This talk presents the progress in the design of the diagnostic system for the burning plasma experimental superconducting tokamak. Different from present diagnostics, new requirements and challenges arising from burning plasma for diagnostics have been investigated first. These specifications facilitate establishing criteria for measurement identification and technique selection. A...
The proposed contribution concerns the development of gas detectors for use in the future reactors. Measurement of soft X-ray (SXR) radiation of magnetic plasmas is a standard method of obtaining valuable information on particle transport and magnetic configuration. Recent consideration of a gas detector for future fusion reactors extends its potential use as part of the plasma control...
Advanced instruments for fusion gamma-rays and alpha-particles monitoring of reactor plasmas
V.G. Kiptily on behalf of JET contributors and the EUROfusion Tokamak Exploitation Team*
UKAEA, Culham Campus, Abingdon, Oxfordshire, OX14 3DB, United Kingdom
In fusion reactors with magnetic confinement the burning plasma control is strictly needed, i.e. the deuterium–tritium...
As we approach the era of burning fusion plasma experiments, the ability to monitor and control the conditions in the plasma core becomes increasingly important. The versatility and reactor relevance of collective Thomson scattering (CTS) makes it an attractive option for diagnosing thermal and energetic confined ions in the core of burning plasmas. Here we review ongoing work related to the...
With the era of burning fusion plasmas approaching, the importance of a thorough understanding of fast-ion physics has never been greater [1]. Burning plasmas are characterised by being predominantly self-heated through the transfer of energy from the fast alpha particles born in fusion reactions to the bulk plasma via collisions. Thus, fast ions will form an integral part of future burning...
M. Scholz1, J. Bielecki1, J. Błądek1, S. Conroy2, B. Coriton6, G. Croci3, J. Dankowski1 W. Dąbrowski4, D. Dworak1, G. Ericsson2, J. Eriksson2, A. Hjalmarsson2, A. Jardin1, R. Kantor5, A. Kovalev6, K. Dojko1, K. Król1, A. Kulińska1, A. Kurowski1,| B. Łach4, G. Mariano4, D. Mazon7,R. Mehrara1, D. Morawski1, M. Rebai3, F. Scioscioli3, M. Tardocchi3, G. Tracz1, A. Wójcik-Gargula1, U. Wiącek1
1...
We present a validation study of a Bayesian integrated data analysis (IDA) approach for current tomography, applied to the WEST tokamak using only external magnetic diagnostics. The methodology was originally developed for DEMO but is here adapted to real data, addressing challenges such as noise, currents in structural elements, and iron core effects [1].
A Gaussian prior distribution was...
Neutron and gamma-ray diagnostics will play a fundamental role in fast-ion detection in burning fusion plasmas. As the fast ion undergoes a fusion reaction, the generated neutron or gamma-ray will carry away some of its energy, which can be detected. In the context of axisymmetric machines with high aspect ratio, it is possible to represent the fast-ion phase space in the reduced...
Runaway Electrons (RE) are one of the main particle populations in tokamaks that must be carefully controlled and understood. Future devices will need to operate either without disruptions or with reliable mitigation strategies. Disruptions are characterised by abrupt losses of plasma confinement, during which strong electric fields can be generated. These fields may accelerate electrons into...
JET, the Joint European Torus, has recently set new fusion records in two successive tritium campaigns in 2021 and 2023. An integral fusion neutron budget of 7.4e20 neutrons was carefully exploited, in the final campaign (DTE3) of JET’s historic mission, to maximise on the scientific impact of a series of campaigns exploring heating, fuelling, plasma control, disruption mitigation and tritium...
J. Flanagan, S. Abouelazayem, O. Asunta, H. Bohlin, P. F. Buxton, T. Brewer, C. Colgan, A. Dnestrovskii, M. Fontana, M Gemmell, J Hakosalo, F. Janky, M. Iliasova, D. Kos, H.F. Lowe, M.P. Gryaznevich, L. Martinelli, S.A.M. McNamara, G. Naylor, M. Romanelli, V. Nemytov, A Prokopyszyn, M. Sertoli, J. Sinha, S Sridhar, J. Varje, H.V. Willett, P. Thomas, Y. Takase, A. Rengle, T. O'Gorman, B....
