scrape-off layer of magnetically confined fusion plasmas" by S. Ahmed et al.

Fusion energy holds the promise of providing a nearly limitless, clean, and sustainable energy source. To achieve this, scientists are working to develop fusion reactors that can confine extremely hot plasma—a state of matter where atoms are stripped of their electrons—using powerful magnetic fields. However, controlling plasma is a significant challenge, as it exhibits turbulent behavior that can lead to energy losses and damage to reactor walls. A new study published in Plasma Physics and Controlled Fusion sheds light on these turbulent fluctuations in the outer regions of plasma, known as the scrape-off layer (SOL), across six different fusion devices.

In fusion reactors, the SOL is the boundary region where plasma interacts with the reactor walls. This region is characterized by bursts of plasma filaments, often called "blobs," which carry particles and heat outward. These blobs can erode reactor walls and reduce the efficiency of the fusion process. Understanding the behavior of these fluctuations is crucial for designing future reactors, such as ITER and SPARC, to minimize damage and improve performance.

The study analyzed plasma fluctuations in six tokamaks—Alcator C-Mod, DIII-D, TCV, KSTAR, MAST, and MAST-U—using data from specialized probes inserted into the SOL. These devices represent a range of sizes, shapes, and magnetic field strengths, providing a comprehensive dataset for comparison. The researchers applied a statistical model, known as a filtered Poisson process, to describe the fluctuations as a series of random pulses. This model allowed them to extract key parameters, such as the duration of each pulse, the time between pulses, and the amplitude of the fluctuations.

The key findings include the following:

1. Density matters: The study found that as the core plasma density increases, the fluctuations in the SOL become more intermittent, with larger and less frequent bursts. This trend was particularly pronounced for the Alcator C-Mod device, where the amplitude of the fluctuations increased sharply as the plasma density approached a critical limit.

2. Impact of magnetic fields: Stronger magnetic fields were associated with shorter fluctuation durations and less intermittent behavior. This suggests that higher magnetic fields, like those planned for future reactors, could help stabilize the plasma.

3. Differences between devices: The study revealed differences in fluctuation behavior between conventional tokamaks (e.g., DIII-D and TCV) and spherical tokamaks (e.g., MAST and MAST-U). Spherical tokamaks exhibited longer fluctuation durations and waiting times, indicating a distinct behavior in their SOL.

4. Engineering implications: The findings suggest that future reactors with strong magnetic fields and high plasma currents, such as ITER and SPARC, may experience less intermittent fluctuations in the SOL. This could reduce the risk of wall damage and improve reactor performance.

By comparing data from multiple fusion devices, this study provides valuable insights into the universal properties of plasma fluctuations and how they depend on key parameters like particle density, magnetic field strength, and reactor geometry. These findings will help scientists refine their models of plasma behavior and design more robust fusion reactors.

As we move closer to realizing fusion energy, understanding and controlling plasma turbulence will be critical. This research represents an important step toward making fusion a practical and reliable energy source for the future.

The manuscript is published as an open access paper by Plasma Physics and Controlled Fusion.

"Two-point model connecting near- and far-SOL" by A. Theodorsen and O. E. Garcia

Researchers at UiT The Arctic University of Norway are advancing our understanding of plasma behavior in fusion devices by developing innovative models of the scrape-off layer (SOL)—the region where plasma interacts with the walls of a fusion reactor. This work, presented at the PSI 2026 conference, extends the classical "two-point model" into a more comprehensive "two-box model" that accounts for both the near-SOL and far-SOL regions.

The team investigates how particles and heat are transported radially outward in the SOL, focusing on the role of filamentary structures, or "blobs," that carry energy and particles to the reactor walls. By incorporating factors like anomalous transport, collisionality, and recycling effects, the model provides new insights into how plasma behaves under different conditions.

Key findings include:

• The far-SOL is primarily sheath-limited, meaning its behavior is dominated by interactions with the reactor walls.

• Higher collisionality reduces the perpendicular heat flux to the walls, which has implications for managing heat loads in fusion devices.

• The relationship between density and temperature in the near-SOL aligns with experimental scaling laws, offering validation for the model.

