Next Step Fusion

What Next Step Fusion does

Next Step Fusion is a privately-held fusion energy technology company founded in April 2023 and headquartered in Bertrange, Luxembourg, with additional engineering and R&D presence in the United Kingdom (London and Abingdon, Oxfordshire) and a US entity in Delaware. The company develops software, simulation, control, and diagnostics for magnetic confinement fusion (MCF) devices, with a particular focus on tokamaks. Its core technology is NSFsim, a proprietary tokamak plasma simulator built on the DINA code approach that solves the 2D free-boundary Grad-Shafranov equilibrium with external circuits, used for full-discharge simulation, scenario development, disruption analysis, equilibrium reconstruction, and reinforcement learning training. NSFsim is exposed as a cloud-based web service through the Fusion Twin Platform (fusiontwin.io), which hosts digital replicas of multiple tokamaks (DIII-D, ISTTOK, NSF NTT, SMART) and offers API access, Jupyter notebooks, and HDF5-based I/O with IMAS compatibility.

The broader product portfolio includes end-to-end Tokamak Integrated Modeling services, a Modular Diagnostics Platform for next-generation MCF systems, AI/ML solutions (RL-based plasma controllers using Soft Actor-Critic, transformer-based plasma boundary surrogates trained on 15,000+ DIII-D shots, and the KARHU MHD stability surrogate), and Plasma Control Solutions. The company is also developing its own Negative Triangularity Tokamak (NSF NTT) as a testbed for ML-based control. The revenue model combines recurring SaaS-style access to the Fusion Twin Platform (with a free tier) with services revenue from integrated modeling, diagnostics, and ML/control engagements. Customers include private fusion companies, tokamak startups, MCF device builders, and academic and government research institutions such as DIII-D (General Atomics), Columbia University, UCLA, UC San Diego, IST, and RFX-mod.

Name

Next Step Fusion

Legal name

Next Step Fusion S.à r.l.

Website

https://nextfusion.org

Company type

Private

Founded year

2023

Operating status

Operating

Headcount range

11–50 employees

Short description

Next Step Fusion is a Luxembourg-based fusion technology company that builds tokamak simulation software (NSFsim), cloud-based digital-twin platforms, and AI-driven plasma control and diagnostics for private fusion companies, tokamak startups, and academic research institutions.

Ownership category

akta.pro rank

Product category

Fusion Simulation Software

NAICS

Computer Systems Design and Related Services (54151)

SIC

Services-Computer Integrated Systems Design (7373), Industrial Instruments For Measurement, Display, And Control (3823)

akta.pro primary industry

Energy Systems Simulation (batteries, fusion/plasma, grid assets) (HDAGAEAE)

akta.pro secondary industry

Simulation & Digital Twin Data for ML Training (HDAAALAI)

Keywords

• Fusion energy software
• Tokamak simulation software
• Plasma control systems
• Fusion diagnostics platform
• Integrated modeling services

Headquarters

HQ city

Bertrange

HQ country

Luxembourg

HQ region

Europe

Offices2 records

Markets served

GTM type

B2B

Offering type

Software

Cost components

Personnel, Technology or R&D, Marketing or Sales, Operations

Revenue model

1. Software/Simulation Services: SaaS-style delivery of simulation tools and platforms to fusion companies and research institutions

Pricing tiers

Go-to-market motion2 records

Distribution channels2 records

Marketing channels7 records

Core offering

Next Step Fusion develops simulation, control, and integrated modeling software for fusion energy devices (primarily tokamaks). Its flagship product NSFsim performs whole-device plasma simulations and is delivered through the Fusion Twin Platform, alongside a Modular Diagnostics Platform and AI/ML-based control tools that support fusion R&D teams.

Product overview

Next Step Fusion provides a platform-plus-services architecture centered on NSFsim, an advanced tokamak plasma simulator, delivered through the cloud-based Fusion Twin Platform. The core product portfolio includes integrated modeling services for tokamak design and engineering, a Modular Diagnostics Platform for next-generation MCF systems, specialized fusion software including NSFsim and open-source tools, machine learning solutions (RL controllers, surrogate models, neural network reconstruction), and plasma control solutions. The company also operates its own Negative Triangularity Tokamak (NSF NTT) for testing ML-based control systems. All solutions are designed to accelerate fusion companies by bridging world-class science with deployable, industry-ready solutions.

Differentiator

Problem solved

Functional benefit

Brands

• Fusion Twin Platform: Cloud-based platform for running tokamak simulations using NSFsim, providing access to digital replicas of DIII-D, ISTTOK, NSF NTT, SMART, and other tokamaks with visualization and analysis tools.
• NSFsim

Products and services

• NSFsim (Next Step Fusion Simulator) GPU-accelerated simulation software for tokamak plasma discharges, designed for fusion researchers and engineers to model and analyze plasma behavior.
• Fusion Twin Platform A self-serve integrated simulation platform providing access to NSFsim and other fusion modeling tools for fusion R&D teams and institutions.
• Modular Diagnostics Platform Software platform for diagnostic data acquisition and analysis in fusion experiments, used by fusion research teams to process and interpret experimental signals.
• NSF NTT (Negative Triangularity Tokamak) A tokamak-related solution/product tied to the company's Negative Triangularity Tokamak modeling and simulation offerings.
• Tokamak Integrated Modeling Integrated modeling services that combine multiple physics modules to simulate and predict tokamak discharges for fusion research programs.