As the global fusion research community moves toward realizing a fusion reactor, the need for robust control strategies is increasing. Furthermore, smaller fusion reactors than ITER are being proposed to accelerate the demonstration of burning conditions. These reactors will require next-generation scenarios and sophisticated control techniques to efficiently confine plasma at high pressure....
Gamma-ray diagnostics play a crucial role in the study of high-energy particle behavior and nuclear processes in tokamak plasmas. Information on the alpha particles produced in fusion is of paramount importance for burning plasma device, such as ITER [1-2]. The fusion rate can be determined by measuring the fluxes of 17-MeV gamma quanta born in D-T fusion reactions, and the fusion product can...
Measurement of alpha-particles and other fast ions which are born in nuclear reactions is of great importance to optimize the heating schemes for ITER and future fusion reactors. Gamma-ray spectrometers have been extensively used on tokamaks for studying the behavior of fast ions including fusion alpha-particles, and runaway electrons.
Gamma-ray diagnostics of Burning plasma Experimental...
As part of the EUROfusion Enhancements Activities for JT-60SA, a feasibility study was launched for a Vertical Neutron Camera (VNC) and a Compact Neutron Spectrometer (CNS) to complement the current Neutron Diagnostics (NDs) already present. This paper describes the conceptual design of a VNC and a CNS that satisfy the rather severe engineering constraints determining the measurement...
The report is devoted to the development of gamma-ray spectrometry methods of energetic particle diagnostics, both in terms of hardware and analysis of experimental data. Measurements in the conditions of a thermonuclear experiment, i.e. in the presence of a stray magnetic field of the tokamak, high neutron and gamma background, hardly allow the use of serial laboratory equipment and require...
A set of gamma-ray spectrometers has been designed for ITER as part of the Radial Gamma Ray Spectrometer (RGRS) project. The aim of this project is to design a system, integrated with the ITER Radial Neutron Camera, capable of measuring gamma rays emitted from the plasma with high energy resolution and at high counting rates (exceeding 500 kHz).
The RGRS will operate during the ITER DT phase...
In magnetically confined fusion plasmas, effective confinement of fast ions—produced by external heating systems and fusion reactions—is essential to ensure efficient plasma heating, current drive, and machine protection. To optimize fast-ion confinement, it is crucial to develop a comprehensive understanding of their interaction with plasma instabilities.
In this context,...
Future fusion reactors will differ significantly from current fusion devices, particularly in that diagnostics will serve exclusively plasma control functions [1]. These diagnostics must operate with high reliability under conditions far harsher than those found, for example, in ITER. The DEMO environment demands novel design solutions for nearly all diagnostics, even though experimental data...
This invited presentation highlights recent advances in developing Micro-Electromechanical Systems (MEMS) for the extreme environments of fusion reactors. There is a critical technological need for diagnosing wall conditions with high spatial and temporal accuracy within a Fusion Pilot Plant (FPP). MEMS encompass a wide range of micron-scale devices that seamlessly integrate mechanical and...
This work presents the Vacuum Ultraviolet Spectrometer (VUV) designed to monitor the divertor region of JT-60SA which is starting its activity in support of the exploitation of ITER and by complementing it in resolving key physics and engineering issues for DEMO. The aim of the spectrometer is to characterize the contribution of impurities to the radiation emitted in the divertor region in...
As tokamak devices prepare to enter the burning plasmas era, as for example with the SPARC [1] experiment, one of the few remaining challenges is represented by runaway electrons (RE). Due to the plasma parameters necessary to create a burning plasma, REs can potentially reach tens of MeV of energy and carry multi-MA of current. Models of the interaction of REs with SPARC first wall [2] show...