This research contributes to the broader goal of optimizing plasma confinement and minimizing material damage in fusion reactors, bringing us closer to achieving sustainable nuclear fusion as a clean energy source.

This work was presented as a poster at the PSI conference and will be written up for publication in the journal Nuclear Materials and Energy.

"Velocity scaling regimes for blob-like filaments in the Alcator C-Mod scrape-off layer" by O. E. Garcia et al.

 In the quest for clean and sustainable energy, nuclear fusion holds immense promise. Fusion reactors, like tokamaks, aim to replicate the processes powering the Sun by confining extremely hot plasma using magnetic fields. However, controlling the plasma near the reactor walls remains a significant challenge. This region, known as the scrape-off layer (SOL), is turbulent and filled with "blobs"—localized structures of high-density plasma that move radially outward. These blobs can carry heat and particles to the reactor walls, potentially causing damage and reducing the reactor's efficiency. Understanding how these blobs behave is crucial for designing future fusion reactors.

In this study, researchers from the FUSENOW center analyzed the size and velocity of plasma blobs in the SOL of the Alcator C-Mod tokamak, a high-field fusion device at MIT. Using advanced imaging techniques and diagnostic tools, they investigated how these blobs change with increasing plasma density in the reactor core. The findings provide new insights into the dynamics of these structures and their implications for plasma-wall interactions.

The key findings are as follows: (i) Blob size and velocity Increase with density: The study revealed that as the core plasma density increases, the average size and velocity of the blobs in the SOL also increase. This behavior is linked to changes in the plasma's collisionality—a measure of how often particles in the plasma collide with each other. (ii) Transition between velocity regimes: At low plasma densities, the blobs behave as "sheath-connected" structures, meaning their motion is influenced by interactions with the reactor walls. At higher densities, the blobs enter a "resistive" regime, where their motion is dominated by collisions within the plasma itself. This transition leads to faster blob velocities and more flattened plasma density profiles in the SOL. (iii)
Implications for future reactors: The study's results suggest that in next-generation fusion devices like SPARC, which will operate at higher magnetic fields and plasma densities, blobs will behave similarly to those in Alcator C-Mod. The researchers estimate that SPARC's blobs will have sizes of about 4–5 millimeters and velocities of 300–600 meters per second. These insights are critical for designing diagnostics and mitigating heat loads on reactor walls.

Why does this matter? Plasma blobs play a central role in determining how particles and heat are transported to the walls of a fusion reactor. If not properly managed, this transport can lead to excessive heat loads, material erosion, and impurity generation, all of which can limit the reactor's performance and lifespan. By understanding the behavior of blobs, scientists can develop strategies to control them, optimize plasma confinement, and improve the overall efficiency of fusion reactors.

This study also highlights the universality of blob dynamics across different fusion devices, providing a foundation for predicting and managing plasma behavior in future reactors. As fusion research progresses toward devices like SPARC and ITER, these findings will help pave the way for achieving practical and sustainable fusion energy.

The manuscript is published as an open access paper by Plasma Physics and Controlled Fusion.

The leader of the FUSENOW center participated this week at the FuseCOM 2026 Retreat in Lisbon, Portugal. The FuseCOM program is an initiative under EUROfusion, the European Consortium for the Development of Fusion Energy. It is designed to foster collaboration and innovation in the field of fusion communication and outreach. The program aims to enhance public understanding, engagement, and support for fusion energy research by developing effective communication strategies and tools. During the 2026 retreat on May 6-8, the FuseCOM members got information and updates from EUROfusion, the ITER Organization, and the EU Commission, as well as training on storytelling and effective science communication. There was also a visit to the Institute for Plasmas and Nuclear Fusion at Instituto Superior Técnico.

Fusion Research Center Norway (FUSENOW) has announced two PhD fellowship positions

Controlled thermonuclear fusion based on magnetic confinement holds the potential as an unlimited source of clean electrical energy for humanity. A major obstacle towards this goal is the interaction of the magnetically confined, hot plasma with material surfaces in reactors. Turbulent motions and transient transport events impose numerous challenges for future power fusion reactors. The fluctuation-induced radial transport results in high particle densities and temperatures in the boundary region and enhanced interactions between the plasma and material surfaces. This leads to erosion of wall material and release of impurities into the confined plasma. The former will ultimately define the plasma facing components lifetime, while the latter may cause significant radiation in the core plasma and limit the power performance of fusion reactors.