Quantifiable outcome

• Accelerated tokamak design cycles through advanced simulation

Named customers4 records

Segments4 records

Ideal customer profiles2 records

Technology focussed Yes

API detail

Has API

Yes

API docs

API detail

Core technology

AI maturity

App detail

Integration3 records

AI capability7 records

Feature5 records

Partnerships

19 partnerships are on record, tiered core and minor.

• D3D FusioncoreStrategic or Co-development PartnerCollaboration on tokamak simulation and modeling for DIII-D tokamak research program
• UC San DiegocoreStrategic or Co-development PartnerAcademic research partnership in plasma physics and fusion technology development
• Columbia UniversitycoreStrategic or Co-development PartnerResearch collaboration on tokamak simulation and plasma physics modeling
• Orlov LabcoreStrategic or Co-development PartnerResearch partnership on advanced tokamak physics and modeling
• UCLAcoreStrategic or Co-development PartnerUniversity research collaboration in fusion energy and plasma science
• Center for Energy ResearchcoreStrategic or Co-development PartnerCollaboration on fusion energy research and development programs
• IST-ID (Instituto Superior Técnico)coreStrategic or Co-development PartnerLisbon-based research partnership on fusion technology and simulation
• TRUST ProjectcoreStrategic or Co-development PartnerCollaborative research project on tokamak simulation and modeling standards
• University of SevilleminorStrategic or Co-development PartnerAcademic collaboration on fusion research
• RFX-modminorStrategic or Co-development PartnerCollaboration on RFX-mod tokamak research program
• CosylabcoreTechnology or IntegrationTechnology integration partner for control systems and data management in fusion devices
• Maritime FusionminorStrategic or Co-development PartnerEmerging fusion company partnership
• Pranos FusionminorStrategic or Co-development PartnerFusion startup collaboration
• Dante FusionminorStrategic or Co-development PartnerFusion energy company partnership
• NDA TritiumminorStrategic or Co-development PartnerTritium handling and fuel cycle technology collaboration
• Fusion Industry AssociationcoreGTM or Marketing PartnerIndustry association membership for advocacy, networking, and ecosystem development in commercial fusion
• European Fusion AssociationcoreGTM or Marketing PartnerEuropean industry association for fusion energy collaboration and advocacy
• NVIDIA StartupscoreTechnology or IntegrationGPU computing partnership providing access to NVIDIA hardware and acceleration technologies for simulation workloads
• FUSENetcoreStrategic or Co-development PartnerEuropean fusion research network for collaborative development and knowledge sharing

Scale indicators2 records

Recent moves7 records

Expansion highlights6 records

Broad incumbents

• ANSYS: Industrial multiphysics simulation platform used across aerospace and energy. Comparable as a broad simulation incumbent whose plasma and electromagnetic modules compete for the same engineering simulation budgets as NSFsim within fusion programs.
• Tokamak Energy: UK private tokamak developer with significant in-house simulation, modeling, and control capabilities. Comparable as a competing consumer of simulation expertise and a potential rival source of fusion modeling services for shared customers.
• Commonwealth Fusion Systems: Well-funded private tokamak company that develops significant internal simulation capabilities for SPARC and ARC. Comparable as both a major potential customer and a potential insourcing threat that could absorb the kind of I&C work Next Step Fusion sells.
• COMSOL: Multiphysics simulation software widely used in fusion plasma physics research and device design. Comparable as a competing general-purpose simulation environment that fusion teams may select instead of a verticalized tool like NSFsim.
• Dassault Systèmes (SIMULIA): Engineering simulation brand of Dassault Systèmes used in fusion device structural, thermal, and electromagnetic analysis. Comparable as a broader industrial simulation incumbent competing for fusion engineering software spend.

Direct peers

• Proxima Fusion: Munich-based stellarator fusion design startup that builds advanced simulation and integrated modeling tools for fusion device design. Highly comparable as a fusion-focused software and modeling company targeting device builders, with a comparable European deep-tech profile.
• Type One Energy: US-based stellarator fusion company that uses advanced computational modeling and high-performance simulation as core design tooling. Comparable as a fusion company for which integrated modeling and simulation is a primary product capability.

Emerging players

• Renaissance Fusion: European fusion startup pursuing HTS-magnet stellarator and FRC designs with significant reliance on advanced simulation and ML. Comparable as a deep-tech European fusion company with adjacent tooling needs.
• TAE Technologies: Field-reversed configuration fusion company that operates extensive simulation, modeling, and ML-driven plasma control pipelines. Comparable as a fusion company for which ML and simulation are core engineering capabilities rather than commercial products.
• Helion: US pulsed FRC fusion company that invests heavily in proprietary simulation, ML-based plasma control, and integrated modeling. Comparable as a well-capitalized fusion developer whose internal simulation capabilities could compete with or substitute for external vendors.

Market position

Strengths5 records

Weaknesses5 records

Competitive moat5 records

Key risks5 records

Key highlights6 records

Customer concentration

• GitHubgithub.com/Next-Step-Fusion
• YouTubeyoutube.com/@NextStepFusion
• LinkedInlinkedin.com/company/nextfusion
• Instagraminstagram.com/nextstepfusion

Revenue estimate

Valuation estimate

Number of profiles

Profiles7 records

Funding overview

Funding rounds

Investors

Funding detail is available on the Subscription and Enterprise plan.Contact sales →

M&A

Investments

M&A and investment is available on the Subscription and Enterprise plan.Contact sales →

Frequently asked questions about Next Step Fusion