This contribution presents the status of the magnetic proton recoil (MPR) neutron spectrometer being developed for SPARC, a high-field tokamak under construction in Devens, MA, USA expected to achieve burning plasma conditions and produce up to 140 MW of DT fusion power. This high-resolution neutron spectrometer will enable critical measurements core plasma performance, including ion...
The SPARC tokamak aims to demonstrate a net fusion power gain in tokamaks for the first time (Qfus>1)[1]. A neutron spectrometer based on the magnetic proton recoil technique [2] is being built to measure neutrons with energy between 1 and 20 MeV emitted by fusion reactions. It will infer the total fusion power emitted by the machine, corroborating the demonstration of Qfus>1 through the...
Obtaining experimental information on the properties of alpha particles, such as their energies and spatial profile, is quite challenging. One of the methods currently planned for the ITER tokamak is gamma-ray spectroscopy.
Until 2023, alpha particle measurements via gamma-ray spectroscopy relied on nuclear reactions between alpha particles and $^{9}$Be impurities. However, since ITER...
Real-time measurement of the fusion power released from Deuterium-Tritium (DT) plasmas remains one of the the most challenging technical aspects of magnetic confinement fusion.
Recently, during the second DT campaign at JET, a novel method was developed to measure fusion power with gamma-ray spectrometers detecting gamma-rays released by the secondary, radiative branch of the DT fusion...
Accurate measurement of fusion power in tokamaks is vital for operational control, licensing, and scientific research. Conventionally, this is achieved by detecting neutrons produced in the T(D,n)⁴He reaction. A novel alternative, gamma-ray spectroscopy of the T(D,γ)⁵He reaction, has recently been demonstrated at JET [1,2]. Unlike neutron diagnostics, which require detailed knowledge of plasma...
Lithium hydride (LiH) is widely used as a neutron attenuator in gamma-ray diagnostics for fusion reactors. These include diagnostics on past machines (e.g., JET) as well as future devices, such as the ITER Neutral Particle Analyser and Radial Gamma-Ray Spectrometer. Despite its utility, LiH remains a hazardous material: it reacts violently with water, including air moisture, producing lithium...
SPARC is a compact, high-field Deuterium-Tritium (DT) tokamak currently under construction by Commonwealth Fusion Systems (CFS). The device aims to achieve net fusion energy, targeting a plasma gain (QP) greater than 5 and producing up to 140 MW of fusion power (PFUS). It will feature a poloidal neutron camera (NCAM) designed to provide energy, time, and space-resolved measurements of neutron...
SPARC is a compact, high field tokamak now under construction in Devens, MA by Commonwealth Fusion Systems. It is predicted to robustly enter the burning plasma regime, $Q_p > 5$, producing at most 140 MW of DT fusion power. A poloidal neutron camera is being designed for the machine to resolve its neutron emission in time, space, and energy. Neutron cameras have been fielded on a variety...
In the framework of the Italian National Recovery and Resilience Plan (NRRP), funded by the European Union NextGenerationEU plan, a project named “New Equipment for Fusion Experimental Research and Technological Advancements with the RFX Infrastructure” (NEFERTARI) has been awarded of funding by the Italian Ministry of University and Research (MUR), with the main aim of strengthening the...
As fusion research advances toward the burning plasma era, the role of neutron diagnostics becomes increasingly central, not only as a tool for assessing fusion performance, but also for probing fast ion behavior, confinement properties, and plasma heating. In this context, RFX-mod2, a major upgrade of the RFX-mod reversed-field pinch experiment, is being equipped with a new suite of neutron...
A novel soft X-ray (SXR) diagnostics system employing Gas Electron Multiplier (GEM) technology is under development for the RFX-mod2 device, the upgraded reversed field pinch (RFP) experiment aimed at advancing magnetic confinement fusion research. The GEM-based system is designed to provide energy-resolved, high-temporal-resolution measurements of SXR emissivity, enabling detailed studies of...