Because of these challenges, turbulence and cross-field transport of particles and heat in the boundary region of magnetically confined plasmas is a field of intense research. The boundary region of magnetically confined plasmas is commonly in an inherently fluctuating state with an order unity relative fluctuation level of the plasma parameters. These fluctuations are generally attributed to magnetic field-aligned plasma filaments that move radially outwards to limiter structures and the main chamber walls. These filaments, commonly referred to as blobs, are localized in the drift plane perpendicular to the magnetic field. Moreover, they have excess pressure compared to the time-average plasma.

This project attempts to elucidate the statistical properties of the fluctuations by first-principles mathematical modelling of the turbulence, numerical simulations of these models, stochastic modelling and advanced data analysis to identify and quantify the role of the filament structures for plasma-wall interactions.

UiT has recently established the Fusion Research Center Norway (FUSENOW) – the first research center on fusion plasma physics in Norway, supported by funding from the Trond Mohn Research Foundation/Tromsø Science Foundation. The research activity comprises stochastic modelling (describing the fluctuation as a super-position of uncorrelated pulses), numerical simulations of turbulent fluctuations and analysis of experimental measurement data from international collaboration partners. More information can be found on the FUSENOW web pages.

The applicant must present a description outlining the academic basis of the PhD project in relation to the research themes of FUSENOW. The project description shall not exceed three pages, literature references included. It must include a description of the topic, research question(s) and a reasoning of the choices. It should also indicate the methodologies to be used. The final project description will be developed in cooperation with the supervisors.

The announcement can be found at Jobbnorge.

Center leader Odd Erik Garcia publishes chronicle on the neglect of fusion energy in Norwegian assessment of nuclear power

The op-ed argues that fusion energy is an overlooked opportunity in Norway’s energy debate. While recent discussions have focused mainly on traditional nuclear fission and small modular reactors, fusion—despite being potentially more forward-looking—has received little attention.

Fusion energy, the process that powers the sun, could provide vast amounts of clean, safe, and virtually limitless energy, without long-lived radioactive waste or major accident risks.

Internationally, development is accelerating: the EU is working toward a demonstration reactor by mid-century, and several private companies aim for commercial fusion in the 2030s. These timelines may even rival or beat the expected rollout of nuclear power in Norway.

The author criticizes the Norwegian nuclear energy report for barely addressing fusion and offering no concrete recommendations, despite its mandate to do so. This is seen as a missed opportunity—especially since Norwegian actors like Equinor are already investing in fusion abroad.

He argues that Norway has the resources, expertise, and industrial base to become a leading player, but lacks political follow-up and strategic commitment. To fix this, he proposes stronger research efforts, dedicated funding programs, expanded international collaboration, and education initiatives in both fission and fusion.

The main conclusion is that fusion energy should be an integral part of Norway’s long-term energy strategy, and that failing to act now risks missing a major technological and industrial opportunity.

The chronicle was published in the newpaper Dagsavisen on April 14th.

"Fluctuation-driven cross-field plasma transport in FELTOR turbulence simulations of the TCV-X23 scenario" by S. Brynjulfsen  and O. E. Garcia

Understanding how plasma behaves in the boundary region of fusion devices is crucial for advancing nuclear fusion as a sustainable energy source. In this region, plasma turbulence drives the transport of particles and heat, which can affect the performance and longevity of fusion reactors. This study investigates these turbulent processes using advanced computer simulations of experiments conducted on the TCV tokamak, a fusion research device located in Switzerland.

The research focuses on "blobs"—localized structures of high plasma density that move radially outward in the boundary region of the plasma, known as the scrape-off layer (SOL). These blobs are key players in cross-field transport, carrying particles and energy from the core plasma to the reactor walls. The study uses a sophisticated simulation tool called FELTOR, which models the plasma behavior in three dimensions, capturing the complex dynamics of turbulence.

The simulations reveal that plasma transport is not uniform but "ballooned," meaning it is concentrated in specific regions around the tokamak's mid-plane. The direction of the magnetic field plays a significant role in shaping this transport. When the magnetic field is oriented in a "favorable" direction, blobs are larger, more frequent, and transport more particles compared to the "unfavorable" direction. This difference arises from how the magnetic field interacts with the plasma's natural drifts and turbulence.

The study also provides new insights into the three-dimensional structure of blobs. These structures are elongated along magnetic field lines, but their shape and dynamics change as they move outward. The simulations show that blobs are not perfectly aligned with the magnetic field and exhibit time delays and amplitude changes along their length. These findings help refine our understanding of blob dynamics and their role in plasma transport.

Importantly, the simulations reproduce universal statistical properties of plasma turbulence observed in experiments, such as the characteristic shapes of fluctuations and their probability distributions. This agreement validates the simulation model and strengthens its utility for studying plasma behavior in fusion devices.

By improving our understanding of turbulence and transport in the plasma boundary, this research contributes to the development of more efficient and robust fusion reactors. Future work will extend these models to include temperature dynamics and interactions with neutral particles, further enhancing our ability to predict and control plasma behavior in fusion experiments.

This article is published in the journal Plasma Physics and Controlled Fusion.

"A two-dimensional conditional averaging method for velocity estimation immune to the barber pole effect" by J. M. Losada and O. E. Garcia

Plasmas, often referred to as the fourth state of matter, are crucial for understanding everything from the behavior of stars to the development of fusion energy. In fusion reactors, such as tokamaks, plasma dynamics in the outermost layer - known as the scrape-off layer (SOL) - play a critical role in determining how heat and particles exhaust. These dynamics are dominated by "blobs," which are filament-like structures that transport particles and energy across magnetic fields. Accurately measuring the velocity of these blobs is essential for improving fusion reactor designs and ensuring stable, efficient operation.

However, measuring blob velocities from imaging data is not straightforward. A common challenge is the "barber pole effect," which occurs when elongated structures move at an angle to their symmetry axis. This effect can distort velocity measurements, leading to inaccurate results. Traditional methods, such as time-delay estimation, often fail to account for this distortion, especially when working with low-resolution imaging data typical of plasma diagnostics.

In this study, researchers from UiT The Arctic University of Norway have developed a novel method to overcome this challenge. Their approach, based on two-dimensional conditional averaging, provides a robust way to estimate blob velocities even in the presence of the barber pole effect. By focusing on the average behavior of large-amplitude structures, the method isolates the true motion of blobs from other noise and distortions in the data.

Key highlights of the study are as follows: (i) Barber pole effect resolved: The two-dimensional conditional averaging method accurately estimates blob velocities regardless of their tilt angle, a scenario where traditional methods often fail. (ii) Validation with synthetic data: The researchers tested their method using computer-generated datasets that mimic real plasma conditions. These tests demonstrated that the conditional averaging method consistently outperforms time-delay estimation techniques. (iii) Two tracking techniques: The study explores two ways to track blob positions - subgrid maximum tracking and contouring. Both approaches work well, but contouring is found to be slightly more accurate and robust. (iv) Broad applicability: While designed for coarse-grained imaging diagnostics like gas puff imaging and beam emission spectroscopy, the method could be adapted for other fields where tracking moving structures in noisy data is required.

Accurate velocity measurements are critical for understanding how blobs contribute to cross-field transport at the boundary of magnetically confined plasmas. This, in turn, affects the design of fusion reactors, as engineers aim to minimize heat and particle losses while maintaining stable plasma confinement. The conditional averaging method provides a new tool for researchers to study plasma turbulence and transport with greater precision, paving the way for advancements in fusion energy research.

The next step is to apply this method to real experimental data from fusion devices like tokamaks. If successful, it could significantly enhance our understanding of plasma behavior and help optimize the performance of future fusion reactors. Beyond fusion, the technique could also find applications in other scientific fields that rely on imaging data to study moving structures, such as fluid dynamics and atmospheric science.

This work, funded by the Trond Mohn Foundation and the Tromsø Research Foundation, represents a significant step forward in plasma physics and highlights the importance of innovative data analysis techniques in tackling complex scientific challenges.