The Neutral Beam Test Facility in Padova, Italy, is the site where the development of the Neutral Beam Injector (NBI) for the ITER tokamak is being carried out. In this context, the Megavolt ITER Injector and Concept Advancement (MITICA), which is the full-scale prototype of the NBI, is in the installation and commissioning phase. The system aims at producing neutrals of 1 MeV energy to be...
Disruptions are one of the major problems for the control of thermonuclear plasmas. The fast termination of the discharge can indeed induce huge heat loads on the plasma-facing components and high electromechanical forces on the structures of the devices. In the commercial reactors, disruptions will have to be completely avoided as much as possible, since even a single disruption could...
Integrated data analysis is essential for the full exploitation of diagnostic measurements. In the past various approaches were investigated but the main techniques utilised were based on Bayesian statistics. Physics-Informed Neural Networks (PINNs) are an alternative worth addressing. Indeed PINNs constitute a new branch of artificial intelligence that gives the possibility of integrating...
In future fusion power plants, full diagnostic coverage may not always be available due to radiation damage, access limitations, or cost constraints. To explore profile control under such conditions, we tested a real-time control scheme on DIII-D that is robust against the loss of primary kinetic diagnostics. The system uses RTCAKENN[1], a neural network trained to infer seven kinetic...
Neutron Emission Spectroscopy is a key diagnostic technique in nuclear fusion research, enabling the characterization of fuel ion populations in fusion plasmas. The state-of-the-art instrumentation for neutron spectroscopy in deuterium plasmas relies on the time-of-flight (TOF) technique [1].
However, despite its performance, it necessitates the deployment of large-scale systems. Recent...
Real-time plasma control systems are at the heart of operation of modern tokamaks. The contribution focuses on plasma real-time control experimental activities recently performed on the TCV Tokamak of the Swiss Plasma Center, EPFL. State of the heart TCV real-time Plasma Control System (PCS) developments will be presented alongside domestic and international plasma real-time control...
In tokamaks the interpretation of many diagnostic signals requires some form of inversion, because the measurements are taken from outside the plasma but what is desired is local internal information. Some examples are the magnetic equilibrium from coils and polarimetry, video cameras and the unfolding of various neutron and gamma detectors. A specific set of diagnostics are also needed to...
Microwave diagnostics present the opportunity for multiplexed plasma control measurements, enabling a minimal plasma-facing footprint and a consolidated measurement suite, though uncommon or new approaches might be necessary for these technologies. The limited set of plasma control and machine monitoring diagnostics expected on future pilot and commercial DT fusion machines will face extreme...
Abstract:
Soft X-ray (SXR) diagnostics are widely used in fusion research to investigate plasma behavior and provide data for detailed studies, particularly, in the context of magnetohydrodynamic (MHD) activities or impurities transport. The outputs can be used for monitoring the plasma stability, such as by tracking impurities during the discharges and their accumulation in the plasma core....
Neutron diagnostics play a crucial role in fusion reactors by providing essential data for plasma control, machine protection, and nuclear safety. In ITER, neutron diagnostics are exposed to a wide spectrum of neutron energies, ranging from thermal to fast neutrons, and operate across a broad neutron flux range (10⁶ to 10¹⁴ n.cm⁻²s⁻¹). These detectors are critical for quantifying fusion plasma...
In the last decade, single crystal diamond detectors have been extensively used at JET for neutron spectroscopy measurements along collimated lines of sight. Although diamonds can measure 2.5 MeV neutrons, their use is optimized for 14 MeV neutrons. This is due to the exploitation of the 12C(n-)9Be nuclear reaction channel which results in a well-defined gaussian peak in the recorded energy...
Neutron measurements are of crucial importance for the forthcoming DT fusion reactors as they allow to measure the fusion power, which is a primary parameter to evaluate the fusion performance.
The standard method for fusion power measurement is based on counting neutrons with fission chambers cross-calibrated with activation foils. This method requires complex Monte Carlo simulations...