This work has been published in the journal Physics of Plasmas.

"Numerical simulations of scrape-off layer plasma turbulence: Role of parallel transport and particle losses" by S. Brynjulfsen and O. E. Garcia

Researchers at UiT The Arctic University of Norway have used advanced computer simulations to uncover new insights into the turbulent behavior of plasma at the boundary of magnetically confined fusion devices. Their findings shed light on how plasma particles escape along magnetic field lines and how this process shapes the violent, burst-like fluctuations that strike reactor walls — a key challenge for future fusion power plants.

In fusion reactors, plasma is confined by strong magnetic fields, but at the outer edge, known as the scrape-off layer, the plasma becomes highly turbulent. Instead of flowing smoothly, it forms filament-like “blobs” that move rapidly outward and deliver heat and particles to material surfaces. Understanding this turbulent region is essential for predicting wall damage and improving reactor designs.

Using long-duration numerical simulations, the researchers systematically varied how quickly particles are lost along magnetic field lines, a quantity closely related to the length of the magnetic connection between the plasma and reactor surfaces. They found that stronger particle losses lead to steeper plasma density profiles, smaller turbulent structures, and more intense, intermittent bursts of plasma. In other words, when plasma can escape more easily along magnetic field lines, the turbulence becomes sharper and more extreme.

Despite these changes, the statistical behavior of the fluctuations remained remarkably consistent. The large bursts of plasma followed simple and universal mathematical patterns, with their sizes and timing described by well-known probability distributions. The turbulence could be accurately modeled as a sequence of random, uncorrelated pulses, much like raindrops hitting a surface. This unexpected simplicity suggests that even complex plasma turbulence follows robust and predictable statistical rules.

The results also showed that turbulent transport spreads plasma much farther than would be expected from ordinary diffusion alone, flattening the overall plasma profile compared to what would occur without collective motion. This highlights the dominant role of blob-like structures in carrying particles across magnetic field lines.

These findings are highly relevant for the design of future fusion reactors, including advanced divertor concepts that aim to control how plasma interacts with material surfaces. By linking magnetic connection length to both plasma profiles and fluctuation properties, the study provides valuable guidance for engineering strategies that seek to reduce heat loads and extend material lifetimes.

Beyond their immediate implications for fusion technology, the simulations establish a powerful new framework for validating more complex turbulence models. The statistical methods used in this work can serve as a benchmark for next-generation plasma simulation tools, helping researchers build more reliable predictions of plasma behavior at the reactor boundary.

The study demonstrates that beneath the apparent chaos of edge plasma turbulence lies a set of universal patterns — a discovery that brings scientists one step closer to controlling one of the most challenging regions in fusion energy research.

The publication is available online in the journal Physics of Plasmas.

"Blob motion and flattened far-SOL profiles in Alcator C-Mod: evidence in support of stochastic modeling" by O. E. Garcia et al.

In this study, researchers investigated the behavior of plasma in the boundary region of the Alcator C-Mod tokamak, a compact, high-field fusion reactor. Using advanced diagnostic tools, they focused on the "scrape-off layer" (SOL), the outermost region of the plasma where particles and heat escape and interact with the reactor walls. This region is critical because it determines how much heat and particle flux the reactor walls must endure, which directly impacts the longevity and safety of fusion devices.

The team observed the movement of "blobs"—coherent structures of plasma that carry particles and heat radially outward. These blobs are like turbulent bursts that can deposit significant energy onto the reactor walls in short, localized pulses. By analyzing data from specialized probes and imaging systems, the researchers discovered that as the core plasma density increases, these blobs become faster, larger, and more dominant throughout the SOL. This leads to a "flattening" of the plasma density profile, meaning the plasma spreads further out toward the walls.

To explain these observations, the researchers used a stochastic model, which treats the plasma fluctuations as a superposition of random, uncorrelated pulses. The model successfully predicted key features of the plasma behavior, including the density profile and the statistical properties of the fluctuations. Importantly, the study showed that the e-folding length of the plasma density profile (a measure of how quickly the density decreases with distance) is directly linked to the velocity of the blobs and the time it takes particles to escape along magnetic field lines.

These findings have significant implications for the design of future fusion reactors. As fusion devices operate at higher densities to achieve better performance, the increased blob activity and flattened profiles could lead to more intense interactions with reactor walls. Understanding and predicting these effects will help engineers design materials and structures that can withstand the harsh conditions at the plasma edge, bringing us closer to realizing the dream of fusion energy.

This research highlights the importance of studying plasma turbulence and edge dynamics in fusion devices. By combining advanced diagnostics with theoretical modeling, the team has provided valuable insights into the complex behavior of plasma at the boundary, paving the way for more robust and efficient fusion reactors in the future.

The publication is available online in the journal Nuclear Fusion.

The leaders of the FUSENOW center has just published a popular science article in Norwegian at forskning.no, descrbing developments in the field of fusion power, activities in Norway and the FUSENOW center.

At the Department of Physics and Technology, University of Bergen, there is a vacancy for a postdoctoral research position within experimental quantum technologies for laser fusion experiments within the NAPLIFE collaboration. The position is for a fixed term of 3 years and is financed by the ongoing Fusion Research Center Norway (FUSENOW) supported by the Trond
Mohn Research Foundation.

The project aims to design, develop and characterize nano-fabricated targets for use in laser fusion experiments, to increase, and improve the target ignition and utilization. In addition to developing and fabricating the targets, a part of the project will be to build a test setup for target characterization at UiB. The most promising targets fabricated will be brought to the ELI-ALPs European laser-infrastructure at Szeged, Hungary, for characterization.

The postdoctoral position involves tasks such as designing, manufacturing and testing the laser fusion targets. The work will include simulation, experimental work, characterization and data analysis. The modelling and analysing of experimental results will be done in collaboration with the local and international NAPLIFE team. The candidate is expected to take an active part in the target design and the continuous development based on experimental results. The candidate will have the chance to take an active role in the development of the research and steer the target development together with the PI.

At UiB the candidate will have access to several lab-facilities with modern fabrication and characterization equipment. The work will be carried out in an active research environment as a member of Nanophysics group.

We encourage applicants that meet the requirements, with a strong motivation for experimental challenges and good ideas to apply.

The position is announced at Jobbnorge.

Four researchers from UiT The Arctic University of Norway and FUSENOW participated at the 29th EU-US Transport Task Force Workshop 2025, arranged in Budapest. The research center presented advances in statistical and computational description of the transport at the boundary of fusion devices through poster presentations and an oral contribution. The goal of the international Transport Task Force is to develop a physics-based understanding of particle, momentum and heat transport in magnetically confined fusion plasmas. This understanding should be of sufficient depth that it allows the development of predictive models of plasma transport that can be validated against experiment, and then used to simulate the future performance of burning plasmas and aid the design and optimization of next-step fusion energy reactors. The contributions at the workshop will be published in a special issue of the journal Plasma Physics and Controlled Fusion.

On August 18, 2025, Johannes Eiriksønn Mørkrid was employed as a PhD fellow in the FUSENOW center at UiT The Arctic University of Norway. Mørkrid has his Bachelor studies in physics from NTNU and a master degree from UiT. The title of his doctoral thesis porject is "Numerical simulations of turbulence at the boundary of magnetically confined fusion plasmas". He will use mathematical modelling and high performance computations to investigate the turbulence-driven transport of particle and heat at the boundary of magnetically confined plasmas. Specifically, he will develop a simulation code in the programming language Julia to solve a set of coupled partial differential equations to simulate turbulent motions and fluctuation-induced transport of particle and heat in the scrape-off layer in fusion plasmas.

First ever research center on fusion energy established in Norway

Durinig the annual celebration of the Tromsø Science Foundation, it was announced that the Trond Mohn Research Foundation will fund the research center Fusion research center Norway (FUSENOW) as a thematic initiative. This is the first fusion reseach center ever to be established in Norway, working to realize clean power from fusion of Hydrogen isotopes. The funding from the research foundation is MNOK 20, with an equal amount matched by UiT The Arctic University of Norway and the University of Bergen. The project comprises both magnetic confinement fusion (at UiT) and laser fusion (at UiB).