Runaway electrons (RE) pose significant challenges to plasma-facing components in large tokamaks due to their high energy, which can damage materials and limit plasma operations. Therefore, understanding and controlling RE is a critical area of research, particularly for devices
like ITER, where runaway events could have severe consequences. In order to address these challenges, the behaviour...
In tokamaks, measuring core electron temperatures becomes challenging at high values (typically >6–7 keV), where discrepancies often arise between diagnostics such as Thomson Scattering and ECE. Yet, accurate temperature measurements are critical for future reactors like ITER, CFETR or DEMO, where core Te is expected to be over 25 keV [1,2,3]. These discrepancies, evident in such high-Te...
Fusion energy represents a transformative opportunity for the global energy sector, offering a safe, zero-carbon, and virtually limitless source of power. Recent scientific and technological advances have accelerated its path toward industrialization, with over 150 fusion projects active worldwide. Eni is at the forefront of this transition, supporting fusion development through technological,...
Diamond detectors are increasingly adopted for fast neutron measurements thanks to their excellent timing resolution, radiation hardness, and low noise. In a dedicated measurement campaign at the ISIS spallation source, we implemented a full digital acquisition chain based on a 500 μm thick single-crystal diamond detector, broadband preamplification, and the CAEN DT5751 digitizer (10-bit,...
In the field of contemporary trigger and data acquisition (DAQ) systems, the utilization of programmable logic devices highlights the benefits of adaptable, reusable mixed-signal platforms, commonly referred to as open FPGA boards. These platforms support the direct incorporation of application-specific processing routines into firmware, making them highly attractive for a wide array of use...
According to the recently released Research Plan ([1] and references therein), ITER operation is currently foreseen to start in 2034, with the long-duration high neutron fluence discharges for the qualification of Test Blanket Modules (TBM) being scheduled for the latest stage of the machine operation (DT-2) – making it potentially susceptible to additional delays. While the role of ITER to...
Accurate measurement of core ion dynamics is essential for understanding and controlling plasma behaviour in reactor-scale devices. We present recent progress in optimising a Collective Thomson Scattering (CTS) system for the European DEMO, with a focus on maximising diagnostic sensitivity to toroidal plasma rotation, ion temperature, and fusion-born alpha particle density. Building on...
The ITER Radial Neutron Camera (RNC) is a key diagnostic system designed to provide time resolved measurements of the neutron source profile through the application of reconstruction techniques to the line-integrated neutron fluxes. It is composed of two subsystems, the In-Port RNC and Ex-Port RNC located, respectively, inside and outside the Plug of Equatorial Port #01. The Ex-Port RNC...
Hall sensors based on antimony-sensitive layers are being deployed on ITER within the Outer Vessel Steady-State magnetic field Sensors (OVSS) system and are also considered for the future European DEMOnstration fusion power reactor (EU-DEMO). Their primary role is to support the determination of key tokamak plasma parameters such as plasma position, shape, and plasma current. Ensuring...
On the pathway to delivering net-energy power plants, microwave diagnostics offer a promising solution for real-time control of several parameters related to electron temperature and density profiles, as well as magnetic-field pitch angle. Microwave diagnostics are promising because the wavelength range is at a sweet spot between a few millimetres and a few centimetres, providing excellent...
The measurement of the total radiative power emitted by the plasma is a key aspect of diagnostics in tokamak fusion reactors, as this quantity represents the energy lost through electromagnetic radiation and is crucial for managing the energy balance. For these measurements, bolometric diagnostics are widely used in fusion experiments due to their precision, reliability, and ease of...
A high-performance imaging neutral particle analyzer (INPA) has been developed and installed on the Experimental Advanced Superconducting Tokamak (EAST). Using carbon foils to ionize charge-exchanged neutral particles and scintillator screens to resolve their energy and radial profiles, the INPA’s capabilities have been significantly enhanced through multiple upgrades. It functions in both...
